共查询到20条相似文献,搜索用时 140 毫秒
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12-钨硅酸制备是大学教材《无机化学实验》中的常规实验。该实验为验证型实验,探究性和综合性不足,实验药品用量大,安全性低。从《化学类专业本科教学质量国家标准》出发,考虑实验设计性、综合性和安全性,对该实验进行了改进,包括无机物的制备、结构表征和性能测定。微型实验和单因素实验探讨Si∶W12配比、温度和时间等对乙醚萃取法制备12-钨硅酸的影响;用紫外和红外光谱表征产品结构;用电化学工作站测定产品的电化学性质。通过实验,引导学生掌握科学系统的研究方法,加深绿色化学理念,进一步理解结构-性能的密切关系,了解杂多酸在科研领域中的应用,培养学生的综合实验能力和创新能力,为后续进行毕业论文和从事科研工作打下基础。 相似文献
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为提高本科学生的创新创业能力,通过高分子化学实验教学使学生深入了解仿生共聚物的制备及性能的相关知识,设计了综合探究性实验。通过原子转移自由基聚合法制备仿生共聚物,并将其修饰在多种材料表面。采用X射线光电子能谱、扫描电子显微镜、生物显微镜分别对修饰材料进行表征。该实验通过共聚物的制备使学生掌握高分子化学中活性可控自由基聚合制备共聚物的方法;掌握仿生共聚物设计及构筑方法;使学生学习科研仪器的操作方法,切实提高学生的实践能力。该实验重复性好、创新性及拓展性强,将共聚物设计制备及应用有机结合,适用于高分子专业本科生综合探究性实验。 相似文献
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Chemical Preparation of Graphene Materials Results in Extensive Unintentional Doping with Heteroatoms and Metals
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Dr. Chun Kiang Chua Dr. Adriano Ambrosi Prof. Zdeněk Sofer Dr. Anna Macková Dr. Vladimír Havránek Dr. Ivo Tomandl Prof. Martin Pumera 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(48):15760-15767
Chemical synthesis of graphene relies on the usage of various chemical reagents. The initial synthesis step, in which graphite is oxidized to graphite oxide, is achieved by a combination of chemical oxidants and acids. A subsequent chemical reduction step eliminates/reduces most oxygen functionalities to yield graphene. We demonstrate here that these chemical treatments significantly contaminate graphene with heteroatoms/metals, depending on the procedures followed. Contaminations with heteroatoms (N, B, Cl, S) or metals (Mn, Al) were present at relatively high concentrations (up to 3 at %), with their chemical states dependent on the procedures. Such unintentional contaminations (unwanted doping) during chemical synthesis are rarely anticipated and reported, although the heteroatoms/metals may alter the electronic and catalytic properties of graphene. In fact, the levels of unintentionally introduced contaminants on graphene are often higher than typical levels found on intentionally doped graphene. Our findings are important for scientists applying chemical methods to prepare graphene. 相似文献
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水中铬污染治理的研究进展 总被引:6,自引:0,他引:6
综述了水中铬污染治理的研究进展,包括物理法、物理化学法、化学法、电化学法和生物处理法,并分别评述了各种处理方法的优缺点,提出了未来含铬废水治理的发展方向。 相似文献
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化学链是指将某一特定的化学反应通过化学介质的作用分多步反应完成的过程.这一概念早在20世纪初就曾被用于以水蒸气与铁反应制备氢气,并于20世纪中期被提出用于二氧化碳的商业化生产.然而,时至今日,尚无商业化的化学链工艺用于化石燃料的转化.在近年来全球气候变暖及能源危机的急迫形势下,化学链循环过程由于其具有可以将碳基燃料直接转化为可供封存的二氧化碳的独特能力而格外受到关注,人们因而加大了对化学链工艺的研究开发力度.现代化学链工艺逐步克服了早期工艺的缺点,并不断尝试开发以煤或者其他固体燃料作为直接进料的新工艺.现有的各种小试及中试装置操作结果及系统模拟分析表明,化学链循环工艺可以有效地降低二氧化碳分离能耗并提高化石能源转化效率,极具商业化潜力.本文主要介绍目前世界范围内现行的使用化石燃料作为原料的化学链循环工艺,重点总结对比了化学链燃烧和化学链气化两个过程的发展现状,并对化学链循环工艺工业化进程中的机遇和挑战进行了简要的讨论. 相似文献
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Ma Z Halling MD Solum MS Harper JK Orendt AM Facelli JC Pugmire RJ Grant DM Amick AW Scott LT 《The journal of physical chemistry. A》2007,111(10):2020-2027
13C chemical shift tensor data from 2D FIREMAT spectra are reported for 4,7-di-t-butylacenaphthene and 4,7-di-t-butylacenaphthylene. In addition, calculations of the chemical shielding tensors were completed at the B3LYP/6-311G** level of theory. While the experimental tensor data on 4,7-di-t-butylacenaphthylene are in agreement with theory and with previous data on polycyclic aromatic hydrocarbons, the experimental and theoretical data on 4,7-di-t-butylacenaphthene lack agreement. Instead, larger than usual differences are observed between