巧做点铜变“银”,点“银”变“金”实验

本文介绍一个简单而有趣味 ,又紧密联系中学有关化学知识的实验 ,让学生看到点铜变“银” ,点“银”变“金”的奇妙变化。1　实验步骤取一 1 0 0ｍＬ的小烧杯 ,盛约 3ｇ的锌粉 ,加入2 0ｍＬ水 ,无明显现象。再加入 4ｇ氢氧化钠固体 ,用玻璃棒搅拌 ,氢氧化钠溶解 ,溶液温度有所升高 ,有少量气泡产生。将一用砂纸擦光的紫红色铜片放入烧杯的溶液里 ,并与锌粉充分直接接触 ,片刻 (2至 3ｍｉｎ)后可见紫红色的铜片慢慢变为银白色 ,后来整块铜片变成为银白色的“银”片了。取出银白色的“银”片 ,用水清洗 ,擦干 ,“银片”银光闪闪 ,很好看。用镊…     

Simple,Versatile, Pseudo “Double Beam” Photoacoustic Spectrometer

Abstract

We describe in this paper a “pseudo-double beam” photoacoustic spectrometer using a wide aperture monochromator (F/2) and a very sensitive cell. The double signals required to get the normalized value, i.e., the sample signal and a carbon black reference signal, are obtained by a slow (1.7 Hz) alternating movement of the two cells support, the sample and the reference being alternately placed at the focus point of the beam which is fixed in space and time. The modulation of the light flux is independently ensured by a mechanical chopper. Such an original device associates good performances in resolution (0.7 nm), signal-to-noise ratio (1200 for HO₂O₃ at 450 nm with a 5 nm bandwidth) and normalization in a wide spectral range.     

Chain reactions, “impossible” reactions,and panenmentalist possibilities

Panenmentalist possibilities are individual pure possibilities existing independently of any mind, actual reality, and possible-world conception. These possibilities are a priori accessible to our intellect and imagination. In this paper, I attempt to shed some panenmentalist light on the discovery of chemical branched chain reactions and its implications on biology and cancer research. I also examine the case of the Belousov–Zhabotinsky reaction which, at first, was believed to be impossible. Finally, I proceed to examine through a panenmentalist lens Szilard’s discovery of the possibility of physical chain reactions and Mullis’s discovery of a polymerase chain reaction. All these major actual discoveries clearly depend on the discovery of the relevant panenmentalist possibilities and the ways in which they relate to one another.     

“主—客体化学”,超分子化学“与多相催化”

美国加州大学洛杉矾分校的克拉姆(Don—ald James Cram)教授和法国路易·巴斯德大学的莱恩(Jean—Marie Lehn)教授由于分别创立了“主—客体化学”(Host—Guest Chemistry)和“超分子化学”(Supramolecular Chemistry)而荣获1987年的诺贝尔化学奖。克拉姆的“主—客体化学”的基本思想是:具有显著“识别能力”的某些冠醚     

Humphry Davy: Analogy,Priority, and the “true philosopher”

This essay explores how Davy fashioned himself as, what he called in his poetry, a “true philosopher.” He defined the “true philosopher” as someone who eschewed monetary gain for his scientific work, preferring instead to give knowledge freely for the public good, and as someone working at a higher level than the mere experimentalist. Specifically, Davy presented himself as using the method of analogy to reach his discoveries and emphasised that he understood the “principle” behind his findings. He portrayed himself as one who perceived analogies because he had a wider perspective on the world than many others in his society. The poem in which he describes the “true philosopher” offers us Davy’s private view of this character; the essay then demonstrates how Davy attempted to depict his own character in this way during critical moments in his career.     

