为什么人工肾能代替肾脏排毒？
Why can an artificial kidney replace the real one for detox?
透析用半透膜，小分子毒素（如尿素）能透过，而血细胞和大分子蛋白被留下，模拟肾脏把废物滤出血液。
Dialysis uses a semipermeable membrane: small toxins (urea) pass through while blood cells and proteins are retained, mimicking the kidney's filtration.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Brenner and Rector's The Kidney, 9th ed., Elsevier Saunders, 2012
Brenner and Rector's The Kidney, 9th ed., Elsevier Saunders, 2012
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL10537815M：Brenner and Rector's t
#透析 #半透膜 #人工肾
气相色谱是怎么分辨多种气体的？
How does gas chromatography tell compounds apart?
挥发性样品随惰性载气通过长柱子，各组分与固定相作用强弱不同，出峰时间不同，据此识别并定量。
Volatile samples ride an inert carrier gas through a long column; differing interactions with the stationary phase give distinct retention times for ID and quantitation.
难度 专业 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#气相色谱 #保留时间 #分离
为什么DNA能在果冻里被分开？
Why can DNA be separated inside a jelly?
凝胶电泳中带负电的DNA在电场里向正极迁移，小的片段跑得快，大的慢，从而按长度分开，用于亲子鉴定和测序。
In gel electrophoresis, negatively charged DNA migrates toward the anode; smaller fragments move faster, separating by length for paternity tests and sequencing.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#电泳 #DNA #分离
为什么镧系元素的化学性质如此相似，分离它们格外困难？
Why are the lanthanides chemically so similar that separating them is notoriously hard?
原因是镧系收缩：4f 电子对核电荷的屏蔽能力差，随原子序数增加，核对最外层电子的引力增强，离子半径缓慢而持续地缩小。镧系元素的最外层电子结构几乎相同，化学性质主要由最外层电子决定，所以它们与同一配体的反应行为差别极小，半径的微小差异又不足以造成明显的化学选择性。工业上只能利用半径差异进行成千上万次离子交换或溶剂萃取循环，才能获得高纯的单一稀土，这也是稀土精炼成本高昂的重要原因。
The cause is the lanthanide contraction: 4f electrons shield the nucleus poorly, so as atomic number rises the nucleus pulls the outer electrons harder and ionic radii shrink slowly and steadily. Because the outermost electron configurations of the lanthanides are nearly identical and chemistry is governed largely by those outer electrons, their reactions with a given ligand are almost indistinguishable, while the small radius differences cannot provide enough chemical selectivity. Industry must run thousands of ion-exchange or solvent-extraction cycles exploiting those tiny radius variations to obtain one high-purity element - a big reason refined rare earths are so expensive.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#镧系收缩 #离子半径 #分离
反渗透净水器是怎么把盐和水分开的？
How does reverse osmosis separate salt from water?
渗透是水穿半透膜流向浓侧，直到两边化学势持平，撑住的压差便是渗透压，稀溶液中近似正比于浓度与热力学温度。反渗透是在浓侧加一道高于渗透压的外压，逼溶剂反向穿膜，盐分留在浓水侧排走：膜过的是溶剂而非溶液。两点常被略过：进料越咸所需压差越大，家用机与海水淡化不同量级；机理也不是把离子筛在孔外，而是致密膜内溶解扩散的快慢差别，二氧化碳等小分子照样透过。
Osmosis is water crossing a semipermeable membrane toward the concentrated side until the chemical potentials match, and the pressure it can hold up is the osmotic pressure, roughly proportional to concentration and absolute temperature in a dilute solution. Reverse osmosis adds a pressure on the concentrated side above that osmotic pressure, forcing the solvent backwards through the membrane while the salt is left in a concentrate that is drained off: what crosses is solvent, not solution. Two points often get skipped: the saltier the feed, the larger the pressure needed, so a household unit and a seawater plant are not on the same scale; and the mechanism is not screening ions out of pores but the difference in dissolution and diffusion through a dense membrane, so small molecules like carbon dioxide still cross.
难度 专业 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#反渗透 #膜 #净水
为什么17种稀土元素那么难分开？
Why are the 17 rare-earth elements so hard to separate?
