为什么要对习题进行变式

习题变式之要义在于明确习题变式的教学立意。习题教学需要习题变式;只有将习题的变式承载正确合适的教学立意,才是有价值的;否则至少会导致习题教学的低效,甚至会沦为题海形成的帮凶。从教学立意的8个方面分析了习题变式,并进行了例证性说明。     

谈提高化学习题教学的效益

化学习题教学是化学教学内容的重要构成之一,是贯穿整个教学过程、落实学生能力培养的一条重要脉络,也是师生双向交流最广泛的教学活动之一。新颁布的《全日制中学化学教学大纲》,明确提出了“加强化学习题教学”的课题。当前,化学习题教学耗时多,效益不高。落实大纲的要求,加强化学习题教学,减轻负担,提高效益,是十分紧迫的任务。1. 应当重新认识化学习题教学的作用,扭转以题海应付考试的不良倾向。     

例谈化学习题教学与探究实验的整合

习题教学是化学教学的重要组成部分。但现今的习题教学存在着量大重复、教师讲评方法刻板、学生解决方式单一等缺点。有效整合习题教学与探究实验,可以提高习题教学的效率,更好促进学生发展。     

人教版高中化学新教材习题系统的分析及教学建议

新课标教材习题系统应包括课文习题与课后习题。高中化学新教材（人教版）习题系统与课文内容相互融合,体现科学探究,题型多样化,问题情境化,语言人性化。在化学教学中应转变观念,重视教材习题系统的教学功能;注重习题的情境性;加强习题的联系,重视变式训练。     

高中化学习题教学中变式探究学习模式的研究

习题教学是高中化学教学的重要一部分,目前对于习题教学的研究仍很薄弱,而针对课程改革而采用的教学模式更是少之又少,针对这一现状介绍了一种合理的习题教学模式及特点。     

研究化学习题 发挥习题的教学作用

化学习题是教材的组成部分,做习题是教学过程的一个重要环节,也是巩固教学效果的重要手段。习题的作用在于巩固“双基”,培养智力,发展能力。只有通过选（布置）习题对学生发出信息和做题,改题接受反馈的信息,教师才能对习题的教学作用作出客观的评价。当前存在对外来习题不选不用和滥选滥用的两种倾向,尤其是后者会加重学生负担,影响身心健康和教学质量的提高,因此研究化学习题,改进习题教学充分发挥习题的教学作用是当今教学改革亟待探索的课题。     

美国化学教材《化学与社会》习题的特点及启示

教材习题的设计对实施有效教学起着重要的作用。美国化学教材《化学与社会》中习题的设计反映了当代美国化学教材习题的编写理念,分析研究教材在习题数量、习题分布、习题内容与信息技术的关联等方面的特点对我国化学教材习题的设计具有重要的借鉴价值。     

三种高中化学新教材（必修）的习题分析和教学建议

本文对人教版、苏教版、山东科技版三种高中化学教材(化学1、化学2)的各章节习题的类型做了归纳和对比,从习题形式、习题与课标的关联、习题功能等方面进行分析,表明了作者对高中化学新课标和新教材习题教学的几点建议。     

发挥习题课的作用 培养学生能力

说起习题,容易使人联想到“题海战术”,其实谁都知道“题海战术”要不得,但化学教学又绝对离不开化学习题,如何不搞“题海战术”而又能充分发挥化学习题在化学教学中的重要作用很值得我们化学教师去研究。我们在摒弃“题海战术”的同时,要以精心设计的习题课为引导,使学生通过做化学习题更全面地培养能力。     

高中生对化学教科书习题的态度和评价的调查研究

以人教版高中化学教科书(必修)为例,调研了高中生对化学教科书习题的态度及评价。研究表明,学生不够重视教科书习题;学生根据教师要求及兴趣有选择地做教科书习题;学生认为教科书习题的题量、难度适中,但题型偏少,趣味性不够,功能不够突出。师生应转变观念,重新认识教科书习题的教学功能;教科书习题编制要考虑学生兴趣和需求;要为教科书习题的有效实施建立配套资源。     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

物质分配系数的测定实验改进

实验教学目的是从解决实际问题出发,以实验技术训练和实验设计思想培养为目标。介绍了将单一的物质分配系数测定实验改进为综合实验,提高了实验效果及实验资源利用率。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

Calculation of enthalpies of hydrogenation of hydrocarbons

Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。