化学竞赛的组织和指导

国际化学奥林匹克竞赛是中学生的世界规模和影响极大的学科竞赛活动之一。近年来,我国中学生在国际化学竞赛中捷报频传,大大地推进了国内化学竞赛的开展,使竞赛不断深化和不断进入新的层次。     

开展化学竞赛活动有利于全面提高中学化学教育质量

我国自参加国际化学奥林匹克竞赛以来,取得了优异成绩,为国争光,这是有目共睹的,化学竞赛不仅仅是培养几个人,而且有利于全面提高中学化学教育质量。     

浅谈化学奥林匹克竞赛选手的选拔与培养

国际化学奥林匹克竞赛随着它日益增长的声望,参加的国家越来越多,是世界上最有影响的中学生化学竞赛活动。近年来,我国中学生在国际化学奥林匹克竞赛中捷报频传。     

从全国青年化学竞赛谈谈中学化学教学中的一些问题

1984年全国青年化学竞赛是建国以来首次在全国范围内开展的带有科普性化学竞赛活动。通过这次竞赛,在全国青年中激发了学化学、用化学的兴趣,促进了化学科技活动的开展,扩大了化学爱好者的队伍,提高了参加者和其它有兴趣者的化学水平。     

全国化学奥林匹克竞赛研讨会会议纪要

由中国化学会主办的全国化学奥林匹克竞赛研讨会于7394年8月2日到8月6日在北京举行。这次会议是在全国化学竞赛开展了10年、我国参加国际化学奥林匹克竞赛8年之后,在第27届国际化学奥林匹克竞赛（27th IChO,1995.7,中国·北京）之前召开的总结经验,继往开来的大会。     

化学奥林匹克教材（ChOTM）建设之我见

国际化学奥林匹克（IChO）是世界范围内的中学生化学竞赛活动。它以发现和培养化学人才为主要目的。同时对于提高中学化学教育水平有积极的意义。     

高中化学竞赛中电子效应和空间效应考点分析——以近年全国化学奥林匹克竞赛试题为例

电子效应和空间效应是有机化学的基础,近年来,这部分知识在全国化学奥林匹克竞赛中的考查比例处于上升趋势。因此,以近年全国化学奥林匹克竞赛试题为例,详细说明电子效应和空间效应在竞赛中的考点,帮助辅导化学竞赛的教师和参加化学竞赛的考生了解该部分知识需要达到的教学标准和掌握层次。     

化学奥林匹克的特点、内涵与反思

化学奥林匹克推动了中学化学课程体系和教学内容的改革,促进了教师教学思想的转变,培养了竞赛选手的综合素质。从竞赛内容看,可以称之为一种“中间化学”、“前沿化学”、“艺术化学”。目前竞赛培训中存在的主要问题包括：重基础理论而轻实践,重奥赛选手而轻教师,重教学而轻研究,少数省、市、自治区还存在重教师辅导而轻激励机制。     

开展化学“奥赛”活动 展示“奥赛”的魅力

随着我国跨入国际化学“奥赛”的行列,连年夺魁,捷报频传,一股化学“奥赛”的浪潮此起彼伏,激荡着中华儿女的心扉。化学“奥赛”活动随着时代的步伐在各地蓬勃地开展着。中国化学会自1987年举办化学冬令营和化学竞赛活动以来,我市历年都有机会参加,成绩也是可喜的。自1988年我市取得第一个全国一等奖后,就拉开了向化学“奥赛”的最高目标冲刺的帷幕。六年来我市在全国荣获一等奖四次,并四次进入国家集训队。成绩的取得是各级科协、化学会、化学竞赛委员会和省市教委教研室协同作战的结果。它将激励着我市中学生在化学“奥赛”的道路上奋勇前进。     

中学化学竞赛训练中几个问题的探讨

随着全国化学竞赛的开展,我国中学生在国际化学奥林匹克的赛场上捷报频传。这强烈地激发了广大青年学生的爱国热情和进取心,对于广大的化学教育工作者也是一种极大的鼓励和鞭策。     

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.     

"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.     

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.     

梦萦魂牵--《化学通报》复刊30年

哲学家和物理学家都喜欢研究和讨论“时间” ,时间之矢告诉人们光阴冉冉不复返 ,矢者失也。然而人们却总想回忆 ,寻找那些美好的或沮丧的过去 ,是安慰或自娱吧。我一直相信生活总是向前的 ,社会总是进步的 ,就和宇宙不停地膨胀一样。《化学通报》复刊已经 3 0年了 ,既然是复刊 ,必然先有停刊。历史总是把破坏和重建放在一起考虑的 ,才能找出规律。人们都说 2 0世纪是自然科学大发达的时代 ,然而 2 0世纪又是人类社会灾难最多的时代。正因如此 ,才促使科学多极化地、多样性地发展起来 ,从欧洲到美洲到亚洲 ,一点点 ,慢慢地扩散开来 ,也许 ,真…     

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.