镧系元素化学性质极相似（镧系收缩），传统方法分离很差；徐光宪创立串级萃取理论，实现高效分离，奠定中国稀土产业基础。
Lanthanides are chemically near-identical (lanthanide contraction), hard to separate; Xu Guangxian's cascade-extraction theory enabled efficient separation, underpinning China's rare-earth industry.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#稀土 #串级萃取 #徐光宪
为什么蒸馏瓶叫alembic？
Why is a still called an alembic?
阿拉伯炼金家（如贾比尔）发展了蒸馏技术，alembic一词源自阿拉伯语，用于制取酒精、精油和无水矿物酸，是伊斯兰黄金时代对化学的重要贡献。
Arab alchemists like Jabir advanced distillation; alembic comes from Arabic and was used for alcohol, essential oils and mineral acids—a key Islamic Golden Age contribution.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#蒸馏 #炼金 #阿拉伯
为什么洗衣机能甩干，实验室也用离心机？
Why do washing machines spin-dry and labs use centrifuges?
离心利用不同密度物质受离心力差异，加速沉降或分层，既能甩干衣物，也能分离血细胞和血浆、轻重液体。
Centrifugation exploits density differences under centrifugal force to speed settling/separation—drying clothes or separating blood cells from plasma.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#离心 #密度 #分离
蒸馏为什么能分开酒精和水？
Why can distillation separate alcohol from water?
乙醇沸点约78℃比水100℃低，加热到两者之间时乙醇先变成蒸气被收集，再冷凝就得到更浓的酒。
Ethanol boils at ~78°C, lower than water's 100°C; heating between them vaporizes ethanol first, which is collected and condensed.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#蒸馏 #沸点 #分离
薄层色谱(TLC)为什么能把混合物分开？
Why can thin-layer chromatography separate a mixture?
不同物质在固定相和流动相之间的分配倾向不同，随溶剂爬升时跑得快慢有别，于是被分成不同斑点。
Compounds partition differently between the stationary and mobile phases, so they travel at different speeds up the plate and separate into spots.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#薄层色谱 #分配 #分离
为什么粗盐加水再结晶会更纯？
Why does recrystallizing crude salt make it purer?
重结晶利用目标物与杂质溶解度随温度变化的差异，冷却时纯物质优先长入晶格，杂质留在母液，从而提纯。
Recrystallization exploits different temperature-dependence of solubility; on cooling the pure substance crystallizes into the lattice while impurities stay in the mother liquor.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#重结晶 #提纯 #溶解度
为什么菠菜汁在滤纸上能爬出几条色带？
Why do several color bands climb up filter paper from spinach juice?
纸色谱中，不同色素在水和纤维素间的分配不同，随溶剂上升快慢不一，把叶绿素a、b和叶黄素等分开。
In paper chromatography, pigments partition differently between water and cellulose, moving up at different rates and separating chlorophyll a/b and lutein.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#纸色谱 #色素 #分离
反相高效液相色谱中,流动相甲醇比例提高对保留时间和选择性有什么影响?
In reversed-phase HPLC, how does increasing the methanol fraction of the mobile phase affect retention time and selectivity?
反相色谱固定相为疏水烷基链,溶质的保留主要靠疏水分配,流动相有机相比例升高会增强溶质在流动相中的溶解度,洗脱强度增大,保留时间按指数规律缩短。甲醇比例变化对不同官能团溶质的保留影响幅度不一,因此相邻色谱峰的相对距离即选择性因子也会改变,有时甚至出现峰序翻转。实际分离常通过梯度洗脱或二元/三元溶剂体系同时优化保留与选择性。
Reversed-phase stationary phases are hydrophobic alkyl chains and retention arises mainly from hydrophobic partitioning; raising the organic fraction increases solute solubility in the mobile phase, raises elution strength, and shortens retention times exponentially. The magnitude of this effect differs among functional groups, so the relative spacing of neighboring peaks - the selectivity factor - also changes, occasionally reversing elution order. Practical separations tune both retention and selectivity through gradient elution or binary/ternary solvent systems.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Snyder L R, Kirkland J J, Dolan J W. Introduction to Modern Liquid Chromatography. 3rd ed. Hoboken: Wiley, 2010: chapter 6.
