全文获取类型
收费全文 | 352篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
化学 | 251篇 |
晶体学 | 30篇 |
力学 | 2篇 |
数学 | 3篇 |
物理学 | 69篇 |
出版年
2023年 | 4篇 |
2022年 | 5篇 |
2021年 | 4篇 |
2020年 | 1篇 |
2019年 | 7篇 |
2018年 | 8篇 |
2017年 | 4篇 |
2016年 | 5篇 |
2015年 | 9篇 |
2014年 | 9篇 |
2013年 | 28篇 |
2012年 | 16篇 |
2011年 | 42篇 |
2010年 | 13篇 |
2009年 | 19篇 |
2008年 | 22篇 |
2007年 | 21篇 |
2006年 | 27篇 |
2005年 | 8篇 |
2004年 | 6篇 |
2003年 | 9篇 |
2002年 | 4篇 |
2001年 | 8篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 16篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1975年 | 1篇 |
排序方式: 共有355条查询结果,搜索用时 15 毫秒
1.
K. Ravikumar B. Sridhar M. Mahesh V. V. Narayana Reddy 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(9):o574-o576
The crystal structures of pyranoquinolines 9‐fluoro‐5‐phenyl‐3,4,4a,5,6,10b‐hexahydro‐2H‐pyrano[3,2‐c]quinoline, C18H18FNO, and 9‐methyl‐5‐phenyl‐3,4,4a,5,6,10b‐hexahydro‐2H‐pyrano[3,2‐c]quinoline, C19H21NO, are isomorphous. In both structures, the pyran ring is exo to the six‐membered N‐heterocyclic ring formed in the cycloaddition step. The torsion angles across the phenyl linkage for the two structures are −91.2 (1) and −88.3 (2)°. The striking feature in both crystal packings is that they do not contain the expected conventional hydrogen bonds, in spite of the presence of good hydrogen‐bonding functionalities. Possible C—H⋯π interactions are, however, observed. 相似文献
2.
Electron paramagnetic resonance and optical absorption spectra of Cr ions in cadmium phosphate glass
R.V.S.S.N. Ravikumar Ryuichi KomatsuKo. Ikeda A.V. ChandrasekharB.J. Reddy Y.P. ReddyP.S. Rao 《Solid State Communications》2003,126(5):251-253
EPR and optical absorption investigations of chromium doped cadmium phosphate glass are carried out. Crystal field, spin-Hamiltonian and bonding parameters are evaluated. From the results and analyses of the EPR and optical studies, the site symmetry of Cr3+ ion in the glass is ascribed to a distorted octahedron. The bonding parameters suggest the ionic nature of Cr3+ ion with the ligands. 相似文献
3.
4.
Metal ion uptake properties of polystyrene-supported chelating polymer resins functionalized with (i) glycine, (ii) hydroxy
benzoic acid, (iii) Schiff base and (iv) diethanol amine have been investigated. The effects of pH, time and initial concentration
on the uptake of metal ions have been studied. The uptake of metal ion depends on pH. The resins are more selective at pH
10 for Pb(II) and Hg(II), whereas at pH 6 they are found to be Cd(II) and Cr(VI) selective. Metal ion uptake properties of
resins follow Freundlich’s equation. The resins are recyclable and are therefore employed for the removal of heavy metal pollutants
from industrial waste water. 相似文献
5.
6.
7.
8.
9.
10.
B. Sridhar K. Ravikumar Y. S. Sadanandam 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(12):o687-o690
The title compound, C22H19N3O2S, crystallizes in two polymorphic forms having the same space group, viz. P, with Z′ = 2 and Z′ = 1. In both polymorphs, the planar thiazole ring is fused cis with the dihydropyrimidine ring, the carbamoyl group is in an extended conformation with an anticlinal orientation with respect to the pyrimidine ring, and the phenyl ring is attached to the pyrimidine ring approximately at a right angle. The two polymorphs have different interplanar angles between the phenyl and thiazole rings. The molecules are linked by N—H⋯O and C—H⋯O hydrogen bonds. 相似文献