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排序方式: 共有163条查询结果,搜索用时 359 毫秒
81.
Wahid M. Basyouni Nagwa M. Abdelazeem Khairy A. M. El-Bayouki Mohamed Y. El-Kady 《合成通讯》2013,43(22):3112-3120
A simple and efficient eco-friendly method was developed for the synthesis of new benzo[4,5]imidazo[1,2-a]pyrimidine-3-carbonitrile derivatives in excellent yields. The synthesis was achieved through the reaction of 2-aminobenzimidazole, aldehydes and active nitriles (malononitrle or ethyl cyanoacetae) in the presence of silica sulfuric acid/ethylene glycol. This protocol offers very short reaction times (in some cases, reaction times were reduced to five minutes), high yields and low cost. This method thus provides an improvement over the existing methods. 相似文献
82.
Yeldez El Kilany Nagwa Rashed Magda Mansour Mohamed Abdel Rahman El Sayed El Astiry 《Journal of carbohydrate chemistry》2013,32(1):199-207
Abstract 3-[1-(p-Fluorophenylhydrazono)-L-threo-2,3,4-tri hydroxybutyl1-2-quinoxalinowe was prepared and trarrsformed to 3-[5-acetoxymetnyl-1-(p-fluorophenyl)-pyrazol-3-yl]-2-quinoxalinone. N-methylation, followed oy dehydrative cyclisation, gave the M-methyl-derivative of the latter pyrazole. Periodate oxidation gave a glyoxalyl derivative whose aldehyde functionality was confirmed by reduction and oximation. 相似文献
83.
Recent observations for a non-zero θ13 have come from various experiments. We study a model of lepton mixing with a 2–3 flavor symmetry to accommodate the sizable θ13 measurement. In this work, we derive deviations from the tri-bimaximal (TBM) pattern arising from breaking the flavor symmetry in the neutrino sector, while the charged leptons contribution has been discussed in a previous work. Contributions from both sectors towards accommodating the non-zero θ13 measurement are presented. 相似文献
84.
85.
Novel Cu 2+ and Fe 3+ chelates derived from L 1 were synthesized and characterized by single crystal X‐ray diffraction. The results indicate that the Fe (III) crystal, [Fe(L1‐H)Cl2], has an orthorhombic structure of the type pc2b while the dimeric Cu (II) crystal, [Cu(L1‐H)Cl … ClCu(L1‐H)], has a monoclinic with space group Cc. X‐ray diffraction and spectroscopic studies revealed that L 1 acts as monobasic tetradentate with octahedral geometry in Fe (III) crystal while it behaves as dibasic tetradentate with distorted‐octahedral in the Cu (II) crystal. Also, the two chelates were characterized by spectral, magnetic and thermal analyses. DFT parameters were used to prove the liberation of a proton from COOH rather than NH groups. The kinetic and thermodynamic parameters of Fe (III) chelate were determined by Coats‐Redfern and Horowitz‐Metzger methods. Cyclic voltammogram provides information about the oxidation states of Cu (II) and Fe (III) chelates. Antitumor activity against Epitheliod carcinoma (Hela), breast cancer (MCF‐7) and antibacterial activities of chelates were investigated. 相似文献
86.
Luntao Liu Rashed Aleisa Yun Zhang Ji Feng Yiqun Zheng Yadong Yin Wenshou Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(45):16453-16459
The fast and reversible switching of plasmonic color holds great promise for many applications, while its realization has been mainly limited to solution phases, achieving solid‐state plasmonic color‐switching has remained a significant challenge owing to the lack of strategies in dynamically controlling the nanoparticle separation and their plasmonic coupling. Herein, we report a novel strategy to fabricate plasmonic color‐switchable silver nanoparticle (AgNP) films. Using poly(acrylic acid) (PAA) as the capping ligand and sodium borate as the salt, the borate hydrolyzes rapidly in response to moisture and produces OH? ions, which subsequently deprotonate the PAA on AgNPs, change the surface charge, and enable reversible tuning of the plasmonic coupling among adjacent AgNPs to exhibit plasmonic color‐switching. Such plasmonic films can be printed as high‐resolution invisible patterns, which can be readily revealed with high contrast by exposure to trace amounts of water vapor. 相似文献
87.
Suzan Saber Miguel Mollar Amany El Nahrawy Nagwa Khattab Ali Eid Mohamed Abo-Aly Bernabé Marí 《Optical and Quantum Electronics》2018,50(6):248
In this study CuInSe2 and CuInS2 thin films were prepared onto ITO glass substrate using the electrodeposition technique in aqueous solution. The electrodeposited films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis. The annealing effects on electrodeposited precursors were investigated. The chalcopyrite structure of CuInSe2/CuInS2 showed an enhancement of crystallinity after subsequent selenization/sulfurization treatment in Se/S atmosphere, respectively. XRD and SEM studies revealed a dramatic improvement of the crystalline quality of CIS films after annealing treatments. Mott–Schottky measurements were used to assess the conductivity type of the films and their carrier concentration. The prepared samples underwent an etching process to remove the binary accumulated Cu2?x(Se,S) phases shown in FESEM pictures. This etching process has shown a noticeable decrease in both, the flat band potential, Vfb (V), and the number of acceptors, NA (cm?3) in selenized CuInSe2 and sulfurized CuInS2 samples. 相似文献
88.
89.
M. M. El-Dessouky F. Abdel-Rehim A. -A. Abdel-Azim I. Gar-Alm Rashed 《Journal of Radioanalytical and Nuclear Chemistry》1988,125(2):485-492
Gamma radiolysis of 2-acetylfuran (AF) in 2-propanol, in absence of atmospheric oxygen, has been investigated. The radiation yields of hydrogen, methane at different doses as well as radiolytic products in solution were determined. The radiolytic products were determined by gas chromatography coupled with mass spectrometry. The mechanisms for formation of detected radiolytic products and the effect of (AF) concentration on hydrogen and methane yields are discussed. 相似文献
90.
Abo-el-Maali N 《Bioelectrochemistry (Amsterdam, Netherlands)》2004,64(1):99-107
A review on the voltammetric analysis of drugs is presented. The review includes a summary of the rules that must be considered for drug analysis and a survey of the use of voltammetry for drug analysis in the period from 1998 till 2002. 相似文献