农业与微气候Phototropin向光蛋白是蓝光感光蛋白（更具体地说，黄素蛋白），可介导多种藻类、真菌和高等植物的向光性反应。向光素遍布植物的叶子。与隐花色素和光敏色素一起，它们使植物能够响应光环境并改变其生长。当向光素受到蓝光照射时，它们会诱导信号转导途径，以不同的方式改变植物细胞的功能。向光素是植物向光感觉系统的一部分，引起植物的各种环境反应。向光素特别会导致茎向光弯曲并且气孔打开。此外，在隐花色素激活之前，向光素介导蓝光下茎伸长的首次变化。
Phototropins are blue light photoreceptor proteins (more specifically, flavoproteins) that mediate phototropism responses across many species of algae, fungi and higher plants. Phototropins can be found throughout the leaves of a plant. Along with cryptochromes and phytochromes they allow plants to respond and alter their growth in response to the light environment. When phototropins are hit with blue light, they induce a signal transduction pathway that alters the plant cells' functions in different ways. Phototropins are part of the phototropic sensory system in plants that causes various environmental responses in plants. Phototropins specifically will cause stems to bend towards light and stomata to open. In addition phototropins mediate the first changes in stem elongation in blue light prior to cryptochrome activation.
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维基百科条目作者 · 获取于 2026-10-04 · CC BY-SA 4.0。简介经过纯文本提取与截取；两个语言版本的内容侧重可能不同。用于概念速查，不替代标准原文。 本条中文为英文百科简介的机器辅助翻译，请结合英文原文核对专业术语。
查看内容许可 ↗查尔（Char），也称为乔拉（chora），是由沉积物沉积形成的动态地貌。这些陆地通常以河道内或河岸上的岛屿形式出现。炭具有短暂性的特点，被河流、湖泊、海洋或海洋等水体包围，其存在和特征在很大程度上取决于水文和沉积过程。
A Char, also known as chora, is a dynamic landform created by sediment deposition. These land masses typically emerge as islands within river channels or along riverbanks. Characterized by their transient nature, chars are surrounded by water bodies such as rivers, lakes, seas, or oceansand their existence and characteristics depend largely on hydrological and sedimentary processes.
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查看内容许可 ↗达西定律（英语：Darcy's law）是描述液体流过孔隙介质的本构方程。这个定律是法国工程师亨利·达西在1856年基于水流过沙的实验结果得到的。 此定律成为了地球科学的一个分支，水文地质学的基础；并且在生理学中也应用在对于血液与微血管的描述中。
Darcy's law is an equation that describes the flow of a fluid through a porous medium and through a Hele-Shaw cell. The law was formulated by Henry Darcy based on results of experiments on the flow of water through beds of sand, forming the basis of hydrogeology, a branch of earth sciences. It is analogous to Ohm's law in electrostatics, linearly relating the volume flow rate of the fluid to the hydraulic head difference (which is often just proportional to the pressure difference) via the hydraulic conductivity. In fact, Darcy's law is a special case of the Stokes equation for the momentum flux, in turn deriving from the momentum Navier–Stokes equation. Darcy's law is analogous to Fourier's law in the field of heat conduction, Ohm's law in the field of electrical networks, and Fick's law in diffusion theory.
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查看内容许可 ↗流域（英语：drainage basin）是以分水岭为界的一个河流、湖泊或海洋等的所有水系所覆盖的区域，以及由水系构成的集水区。地面上以分水岭为界之区域称为流域。流域内之径流集中于最低点而流出。最低点通常设有水文站量测流量或水位。流域内水文现象与流域特性有密切关系。 按水体是否与海洋连通，可分为外流区和内流区。外流区可按连通的大洋分为太平洋流域、大西洋流域、印度洋流域和北冰洋流域。并可进一步按河流、湖泊甚至一个支流细分，如长江流域。世界上流域面积最大的河流是亚马孙河。 太平洋流域约占地球上陆地面积的13%，印度洋流域也占约13%，而大西洋流域最多，约占47%──这其中包括密西西比河、刚果河和亚马孙河等大河流域。
A drainage basin is an area of land in which all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, the drainage divide, made up of a succession of elevated features, such as ridges and hills. A basin may consist of smaller basins that merge at river confluences, forming a hierarchical pattern. In North America, this is commonly called a watershed, though in other English-speaking places, "watershed" is used only in its original sense, that of the drainage divide line. Other terms for a drainage basin are catchment area, catchment basin, drainage area, river basin, water catchment, water basin, and impluvium. A drainage basin's boundaries are determined by watershed delineation, a common task in environmental engineering and science.
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查看内容许可 ↗古地下水，又称原生水或化石水（英语：Fossil Water），是一种很长时期密封于蓄水层里的地下水。数千甚至数百万年前因为周围地质的变化，某些地下水从此被密封于“化石含水层”里，而不再受到地下水循环的补充，就成了所谓的化石水。 努比亚砂岩含水层系统是其中最显着的化石水储量之一。此外，在撒哈拉沙漠，喀拉哈里沙漠及美国大平原的地下也存有化石蓄水层。 化石水是种不可再生的的资源，因为不像多数的含水层般能得到自然降雨渗透水的补给，化石含水层所得到的补给基本上非常少。在沙特阿拉伯，化石水尤其被大量开采为农业灌溉。
Fossil water, fossil groundwater, or paleowater is an ancient body of water that has been contained in some undisturbed space, typically groundwater in an aquifer, for millennia. Other types of fossil water can include subglacial lakes, such as Antarctica's Lake Vostok. UNESCO defines fossil groundwater as "water that infiltrated usually millennia ago and often under climatic conditions different from the present, and that has been stored underground since that time." Determining the time since water infiltrated usually involves analyzing isotopic signatures. Determining "fossil" status—whether or not that particular water has occupied that particular space since the distant past—involves modeling the flow, recharge, and losses of aquifers, which can involve significant uncertainty. Some aquifers are hundreds of meters deep and underlie vast areas of land.
