化学复习应重在促进知识迁移

促进知识迁移是化学复习的一项重要任务。目前的化学复习 ,教师还是以大量的习题训练学生 ,重在知识的熟练。这种做法难以培养学生运用知识分析问题和解决问题的能力 ,应对能力立意的高考。化学复习应重在促进知识迁移以顺应时代发展要求。本文从在化学复习中应引导学生深刻理解知识、扩大知识的应用范围、培养学生的知识情境化意识和提高学生辨认情境中所含知识的能力等方面来探讨如何在化学复习中促进知识迁移。1　化学复习应引导学生深刻理解知识迁移是一种长期受到人们关注的心理现象 ,它的基本含义是 :在先前的学习 (或训练 )中获得的…     

“生命活动的物质基础”复习课教学与反思

利用"营养快线"饮料建构了"生命活动的物质基础"复习课,让学生体验食品中的化学,再到生活中的化学,最后到自然界中的化学,感悟化学是无处不在的。同时,在复习课教学中,利用化学实验手段、化学思维方式和化学符号向学生展示了化学学科特色,渗透了"化学观"教育,培养了学生的学科素养,在收获知识的同时提升能力。     

化学思想在高考中的体现与对学生复习的启示

化学思想是化学学科的灵魂。化学思想在高考中体现非常明显。通过分析化学思想,可以提高学生对于化学的理解,提高化学高考复习效率。     

宏观把握微观掌握──利用思维导图上好化学复习课

介绍了在化学复习课教学中,如何利用思维导图从课前、课中和课后3个阶段引导学生对知识进行系统化的整理,以形成知识体系,并从细节上把握各知识点的应用;同时探讨了思维导图在复习课教学方面的优势。     

引入源头活水激活高三化学教学

研究性学习能提高学生分析问题、解决问题的能力和创造能力,而高三化学的实际又决定了很难让学生开展研究性学习,本文探讨了如何将研究性学习融入到高三化学复习中,如何利用研究性学习优化高三复习、提高学生能力的一些做法。     

运用概念心理表征特点提高化学复习质量

做好化学基本概念的复习,教师必须了解学生对化学概念的掌握情况。教师要知晓化学概念的表征特点和学生在学习时的具体表征形式,才能在复习时有针对性地采用互补的表征方式、绘制化学概念图等策略,切实提高化学复习的效果。     

“关系式在初中化学计算中的应用”课例研究

基于《化学教育》等期刊文献和核心素养的研究成果,分析了关系式在初中化学计算中的地位和作用。通过“关系式在初中化学计算中的应用”课例,提出了高效复习的建议：要宏观认识复习课的目标和功能,帮助学生形成基本的化学观念、提高问题的解决能力、树立自信心。还应精心设计好各个微环节的活动,达到复习效益最大化。     

优化教学程序 提高高考化学复习的效度

从如何解读《考试说明》,严控高三化学复习的范围;如何研究近两年全国各地的高考试题,提高高三化学复习的针对性;如何捕捉学生的化学知识薄弱点与盲点;如何提高高三化学复习课的效度;如何狠抓“三化”,提高学生的答题效率与成功率等方面介绍了进行高考复习的成功经验。     

浅谈新课程标准下高三化学复习模式的构建

2003年3月,教育部颁发了《普通高中化学课程标准(实验)》。课程标准立足于学生科学素养的培养,着眼于学生未来的发展,体现了高中化学课程的时代性、基础性与选择性。笔者以新的化学课程标准作指导,在构建高三化学复习新模式方面作了初步尝试,收到了显著效果。1立足基础着眼应用     

高三化学复习中的“偏差”现象及防偏对策

高三化学复习的应遵循“高效性、有效性、针对性”的原则.本文重点结合镇江市的复习教学实践和所见所闻所思探讨复习中常见的3种偏差现象及防偏策略,以便更好地提高复习效率,进一步提升学生的化学素养.     

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.     

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.     

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。     

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。