全文获取类型
收费全文 | 32450篇 |
免费 | 4400篇 |
国内免费 | 3815篇 |
专业分类
化学 | 23470篇 |
晶体学 | 462篇 |
力学 | 1611篇 |
综合类 | 298篇 |
数学 | 4204篇 |
物理学 | 10620篇 |
出版年
2024年 | 56篇 |
2023年 | 513篇 |
2022年 | 576篇 |
2021年 | 886篇 |
2020年 | 1095篇 |
2019年 | 1086篇 |
2018年 | 952篇 |
2017年 | 915篇 |
2016年 | 1324篇 |
2015年 | 1326篇 |
2014年 | 1563篇 |
2013年 | 2203篇 |
2012年 | 2669篇 |
2011年 | 2898篇 |
2010年 | 2059篇 |
2009年 | 2039篇 |
2008年 | 2248篇 |
2007年 | 2032篇 |
2006年 | 1812篇 |
2005年 | 1593篇 |
2004年 | 1238篇 |
2003年 | 1033篇 |
2002年 | 1053篇 |
2001年 | 887篇 |
2000年 | 725篇 |
1999年 | 664篇 |
1998年 | 553篇 |
1997年 | 480篇 |
1996年 | 493篇 |
1995年 | 414篇 |
1994年 | 402篇 |
1993年 | 371篇 |
1992年 | 344篇 |
1991年 | 302篇 |
1990年 | 256篇 |
1989年 | 199篇 |
1988年 | 176篇 |
1987年 | 137篇 |
1986年 | 153篇 |
1985年 | 162篇 |
1984年 | 111篇 |
1983年 | 73篇 |
1982年 | 80篇 |
1981年 | 54篇 |
1980年 | 54篇 |
1979年 | 59篇 |
1978年 | 41篇 |
1976年 | 38篇 |
1974年 | 43篇 |
1973年 | 49篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
91.
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
92.
93.
94.
95.
96.
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
97.
98.
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
99.
Richard Becker Mladen Prester Ping Hui Lin Mats Johnsson Ivica Zivkovic 《Journal of solid state chemistry》2007,180(3):1051-1059
Two new isostructural cobalt selenite halides Co5(SeO3)4Cl2 and Co5(SeO3)4Br2 have been synthesized. They crystallize in the triclinic system space group P−1 with the following lattice parameters for Co5(SeO3)4Cl2: a=6.4935(8) Å, b=7.7288(8) Å, c=7.7443(10) Å, α=66.051(11)°, β=73.610(11)°, γ=81.268(9)°, and Z=1. The crystal structures were solved from single-crystal X-ray data, R1=3.73 and 4.03 for Co5(SeO3)4Cl2 and Co5(SeO3)4Br2, respectively. The new compounds are isostructural to Ni5(SeO3)4Br2.Magnetic susceptibility measurements on oriented single-crystalline samples show anisotropic response in a broad temperature range. The anisotropic susceptibility is quantitatively interpreted within the zero-field splitting schemes for Co2+ and Ni2+ ions. Sharp low-temperature susceptibility features, at TN=18 and 20 K for Co5(SeO3)4Cl2 and Co5(SeO3)4Br2, respectively, are ascribed to antiferromagnetic ordering in a minority magnetic subsystem. In isostructural Ni5(SeO3)4Br2 magnetically ordered subsystem represents a majority fraction (TN=46 K). Nevertheless, anisotropic susceptibility of Ni5(SeO3)4Br2 is dominated at low temperatures by a minority fraction, subject to single-ion anisotropy effects and increasing population of Sz=0 (singlet) ground state of octahedrally coordinated Ni2+. 相似文献
100.
Several functionalized β-diketones and their europium complexes have been synthesized and characterized. The UV-Vis absorption, photoluminescent spectra, thermal and electrochemical properties of these complexes were investigated. The thermal analysis shows that the complexes have good thermal stability. By introducing the number of extended phenyl rings we succeeded in obtaining europium complexes with extremely high photoluminescent quantum yield (PLQY) in solution due to strong site isolation effect. 相似文献