基于核心素养的中学化学实验教学——评《中学化学实验研究》

基于核心素养的中学化学实验教学——评《中学化学实验研究》     

中学化学手持技术数字化实验研究的演进及展望*

正手持技术数字化实验是信息技术在中学化学实验教学中的有效使用,有利于开展验证性实验和探究性实验教学及推进信息技术与教育教学的深度融合,也利于培养学生的实验技能和提升学生的科学研究素养。1 中学化学手持技术数字化实验研究的演进经文献统计分析,得出中学化学手持技术数字化实验的演进及特点:(1)大致可分为3个阶段;2004-2007年为酝酿期,2008-2012年为徘徊期,2013-至今为快速发展期;(2)在被引较高的前10篇文     

生物化学实验教学的实践与研究——评《生物化学实验教程》

生物化学实验教学的实践与研究——评《生物化学实验教程》     

中学化学实验教学研究的现状分析报告

分析了中学化学实验教学研究中存在的十“多”、十“少”现状,并对中学化学实验教学的研究方向和策略提出了建议：关注学生探究能力和创新能力的培养;关注各个模块互通的、综合性的实验;关注国内外化学实验教学比较等。     

我国2001-2013年中学化学实验学习研究热点的知识谱图

为比较准确地了解国内中学化学实验学习研究的热点和重点,为今后中学化学实验学习研究提供有力的数据与支撑,利用bicomb1.0软件与IBM SPSS20.0软件,对从中国知网中查询到的2001-2013年的518篇关于实验与化学学习的相关文献进行了知识谱图的绘制.研究结果表明,我国中学化学实验学习的研究主要涉及4大领域,分别是:高中新课程,化学实验对于化学知识的学习、素质教育,创新、观察等能力的培养等相关领域研究热点;中学化学实验对于激发学生兴趣、培养学生动手能力和课外活动作为化学教学的一种方法途径的研究热点;课堂教学中,实验教学与多媒教学等教学模式的改革、创新提升教学质量的研究热点;采用化学实验微型化、绿色化等策略来强化对学生的能力的培养.     

对天津市化学实验教学研究现状的调查分析

实验是化学教学中永恒的主题。化学新课程的教学实践中,实验教学是不可忽视的重要组成。本文以化学新课程为背景,将化学实验条件、实施及理论、科学观念等问题编制为问卷,在天津市部分中学化学教师中进行调查,并对调查结果分析思考后得到若干启示,以利促进或加强当前新课程背景下的化学实验教学。     

高师“中学化学实验教学技能训练”课程教学现状调查与分析*

实验教学能力是化学教师专业发展的重要标志。“中学化学实验教学技能训练”课程是化学师范生必修的综合性实验教学训练课程,对化学师范生实验教学技能的培养有着至关重要的作用。研究从“中学化学实验教学技能训练”课程的总体评价、学习态度、教学方式和评价方式以及学习困难等方面对化学师范生进行了调查分析。针对发现的问题,提出统筹课程设置、明确课程价值、建立学习共同体、加强实验思维训练等教学建议。     

中学化学实验教学改革及其反思

从4个方面反思中学化学实验教学改革,指出中学化学实验教学改革的基本思路是:如何更好地发挥教材中各类实验在中学化学教学的作用,从而实现中学化学教学目标;验证是化学实验的最根本功能,实验的验证性与实验在情感领域和能力、方法领域的功能并不矛盾,而是实现这些领域的功能的基础;实验教学若能从学生出发,引发学生的想法并加以验证,则能有效地发挥教材中的各类实验在化学教学中的作用,提高中学化学教学质量.     

