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排序方式: 共有146条查询结果,搜索用时 15 毫秒
1.
Silica@copper (SiO2@Cu) core–shell nanoparticles were synthesized and well characterized by XRD, TEM, AFM, XPS, UV/Vis, TGA–MS, and ICP–AES techniques. The synthesized SiO2@Cu core–shell nanoparticles were employed as catalysts for the conjugate addition of amines to α,β‐unsaturated compounds in water to obtain β‐amino carbonyl compounds in excellent yields in shorter reaction times. Furthermore, the catalyst works well for hetero‐Michael addition reactions of heteroatom nucleophiles such as thiols to α,β‐unsaturated compounds. As the reaction is performed in water, it allows for easy recycling of the catalyst with consistent activity. 相似文献
2.
Friedel-Crafts alkylation of indoles with epoxides to afford 3-alkyl indole derivatives at room temperature with moderate to good yields and high regioselectivity using nanocrystalline titanium(IV) oxide catalyst is described. 相似文献
3.
Transverse flow transversely excited (TFTE) CO2 lasers are easily scalable to multikilowatt level. The laser power can be scaled up by increasing the volumetric gas flow
and discharge volume. It was observed in a TFTE CW CO2 laser having single row of pins as an anode and tubular cathode that the laser power was not increasing when the discharge
volume and the gas volumetric flow were increased by increasing the electrode separation keeping the gas flow velocity constant.
The discharge voltage too remained almost constant with the change of electrode separation at the same gas flow velocity.
This necessitated revision of the scaling laws for designing this type of high power CO2 laser. Experimental results of laser performance for different electrode separations are discussed and the modifications
in the scaling laws are presented. 相似文献
4.
Kótai László Gács István Kazinczy Béla Sajó István E. Sreedhar B. 《Transition Metal Chemistry》2003,28(3):292-295
The theoretical investigation on the distribution of chemical species obtainable as a function of the temperature of the aqueous solutions of metal complexes containing a basic ligand, altogether with the solubility relationship of the compounds to be formed, offers a simple means of planning the preparation of various types of complexes, double and single salts of the central metal cation and onium type compounds of protonated ligand of the central ion and the anion. 相似文献
5.
The electrochemical characteristics of deltamethrin have been determined by means of electrochemical techniques such as d.c. polarography, cyclic voltammetry and differential pulse polarography over a wide range of pH from 2.0-12.0. The title compound exhibits a single well defined peak due to the reduction of the CC moiety present in deltamethrin. The overall reduction process is diffusion-controlled and adsorption free in nature. The variation of half-wave potential with the pH, concentration of the title compound, and other experimental conditions is described. A possible mechanism for the reduction is suggested. The number of electrons involved in the electrode reduction is two. Investigation was also undertaken for the determination of deltamethrin in vegetables and in storage bags of rice and wheat under FCI's storage system. 相似文献
6.
7.
Paulson Mathew Satheesh K. Nair K. M. Sreedhar V. N. Rajasekharan Pillai 《合成通讯》2013,43(16):2157-2161
When α‐oxoketene dithioacetals 1a–n were treated with the bromine complex of a copolymer of 1‐vinyl‐2‐pyrrolidone and 4‐vinylpyridine, the corresponding thiolcarboxylates 2a–n were formed in excellent yields. The reaction also works with other 1‐vinyl‐2‐pyrrolidone‐derived polymers as well as commercially available polyvinylpyrrolidone–bromine complexes. The method is suitable for preparing aliphatic, aromatic, and γ,δ‐unsaturated β‐oxothiolcarboxylates. 相似文献
8.
An ultrasound‐accelerated fast and efficient three‐component reaction for the regioselective synthesis of l,4‐disubstituted 1,2,3‐triazoles using different alkyl and allyl halides, terminal alkynes, and sodium azide in water at room temperature has been developed using CuI as catalyst. Ultrasonication dramatically decreases the reaction times. 相似文献
9.
M. R. R. Prasad K. Sudhakarbabu B. Sreedhar D. Keerthi Devi 《Journal of Thermal Analysis and Calorimetry》2014,116(2):1027-1031
Mechanistic aspects of the thermal decomposition of benzyl-triethyl-ammonium tetrafluoroborate (BTEATFB) employing simultaneous TG-DSC coupled with a quadrupole mass spectrometer are considered in this work. The experiments were conducted in an inert atmosphere of helium. The decomposition of BTEATFB proceeds through several competing mechanisms. While nucleophilic substitution reaction occurs through the formation of a tertiary amine and plays an important role in the initial stages of the decomposition, and the probability of Hoffman elimination also exists. 相似文献
10.
黄铜矿铜铟硒化合物CuInSe2及其与硫或嫁的合金CuIn(Se,S)2或CuInGa(Se,S)2,即所说的CIGS,已通过20%的实验室规模器件光电转换效率展示了其地面光伏应用的巨大潜力。为了减少初始资金成本,提高材料利用率,科研工作者们已经尝试了许多努力通过非真空制程沉积CIGS。这些制程包括电镀工艺,基于颗粒(浆或纳米颗粒)的制程和基于分子量级前趋体的制程。原则上,分子量级前趋体可以使组分元素达到充分混合,可以最大程度地实现组份在基板不同区域的均一分布。这对于一个复杂的涉及到五个主要元素的化合物系统尤为重要。从这个角度来看,分子前趋体的方法具有大面积均匀沉积铜铟镓硒的巨大潜力。这篇综述将着重讨论使用分子前趋体沉积铜铟镓硒制程的最新发展。 相似文献