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查看内容许可 ↗水文地球物理学是一个跨学科的研究领域，利用地球物理学来确定参数（特征；限制或边界的测量）并监测水资源、污染和生态研究等水文研究的过程。该领域利用地质学、水文学、物理学、地球物理学、工程学、统计学和岩石物理学的知识和研究人员。它利用地球物理学，使用微创方法提供有关水文地质参数的定量信息。水文地球物理学与地球物理学的不同之处在于其具体用途和方法。尽管地球物理知识和方法在过去半个世纪中已经存在并不断发展，用于采矿和石油工业，但水文地质研究地点的地下条件与这些工业不同。
Hydrogeophysics is a cross-disciplinary area of research that uses geophysics to determine parameters (characteristics; measurements of limitations or boundaries) and monitor processes for hydrological studies of matters such as water resources, contamination, and ecological studies. The field uses knowledge and researchers from geology, hydrology, physics, geophysics, engineering, statistics, and rock physics. It uses geophysics to provide quantitative information about hydrogeological parameters, using minimally invasive methods. Hydrogeophysics differs from geophysics in its specific uses and methods. Although geophysical knowledge and methods have existed and grown over the last half century for applications in mining and petroleum industries, hydrogeological study sites have different subsurface conditions than those industries.
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维基百科条目作者 · 获取于 2026-10-04 · CC BY-SA 4.0。简介经过纯文本提取与截取；两个语言版本的内容侧重可能不同。用于概念速查，不替代标准原文。 本条中文为英文百科简介的机器辅助翻译，请结合英文原文核对专业术语。
查看内容许可 ↗朱林定律（英语：Jurin's Law）描述液体在毛细管中上升或下降的规律。此定律的文字表述是：在确定的温度下，液体在毛细管内升高的最大高度和毛细管的直径成反比。其数学表达式为： h = 2 γ cos θ ρ g r 0 {\displaystyle \qquad h={\frac {2\gamma \cos \theta }{\rho gr_{0}}}} 其中 h {\textstyle h} 是毛细管内液体的最大高度； γ {\textstyle \gamma } 是液体的表面张力； θ {\textstyle \theta } 是液体和毛细管壁间的接触角； ρ {\textstyle \rho } 是液体的密度； g {\textstyle g} 是重力加速度； r 0 {\textstyle r_{0}} 是毛细管的半径。
Jurin's law, or capillary rise, is the simplest analysis of capillary action—the induced motion of liquids in small channels—and states that the maximum height of a liquid in a capillary tube is inversely proportional to the tube's diameter. Capillary action is one of the most common fluid mechanical effects explored in the field of microfluidics. Jurin's law is named after James Jurin, who discovered it between 1718 and 1719. The difference in height between the surroundings of the tube and the inside, as well as the shape of the meniscus, mathematical expression of this law can be derived directly from hydrostatic principles and the Young–Laplace equation. Jurin's law allows the measurement of the surface tension of a liquid and can be used to derive the capillary length.
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查看内容许可 ↗土层（soil horizon）又称土壤层、土壤发生层、土壤化育层，是大致平行于土壤的层，其物理特性不同于上面和下面的层。地平线在大多数情况下由明显的物理特征（主要是颜色和纹理）来定义。这些可以以绝对术语（例如纹理的粒度分布）和相对于周围材料（即，比上面和下面的层位“更粗糙”或“更陡峭”）的术语描述。 层位（horizon）于复合词中简称层，是依土壤的特性与其年代的不同而将其分为若干层序，并建立形成其在地质年代的地位。土壤分化为明显的层位，主要是源自土壤—大气界面的影响，如空气，水，太阳辐射和植物材料。由于土壤的风化首先发生在表面并向下工作，最上层已经改变最多，而最深层最类似于原始母材料。 科学家经常挖一个大洞，称为土坑（有时几米深，大约一米宽），以暴露土壤层进行研究。 将一组层位从地面暴露于母岩的垂直部分称为土壤剖面。大多数土壤，特别是在温带气候下，符合类似的一般层位模式，在图表中通常表示为“理想”土壤。此外，许多亚热带和热带地区有土壤，如氧化物溶液或干旱与“理想”的土壤有非常不同的地平线，或根本没有地平线。
A soil horizon is a layer parallel to the soil surface whose physical, chemical and biological characteristics differ from the layers above and beneath. Horizons are defined in many cases by obvious physical features, mainly colour and texture. These may be described both in absolute terms (particle size distribution for texture, for instance) and in terms relative to the surrounding material, i.e. "coarser" or "sandier" or "darker" than the horizons above and below. The identified horizons are indicated with symbols, which are mostly used in a hierarchical way. Master horizons (main horizons) are indicated by capital letters. Suffixes, in form of lowercase letters and figures, further differentiate the master horizons. There are many different systems of horizon symbols in the world. No one system is more correct—as artificial constructs, their utility lies in their ability to accurately describe local conditions in a consistent manner. Due to the different definitions of the horizon symbols, the systems cannot be mixed.
