开放性 探究性 实践性——在化学教学中实施研究性学习的实践

研究性学习的特点是开放性、探究性、实践性。它们是一个完整的整体,但在课堂教学、实验教学、化学活动等不同形式的化学教学活动中,又有所侧重。我结合新教材的使用,在近年的化学教学中开展研究性学习,主要采取了以下方法。     

乙二酸受热分解的探究性教学

1主题与背景《普通高中化学课程标准(实验)》指出:有效的化学学习活动,不能单纯的依赖、模仿与记忆。动手实践,自主探索与合作交流是学生学习化学的重要方式。在新课程理念下,我们必须改革课堂教学,把思考还给学生,让学生成为课堂的主人。在课堂实践中尝试让学生进行探究性学习     

自主探究性虚拟化学实验设计——以碱金属化学性质探究为例

自主探究是一种重要而有效的学习方式,化学实验则是进行自主探究的重要途径。国内已有的虚拟实验还存在自主性与开放性不足、操作过程线性化等缺点。笔者结合探究性学习的特点,设计完成了自主性、开放性较高的自主探究性虚拟实验,实现了“问题-探究-结论-问题-再探究”的开放式学习过程。阐述了自主探究性虚拟实验的设计理念并以碱金属为例详细介绍了自主探究性虚拟实验的设计。     

在垃圾分类中寻找化学元素*——基于生活情境的探究性学习

介绍一个结合4种教学策略(情境教学、探究性学习、合作学习、混合式教学)面向非化学专业类大一学生开展元素化学教学的案例。以垃圾分类为主题,学生分组协作完成探究性学习任务,调查不同种类垃圾中存在的化学元素及其用途,通过线下课堂展示、线上成果共享以及校外推广等3项活动传播探究结论。对比活动前后收集的数据,活动前有75%的学生只认识原子序数前20的化学元素,活动后学生认识的元素数量明显增多,平均值是原来的1.7倍。元素中文名称与元素符号记忆混乱的情况得到改善。最后问卷调查表明活动提高了学生上课的积极性并且对了解生活中的化学元素有帮助。     

化学新教材探究性学习策略的思考——以"化学反应中的能量变化"一节的教学为例

以“化学反应中的能量变化”一节课的教学案例为载体,阐述了如何创设真实的问题情景和建构性的学习过程,在探究性学习过程中培养学生的高级认知能力、创新精神与实践能力以及通过对知识的深刻理解和学以致用,培养学生终生学习化学的兴趣和能力。     

高中新课程下化学探究性实验教学初探

高中新课程从2006年秋季开始在我省全面启动,本文从厦门市中学课改现状及探究性实验在新课程的重要性出发,在对各种版本的化学教材认真研读的基础上,探讨了分层次、多角度设计探究性实验的教学思路及创设体现实验“开放性、研究性”的实验环境的几点做法。     

化学探究性实验活动表现评价的设计探讨

活动表现评价是新课程改革倡导的一种新型的评价方式。本文对化学新课程中探究性实验的一般程序、内容选择、活动表现评价的方法、工具设计和成绩评定等方面进行了探讨。     

例谈化学探究性教学中有效问题的设计

针对新课程倡导的探究性教学的有效性和促进学生认识发展,提出了化学探究性教学的有效问题设计要体现课程目标、贴近学生的知识经验和关注教学生成性资源,并结合课堂观察和教学案例进行了初步的分析与探讨。     

高中化学探究性实验设计一例——含磷洗衣粉对水藻生长的影响

结合高中新课程教科书,设计高中化学探究性实验——含磷洗衣粉对水藻生长的影响,通过实验原理、方法和具体实验过程得出结论,有效地促进了学生对化学知识的理解和掌握,培养学生实验设计和探究能力,达到知识、能力、情意目标。     

谈提问与实施探究性教学——使用普通高中新课程标准实验教科书进行探究性教学

针对普通高中化学课程使用新实验教科书时遇到的困难,本文从分析新、以往教材内容呈现方式的不同入手,提出在教学中运用提问的方式能够顺利地开展探究性教学.本文将提问的方式分为教师提问及学生自己发现问题,并结合化学教学中的实例,论述了如何运用提问的方式开展探究性教学.     

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。