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   74篇
  免费   5篇
化学   65篇
数学   8篇
物理学   6篇
  2022年   2篇
  2021年   4篇
  2020年   3篇
  2019年   5篇
  2016年   4篇
  2015年   1篇
  2014年   1篇
  2013年   2篇
  2012年   4篇
  2011年   7篇
  2010年   1篇
  2009年   1篇
  2008年   5篇
  2007年   5篇
  2006年   4篇
  2005年   3篇
  2004年   3篇
  2003年   4篇
  2002年   6篇
  2001年   3篇
  1999年   1篇
  1997年   1篇
  1992年   1篇
  1985年   1篇
  1984年   2篇
  1982年   1篇
  1978年   2篇
  1976年   2篇
排序方式: 共有79条查询结果,搜索用时 31 毫秒
1.
A novel two-step synthesis of isonitrosoacetanilides [2-(hydroxyimino)-N-phenylacetamides] has been developed, involving the initial acylation of aniline derivatives with 2,2-diacetoxyacetyl chloride, followed by reaction with hydroxylamine hydrochloride. The method works equally well with a variety of different aniline derivatives, including those with poor aqueous solubility and those containing electron rich ortho-substituents, neither of which react well under traditional conditions.  相似文献   
2.
Gentle heating of allyloxyanthraquinones with sodium dithionite in dimethylformanide - water effects a rapid and controlled rearrangement to give high yields of 2-allyanthraquinones.  相似文献   
3.
Several enones are converted into their alpha-iodo derivatives in excellent yields and carbonylated with palladium catalysis in the presence of alcohol or amines to the alpha-carbonyl enones in satisfactory yields.  相似文献   
4.
Allylrhodium species generated from potassium allyltrifluoroborates can undergo isomerization by 1,4‐rhodium(I) migration to give more complex isomers, which then react with cyclic imines to provide products with up to three new stereochemical elements. High enantioselectivities are obtained using chiral diene–rhodium complexes.  相似文献   
5.
6.
7.
8.
9.
10.
The formation processes of metal–organic frameworks are becoming more widely researched using in situ techniques, although there remains a scarcity of NMR studies in this field. In this work, the synthesis of framework MFM-500(Ni) has been investigated using an in situ NMR strategy that provides information on the time-evolution of the reaction and crystallization process. In our in situ NMR study of MFM-500(Ni) formation, liquid-phase 1H NMR data recorded as a function of time at fixed temperatures (between 60 and 100 °C) afford qualitative information on the solution-phase processes and quantitative information on the kinetics of crystallization, allowing the activation energies for nucleation (61.4 ± 9.7 kJ mol−1) and growth (72.9 ± 8.6 kJ mol−1) to be determined. Ex situ small-angle X-ray scattering studies (at 80 °C) provide complementary nanoscale information on the rapid self-assembly prior to MOF crystallization and in situ powder X-ray diffraction confirms that the only crystalline phase present during the reaction (at 90 °C) is phase-pure MFM-500(Ni). This work demonstrates that in situ NMR experiments can shed new light on MOF synthesis, opening up the technique to provide better understanding of how MOFs are formed.

A new in situ NMR methodology for studying the formation processes of MOFs is reported, supported by SAXS and PXRD experiments. Synthesis of a phosphonate-based MOF is described, from molecular aggregation through to nucleation and crystallisation.  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