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查看内容许可 ↗黄土一种浅黄或褐黄色的土，颗粒成分以粉土粒级为主（含量＞50%），物质粒径均一，具孔隙，无层理，疏松，垂直节理发育。富含碳酸钙,有时含硫酸盐或氯化物盐类，具有肉眼可见孔隙的第四纪陆相沉积物。黄土有时具有湿陷性。另外，其在矿物成分方面高度复杂，多达60多种矿物，包括岩浆岩、变质岩和沉积岩的矿物成分，而且与其中任何一种岩石的矿物成分都不相同。各地区黄土矿物成分大体相同，无论矿物种类还是百分含量都基本相似，并有比较多的易风化不稳定矿物。在化学成分中含量最多的是SiO2、Al2O3、CaO、Na2O，含有比较多的易溶盐类，主要是：氧化物、碳酸盐、硫酸盐、CaCO3,含量在10％-16％之间。在所含生物化石方面以耐旱草本植物花粉和耐干旱动物化石为主，而且含有喜暖湿的动植物化石。最早李希霍芬（1877年）对欧洲莱茵河流域及中国大陆的黄土提出的定义为：黄－褐色，含石灰质，以粉土为主的粉状土；没有层理，含陆生蜗牛，有垂直节理。历史方面，“黄土”一词，在中国古代文献中及民间就已出现。 西方国家在19世纪后期将德国莱茵河流域的黄色松散堆积物命名为“lœss”，由此音译出英（loess）、俄（Лёсс）等文，不同学者曾以不同观点提出黄土的定义。1933年奥布鲁切夫(Β.Α. Обручев)将没有层理的黄土称为原生黄土，并认为是风成成因的；次生黄土是其他各种成因形成的。由于冰川的活动，把四周的岩石研磨成非常微细、像面粉一样幼细的尘土。这些尘土干了以后，很容易被风带走，送到很远的地方去，并累积起来。当这些微细的泥土不断的沉积，可以堆成很高的山。 有时因淋洗作用较强而使粘粒明显往剖面下层移动，养分有的已流失而呈黄、黄棕或红棕色。多生成于丘陵地上之相对地形较安定、坡度起伏较缓和处。土壤多呈弱酸性，肥沃度偏低，须进行施肥管理及水土保持，才可做农牧用地。此土壤在新分类上属弱育土或淋溶土。 。
Loess (US: , UK: ; from German: Löss [lœs]) is a clastic, predominantly silt-sized sediment that is formed by the accumulation of wind-blown dust. Ten percent of Earth's land area is covered by loesses or similar deposits. Loess is a periglacial or aeolian (windborne) sediment, defined as an accumulation of 20% or less of clay with a balance of roughly equal parts sand and silt (with a typical grain size from 20 to 50 micrometers), often loosely cemented by calcium carbonate. Usually, they are homogeneous and highly porous and have vertical capillaries that permit the sediment to fracture and form vertical bluffs.
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查看内容许可 ↗冰碛物是指在冰川作用下由侵蚀所形成的沉积物。由于未经分选，故颗粒大可至大石，小可至粉砂。可经成岩作用成为冰碛石。 冰碛物有不同的分类标准，如可分为原生矿床和次生矿床。
Till, or glacial till, is unsorted glacial sediment. Till is derived from the erosion and entrainment of material by the moving ice of a glacier. It is deposited some distance down-ice to form terminal, lateral, medial and ground moraines. Till is classified into primary deposits, laid down directly by glaciers, and secondary deposits, reworked by fluvial transport and other processes.
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查看内容许可 ↗冲积扇（英语：Alluvial fan）是山地河流流出谷口时，因坡度骤降、水道趋于开阔，导致水流速度减慢、搬运能力降低，挟带的泥沙砾石在谷口大量堆积而成的扇状地貌。这类地形广泛分布于干旱、半干旱或部分湿润与现代冰河地区的山麓地带。其面积因地而异，小至不足1平方公里，大可达20,000平方公里。 冲积扇的形成动力主要来自泥石流或间歇性、常流性的溪流；河流向下游进入平原后，亦可能进一步塑造出广阔的冲积平原。 除了地球，科学家也在火星与土卫六（泰坦）上发现明显的冲积扇地貌，证实了这些外星天体过去或现在存在流体冲刷地表的作用。在陆域现代冲积扇中，位于中国新疆的塔里木盆地沙漠冲积扇为全球规模最大的扇体。由于冲积扇上的河道极易频繁改道（节点改道），一旦发生洪水，往往容易造成严重的灾害，例如2008年印度的戈西河洪灾便是典型案例。
An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to semiarid climates, but are also found in more humid environments subject to intense rainfall and in areas of modern glaciation. They range in area from less than 1 square kilometer (0.4 sq mi) to almost 20,000 square kilometers (7,700 sq mi). Alluvial fans typically form where a flow of sediment or rocks emerge from a confined channel and are suddenly free to spread out in many directions. For example, many alluvial fans form when steep mountain valleys meet a flat plain. The transition from a narrow channel to a wide open area reduces the carrying capacity of flow and results in deposition of sediments. The flow can take the form of infrequent debris flows like in a landslide, or can be carried by an intermittent stream or creek. The reduction of flow is key to the formation of alluvial fans.
