中学化学有效数字教学建议

通过一则教学案例反映中学化学有效数字教学的薄弱,强调客观、正确、合理地使用有效数字是化学工作者必备的基础素质之一,探讨了学生不规范记录和处理数据的现象及原因,并提出相应的改进措施。     

移液管体积该是几位有效数字?

有效数字的概念及运算在分析化学中的重要性是不言而喻的.在滴定分析时,如用0.1008mol·dm~(-3)的NaOH标准溶液滴定HCl溶液,用移液管取25mI HCl溶液于锥形瓶中(这种语言屡见不鲜),滴定管读取消耗NaOH标准溶液的体积为18.65ml.计算HCl溶液的浓度时,就会出现算式18.65×0.1008/25学生直接按此式算出结果得0.07520,但是学生可能根据有效数字运算:     

分析化学中有效数字浅谈

在科学研究和生产实践中,往往接触到大量数据,这些数据为大家提供了非常有用的信息,可以帮助人们认识客观事物的内在规律性,是人类为进一步向客观世界作斗争中采取有效措施的重要依据。记录数据时,其所表示的准确程度应与所用测量仪器的精度相一致,有效数字保留几位是根据测量仪器的准确度来决定,一般应使测量的数据中只有最后的一位数字可疑,也就是除了末位之外,均为准确知     

称量和吸量操作中数据有效数字的讨论

理化检验中,通常要用天平和架盘天平称量物质,用玻璃量器吸量液体,并根据其精度,用有效数字准确记录下来。本文将对称量和吸量操作中数据有效数字进行探讨。 1 有效数字新见解 有效数字,是指在理化检验中,实际上能测定到的数字。它是可靠数字和可疑数字的总称。它的位数包括从左端非零数字开始的所有位数,除末尾一位是可疑外,其他各位都是准确的。通常把一般测量数据理解为在可疑数字上有±1或其下一位上有±5的误差。但由于所用天平、架盘天平和玻璃量器的允许误差在末     

浅谈环境水质分析结果的审核工作

对分析结果的有效数字和数据之间的合理性关系问题从理论上进行了研究,为数据审核工作提供科学参考。     

检测结果的数值修约和数据处理探讨

<正>数值修约和有效数字广泛应用于多个行业的分析方法标准[1-5]和检测结果数据处理[6-9]。检测数据不同于数学中的数字,它不仅要反映检测对象的大小,而且还要反映其精确程度[10]。在检测实验室,正确记录和科学处理检测数据不仅是计量认证和实验室认可有关准则的要求,同时也涉及检测结果的科学表达。因此,为了合理地取值和科学地计算,检测数据必须按照《数值修约规则与极限数值的表示和判定》及其它有关标准的要求进行处理。而在实     

有效数字在环境监测中的应用

对实验中常用的玻璃量具如单标线吸管、容量瓶、比色管、刻度吸管等进行分析,确定了直读式数据的读数规则及有效位数。如10mL单标线吸管有效数字位数为5位,而10mL刻度吸管随移取溶液体积不同其有效数字位数可能为2,3或4位。分析了环境监测中间接式数据的来源,如标准溶液的浓度、标准曲线的截距、斜率、样品最终浓度等,这些数据应当遵守一定的修约及运算规则,由此确定了间接式数据应当保留合理的有效位数。研究结果可以为环境监测人员开展实验及数据处理提供依据。     

物理化学理论课与实验课的融合教学模式探索

开展物理化学理论课与实验课相融合的教学。理论课教学过程中找准切入点融入实验原理,加深学生对知识的理解,调动学生的学习兴趣和求知欲,课堂气氛活跃,学生融入课堂并互动。实验课上引导学生学习实验设计思路与方法,提出严格的数据记录与处理要求,学生实验报告的逻辑性增强,可独立对实验结果进行讨论,能够正确分析实验误差可能的原因,对实验方案、方法和仪器可提出改进的意见和建议。通过理论课与实验课融合的教学模式可培养学生的逻辑思维能力和实践能力。该教学模式的实施需要学校和系部强有力的政策保障。     

做好教学笔记是实验教学的重要环节

实验教学是复杂、细致而艰巨的工作,几年来,我在有机化学实验教学中坚持做教学笔记,获益匪浅。一、教学笔记的内容教学笔记是实验教学活动的记录、分析和总结。所记载内容包括：1．准备实验的情况。包括实验器材准备中的注意事项、实验条件的探索、实验现象数据的记录,特别是对于异常实验现象的记录和分析。2．实验中出现的问题、处理措施及原因分析。3．对学生实验过程的观察和分析,对学生进行指导和教育的记录以及学生的反馈信息。4．实验教学的经验和教训。5．对实验内容改进和完善的意见。二、教学笔记的作用通过几年的教学实践,…     

第三届全国化学教育专题学术研讨会通知(第一轮)

在审稿过程中，发现不少作者对有效数字问题不够重视，数据表达不合理、不精确、不科学、不规范，显得随意、凌乱，这是不符合科学规范的。特整理相关规则，供大家参考，请大家在写文章时注意：     

分析化学有效数字教学中常见问题及分析

Analytical chemistry often involves a large amount of experimental data, and the reliability and accuracy of the experimental results are related to whether the original data can be properly recorded and calculated. In this paper, starting from the importance of significant figures, analyzing the frequently encountered problems related to the significant figures in teaching process, and giving some solutions, we try to help students to learn and master the concept of significant figures, rounding off numerical values, rule of operation and data processing.     