实行“边讲边实验”教学法,如何解决“准备实验”的问题

最近,很多学校都学习苏联先进经验,实行了“边讲边实验”教学法。这种方法具有很多优点,受到广大学生的热烈欢迎;这种方法对提高教育质量、培养学生实验技能技巧,贯彻基本生产技术等方面,都起着重要的作用。但是,突行这种教学法也存在着一些困难,最大的困难就是准备实验的问题。因为实行“边讲边实验”,教学法,在每节课差不多都有学生实验。而且学生实验要分25组以上进行,(每两人一组。如果人多了做实验时学生就要离开座位,影响课堂秩序)每一个班就要准备25份以上的仪器,药品。如果一天有三个班上课,突验的准备工作就成了大问题。最初,我们学校既没有实验室管理员,又没有供讲     

Editorial board page for “Analytical Letters”, Volume 9, Number 9

Abstract

This is a scanned image of the original Editorial Board page(s) for this issue.     

Editorial board page for “Analytical Letters”, Volume 3, Number 3

Abstract

This is a scanned image of the original Editorial Board page(s) for this issue.     

Determination of some cathinones,tropane alkaloids,and “pharmaceutical narcotics” in urine

A procedure is proposed for determining some narcotic and psychoactive substances (cathinones, tropane alkaloids, derivatives of ?-aminobutyric acid) in urine, including sample preparation and the determination of analytes by HPLC coupled with electrospray ionization tandem mass spectrometry. Sample preparation involved acid hydrolysis or the dilution of the sample. The lower limit of quantification is 200 pg/mL; the limit of detection is 100 pg/mL; and the calibration curves are linear in the range 0.2–50 ng/mL. The procedure was tested on real samples provided by the Toxicological Department of the Krasnodar Regional Narcological Dispensary. The high sensitivity of the analytical system ensures its use for the determination of narcotic preparations within a certain time after their intake, which may be of particular importance for forensic examinations.     

“Multitracer” a new tracer technique — Its principle,features, and application

We established Multitracer, a new versatile radiotracer technique, for simultaneous tracing of a number of elements in various chemical, environmental, and biological systems. Metal foil targets (typically Au, Ag, Ge, Cu and Fe) are irradiated with C, N, or O ions accelerated up to 135 MeV/nucleon by RIKEN Ring Cyclotron. Radiochemical procedures have been developed to remove the target material leaving the nuclides as Multitracer solutions containing various radionuclides of Be, Na, Mg, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Br, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Te, I, Ba, Ce, Pm, Eu, Gd, Tb, Tm, Yb, Lu, Hf, W, Re, Os, Ir, Pt, and Hg. Multitracers enable efficient tracing of a number of elements, and comparison of their behavior under strictly identical experimental conditions. Such features will be demonstrated by means of an example of application to a model experiment for the study of removal mechanism of various elements from the ocean.     

Scientific session “Chernobyl and scientific problems (radiobiology,radioecology, sociology)”

Information Congresses, Conferences, Symposia, Meetings, and Seminars held with the Participation of the Russian Academy of Sciences

Scientific session Chernobyl and scientific problems (radiobiology, radioecology, sociology)     

“两极互补”和“相似者相容”原理在生物,药物作用中的体现

“两极互补”和“相似者相容”原理在生物、药物作用中的体现１９９５－０６－１２收稿，１９９６－０３－２５修回杨频（山西大学分子科学研究所，太原０３０００６１两极互补原理和相似者相容原理矛盾双方的对立统一是宇宙间最根本的规律之一［１］，我国古代的太极图（...     

Synthesis,structure and isomerism of “three-bridge” exo-nido-osmacarborane clusters

The reaction of OsCl₂(PPh₃)₃ with [nido-7-R¹-8-R²-C₂B₉H₁₀]K⁺ produced a series of new exo-nido-osmacarborane complexes exo-nido-5,6,10-[Cl(Ph₃P)₂Os]-5,6,10-(-H)₃-10-H-7-R¹-8-R²-7,8-C₂B₉H₆ (1: R¹ = R² = H; 2: R¹ = R² = Me; 3: R¹ = R² = PhCH₂; 4: R¹ + R² = 1,2-C₆H₄(CH₂)₂; 5: R¹ = H, R² = Me) in which the osmium-containing group is linked to the nido-carborane ligand through three two-electron three-center bonds. Compounds 1—5 are formed as mixtures of symmetric (a) and asymmetric (b) isomers; pure symmetric isomers 2a and 4a were isolated by fractional crystallization, and the mixture of isomers 3a, was quantitatively separated into individual compounds 3a and 3b by column chromatography on silica gel. Detailed analysis of the ³¹P{¹H}, ¹H, ¹¹B NMR spectra of 1a,b—5a,b and 2D ¹H-¹H{¹¹B} and ¹¹B{¹H}-¹¹B{¹H} NMR spectra of 3a and 3b was performed. The structures of isomers 2a and 4a were confirmed by an X-ray diffraction study. According to the NMR and X-ray diffraction data, the isomerism of exo-nido-complexes 1a,b—5a,b is actually the cis—trans-isomerism of ligand arrangement in the octahedral coordination of the Os atom.     

