明确概念的思维方法及其应用示例

简要介绍了概念的有关知识和方法,包括概念的内涵与外延,概念的限制、划分、分解以及定义等,指出一些化学教科书中存在的划分不恰当、定义不准确等问题,并给出合乎思维规则的划分和定义。     

反应速率控制步骤定义的更新

一、引言反应速率控制步骤的概念在连串反应中得到广泛的应用,它是一个化学动力学中的重要基本概念。然而,对什么是反应速率控制步骤,近年来在教科书和杂志上曾出现各种定义及修正;在叫法上亦存在着速率     

催化反应中休眠期与诱导期之区别

许多化学反应中都存在一个被定义为"诱导期"的起始反应速率较低的阶段，例如一些自由基反应、放热反应和催化反应。与之相比，在极少数的催化反应中研究者观察到一个反应速率始终为零的特殊阶段，在这个阶段之后反应自发开始。这两种阶段形成的原因与反应的机理尤其是催化剂的活化和失活有关。然而，这两个具有明显不同特征的阶段往往被混淆。本文通过所选取的一些代表性的催化反应分别介绍了"诱导期"和"休眠期"的动力学特征，讨论了两者之间的区别。期待这些隐藏在稳态催化循环之前的阶段能够得到更多的关注，这将有利于研究人员深度理解有机化学反应中的前催化循环和详细的反应机理。     

美国高中化学教科书中氧化还原反应图片设计分析

统计了美国高中化学教科书《化学：概念与应用》中氧化还原反应的知识内容所包含的图片类型，分析研究其作用，同时针对我国化学教科书图片设计提出了建议。     

化学社会课程资源开发及教学范例——水的净化与水资源保护

课程资源逐步走向开放化、共享化和社会化，社会已成为实施教育教学活动的重要场所。以"水的净化与水资源保护"主题内容为教学范例，提出了化学社会课程资源开发的思路和教学实施流程：在"前置学习"中通过社会课程资源的亲身实践，把化学的课堂延伸到社会领域；在"展示分享"中将获取的有效资源与课堂学习关联，实现知识与生活的有效链接；在"整理评价"中完成知识建构和巩固过程，让学生感受真实、有用的化学。     

Rasch模型在“化学键”概念教学评价中的应用研究

运用Rasch模型探查高二学生对"化学键"概念的认知情况，运用Conquest软件和Winsteps软件对测试结果进行分析。结果表明：基于Rasch模型编制的测试卷能客观有效地检测学生对"化学键"概念的理解，为一线教师的有效教学提供学情基础。     

医用有机化学波谱分析绪论部分的教学研究

概述了问题导向式的研究型教学设计在医科院校"医用有机化学"课程中有机波谱分析章节的应用情况。该部分内容具有学生"难学" "难考" ，教师"难教"的教学特点。基于此，通过层层设问、循序解答的授课方式，结合丰富的应用示例，进行有机波谱分析核心概念（绪论）的理论教学。结果表明，该教学方法可有效提高学生学习兴趣，降低学习难度，使学生在有限的学时内掌握有机波谱分析的基础理论与核心概念，为后续识谱、解谱能力的培养夯实基础。     

我国高中化学教科书中习题的变迁

通过对清末至今我国出版的高中化学教科书中习题的整体梳理和样本研究,发现其变化存在一些特点：它是逐步变为教科书的必要组成的,且数量增长呈折线形;其位置从集中在书后,逐步变为分散在知识内容当中;题目类型越来越丰富;习题的内容不断注重实验过程和情境应用,并逐渐注重价值导向。这些变化反映了教育理念的变迁,为今后教科书习题的编写与使用提供了思路。     