探讨中学化学实验教学模式的创新与应用

提出在中学化学实验教学模式上创新性地使用任务驱动、参与分享、合作交流、自主学习等新型教学模式,并以初三化学实验“任务驱动式学生自主实验-自制简易净水器净化护城河水”为案例阐述如何使用上述教学模式以及效果评析,利于克服传统中学化学实验教学学生学习被动、过于机械、能力和情感得不到足够培养等弊端,对中学化学实验教学的改革有一定借鉴意义和推广价值。     

优化中学化学实验教学环境实做举措

从实验环境入手,主要解决当前困扰中学化学实验教学的难题,着眼于优化中学化学实验教学环境,着重解决了5个方面的问题：（1）明确指出了中学化学实验的现实环境;（2）做好高一学生的“起始”工作;（3）改学生分组实验中的验证性实验为探究性实验,开放实验室并重新设计活页的《化学实验报告》;（4）利用数码摄像机拍摄课堂上难以完成的实验,提高实验教学的质量和容量;（5）引导学生做实验题时将虚拟环境转化为现实环境。     

On-line fermentation gas analysis: Error analysis and application of mass spectrometry

On-line fermentation gas analysis is of general interest because it permits the determination of metabolic rates in almost any biological process using living organisms. The consumption and production of gases (O₂, CO₂, CH₄, etc.) and volatile compounds may be determined without causing any risk of infection. Elemental balancing permits the determination of other metabolic rates if the stoichiometry is known. This was studied with the production of poly-β-hydroxybutyrate (PHB) by Alcaligenes latus. Estimations were based on the measurement of gas partial pressure and flow-rates, pH and alkali consumption rate. Experiments with a small quadrupole mass spectrometer showed unacceptable error propagation. Therefore, dynamic error propagation for all rates was studied using simulation. It was found that, for example, a 1% relative offset-calibration error for oxygen can result in an error in PHB estimation of > 50%. It is suggested that this culture is used in combination with elemental balancing for thorough tests of the accuracy of on-line gas analysis equipment. An on-line process gas analyser based on a quadrupole mass spectrometer (Balzers PGM 407) gave the following precision values (abs. vol.?%) during cultivation of Bacillus subtilis: nitrogen (m/z 14), 0.024; oxygen (m/z 32), 0.020; argon (m/z 40), 0.0011; and carbon dioxide (m/z 44), 0.0034. These values, combined with automatic recalibration, would be sufficient for reasonable estimation of PHB, biomass and substrates.     

Impact of alkali treatment on physico-chemical,thermal, structural and tensile properties of Carica papaya bark fibers

This study aims to examine the effect of sodium hydroxide (NaOH) treatment on the physico-chemical properties, structure, thermal, tensile and surface topography of Carica papaya fibers (CPFs). The surface of raw CPFs was modified by soaking with 5% NaOH solution for 15, 30, 45, 60, 75 and 90?min. The results of thermo-gravimetric analysis revealed that the optimum treatment time for alkali treatment was 60?min. It was found that the alkali treatment improved the properties of the CPFs. The results of TGA, FT-IR, XRD and AFM suggest that the treated CPF is a suitable alternative as reinforcement in polymer composites.     

Chemometric and trend analysis of water quality of the South Chennai lakes: an integrated environmental study

In order to bring out the nature of the factors influencing lake water composition, multivariate statistical analysis and trend analysis were performed based on the hydrochemical data of the study area, namely, South Chennai. Change in land use pattern and settlements along the banks of the lakes alters the quality and quantity of the surface water. In the present study, the R‐mode factor analysis and cluster analysis were applied to the geochemical parameters of the water to identify the factors affecting the chemical composition of the lake water. Dendograms of both the seasons give three major clusters, reflecting the groups of unpolluted to moderately polluted, polluted, and heavily polluted stations. The movement of stations from one cluster to another clearly brings out the seasonal variation in the chemical composition of the lake water. The complex hydrochemical data of the surface water were interpreted by condensing them into three major factors. Factor score analysis was used successfully to delineate the stations under study and the role of the contributing factors, and the nature of factors responsible for the variation in chemical composition of the water has been clearly brought out. Results of trend analysis using ArcGIS clearly indicate that the trend in water quality is deteriorating at a faster rate in the eastern part of the study area. It is understood that although natural shifts probably can account for some of the variation, it is most likely that human activities play a major role in affecting the water quality on a regional scale. Copyright © 2014 John Wiley & Sons, Ltd.     