建立高端仪器标准,发力“中国制造2025”

<正>为认真落实《中国制造2025》中明确的制造业标准化提升计划,国家标准委近日制定4个重点工作,明确标准制定任务,为"中国制造2025"发力。其中,以研制智能传感器、高端仪表为重点项目。国家标准委还将加快标准创新研究基地建设,积极发挥已批准筹建中关村、华南中心、广州等3个国家技术标准创     

在“旋光异构”教学中,加强基本概念初探

立体化学是现代有机化学的重要内容。部颁大纲规定,在基础有机中学习立体化学的任务是“初步掌握立体化学的基本知识和基本理论”。就其内容而论,重点是静态立体化学(即分子在基态时的立体异构现象),动态立体化学(即反应过程中,分子运动变化中的立体化学)仅是初窥门径。为了让学生明确学习立体化学的目的,我们举出一些生产和生活实例来说明旋光异构现象的普遍性,藉以说明没有立体化学也就没有有机化学的今天。     

学习“三个面向”指示,进一步搞好化学教研工作

我们宁波市有市、县二级化学教研员共十人,在各级教育行政部门直接领导下,在省有关部门指导,支持下,近几年来在深入开展化学教研工作方面做了一些工作。     

快检设备迅速崛起,食品安全不再“纸上谈兵”

<正>民以食为天,食以安为先。食品安全是人们身体健康和生命安全最基本的保障,必须加强检查、严格监督。一些不良企业利益熏心,为了谋求暴利,不顾消费者的生命安全,添加过量的食品添加剂、浸泡有毒物质、生产假冒伪劣食品,依靠一切不良手段,向消费者出售一些不安全食品,给人们的身体健康造成极大威胁。     

“Anhydrolycaconitine”, a new diterpene alkaloid fromAconitum septentrionale K

A new alkaloid, anhydrolycaconitine (C₃₆H₄₆N₂O₉), was isolated from roots ofAconitum septentrionale K. Based on the results of¹H and¹³C NMR and IR spectroscopy and mass spectrometry of the alkaloid and the product of its alkaline hydrolysis and on the data of X-ray diffraction analysis of the hydrolysis product, the structure of 1α, 6β, 14α, 16β-tetramethoxy-7-oxo-18-succinylanthranoyloxy-17-(7→8)abeo-aconane was assigned to anhydrolycaconitine. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1640–1644, September, 2000.     

“Meta Elimination,” a Diagnostic Fragmentation in Mass Spectrometry

The diagnostic value of the “ortho effect” for unknown identification by mass spectrometry is well known. Here, we report the existence of a novel “meta effect,” which adds to the repertoire of useful mass spectrometric fragmentation mechanisms. For example, the meta-specific elimination pathway described in this report enables unequivocal identification of meta isomers from ortho and para isomers of carboxyanilides. The reaction follows a specific path to eliminate a molecule of meta-benzyne, from the anion produced after the initial decarboxylation of the precursor. Consequently, in the CID spectra of carboxyanilides, a peak for the (R-CO-NH)^– anion is observed only for the meta isomers. For example, the peaks observed at m/z 58, 86, 120, 128, and 170 from acetamido-, butamido-, benzamido, heptamido-, and decanamido-benzoates, respectively, were specific only to the spectra of meta isomers.