国内外关于"物质的量"概念的研究及启示

从3个方面对国外"物质的量"概念的研究进行了分析:(1)关于"物质的量"相异概念心理机制的研究;(2)关于学生"物质的量"问题解决的学习方式的研究;(3)关于学生对"摩尔"的直观认识的培养研究。同时,结合国内"物质的量"概念教学研究的现状,通过比较得出了一些有借鉴价值的启示。     

“物质的量”教学中学生认知建构探微

本文以现代认知心理学的学习理论，分析了学生对“物质的量”进行有意义学习的条件，并试图揭示出学生学习过程中的认知建构机制。     

中学化学实验教学中的问题与思考

化学实验是中学化学教学的主要内容之一,对全面提高学生的科学素养有着极为重要的作用。目前,中学化学教学是否重视化学实验?相关资料查阅和与教研员交流情况表明,情况很不理想。原因主要有:(1)有理念少行动;(2)有开发少实用;(3)有情境少建构;(4)有教师少实验员;(5)有实验室少用品;(6)有活动少专题;(7)有考核少监督。同时,对此进行了分析与思考。     

以"有意义的接受学习"进行"物质的量"教学

现代认知心理学认为：学习是建构内在心理表征的过程,学习者并不是把知识从外界搬到记忆中,而是以已有的经验为基础,通过与外界的相互作用来建构新的理解。如果语言文字或符号所表述的新知识能与学习者原有的认知结构中的某些有关的观念发生相互影响,产生同化作用,建立起非人为的、     

论中学生化学元素观的建构

化学元素观是中学化学学习中的核心观念。化学元素观的建构有利于中学生对物质世界形成有序的认识,有利于中学生形成化学的思维方法。化学元素观建构的基本策略是:(1)在元素概念基础上形成物质的基本分类;(2)在原子结构认识的基础上理解元素是如何形成物质的;(3)在元素周期律学习的基础上形成元素性质研究的基本模型;(4)在专题性学习中建构化学元素观;(5)在元素观指导下的应用性学习中丰富元素观;(6)利用概念图技术帮助化学元素观的建构。     

以物质的量为核心的化学计量系统构建及其产生式教学策略

从认知心理学知识学习角度分析以物质的量为核心的化学计量系统,从教学策略角度,可以将其划分为知识系统和操作系统2大部分,其知识系统主要属于陈述性知识,而操作系统则主要属于程序性知识。按照陈述性知识的认知特点设计体现物质的量相关知识系统网络结构功能的探究教学;按程序性知识的认知规律设计产生式自展过程等较高层次的思维运作。从而形成了以物质的量为核心的化学计量系统知识建构的探究教学方法与实际问题解决的小步子产生式策略。其意义在于以结构化系统替代零散知识,用逻辑性思维替代常识比喻,以智能化产生替代机械运算,为以物质的量为核心的化学计量系统教学探索更加有效的策略与方法。     

论化学学习中的能量观建构

能量观是中学化学学习中的核心观念。能量观的建构有利于学生形成核外电子运动的能量思维方式,了解从能量的角度研究物质及其转化的思维方法等。能量观建构的基本策略是:(1)在物质的微粒性认识学习中形成物质的微粒具有热能的观念;(2)在原子结构学习中形成核外电子运动的能量思维方式;(3)在元素及其化合物学习中发展高能量的最外层电子不稳定的认识;(4)在化学变化现象的积累学习中强化物质转化伴随有能量变化的认识;(5)通过化学键概念及其理论学习理解物质转化过程中伴随有能量变化;(6)在影响化学反应速率的条件讨论中深化理解有效碰撞理论;(7)在化学热力学问题研究中进一步理解能量守恒;(8)利用概念图技术帮助化学能量观的建构。     

高一学生自主性学习基本情况的调查与分析

学习理论认为,学习是学习者与学习对象之问不断地相互作用,作用的结果使学习者原有的认知结构建构成为新的认知结构。作为学习主体的学生 对学习过程高度的责任心,以及参与学习活动的主动性、积极性,即学习的自主性,将成为制约学习成败的关键因素之一。     

发展学生认识角度和深度的化学教学转变——以“化学反应原理”模块为例

以"化学反应原理"模块的4课为例,从分析"化学反应原理"的模块功能出发,探讨了发展学生认识角度和深度的教学转变.这些转变包括:(1)转变教学目标取向,从传授具体性知识为本转向建构学科核心观念;(2)转变对学科本体知识的认识,从忽视学科本体知识的内涵到深入挖掘学科本体知识内涵;(3)转变学生观,从笼统关注学生转向对学生已有认识及认识发展点的深度关注;(4)转变教学素材定位,从追求多样化、有新意向匹配教学功能定位、匹配学生认识发展层级、实现教学功能最大化转变;(5)转变对思路外显重要性的认识,从忽视思路外显重要性转变为通过多次外化促进思路外显;(6)转变学案设计方式,从填空式学案转变为过程引导式学案.     

高中生化学图形认知能力现状探查

运用问卷调查、访谈和放声思维等手段,探查了高中生化学图形认知能力的现状.探查结果显示:(1)高中生化学图形认知能力并没有随年级增长;(2)不同学业成绩学生化学图形识别能力差异显著;(3)不同思维风格学生化学图形认知能力具有显著性差异;(4)学生对图形的识别具有一定的倾向性和目的性;(5)学生图形理解能力中关系理解能力较弱;(6)学生图形再造想象能力有待于提高.     