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查看内容许可 ↗水文地质学是研究地下水的科学。它研究与岩石圈、水圈、大气圈、生物圈以及人类活动相互作用下地下水水量和水质的时空变化规律，并研究如何运用这些规律去兴利除害，为人类服务。 水文地质学是从寻找和利用地下水源开始发展的，围绕实际应用，逐渐开展了理论研究。目前已形成了一系列分支。 地下水动力学 地下水动力学是研究关于地下水运动的基本理论，运用这些理论分析水文地质问题，建立相应的数学模型并提出恰当的计算方法，对地下水资源进行定量评价，预测地下水污染的发展趋势，控制地下水污染的学科。 水文地球化学 供水水文地质学 矿床水文地质学 农业水文地质学 区域水文地质学 古水文地质学 环境水文地质学 医学水文地质学
Hydrogeology (hydro- meaning water, and -geology meaning the study of the Earth) is the area of geology that deals with the distribution and movement of groundwater in the soil and rocks of the Earth's crust (commonly in aquifers). The terms groundwater hydrology, geohydrology, and hydrogeology are often used interchangeably, though hydrogeology is the most commonly used. Hydrogeology is the study of the laws governing the movement of subterranean water, the mechanical, chemical, and thermal interaction of this water with the porous solid, and the transport of energy, chemical constituents, and particulate matter by flow. Groundwater engineering is a branch of engineering which is concerned with groundwater movement and the design of wells, pumps, and drains. The main concerns in groundwater engineering include groundwater contamination, conservation of supplies, and water quality. Wells are constructed for use in developing nations, as well as for use in developed nations in places which are not connected to a city water system.
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维基百科条目作者 · 获取于 2026-10-04 · CC BY-SA 4.0。简介经过纯文本提取与截取；两个语言版本的内容侧重可能不同。用于概念速查，不替代标准原文。
查看内容许可 ↗固氮是一种化学过程，通过该过程，丰富但相对惰性的分子二氮 (N2) 转化为生物可利用的氮化合物，例如氨 (NH3) 和硝酸盐 (NO3)。它在生物和非生物方面都发生，后者要么通过天气现象（例如闪电）自然发生，要么通过化学工业人为发生。生物固氮或固氮是由蓝藻和根瘤菌等微生物产生的固氮酶催化的。这些酶复合物由 Nif 基因（或 Nif 同系物）编码，含有铁，通常含有第二种金属（通常是钼，但有时是钒）。一些固氮细菌与植物有共生关系，特别是豆科植物、苔藓和水生蕨类植物，如满江红。
Nitrogen fixation is a chemical process by which the abundant but relatively inert molecular dinitrogen (N2) is converted into bioavailable nitrogen compounds such as ammonia (NH3) and nitrates (NO3). It occurs both biologically and abiologically, the latter either naturally through weather phenomena (e.g. lightning) or artificially by chemical industries. Biological nitrogen fixation or diazotrophy is catalyzed by enzymes called nitrogenases, produced by microorganisms such as cyanobacteria and rhizobia. These enzyme complexes are encoded by the Nif genes (or Nif homologs) and contain iron, often with a second metal (usually molybdenum, but sometimes vanadium). Some nitrogen-fixing bacteria have symbiotic relationships with plants, especially legumes, mosses, and aquatic ferns such as Azolla.
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维基百科条目作者 · 获取于 2026-10-04 · CC BY-SA 4.0。简介经过纯文本提取与截取；两个语言版本的内容侧重可能不同。用于概念速查，不替代标准原文。 本条中文为英文百科简介的机器辅助翻译，请结合英文原文核对专业术语。
查看内容许可 ↗反硝化是一种微生物促进的过程，其中硝酸盐 (NO3) 被还原，并最终通过一系列中间气态氮氧化物产物产生分子氮 (N2)。兼性厌氧细菌进行反硝化作为一种呼吸作用，响应电子供体（例如有机物）的氧化而减少氮的氧化形式。优选的氮电子受体按照热力学有利程度从高到低的顺序包括硝酸盐(NO3)、亚硝酸盐(NO2)、一氧化氮(NO)、一氧化二氮(N2O)，最终产生N2，完成氮循环。反硝化微生物需要低于 10% 的极低氧气浓度，以及电子供体，如有机碳、氢气或还原硫作为能量。
Denitrification is a microbially facilitated process where nitrate (NO3) is reduced and ultimately produces molecular nitrogen (N2) through a series of intermediate gaseous nitrogen oxide products. Facultative anaerobic bacteria perform denitrification as a type of respiration that reduces oxidized forms of nitrogen in response to the oxidation of an electron donor such as organic matter. The preferred nitrogen electron acceptors in order of most to least thermodynamically favorable include nitrate (NO3), nitrite (NO2), nitric oxide (NO), nitrous oxide (N2O), finally resulting in the production of N2, completing the nitrogen cycle. Denitrifying microbes require a very low oxygen concentration of less than 10%, as well as an electron donor, like organic C, hydrogen gas, or reduced sulfur for energy.
