搜索结果: 211-225 共查到“知识库 有机化学”相关记录3860条 . 查询时间(1.187 秒)
对竹山和马鞍山两地绿松石的微量元素和稀土元素特征作了对比研究,同时分析了两地绿松石矿物特征和结构特征。采用X射线能谱、电感耦合等离子体质谱、X射线衍射、红外吸收光谱和扫描电镜等测试技术对竹山和马鞍山地区的绿松石样品进行岩石矿物学特征分析。结果表明,竹山与马鞍山地区绿松石在微量元素的含量上存在较大的差别,但主成分含量基本一致;两地区绿松石的稀土元素均富集重稀土,二者的稀土配分模式图出现镨反向,马鞍山...
导数紫外光谱法研究pH诱导牛血清蛋白 构象变化
牛血清蛋白 构象变化 导数紫外光谱
2011/12/23
采用二阶导数紫外光谱,研究了牛血清蛋白(BSA)中色氨酸(Trp)、酪氨酸(Tyr)和苯丙氨酸(Phe)3种芳香族氨基酸残基的精细吸收谱带,并结合其肽键的吸收谱带综合分析了BSA pH值在2.3~12区间的构象变化.研究结果表明,BSA在等电点(pH值 4.7)附近时构象变化较大;而在pH 值5.7~10区间,构象变化较小;在强酸(pH值2.3)和强碱(pH值12)环境中,BSA构象变化非常明显....
Direct reductive amination of carbonyl compounds using sodium borohydride-silica chloride
Reductive amination silica chloride sodium borohydride
2010/10/15
A simple and convenient procedure for reductive amination of aldehydes and ketones using sodium borohydride in the presence of silica chloride as an active, inexpensive, recoverable, and recyclable ca...
Isolation of bis(1,4-diphenyl-1,4-bis(2-pyridyl)-2,3-diaza-1,3-butadiene) disilver with bridging (N-N) dinucleating subunits: formation of a 6-membered chelate ring
Isolation dinucleating subunits formation a 6-membered chelate ring
2010/10/15
A novel Ag(I) dinuclear complex {[(C6H5)(C5H4N)-C=N-N=C- (C5H4N)(C6H5)]Ag}2.ClO4(ClO4) (1/2CH3CN) (1) that was derived under mild conditions, during the course of combination of AgClO4 with a polymorp...
Synthesis, structural determination, and biological activity of new 7-hydroxy-3-pyrazolyl-4H-chromen- 4-ones and their o-b-D-glucosides
Chromones pyrazoles glucopyranosyl bromide glucosylation
2010/10/15
A convenient route to synthesize some new medicinally important 7-hydroxy-3-pyrazolyl chromones (3a-i) is described. The interaction of 7-hydroxy-3-formyl chromone (1) with various substituted acetoph...
Synthesis and antimicrobial activity of N-alkyl substituted p-methyl (E)-3- and 4-azachalconium bromides
N-Alkyl p-Methyl-(E)-3-, 4-azachalconium bromides antimicrobial activity
2010/10/15
Twenty new N-alkyl substituted p-methyl (E)-3- and 4-azachalcones (1a-j, 2a-j){3-[(1E)-3-(4-methylp-henyl)-3- oxoprop-1-en-1-yl]-1-alkyl (C_{5-12,_{14-15) pyridinium bromides (1a-j) and 4-[(1E)-3-(4-m...
Ionic liquids as solvent for efficient esterification of carboxylic acids with alkyl halides
Ionic liquids green solvent esterification
2010/10/15
The selective esterification of carboxylic acid derivatives with a variety of alkyl halides was carried out using ionic liquid as solvent in the presence of triethylamine. The reaction was found to pr...
Highly stereoselective and efficient synthesis of the dopa analogue in pepticinnamin E via enantioselective hydrogenation of dehydroamino acids
Synthesis dopa analogue enantioselective hydrogenation
2010/10/15
An efficient and new method was developed to prepare the dopa analogue 11 in natural pepticinnamin via catalytic hydrogenation of dehydroamino acids (DDAA) with a good yield and ee. Product 11 is a ke...
Synthesis of some new biheterocyclic triazole derivatives and evaluation of their antimicrobial activity
1,2,4-Triazole 1H-indole 1,3,4-thiadiazole
2010/10/15
2-{3-(4-Substitutedbenzyl)-4-[2-(1H-indol-3-yl)ethyl]-5-oxo-4,5- dihydro-1H-1,2,4-triazol-1-yl}-N'-(aryl-methylene)acetohydrazides (5a-g), 4-amino-2-{-(4-substitutedbenzyl)-5-oxo-4,5-dihydro-1H-1,2,4-...
Application of a Three-Stage Sequential Extraction Procedure for the Determination of Extractable Metal Contents in Highway Soils
Sequential extraction heavy metals highway soils enrichment flame atomic absorption spectrometry
2010/4/21
A sequential extraction procedure, a three-step protocol proposed by the Standards, Measurements and Testing programme (SM & T--formerly BCR) of the European Union, was applied to soil samples for the...
Synthesis, Characterization and Biological Applications of Organotin(IV) Derivatives of 2-(2-Fluoro-4-biphenyl)propanoic Acid
Synthesis Characterization Biological 2-(2-Fluoro-4-biphenyl)propanoic Acid
2010/4/21
A series of organotin(IV) derivatives with the general formula R4 - nSnLn (where n = 1 or 2, R = Me, Et, n-Bu, Ph and L = 2-(2-fluoro-4-biphenyl)propanoate) have been synthesized and characterized by ...
3,4,5-三甲氧基苯甲醛标准样品的研制
3,4,5-三甲氧基苯甲醛 标准样品 定值 均匀性检验
2012/8/4
研究了3,4,5-三甲氧基苯甲醛标准样品的制备、均匀性和稳定性及其定值试验。用3,4,5-三甲氧基苯甲醛工业品与亚硫酸氢钠溶液加成反应,经H2SO4酸化,结晶;再用乙醇溶解,纯水稀释重结晶,得到高纯度的3,4,5-三甲氧基苯甲醛标准样品。标准样品含量测定采用气相色谱面积归一化法,并通过了均匀性检验和稳定性检验(9个月)。经定值检测,3,4,5-三甲氧基苯甲醛标准样品的质量分数为99.42%±0.0...
Hydrogenation of Citral over Ni and Ni-Sn Catalysts
Citral, hydrogenation citronellol Ni Ni-Sn zeolite
2010/4/16
Liquid phase citral hydrogenation over zeolite-supported monometallic Ni and bimetallic Ni-Sn catalysts was studied. The zeolite support materials were Na-Y, Na-mordenite, and clinoptilolite. Ni and S...
Synthesis of Piperazine Based Polyimide in the Presence of Ionic Liquids
Ionic liquids polyimide catalysts condensation polymers
2010/4/8
Ionic liquids derived from imidazolium, pyridinium, and alkylammonium salts were investigated not only as catalysts but also as solvents in polymerization of 1,4-bis(3-aminopropyl) piperazine. Results...