The applicability of the second-derivative method to room-temperature phosphorescence analysis

The use of the second-derivative (d²) technique to overcome some of the problems encountered in room-temperature phosphorescence analysis is investigated. Despite some reduction in the signal-to-noise values, the d²-technique was shown to be particularly suited to improving the selectivity of the assay. The utility of this method for applications in multicomponent mixture analysis is discussed. The two most significant figures of merit for room-temperature phosphorescence are the reduction of spectral overlap and the decrease of background interference.     

A new and efficient variable selection algorithm based on ant colony optimization. Applications to near infrared spectroscopy/partial least-squares analysis

A new variable selection algorithm is described, based on ant colony optimization (ACO). The algorithm aim is to choose, from a large number of available spectral wavelengths, those relevant to the estimation of analyte concentrations or sample properties when spectroscopic analysis is combined with multivariate calibration techniques such as partial least-squares (PLS) regression. The new algorithm employs the concept of cooperative pheromone accumulation, which is typical of ACO selection methods, and optimizes PLS models using a pre-defined number of variables, employing a Monte Carlo approach to discard irrelevant sensors. The performance has been tested on a simulated system, where it shows a significant superiority over other commonly employed selection methods, such as genetic algorithms. Several near infrared spectroscopic experimental data sets have been subjected to the present ACO algorithm, with PLS leading to improved analytical figures of merit upon wavelength selection. The method could be helpful in other chemometric activities such as classification or quantitative structure-activity relationship (QSAR) problems.     

中外合作办学中创新人才培养的化学实验教学探索与实践

The Sino-foreign educational cooperation program is one of the important forms of higher education in China. The innovation and exploration of teaching modes and methods were carried out to tackle problems in teaching inorganic and analytical chemistry laboratory at Beijing University of Chemical Technology. These problems can be found in logical thinking, combining basic theory with practice, and software used in treatment of experimental data. The teaching reform was carried out on the aspects of improving students' innovative consciousness, combining theory with the experiment, integrating ideological and political education into classroom, application of software in experimental data treatment, which will improve the subjective initiative and problem-solving ability of students in learning inorganic and analytical chemistry laboratories. It will lay a solid foundation for the students of international bioengineering class to successfully connect with foreign follow-up courses in the future.     

激光解吸/傅里叶变换质谱法研究聚醚的平均分子量和分布

激光解吸/傅里叶变换质谱(Laser Desorption/Fourier Transform MassSpectrometry,LD/FTMS)技术是测定高分子低聚物(MW=1000-10000)平均分子量和分布的一种新的有效方法。采用这项技术,本文研究了一系列的均聚醚和共聚醚,得到了占主导地位的含K~+的准分子离子分布图,用自编程序处理这些数据得到的数均分子量与VPO、GPC、NMR等方法的测定值相一致。还讨论了样品制备中的碱金属盐和实验参数对测定结果的影响等问题。     

A comprehensive approach to method validation based on object technology

 Method validation procedure requires a strategy for collecting those validation data that are best adapted to the analytical technique used. A flexible and general approach based on Object Linking and Embedding technology is proposed. It allows a traceable validation strategy using modular objects which encapsulate documentation, analytical data and processing logic. The contents of these objects are accessible through a standard user interface. This paper demonstrates how this can reduce experiment time, simplify evaluation efforts, and increase the ease of use of validation figures of merit. An illustration using Microsoft Visual Basic for Applications is presented, and some specific aspects are described. It consists of the evaluation of a time domain NMR technique for determining the moisture content of foods involving a multivariate calibration step. This study also illustrates how guidelines such as Good Validation Practices could be defined to present all validation documents in a standardised manner. Received: 3 September 1996 Accepted: 14 October 1996     

烯烃亲电加成反应的教学研究

烯烃的典型反应是亲电加成反应.大学有机化学教学目标要求学生掌握并能熟练应用烯烃亲电加成反应的区域选择性、立体选择性以及烯烃的反应活性解决实际问题.具体包括:(1)使用区域选择性预测加成主副产物;(2)使用立体选择性判断加成产物立体结构;(3)综合考虑电子效应,熟练比较各种烯烃的反应活性.由于烯烃亲电加成反应底物多、影响...     

Validation of chemometric models – A tutorial

In this tutorial, we focus on validation both from a numerical and conceptual point of view. The often applied reported procedure in the literature of (repeatedly) dividing a dataset randomly into a calibration and test set must be applied with care. It can only be justified when there is no systematic stratification of the objects that will affect the validated estimates or figures of merits such as RMSE or R². The various levels of validation may, typically, be repeatability, reproducibility, and instrument and raw material variation. Examples of how one data set can be validated across this background information illustrate that it will affect the figures of merits as well as the dimensionality of the models. Even more important is the robustness of the models for predicting future samples. Another aspect that is brought to attention is validation in terms of the overall conclusions when observing a specific system. One example is to apply several methods for finding the significant variables and see if there is a consensus subset that also matches what is reported in the literature or based on the underlying chemistry.