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维基百科条目作者 · 获取于 2026-10-04 · CC BY-SA 4.0。简介经过纯文本提取与截取；两个语言版本的内容侧重可能不同。用于概念速查，不替代标准原文。 本条中文为英文百科简介的机器辅助翻译，请结合英文原文核对专业术语。
查看内容许可 ↗对流是指流体内部的分子运动，是热传与质传的主要模式之一。热对流（亦称为对流传热）是三种主要热传方式中的其中一种（另外两种分别是热传导与热辐射）。
Convection is the transfer of heat through the physical movement of fluids (liquids or gases), where warmer, less-dense material rises and cooler, denser material sinks. It is a single-phase or multiphase fluid flow that occurs spontaneously through the combined effects of material property heterogeneity and body forces on a fluid. When the cause of the convection is unspecified, convection due to the effects of thermal expansion (change in density) and gravity/buoyancy can be assumed (see convection in heat transfer). Convective flow may be transient (such as when a multiphase mixture of oil and water separates) or steady state (see convection cell). The convection may be due to gravitational, electromagnetic or fictitious body forces. Heat transfer by natural convection plays a role in the structure of Earth's atmosphere, its oceans, and its mantle. Discrete convective cells in the atmosphere can be identified by clouds, with stronger convection resulting in thunderstorms. Natural convection also plays a role in stellar physics.
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维基百科条目作者 · 获取于 2026-10-04 · CC BY-SA 4.0。简介经过纯文本提取与截取；两个语言版本的内容侧重可能不同。用于概念速查，不替代标准原文。
查看内容许可 ↗在流体力学中，雷诺数（英语：Reynolds number）是流体的惯性力 ρ v 2 L {\displaystyle {\frac {\rho v^{2}}{L}}} 与黏性力 μ v L 2 {\displaystyle {\frac {\mu v}{L^{2}}}} 的比值，它是一个无量纲量。 雷诺数较小时，黏滞力对流场的影响大于惯性力，流场中流速的扰动会因黏滞力而衰减，流体流动稳定，为层流；反之，若雷诺数较大时，惯性力对流场的影响大于黏滞力，流体流动较不稳定，流速的微小变化容易发展、增强，形成紊乱、不规则的紊流流场。
In fluid dynamics, the Reynolds number (Re) is a dimensionless quantity that helps predict fluid flow patterns in different situations by measuring the ratio between inertial and viscous forces. At low Reynolds numbers, flows tend to be dominated by laminar (sheet-like) flow, while at high Reynolds numbers, flows tend to be turbulent. The turbulence results from differences in the fluid's speed and direction, which may sometimes intersect or even move counter to the overall direction of the flow (eddy currents). These eddy currents begin to churn the flow, using up energy in the process, which for liquids increases the chances of cavitation. The Reynolds number has wide applications, ranging from liquid flow in a pipe to the passage of air over an aircraft wing. It is used to predict the transition from laminar to turbulent flow and is used in the scaling of similar but different-sized flow situations, such as between an aircraft model in a wind tunnel and the full-size version.
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查看内容许可 ↗普兰特数（英语：Prandtl number，缩写： P r {\displaystyle \mathrm {Pr} } ） ，是一个流体力学无因次的标量，以德国力学家路德维希·普朗特的名字命名，表示动黏滞系数和热扩散率的比例，也可以视为动量传输及热量传输速率的比例。
The Prandtl number (Pr) is a dimensionless number, named for the German fluid dynamicist Ludwig Prandtl. It is defined as the ratio of momentum diffusivity to thermal diffusivity.
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查看内容许可 ↗佩克莱特数是流体力学中的无量纲数，指流体中对流和扩散质量、热量之比，计算式为： P e = R e P r = V L α {\displaystyle \mathrm {Pe} =\mathrm {Re} \mathrm {Pr} ={\frac {VL}{\alpha }}} 其中： R e {\displaystyle \mathrm {Re} } 为雷诺数 P r {\displaystyle \mathrm {Pr} } 为普朗特数 V {\displaystyle V} 为平均流速 L {\displaystyle L} 为特征长度 α {\displaystyle \alpha } 为扩散系数或热扩散率 佩克莱特数以Pe表示，是一个无因次参数，用来表示对流速率与扩散速率之比。若Pe >> 1，表示流速大，扩散十分缓慢，故当物质被带往下游时，扩散云团之尺度几乎不变，扩散云团可视为一凝结云团向下游平移，扩散对浓度的影响可予以忽略。反之，当Pe << 1时，表示扩散十分快速，而扩散主导浓度的变化。
In continuum mechanics, the Péclet number (Pe, after Jean Claude Eugène Péclet) is a class of dimensionless numbers relevant in the study of transport phenomena in a continuous environment. It is defined to be the ratio of the rate of advection of a physical quantity by the flow to the rate of diffusion of the same quantity driven by an appropriate gradient. In the context of species or mass transfer, the Péclet number is the product of the Reynolds number and the Schmidt number (Re × Sc). In the context of the thermal fluids, the thermal Péclet number is equivalent to the product of the Reynolds number and the Prandtl number (Re × Pr).