"Alpha"-, "beta"- and "delta"-anhydrodigitoxigenin

The syntheses of 3β-hydroxy-5β-carda-14, 20:22-dienolide (= «β»-anhydro-), 3β-hydroxy-5β-carda-8:14, 20:22-dienolide (= «α»-anhydro-) and «δ»-anhydro-digitoxigenin (= probably 3β-hydroxy-5β, 14β-carda-8, 20:22-dienolide) by the best ways known to date, have been described. «δ»-Anhydro-digitoxigenin represents the thermodynamically most stable isomer. In this isomer the double bond in position 8 is unaffected by hydrogenation with Pt in acetic acid; with perbenzoic acid an epoxide results from which, on hydrogenation, the double bond can be regenerated in its original position. Analogous reactions are known to occur in the 8:14-epoxides.     

化“材”为“筑”

Chemistry is a central, practical and creative discipline. The development of chemistry plays an important role in the progress of science and society, as well as the improvement of the quality of human life. This paper introduces the chemical knowledge of stone, concrete, glass and other inorganic nonmetallic building materials by the anthropomorphically story. Taking nanomaterials as an example, the prospect of building materials development in the future is put forward.     

Making "wheels" and "cubes" from triangles

[Mn(IV)Mn(II)3] triangular units directed by the presence of tripodal alcohols self-assemble in the presence of azide and acetate ligands to form either a [Mn24] "wheel" or a [Mn32] "cube".     

"Turn-on" fluorescent sensing with "reactive" probes

Chemical probes are valuable tools for the investigation of biochemical processes, diagnosis of disease markers, detection of hazardous compounds, and other purposes. Therefore, the development of chemical probes continues to grow through various approaches with different disciplines and design strategies. Fluorescent probes have received much attention because they are sensitive and easy-to-operate, in general. To realize desired selectivity toward a given analyte, the recognition site of a fluorescent probe is designed in such a way to maximize the binding interactions, usually through weak molecular forces such as hydrogen bonding, toward the analyte over other competing ones. In addition to such a supramolecular approach, the development of fluorescent probes that sense analytes through chemical reactions has witnessed its usefulness for achieving high selectivity, in many cases, superior to that obtainable by the supramolecular approach. Creative incorporations of the reactive groups to latent fluorophores have provided novel chemical probes for various analytes. In this feature article, we overview the recent progress in the development of turn-on fluorescent probes that are operating through chemical reactions triggered by target analytes. Various chemical reactions have been implemented in the development of many reactive probes with very high selectivity and sensitivity toward target analytes. A major emphasis has been focused on the type of chemical reactions utilized, with the hope that further explorations can be made with new chemical reactions to develop reactive probes useful for various applications.     

"Decoking" of a "coked" zeolite catalyst in a glow discharge

'Decoking' of a 'coked' zeolite catalyst in a glow discharge in oxygen is investigated. The 'decoking' process involves reactions of atomic oxygen (O atoms) with 'coke' and yields gases such as CO, CO₂ as well as other gaseous products that could be easily pumped out.Three different modes of discharge were investigated including a static mode, a flowing-gas mode, and a periodic-purge mode where the oxygen and other gaseous products of the discharge were replaced by fresh O₂ gas after short but regular intervals of time. In some cases, additional heating was also used to provide base temperatures of the order of 100 °C to facilitate penetration of oxygen atoms into the inner layers and cages of the zeolite catalyst.This paper presents some results of spectroscopic analytical techniques used to monitor the atomization of oxygen, oxidation of 'coke', and to confirm the process of 'decoking'. More specifically, radiation emission on the 3 s ⁵S– 3p ⁵P transitions of O around 777.2–777.5 nm were selected for monitoring the atomization of O₂. On the other hand, X-ray photo-electron spectroscopy (XPS) was used to determine the amount of residual carbon and extent of 'decoking'. Furthermore, evolution of CO and CO₂ gases as a function of time was systematically monitored in real time. For CO, the 451.1 nm band head belonging to the B¹ - A¹ bands of the Angstrom system of the CO spectrum was used, while for CO₂, the band head at 353.4 nm belonging to the CO₂⁺ spectrum was used. The rates of evolution of CO and CO₂ were related to the rate of 'decoking' of the catalyst. It is noted that in the periodic-purge mode, about 63% of the total yield of CO from a given sample of the catalyst appears in the first 3-min exposure to discharge whereas it takes up to 15 min to remove nearly 94% of the removable carbon under our experimental conditions.     

营养化学课程翻转课堂的探索与实践

With its tailored learning content, flexible learning environment and directed teacher guidance, the flipped classroom in "nutrition chemistry" has effectively solved the problems of students' specialty, large number and limited time in the course of elective course. The teaching mode based on the cultivation of students' ability and the core of improving scientific literacy was constructed.     

Size evolution study of "molecular" and "atom-in-cluster" polarizabilities of medium-size gold clusters

A study on static polarizabilities for a family of gold clusters (Au(n), n = 6, 12, 20, 34, 54) is presented. For each cluster, a density functional theory perturbation theory calculation was performed to compute the cluster polarizability and the polarizability of each atom in the cluster using Bader's "quantum theory of atoms in molecules" formalism. The cluster polarizability tensor, α(cluster), is expressed as a sum of the atom-in-molecule tensors, α(cluster)=∑(Ω)α(Ω). A strong quadratic correlation (R(2) = 0.98) in the isotropic polarizability of atoms in the cluster and their distance to the cluster center of mass was observed. The cluster polarizabilities are in agreement with previous calculations.