通过实验探究建构科学规律的教学——以“温度、压强对化学平衡的影响”为例

介绍了"温度、压强对化学平衡的影响"的教学设计思路，展现了如何利用丰富的实验素材来帮助学生建立温度、压强的影响规律。主要涉及2个环节：（1）通过探讨3种不同特点的平衡体系在冰水和热水浴中的变化过程，帮助学生打破温度影响因素的迷思概念，建立科学规律；（2）通过分析手持技术表征出的汽水平衡和NO₂平衡移动过程中压强的变化特点，帮助学生建立压强的影响规律。     

酸碱滴定：滴定剂液滴尺寸与滴定突跃

存在滴定突跃是滴定分析可以进行的先决条件。国内教科书讨论突跃范围的概念时均利用了滴定分数100±0.1%的条件,即按照滴定分数99.9%和100.1%来计算突跃范围。实际上,滴定过程中滴定剂是以液滴为单位加入到被测溶液中的,指示剂滴定法中也是以一滴或半滴标准溶液加入后被测溶液颜色发生改变来确定终点的,因此,按照化学计量点前后欠缺或过量半滴标准溶液来计算突跃范围更具科学性和实用价值。本文将计量点附近单滴滴定剂加入被测溶液引起的p H变化定义为突跃范围。对强碱滴定一元强酸体系的突跃范围进行了数学计算。结果表明,突跃范围与被测溶液的体积和浓度、滴定剂的浓度和液滴尺寸、被测溶液和滴定剂的浓度比等因素都有密切相关性,给出了不同于教科书的某些重要结论,这些新结论与实际滴定情形相符,对指导滴定分析具有重要参考价值。     

国内光催化研究进展简述

分1975~1985, 1985~1995和1995~2012三个时期简要介绍了国内光催化研究进展, 主要侧重于光催化材料及其改性、应用和反应机理方面的研究进展, 并指出了当前光催化领域存在的一些重要问题和未来的发展趋势, 涉及到光解水、CO₂还原、环境净化和选择性有机合成等方面.     

青蒿素研究进展

青蒿素是目前治疗疟疾的特效药。本文对自青蒿素发现以来的最新研究进展进行了比较详尽的综述。内容包括: 青蒿素的发现及历史, 青蒿素的来源, 青蒿素的全合成,青蒿素的生物合成, 青蒿素衍生物以及植物组织培养生产青蒿素。     

Reactions in droplets in microfluidic channels

Fundamental and applied research in chemistry and biology benefits from opportunities provided by droplet-based microfluidic systems. These systems enable the miniaturization of reactions by compartmentalizing reactions in droplets of femoliter to microliter volumes. Compartmentalization in droplets provides rapid mixing of reagents, control of the timing of reactions on timescales from milliseconds to months, control of interfacial properties, and the ability to synthesize and transport solid reagents and products. Droplet-based microfluidics can help to enhance and accelerate chemical and biochemical screening, protein crystallization, enzymatic kinetics, and assays. Moreover, the control provided by droplets in microfluidic devices can lead to new scientific methods and insights.     

Interpretation of inorganic arsenic metabolism in humans in the light of observations made in vitro and in vivo in the rat

The toxicity of inorganic trivalent arsenic for living organisms is reduced by in vivo methylation of the element. In man, this biotransformation leads to the synthesis of monomethylarsonic (MMA) and dimethylarsinic (DMA) acids, which are efficiently eliminated in urine along with the unchanged form (As_i). In order to document the methylation process in humans, the kinetics of As_i, MMA and DMA elimination were studied in volunteers given a single dose of one of these three arsenicals or repeated doses of As_i. The arsenic methylation efficiency was also assessed in subjects acutely intoxicated with arsenic trioxide (As₂O₃) and in patients with liver diseases. Several observations in humans can be explained by the properties of the enzymic systems involved in the methylation process which we have characterized in vitro and in vivo in rats as follows: (1) production of As_i metabolites is catalyzed by an enzymic system whose activity is highest in liver cytosol; (2) different enzymic activities, using the same methyl group donor (S-adenosylmethionine), lead to the production of mono- and di-methylated derivatives which are excreted in urine as MMA and DMA; (3) dimethylating activity is highly sensitive to inhibition by excess of inorganic arsenic; (4) reduced glutathione concentration in liver moderates the arsenic methylation process through several mechanisms, e.g. stimulation of the first methylation reaction leading to MMA, facilitation of As_i uptake by hepatocytes, stimulation of the biliary excretion of the element, reduction of pentavalent forms before methylation, and protection of a reducing environment in the cells necessary to maintain the activity of the enzymic systems.     