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查看内容许可 ↗努塞尔特数是流体力学中的无因次参数，以德国物理学家威廉·努塞尔特（Wilhelm Nusselt）的名字命名，其意义为流体系统的特征长度与热边界层厚度之比，计算式为： N u = h L k fluid {\displaystyle \mathrm {Nu} ={\frac {hL}{k_{\text{fluid}}}}} 其中， h {\displaystyle h} 为热对流系数 L {\displaystyle L} 为特征长度 k fluid {\displaystyle k_{\text{fluid}}} 为流体的热导率
The Nusselt number is a nondimensionalization of the convective heat transfer coefficient. Like the heat transfer coefficient, the Nusselt number may be defined locally, at a single position on a surface, or as an average value that represents the heat flow from the entire surface. The Nusselt number is named in honor of Wilhelm Nusselt, who first identified this dimensionless group in 1915. Analytical results and empirical correlations allow the Nusselt number to be estimated in many situations. For forced convection, these expressions depend on the Reynolds number and the Prandtl number. For natural convection (or "free" convection) the predictions use the Grashof number or Rayleigh number along with the Prandtl number. The mass transfer analog of the Nusselt number is the Sherwood number.
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维基百科条目作者 · 获取于 2026-10-04 · CC BY-SA 4.0。简介经过纯文本提取与截取；两个语言版本的内容侧重可能不同。用于概念速查，不替代标准原文。
查看内容许可 ↗舍伍德数是流体力学中的无量纲数，也被称为质量传递努塞尔特数，指动量与扩散传质系数之比，计算式为： S h = h D L D f l u i d {\displaystyle \mathrm {Sh} ={\frac {h_{D}L}{D_{fluid}}}} 其中， h D {\displaystyle h_{D}} 为质量传递系数 L {\displaystyle L} 为特征长度 D f l u i d {\displaystyle D_{fluid}} 为扩散传质系数
The Sherwood number (Sh) (also called the mass transfer Nusselt number) is a dimensionless number used in mass-transfer operation. It represents the ratio of the total mass transfer rate (convection + diffusion) to the rate of diffusive mass transport, and is named in honor of Thomas Kilgore Sherwood.
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查看内容许可 ↗风切变（Wind shear/Windshear），又称风剪、风切，是指大气中在相对较短的距离内，风速和/或风向发生变化的现象。大气风切变通常分为垂直风切变和水平风切变。 风切变本身属于微尺度气象现象，发生距离极短，但它常与飑线、冷锋等中尺度或天气尺度的天气系统相伴随。这种现象常见于雷暴引起的微爆气流和下击暴流附近，也常见于锋面、低空急流（局部低空风速较大区域）、山脉附近、因晴空微风引发的辐射逆温层、建筑物、风力发电机以及帆船周围。风切变对飞机的操控有重大影响，是导致许多飞行事故的唯一原因或诱因。 除此之外，声音在大气中的传播也会受到风切变的影响。风切变会使声波前发生弯曲，导致在通常听不到声音的地方也能听到声音。此外，对流层内强烈的垂直风切变会抑制热带气旋的发展，但有助于将单一雷暴组织成生命周期更长的强对流天气。热风概念则阐明了不同高度的风速差异如何取决于水平温度差异，并解释了急流的存在。
Wind shear (; also written windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizontal wind shear. Vertical wind shear is a change in wind speed or direction with a change in altitude. Horizontal wind shear is a change in wind speed with a change in lateral position for a given altitude. Wind shear is a microscale meteorological phenomenon occurring over a very small distance, but it can be associated with mesoscale or synoptic scale weather features such as squall lines and cold fronts. It is commonly observed near microbursts and downbursts caused by thunderstorms, fronts, areas of locally higher low-level winds referred to as low-level jets, near mountains, radiation inversions that occur due to clear skies and calm winds, buildings, wind turbines, and sailboats. Wind shear has significant effects on the control of an aircraft, and it has been the only or a contributing cause of many aircraft accidents.
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查看内容许可 ↗在电磁学里，相对电容率，又称为相对介电常数，定义为电容率与真空电容率的比例∶ ε r = d e f ε ε 0 {\displaystyle \varepsilon _{r}\ {\stackrel {\mathrm {def} }{=}}\ {\frac {\varepsilon }{\varepsilon _{0}}}} ； 其中， ε r {\displaystyle \varepsilon _{r}} 是电介质的相对电容率， ε {\displaystyle \varepsilon } 是电介质的电容率， ε 0 {\displaystyle \varepsilon _{0}} 是真空电容率。
The relative permittivity (in older texts, dielectric constant) is the permittivity of a material expressed as a ratio with the electric permittivity of a vacuum. A dielectric is an insulating material, and the dielectric constant of an insulator measures the ability of the insulator to store electric energy in an electrical field. Permittivity is a material's property that affects the Coulomb force between two point charges in the material. Relative permittivity is the factor by which the electric field between the charges is decreased relative to vacuum. Likewise, relative permittivity is the ratio of the capacitance of a capacitor using that material as a dielectric, compared with a similar capacitor that has vacuum as its dielectric. Relative permittivity is also commonly known as the dielectric constant, a term still used but deprecated by standards organizations in engineering as well as in chemistry.
