全文获取类型
收费全文 | 28402篇 |
免费 | 3698篇 |
国内免费 | 3152篇 |
专业分类
化学 | 20710篇 |
晶体学 | 363篇 |
力学 | 1398篇 |
综合类 | 234篇 |
数学 | 3537篇 |
物理学 | 9010篇 |
出版年
2024年 | 47篇 |
2023年 | 438篇 |
2022年 | 492篇 |
2021年 | 757篇 |
2020年 | 908篇 |
2019年 | 925篇 |
2018年 | 788篇 |
2017年 | 752篇 |
2016年 | 1120篇 |
2015年 | 1141篇 |
2014年 | 1351篇 |
2013年 | 1902篇 |
2012年 | 2275篇 |
2011年 | 2514篇 |
2010年 | 1765篇 |
2009年 | 1736篇 |
2008年 | 1932篇 |
2007年 | 1759篇 |
2006年 | 1579篇 |
2005年 | 1392篇 |
2004年 | 1109篇 |
2003年 | 902篇 |
2002年 | 882篇 |
2001年 | 740篇 |
2000年 | 622篇 |
1999年 | 581篇 |
1998年 | 504篇 |
1997年 | 443篇 |
1996年 | 474篇 |
1995年 | 386篇 |
1994年 | 367篇 |
1993年 | 341篇 |
1992年 | 319篇 |
1991年 | 276篇 |
1990年 | 232篇 |
1989年 | 191篇 |
1988年 | 167篇 |
1987年 | 128篇 |
1986年 | 141篇 |
1985年 | 154篇 |
1984年 | 101篇 |
1983年 | 64篇 |
1982年 | 71篇 |
1981年 | 53篇 |
1980年 | 52篇 |
1979年 | 58篇 |
1978年 | 40篇 |
1976年 | 37篇 |
1974年 | 40篇 |
1973年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
71.
NianYuanTAN XiaoMingXIAO ZeLinLI TakekoMATSUMURA-INOUE 《中国化学快报》2004,15(6):687-690
A new cobalt(Ⅱ) complex with tridentate ligand 2, 6-bis (benzimidazol-2-yl)pyridine has been synthesized by microwave irradiation method and characterized by elemental analysis,electrochemical and spectral methods. The binding of the complex with calf thymus DNA has also been investigated by absorption and fluorescence spectra. 相似文献
72.
Baker‘s yeast mediated reduction of optically active diketone is described. The two keto groups are efficiently differentiated and the ee value of the recovered material is considerably raised. It affords highly optically active key intermediates efficiently for the synthesis of natural polyhydroxylated agarofuran products. 相似文献
73.
74.
Thermal oxidation of polyethylene filled with dispersed copper and containing an amine antioxidant was studied. The concentration ranges in which the catalytic effect of the metal on the polymer oxidation or the stabilizing effect of the antioxidant prevails were determined. Under certain conditions, dispersed copper enhances the stabilizing effect of the antioxidant. 相似文献
75.
Lin Huaxin 《数学年刊B辑(英文版)》1993,14(3):387-396
The author studies the problem whether a multiplier of a hereditary C^*-subalgebra B of a C^*-algebra A can be extended to a multiplier of A. One related problem is the Hahn-Banach extension theorem for Hilbert modules over C^*-algebras. It is shown that every self-dual Hilbert module over W^*-algebra or an injective C^*-algebra is injective. 相似文献
76.
77.
78.
The products from the condensation of acetone-anils ( 1 ) and TCNE reaction were characterized after separation. The main products, tricyanoethylene derivatives ( 7–9 ) were isolated with the malonodinitrile derivatives ( 10–12 ), respectively. The [2+2] cycloaddition product ( 13 ), namely 5-methoxy-3,4-(2′,2′,3′,3′-tetracyanocyclobutano)-l,2-dihydro-2,2,4-trimethylquinoline also has been isolated. The distribution of these three products is substituent dependent. 相似文献
79.
80.
Chii-Wann Lin Kuo-Ping Chen Ming-Chii Su Chih-Kung Lee Chih-Chung Yang 《Optical and Quantum Electronics》2005,37(13-15):1423-1437
We have reported a novel design of surface plasmon resonance (SPR) device, which uses alternating dielectric layers to enhance the SPR signal quality and modulate its resonant position. Admittance loci method of thin film design has been used in the design of such a device. The use of biomolecular thin film, such as DNAs or Porteins, in this design can result in resonant condition of wavelength changes as well. Bio-plasmonics is proposed for the research and development of novel devices, which use biomolecules as a part of the plasmon oscillation system to actively interact with nano/micro structure. 相似文献