分析测试数据的表示方法

目前随着概率理论在误差原理方面的引用,分析测试数据的处理方法和表示形式,对于测定中的偶然误差,即偶然因素影响的数字特征,已普遍使用算术平均(?)描述数据的集中     

提高高聚物化学分析结果准确度的方法

从分析方法、分析过程、仪器与试剂、实验环境条件、试样组成的变动性、试样中被测组分分布的不均匀性等方面分析了高聚物材料化学分析结果的误差来源,提出了提高高聚物化学分析结果准确度的方法。     

用数理统计知识探讨分析化学中的数据处理问题

在分析化学中,误差及分析数据处理是分析化学中的基础知识,而在许多教材中这方面知识给得比较直接、比较简单。本文从数理统计的角度出发详细地解释一些基本概念和具体地推导一些公式,并以数理统计方法解决分析化学中的一些常见问题作为对比。     

以化学定量实验为载体促进学生策略性知识的构建

化学定量实验是以定性实验为基础的研究活动,有利于培养学生严谨务实、认真规范的科学精神,有利于培养学生分析问题、解决问题的能力。通过定量实验的探究可以引导学生构建方案设计、简约表征、误差分析、实验创新等方面的策略性知识。     

对单电子近似方法的介绍

介绍单电子近似的引入、处理方法和改进,并分析了单电子近似带来的误差（相关能效应）和校正误差的方法。     

滴定分析中误差正负判断的新方法

滴定分析中的误差有正有负。通常情况下,在进行误差分析时,把引起误差的各种因素转化为消耗的滴定剂的体积变化,再来确定最后分析结果误差的正负。使用该法时,一般要进行变量转换,学生时常出错。本文介绍的方法是：先列出待测结果的计算公式,再找出公式中存在问题（即有偏差）的代入项,比较其与真实值（或有效值）的大小,最后由公式判定待测结果误差的正负。学生用此方法判断滴定分析中误差的正负,结果快速而准确,展示了该方法的实效性。     

离子色谱法测定固体样品中杂质离子的样品处理方法

离子色谱法(IC)是20世纪70年代发展起来的一项液相色谱技术,主要用于水溶液中阴、阳离子或离子型化合物的分析,是分析阴离子的首选方法。对于微量成分的测定来说,随着仪器的灵敏度、精度和自动化程度的不断提高,耗时、繁琐和容易引入误差的样品前处理成为分析过程中的一个难点。在样品前处理方面,针对不同的样品采用相应的样     

纳氏试剂比色法测定水中氨氮的干扰分析

就实验过程中的各种干扰来源及带来的误差进行了分析,并着重对絮凝沉淀法带来的误差及误差消除进行了研究。     

土壤中铅的测量不确定度的评定

对依次用盐酸、硝酸、氢氟酸和高氯酸消解土壤样品后直接用火焰原子吸收分光光度法测定土壤中铅含量的过程,从标准溶液、样品称量、消解、定容、校正曲线和分析仪器等方面分析误差来源,计算求得合成相对标准不确定度为4．6％,扩展不确定度为9．2％。     

化学反应摩尔焓变测定实验中误差原因分析教学反思*

化学反应摩尔焓变测定是大学化学(普通化学)实验中的经典实验,实验数据的误差原因分析是该实验的教学目标之一。对724名学生的实验报告中误差产生原因相关数据进行了回顾性分析,通过对实验报告列举的误差按来源与性质进行分类汇总,总结归纳了学生对该实验误差认知的特点,指出其分析思路受教材或教师讲解影响较大,反思通过强化学生证据意识和推理逻辑来提高该实验误差分析能力。     

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。     

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.     

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。     

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。     

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。     

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.     

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.     

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.