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查看内容许可 ↗电阻率（英语：resistivity），也称为体积电阻率或比电阻，是材料的特性，用于测量其电阻或抵抗电流的能力。 低电阻率表示材料容易通过电流。 电阻率通常用希腊字母ρ表示。电阻率的SI单位是欧姆·米（Ω· m）。例如，如果1 m3实心立方体材料在两个相对面上具有片状触点，这些触点之间的电阻为1 Ω，则材料的电阻率为1 Ω·m。 电导率（英语：conductivity），或比电导，是电阻率的倒数，代表材料传导电流的能力。 通常用希腊字母σ表示（西格玛），但特别在电气工程中，有时会用到字母κ（kappa ）和γ（gamma）。电导率的SI单位是西门子每米（S/m）。 电阻率和电导率是材料的内含性质。电阻和电导是相对应的外延属性，它们表现特定物体对电流相反的反应。
In physics, electrical resistivity and electrical conductivity are two intrinsic properties of materials that measure a material's local, intrinsic ability to conduct electric current. They are reciprocals of each other, so each can be deduced from the other. They are usually numbers or scalar fields, but can be generalized to tensor quantities when the material is non-isotropic, or to complex quantities in the setting of time-varying currents. Electrical resistivity (also called volume resistivity or specific electrical resistance) is a fundamental specific property of a material that measures its electrical resistance or how strongly it resists electric current. A low resistivity indicates a material that readily allows electric current. Resistivity is commonly represented by the Greek letter ρ (rho). The SI unit of electrical resistivity is the ohm-metre (Ω⋅m).
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维基百科条目作者 · 获取于 2026-10-04 · CC BY-SA 4.0。简介经过纯文本提取与截取；两个语言版本的内容侧重可能不同。用于概念速查，不替代标准原文。
查看内容许可 ↗透地雷达（Ground-penetrating radar，缩写：GPR）是以雷达脉冲波探测地表以下状况并成像的仪器。这是以无线电谱上的微波（UHF/VHF）波段电磁波进行的一种无损检测方式，并接收因为地表下各种物体结构造成的雷达反射波。透地雷达可以在岩石、土壤、冰、淡水、人行道以及各种结构物等介质使用。透地雷达可探测到地表下的物质、材质变化、空隙和裂隙等。
Ground-penetrating radar (GPR) is a geophysical method that uses radar pulses to image the subsurface. It is a non-intrusive method of surveying the sub-surface to investigate underground utilities such as concrete, asphalt, metals, pipes, cables or masonry. This nondestructive method uses electromagnetic radiation in the microwave band (UHF/VHF frequencies) of the radio spectrum, and detects the reflected signals from subsurface structures. GPR can have applications in a variety of media, including rock, soil, ice, fresh water, pavements and structures. In the right conditions, practitioners can use GPR to detect subsurface objects, changes in material properties, and voids and cracks. GPR uses high-frequency (usually polarized) radio waves, usually in the range 10 MHz to 2.6 GHz. A GPR transmitter and antenna emits electromagnetic energy into the ground. When the energy encounters a buried object or a boundary between materials having different permittivities, it may be reflected or refracted or scattered back to the surface.
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查看内容许可 ↗电阻率层析成像 (ERT) 或电阻率成像 (ERI) 是一种地球物理技术，用于通过在地表或通过一个或多个钻孔中的电极进行的电阻率测量来对地下结构进行成像。如果电极悬挂在钻孔中，则可以研究更深的部分。它与医学成像技术电阻抗断层扫描（EIT）密切相关，在数学上也是同样的逆问题。然而，与医疗 EIT 不同的是，ERT 本质上是一种直流电方法。相关的地球物理方法，诱导极化（或光谱诱导极化），测量瞬态响应，旨在确定地下荷电特性。
Electrical resistivity tomography (ERT) or electrical resistivity imaging (ERI) is a geophysical technique for imaging sub-surface structures from electrical resistivity measurements made at the surface, or by electrodes in one or more boreholes. If the electrodes are suspended in the boreholes, deeper sections can be investigated. It is closely related to the medical imaging technique electrical impedance tomography (EIT), and mathematically is the same inverse problem. In contrast to medical EIT, however, ERT is essentially a direct current method. A related geophysical method, induced polarization (or spectral induced polarization), measures the transient response and aims to determine the subsurface chargeability properties.
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维基百科条目作者 · 获取于 2026-10-04 · CC BY-SA 4.0。简介经过纯文本提取与截取；两个语言版本的内容侧重可能不同。用于概念速查，不替代标准原文。 本条中文为英文百科简介的机器辅助翻译，请结合英文原文核对专业术语。
查看内容许可 ↗稀有元素是指自然界中储量稀少（一般地壳丰度为100ppm以下）或分布稀散、很少富集成矿的元素。部分稀有元素常用来制造特种金属材料或特殊元件，如特种钢、合金、永久磁铁等，在飞机、火箭、汽车、原子能、半导体等工业领域属于关键性材料。代表性的稀有金属有铍、镓、铟、铼以及稀土金属等。
A trace element is a chemical element of a minute quantity, a trace amount, especially used in referring to a micronutrient, but is also used to refer to minor elements in the composition of a rock, or other chemical substance. In nutrition, trace elements are classified into two groups: essential trace elements, and non-essential trace elements. Essential trace elements are needed for many physiological and biochemical processes in both plants and animals. Not only do trace elements play a role in biological processes but they also serve as catalysts to engage in redox – oxidation and reduction mechanisms. Trace elements of some heavy metals have a biological role as essential micronutrients.