Time-series analysis in analytical process control

Analysis of time series tries to extract tendencies from measured values dependent on time. For this purpose the cusum technique has proved to be a very sensitive tool for the evaluation of both current and completed time series. Even very weak tendencies can be detected at a high level of noise. Time-series analysis further tries to predict values to come from hitherto performed measurements. As a very flexible model exponential smoothing could be successfully used. Even for processes with a high extent of non-stationarity this model allowed a good prediction owing to the dynamics of the process. Three types of time-series analysis, i.e., evaluation of current measurements, retrospective evaluation and prediction of data (also known as “in vivo”, “post mortem” and “in futurum” time-series analysis) are demonstrated for problems stemming from analytical process control.     

新材料的发展与分析化学

文章介绍了新材料的重要性及发展方向,分析化学在新材料研制中起着耳目的作用,另一方面新材料也为分析化学的进展提供了课题与条件。微量分析、微区分析、表面分析是此领域中的重点。在未来的发展中,分析化学在材料的发展中的地位不会改变,并期待着分析灵敏度与空间分辩率的进一步提高。     

Determination of rank by augmentation (DRAUG)

Determining the rank of a chemical matrix is the first step in many multivariate, chemometric studies. Rank is defined as the minimum number of linearly independent factors after deletion of factors that contribute to random, nonlinear, uncorrelated errors. Adding a matrix of rank 1 to a data matrix not only increases the rank by one unit but also perturbs the primary factor axes, having little effect on the secondary axes associated with the random errors in the measurements. The primary rank of a data matrix can be determined by comparing the residual variances obtained from principal component analysis (PCA) of the original data matrix to those obtained from an augmented matrix. The ratio of the residual variances between adjacent factor levels represents a Fisher ratio that can be used to distinguish the primary factors (chemical as well as instrumental factors) from the secondary factors (experimental errors). The results gleaned from model studies as well as those from experimental studies are used to illustrate the efficacy of the proposed methodology. The method is independent of the nature of the error distribution. Limitations and precautions are discussed. An algorithm, written in MATLAB format, is included. Copyright © 2011 John Wiley & Sons, Ltd.     

Determination of Mercury in Geological Materials by Continuous-Flow,Cold-Vapor,Atomic Absorption Spectrophotometry

Abstract

To determine mercury in geological materials, samples are digested with nitric acid and sodium dichromate in a closed teflon vessel. After bringing to a constant weight, the digest is mixed with air and a sodium chloride-hydroxylamine hydrochloride-sulfuric acid solution and then Hg(II) is reduced to Hg with stannous chloride in a continuous flow manifold. The mercury vapor is then separated and measured using cold vapor atomic absorption spectrophotometry (CV-AAS). For a 100 mg sample the limit of detection is 20 parts per billion (ppb) Hg in sample. To obtain a 1% absorption signal, the described method requires 0.21 ppb Hg solution (equal to 16 ppb in sample). Precision is acceptable at less than 1.2% RSD for a 10 ppb Hg aqueous standard. Accuracy is demonstrated by the results of the analysis of standard reference materials. Several elements do interfere but the effect is minimal because either the digestion procedure does not dissolve them (e.g., Au or Pt) or the; are normally of low abundance (e.g., Se or Te).     

钴-5-Br-PADAP极谱催化波研究

许多作者研究了某些有机试剂存在时钴的极谱行为.本文报道在氢氧化钠和盐酸羟胺底液中,钴-5-Br-PADAP配合物的极谱行为,证明峰电流为配合物吸附波.将铁分离后测定标钢中微量钴,与光度法结果一致,直接测定茶叶中钴,结果满意.