Snyder, Kirkland & Dolan, Introduction to Modern Liquid Chromatography, 3rd ed., Wiley, 2010, ch. 6.
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL3295048W：Introduction to modern
#反相液相色谱 #洗脱强度
范第姆特方程中的涡流扩散、纵向扩散与传质阻力三项如何共同解释塔板高度随流速变化的典型曲线形状？
How do the eddy-diffusion, longitudinal-diffusion, and mass-transfer terms of the van Deemter equation together explain the typical shape of the plate-height-versus-flow-rate curve?
H = A + B/u + Cu：A 由填料粒径分布与流道不均匀性决定，与流速无关；B/u 在低流速下占优，溶质沿柱轴的纵向扩散把谱带拉宽；Cu 在高流速下占优，固定相内外传质跟不上流动相导致峰展宽。三项叠加使 H-u 曲线呈开口向上的双曲形，最低点对应最佳线速度，而实际方法常选稍快流速换取更短的分析时间。亚 2 微米填料同时缩小 A 与 C 项，这正是 UHPLC 能在高线速下保持柱效的原因。
H = A + B/u + Cu sums three band-broadening channels: A reflects eddy diffusion set by particle-size spread and bed irregularity and ignores flow rate; B/u dominates at low velocity where solutes diffuse longitudinally along the column; Cu dominates at high velocity because equilibration between mobile and stationary phases cannot keep pace. Their superposition bends the H-u plot into an upward-open hyperbola whose minimum marks the optimum linear velocity, although practical methods often run slightly faster to trade a little efficiency for shorter runs. Sub-2-micron packings shrink both the A and C terms, which is precisely why UHPLC holds its efficiency at high linear velocities.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
van Deemter J J 等，纵向扩散与传质阻力作为色谱非理想性的成因，Chemical Engineering Science，1956 年第 1 卷
J. J. van Deemter, F. J. Zuiderweg, A. Klinkenberg, Longitudinal Diffusion and Resistance to Mass Transfer as Causes of Nonideality in Chromatography, Chemical Engineering Science, vol. 1, p. 271 (1956)
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.1016/0009-2509(56)80003-1：Longitudinal di
#分离科学 #色谱理论
色谱分离的基本原理是什么？
What is the basic principle of chromatographic separation?
混合物各组分在固定相与流动相之间的分配（吸附、溶解度或亲和力）不同，迁移速度有别而得以分离。例如气相/液相色谱按保留时间区分组分，薄层色谱按比移值 Rf 区分。
Components of a mixture partition differently between stationary and mobile phases (by adsorption, solubility, or affinity), so they migrate at different rates and separate. GC/HPLC resolve by retention time; TLC by the Rf value.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#色谱 #固定相 #分离
浮选是怎么把矿石和石头分开的？
How does flotation separate ore from rock?
气泡黏附疏水的矿粒让它上浮、亲水的脉石沉底，靠捕收剂调控表面性质来分选。
Bubbles stick to hydrophobic mineral particles and float them up while hydrophilic gangue sinks, separated by collectors tuning surface properties.
难度 入门 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#浮选 #捕收剂 #选矿
为什么海边能晒出食用盐？
Why can edible salt be sun-dried by the sea?
海水引入盐田，日晒风吹使水蒸发，NaCl先达到饱和结晶析出，与氯化镁等杂质分离，是中国自古的制盐法。
Seawater in salt pans evaporates; NaCl crystallizes first at saturation, separating from MgCl2 etc.—an ancient Chinese salt-making method.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#晒盐 #蒸发 #结晶
验孕试纸为什么一条线没怀、两条线怀了？
Why does one line mean not pregnant and two lines mean pregnant?
试纸用免疫层析捕获尿液中的妊娠激素(hCG)，出现第二条线代表检测到了该物质，即很可能怀孕。
The strip uses lateral-flow immunoassay to capture the pregnancy hormone (hCG); a second line means hCG was detected, i.e., likely pregnant.
难度 入门 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#验孕 #免疫层析 #hCG