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   75篇
  免费   7篇
化学   51篇
晶体学   10篇
力学   1篇
数学   3篇
物理学   17篇
  2023年   1篇
  2022年   1篇
  2021年   1篇
  2019年   2篇
  2017年   1篇
  2016年   6篇
  2015年   3篇
  2014年   4篇
  2013年   7篇
  2012年   3篇
  2011年   4篇
  2010年   12篇
  2009年   8篇
  2008年   11篇
  2007年   6篇
  2006年   5篇
  2005年   2篇
  2004年   2篇
  2003年   1篇
  2002年   1篇
  2001年   1篇
排序方式: 共有82条查询结果,搜索用时 0 毫秒
81.

Abstract  

A new 3,3′-dibenzoyl-1,1′-propan-1,3-diyl)bisthiourea was synthesized by using benzoylisothiocyanate with 1,3-diaminopropane in aprotic solvent. The structure was determinated by means of FT-IR, 1H-NMR, 13C-NMR and mass spectroscopic techniques. The crystal structure of 3,3′-dibenzoyl-1,1′-(propan-1,3-diyl)bisthiourea has also been examined by using X-ray crystallographic techniques and found to be crystallized in the monoclinic space group P2 1 /c with the unit cell parameters: a = 5.968(1) ?, b = 19.471(2) ?, c = 16.585(2) ?, β = 98.32(1)°, V = 1907.0(4) ?3, Dx = 1.395 g cm−3, and Z = 4 respectively.  相似文献   
82.
The molecular and crystal structure of (E)-2-Acetyl-4-(2-bromophenyldiazenyl)phenol (1) and (E)-2-Methyl-4-(o-tolyldiazenyl)phenol (2) were characterized and determined by single crystal X-ray diffraction method besides spectroscopic means. The periodic organization of 1 is stabilized by C–H···O type weak H-bond and Br···O type weak halogen bonding and thus, a two dimensional puckered network is established almost parallel to () the plane. Molecules of 2 are linked into C(7) chains generated by translation along the [1 0 1] direction with the aid of O–H···N type H-bonds, and these chains are strengthened by C–H···π interactions involving o-tolylphenol ring. Quantum chemical studies at B3LYP/6-311 ++G(d,p) level reveal that potential barrier of the compounds around Ar–N torsions is of double minimum character unless it is defected by the presence of o-substituent groups in the vicinity of the azo bridge. The results from crystallographic and quantum chemical studies suggest that azo benzene compounds may adapt non-planar geometry apart from the most stable planar conformation, which is located on the secondary minima of double potential barrier regarding rotational motion around Ar–N bonds.  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