the experimental chemical shift components and the chemical shielding tensor components calculated on a single molecule of 4,7-di-t-butylacenaphthene, with a root mean square (rms) error of +/-7.0 ppm. The greatest deviation is concentrated in the component perpendicular to the aromatic plane, with the largest value being a 23 ppm difference between experiment and theory for the 13CH2 carbon delta11 component. These differences are attributed to an intermolecular chemical shift that arises from the graphitelike, stacked arrangement of molecules found in the crystal structure of 4,7-di-t-butylacenaphthene. This conclusion is supported by a calculation on a trimer of molecules, which improves the agreement between experiment and theory for this component by 14 ppm and reduces the overall rms error between experiment and theory to 4.0 ppm. This intermolecular effect may be modeled with the use of nuclei independent chemical shieldings (NICS) calculations and is also observed in the isotropic 1H chemical shift of the CH2 protons as a 4.2 ppm difference between the solution value and the solid-state chemical shift measured via a 13C-1H heteronuclear correlation experiment. 相似文献
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We introduce and investigate a chemical model based on perturbative corrections to the product of singlet-type strongly orthogonal geminals wave function. Two specific points are addressed (i) Overall chemical accuracy of such a model with perturbative corrections at a leading order; (ii) Quality of strong orthogonality approximation of geminals in diverse chemical systems. We use the Epstein-Nesbet form of perturbation theory and show that its known shortcomings disappear when it is used with the reference Hamiltonian based on strongly orthogonal geminals. Application of this model to various chemical systems reveals that strongly orthogonal geminals are well suited for chemical models, with dispersion interactions between the geminals being the dominant effect missing in the reference wave functions. 相似文献
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Dr. Fei Ma Dr. Jie Li Shuning Zhang Yuang Gu Tingting Tan Wanting Chen Shuyue Wang Dr. Peixiang Ma Dr. Hongtao Xu Prof. Guang Yang Prof. Richard A. Lerner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(31):8214-8220
DNA-encoded combinatorial chemical library (DEL) technology, an approach that combines the power of genetics and chemistry, has emerged as an invaluable tool in drug discovery. Skeletal diversity plays a fundamental importance in DEL applications, and relies heavily on novel DNA-compatible chemical reactions. We report herein a phylogenic chemical transformation strategy using DNA-conjugated benzoyl hydrazine as a common versatile precursor in azole chemical expansion of DELs. DNA-compatible reactions deriving from the common benzoyl hydrazine precursor showed excellent functional group tolerance with exceptional efficiency in the synthesis of various azoles, including oxadiazoles, thiadiazoles, and triazoles, under mild reaction conditions. The phylogenic chemical transformation strategy provides DELs a facile way to expand into various unique chemical spaces with privileged scaffolds and pharmacophores. 相似文献
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近年来,国内外不断发生的化学恐怖袭击和化学事故仍然是当今人类生存、国家安全所面临的重大威胁。化学侦检是防化应急处置与救援的眼睛,熟练掌握和正确使用侦检装备是应对化学威胁、降低损失和伤亡的关键因素。基于化学传感等技术的侦检装备具有响应快速、智能便携的特点,并且在远程监测和实时值守等方面具有优势。该文针对涵盖电化学传感器、质量敏感型传感器、红外传感器、拉曼传感器、离子迁移谱仪、火焰光度检测器、光致电离检测器、远程遥测传感装备等在内的现场侦检装备,从原理、性能、优势和不足等方面进行了概述,重点阐述了侦检装备在应对化学威胁方面的最新进展,并对其发展趋势、应用前景进行了展望,以期为化学侦检装备在应对化学威胁中的深入研究与应用提供参考。 相似文献