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维基百科条目作者 · 获取于 2026-10-04 · CC BY-SA 4.0。简介经过纯文本提取与截取；两个语言版本的内容侧重可能不同。用于概念速查，不替代标准原文。
查看内容许可 ↗在热力学中，某种物质的化学势指的是，在化学反应或者相变中，此物质的粒子数发生改变时所吸收或放出的能量。在混合物中的某种物质的化学势定义为此热力学系统的吉布斯自由能对此物质粒子数的变化率，即偏导数（其他物质的粒子数及其他系统参数保持不变）。当温度和压强固定时，化学势也被称作偏摩尔吉布斯自由能，或者摩尔化学势。在化学平衡或相平衡状态下，自由能处于极小值，各种物质的化学势与化学计量系数乘积之和为零。 在半导体物理中，零温电子系统的化学势被称为费米能。
In thermodynamics, the chemical potential of a species is the energy that can be absorbed or released due to a change of the particle number of the given species, e.g. in a chemical reaction or phase transition. The chemical potential of a species in a mixture is defined as the rate of change of free energy of a thermodynamic system with respect to the change in the number of atoms or molecules of the species that are added to the system. Thus, it is the partial derivative of the free energy with respect to the amount of the species, all other species' concentrations in the mixture remaining constant. When both temperature and pressure are held constant, and the number of particles is expressed in moles, the chemical potential is the partial molar Gibbs free energy. At chemical equilibrium or in phase equilibrium, the total sum of the product of chemical potentials and stoichiometric coefficients is zero, as the free energy is at a minimum. In a system in diffusion equilibrium, the chemical potential of any chemical species is uniformly the same everywhere throughout the system.
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维基百科条目作者 · 获取于 2026-10-04 · CC BY-SA 4.0。简介经过纯文本提取与截取；两个语言版本的内容侧重可能不同。用于概念速查，不替代标准原文。
查看内容许可 ↗朗缪尔吸附模型（英语：Langmuir adsorption model）也常被称为朗缪尔吸附等温式。这一模型假设在等温吸附过程中，吸附质的分子与理想气体的分子类似，吸附和解吸是一对可逆过程。也解释了吸附质的分压 p A {\displaystyle p_{A}} 与固体吸附剂上吸附质的体积之间的关系。其中的吸附剂被假设为一个理想的固体表面，具有一系列能够与吸附质结合的位点。这种结合被视作气相的吸附质分子 A g {\displaystyle A_{\text{g}}} 和空的位点S的相互作用。
The Langmuir adsorption model explains adsorption by assuming an adsorbate behaves as an ideal gas at isothermal conditions. According to the model, adsorption and desorption are reversible processes. This model even explains the effect of pressure; i.e., at these conditions the adsorbate's partial pressure p A {\displaystyle p_{A}} is related to its volume V adsorbed onto a solid adsorbent. The adsorbent, as indicated in the figure, is assumed to be an ideal solid surface composed of a series of distinct sites capable of binding the adsorbate. The adsorbate binding is treated as a chemical reaction between the adsorbate gaseous molecule A g {\displaystyle A_{\text{g}}} and an empty sorption site S.
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维基百科条目作者 · 获取于 2026-10-04 · CC BY-SA 4.0。简介经过纯文本提取与截取；两个语言版本的内容侧重可能不同。用于概念速查，不替代标准原文。
查看内容许可 ↗菲克定律（英语：Fick's law）描述扩散作用，可以使用这条定律来求得扩散系数：D。定律由德国生理学家阿道夫·菲克于1855年推导出来。
Fick's laws of diffusion describe diffusion and were first posited by Adolf Fick in 1855 on the basis of largely experimental results. They can be used to solve for the diffusion coefficient, D {\displaystyle D} . Fick's first law can be used to derive his second law, which in turn is identical to the diffusion equation. Fick's first law: Movement of particles from high to low concentration (diffusive flux) is directly proportional to the particle's concentration gradient. Fick's second law: Prediction of change in concentration gradient with time due to diffusion. A diffusion process that obeys Fick's laws is called normal or Fickian diffusion; otherwise, it is called anomalous diffusion or non-Fickian diffusion.
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维基百科条目作者 · 获取于 2026-10-04 · CC BY-SA 4.0。简介经过纯文本提取与截取；两个语言版本的内容侧重可能不同。用于概念速查，不替代标准原文。
查看内容许可 ↗热力学（英语：thermodynamics） 是物理学的一个分支，研究热现象中能量的转换规律，特别是研究热、功和温度，以及它们与能量和熵的关系。热力学应用于许多科学和工程领域，特别是物理化学、生物化学、化学工程和机械工程，以及气象学等领域。 热力学发端于18世纪对气体和蒸汽机的研究。在19世纪，随着对热机效率和功与热量之间能量转换的研究。开始建立起热力学定律，标志着热力学理论的成熟。随着研究的深化，热力学研究被拓展到很多方面，比如相变化、化学反应、输运现象甚至是黑洞。 热力学的研究对象是由大量微观粒子组成的热力学系统。热力学系统温度、压强和内能等由宏观物理量描述，这些物理量的行为受到四个热力学定律的约束。热力学定律是从实验中总结出来的，但也可以通过统计力学从微观角度来解释。
Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of thermodynamics, which convey a quantitative description using measurable macroscopic physical quantities but may be explained in terms of microscopic constituents by statistical mechanics. Thermodynamics applies to various topics in science and engineering, especially physical chemistry, biochemistry, chemical engineering, and mechanical engineering, as well as other complex fields such as meteorology. Historically, thermodynamics developed out of a desire to increase the efficiency of early steam engines, particularly through the work of French physicist Sadi Carnot (1824).
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维基百科条目作者 · 获取于 2026-10-04 · CC BY-SA 4.0。简介经过纯文本提取与截取；两个语言版本的内容侧重可能不同。用于概念速查，不替代标准原文。
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