首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   42篇
  免费   1篇
化学   35篇
数学   7篇
物理学   1篇
  2022年   2篇
  2021年   1篇
  2020年   3篇
  2019年   3篇
  2017年   2篇
  2016年   2篇
  2014年   2篇
  2013年   3篇
  2012年   1篇
  2011年   9篇
  2010年   1篇
  2009年   2篇
  2008年   2篇
  2007年   1篇
  2006年   1篇
  2005年   3篇
  2004年   2篇
  1998年   1篇
  1995年   1篇
  1993年   1篇
排序方式: 共有43条查询结果,搜索用时 0 毫秒
41.
Use of solid-phase synthesis for the derivatization of carboxylic acids with biotinylated spacers consisting of ethylenoxy units is described. An aminomethylated resin provided with an acid-labile aldehyde linker is used as the polymer support and three different systems with a reactive amino group are introduced. Acylation of each system was tested with a set of model carboxylic acids and afforded crude products of excellent purity. The preloaded resins are similar to the Biotin-PEG-NovaTagTM resin but offer several advantages including simple elongation of the spacer arm. The protocols described represent a very efficient way of modifying compounds to obtain ligands for affinity chromatography studies.  相似文献   
42.
New de-tert-butyltetrathiacalix[4]arenes with acetylhydrazide substituents in cone and 1,3-alternate conformations have been synthesised with good yield by the hydrazinolysis of calix[4]arene ester derivatives. The recognition ability of synthesised macrocycles towards transition and alkali metals has been investigated by the picrate extraction method. The stoichiometry of complexes and the extraction constants have been determined. It has been found that tetrahydrazides do not extract alkali metal ions, but show an excellent affinity towards transition and heavy metal cations. The 1,3-alternate conformer of de-tert-butyltetrathiacalix[4]arene has revealed a remarkable selectivity for Ni2+ and Ag+ in the row of d-elements and for Cd2+ ion among the toxic heavy metals. The experimental data show that the removal of tert-butyl groups from tetrathiacalix[4]arene framework leads to the drastic improvement of extraction efficiency and selectivity of new tetrahydrazides.  相似文献   
43.
A one-step simple synthesis of silver colloid nanoparticles with controllable sizes is presented. In this synthesis, reduction of [Ag(NH(3))(2)](+) complex cation by four saccharides was performed. Four saccharides were used: two monosaccharides (glucose and galactose) and two disaccharides (maltose and lactose). The syntheses performed at various ammonia concentrations (0.005-0.20 mol L(-1)) and pH conditions (11.5-13.0) produced a wide range of particle sizes (25-450 nm) with narrow size distributions, especially at the lowest ammonia concentrations. The average size, size distribution, morphology, and structure of particles were determined by dynamic light scattering (DLS), transmission electron microscopy (TEM), and UV/Visible absorption spectrophotometry. The influence of the saccharide structure (monosacharides versus disaccharides) on the size of silver particles is briefly discussed. The reduction of [Ag(NH(3))(2)](+) by maltose produced silver particles with a narrow size distribution with an average size of 25 nm, which showed high antimicrobial and bactericidal activity against Gram-positive and Gram-negative bacteria, including highly multiresistant strains such as methicillin-resistant Staphylococcus aureus. Antibacterial activity of silver nanoparticles was found to be dependent on the size of silver particles. A very low concentration of silver (as low as 1.69 mug/mL Ag) gave antibacterial performance.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号