Recent Advances in Analytical Methodology for in vivo Electrochemistry in Mammals

Electrochemistry is one of the most advanced techniques for monitoring neurochemical activities in the living brain because electrochemical approaches bear the advantageous features of high spatial and temporal resolutions, which facilitate its tremendous potential in investigating the highly spatially heterogeneous brain system and the fast dynamics of neurochemical activities. On the other hand, since brain is the most complicated organ in the sense of its numerous kinds of neurochemical species, high selectivity is always required for any analytical methods that approach the brain. In this review, we will discuss various electrochemical methodologies to achieve selective detection of neurochemicals in mammalian brain and the strategies developed mainly by our group towards selective monitoring of both electrochemically active and inactive neurochemicals. At the end, we will discuss possible solutions towards brain mapping of neurochemical species and combination of neurochemical detection strategy with electrophysiology as the direction of future development of electroanalysis in living brain.     

乙基香兰素研究前景

报导了近几十年来国内外关于乙基香兰素的研究进展与动态,并简单介绍了本文作者在该方面所取得的研究成果,参考文献33篇。     

Gemini表面活性剂合成进展

系统总结了近百种Gemini表面活性剂的合成路线和方法,并且按照其结构特点分门别类地进行比较和归纳,对今后Gemini表面活性剂的合成发展方向提出了一些看法,这对促进此类新颖表面活性剂的工业化进程将具有指导意义。     

钙与人体及临床

钙是宏量元素，是人体中含量较高的元素之一，体内99％的钙构成骨骼和牙齿以及维持骨骼结构，1％的钙调节人体重要生理功能。钙的含量过高或过低都与许多疾病有关，只有保持一种平衡状态，才能使机体处于正常环境。     

Trends in education in analytical chemistry

Summary At the session of the WPAC of Fechem on education in analytical chemistry it was concluded that it is now essential to include chemometrics and basic knowledge of computers in all courses on analytical chemistry.

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Tendenzen in der analytisch-chemischen Ausbildung

Zusammenfassung Bei einer Tagung der WPAC über die Lehre auf dem Gebiet der analytischen Chemie wurde bei der Betrachtung neuer Aspekte festgestellt, daß vor allem Chemometrie und Grundkenntnisse in Computertechnik in die Ausbildung aufgenommen werden sollten.

     

AGET ATRP in the Presence of Air in Miniemulsion and in Bulk

Summary: The recently developed initiation system, activators generated by electron transfer (AGET), is used in atom transfer radical polymerization (ATRP) in the presence of a limited amount of air. Ascorbic acid and tin(II ) 2‐ethylhexanoate are used as reducing agents in miniemulsion and bulk, respectively. An excess of reducing agent consumes the oxygen present in the system and, therefore, provides a deoxygenated environment for ATRP. ATRP of butyl acrylate is successfully carried out in miniemulsion and in the presence of air. During polymerization the radical concentration remains constant. The polymerization reaches over 60% monomer conversion after 6 h, which results in polymers with a predetermined molecular weight = 14 000 g · mol⁻¹ and a low polydispersity ( = 1.23). AGET ATRP of styrene is also successful in bulk in the presence of air, as evidenced by linear semi‐logarithmic kinetics, which leads to polystyrene with an of 13 400 g · mol⁻¹ and a low polydispersity index ( = 1.14).

Appearance of miniemulsion before and after the reducing agent ascorbic acid was added (left); and GPC traces representing molecular weights during the AGET ATRP of BA in miniemulsion in the presence of air (right).