全文获取类型
收费全文 | 325篇 |
免费 | 9篇 |
国内免费 | 2篇 |
专业分类
化学 | 181篇 |
晶体学 | 10篇 |
力学 | 25篇 |
数学 | 82篇 |
物理学 | 38篇 |
出版年
2023年 | 1篇 |
2022年 | 9篇 |
2021年 | 14篇 |
2020年 | 11篇 |
2019年 | 15篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 8篇 |
2014年 | 13篇 |
2013年 | 39篇 |
2012年 | 20篇 |
2011年 | 31篇 |
2010年 | 24篇 |
2009年 | 22篇 |
2008年 | 12篇 |
2007年 | 17篇 |
2006年 | 10篇 |
2005年 | 12篇 |
2004年 | 10篇 |
2003年 | 11篇 |
2002年 | 5篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1993年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有336条查询结果,搜索用时 16 毫秒
1.
2.
Toner AJ Donnadieu B Sabo-Etienne S Chaudret B Sava X Mathey F Le Floch P 《Inorganic chemistry》2001,40(13):3034-3038
The bis(dihydrogen) complex RuH(2)(H(2))(2)(PCy(3))(2) (1) reacts with 2-phenyl-3,4-dimethylphosphaferrocene (L(1)) to give RuH(2)(H(2))(PCy(3))(2)(L(1)) (2). This dihydride-dihydrogen complex has been characterized by X-ray crystallography and variable-temperature (1)H and (31)P NMR spectroscopy. The exchange between the dihydrogen ligand and the two hydrides is characterized by a DeltaG() of 46.2 kJ/mol at 263 K. H/D exchange is readily observed when heating a C(7)D(8) solution of 2 (J(H-D) = 30 Hz). The H(2) ligand in 2 can be displaced by ethylene or carbon monoxide leading to the corresponding ethylene or carbonyl complexes. The reaction of 1 with 2 equiv of 3,4-dimethylphosphaferrocene (L(2)) yields the dihydride complex RuH(2)(PCy(3))(2)(L(2))(2) (5). 相似文献
3.
4.
Guo Chang Zhuo Xiaoyang Constantinescu Corina Pamen Olivier Menoukeu 《Methodology and Computing in Applied Probability》2018,20(4):1477-1502
Methodology and Computing in Applied Probability - In this paper, we pursue the optimal reinsurance-investment strategy of an insurer who can invest in both domestic and foreign markets. We assume... 相似文献
5.
Ukrainian Mathematical Journal - We introduce new definitions related to the notions of asymptotically Iλ -statistical equivalent of order α to multiple L and strongly Iλ... 相似文献
6.
The reactions of 2,2,2-trichloro-1-phenylethanone with various oxygen, carbon and sulfur nucleophiles were investigated with a view of widening the use of trichloroethanones as acylating agents. 相似文献
7.
The paper deals with the study of the thermotropic liquid crystalline properties of a new azomethinic symmetric dimer and some of its structural heterogeneous mixtures with one of its reagents. Their thermotropic behaviour was monitored by polarised light microscopy, differential scanning microscopy and variable temperature X-ray diffraction measurements. The influence of the structural heterogeneity on the mesomorphic behaviour was established and some similarities with the mesomorphic behaviour of the polydisperse polymers were underlined. 相似文献
8.
JPC – Journal of Planar Chromatography – Modern TLC - This paper was aimed at analytical and antioxidant activity studies on a series of European beech (Fagus sylvatica L.) leaves... 相似文献
9.
10.
Emil I. Muresan Mioara Drobota Alexandra Bargan Corina A. M. Dumitriu 《Central European Journal of Chemistry》2014,12(4):528-536
This paper reports a systematic study on the preparation, characterization and testing of metallosilicate macrobeads that contain chromium ions as active catalytic centers. In order to obtain hard macrospheres, four metals (Cr, Al, Zr and Zn) were incorporated into the silica matrix using chitosan as a template and shape generator. Metallosilicate macrospheres were synthesized at room temperature using tetraethylorthosilicate as silicon source and chlorohydric acid as catalyst. The size of metallosilicate macrospheres was in the range 0.9 — 1.1 mm. The catalyst was characterised by means of water sorption technique, FTIR spectroscopy and SEM/EDX analyses. FTIR spectra put into evidence the presence of metallic ions within the silica framework. EDX analyses confirmed the efficient incorporation of metals within the silica matrix (the content of metals from the calcined catalyst is almost the same as that from the initial gel mixture). Porous structure of catalyst investigated by water sorption technique and by pycnometric methods (with n-heptan and mercury respectively) proved that the synthesized catalyst had micro, meso and macropores. Catalyst was tested in the esterification reaction of acetic acid with epichlorohydrin. The temperature and the amount of catalyst exerted a marked influence on reaction rate. This work opens new perspectives for heterogeneous catalysis encouraging the replacement of powder catalysts with macrospherical catalysts that are easy to recover and to reuse. 相似文献