全文获取类型
收费全文 | 15182篇 |
免费 | 2645篇 |
国内免费 | 2182篇 |
专业分类
化学 | 11244篇 |
晶体学 | 172篇 |
力学 | 864篇 |
综合类 | 150篇 |
数学 | 1909篇 |
物理学 | 5670篇 |
出版年
2024年 | 27篇 |
2023年 | 302篇 |
2022年 | 556篇 |
2021年 | 559篇 |
2020年 | 625篇 |
2019年 | 706篇 |
2018年 | 530篇 |
2017年 | 508篇 |
2016年 | 728篇 |
2015年 | 771篇 |
2014年 | 922篇 |
2013年 | 1134篇 |
2012年 | 1366篇 |
2011年 | 1414篇 |
2010年 | 995篇 |
2009年 | 1018篇 |
2008年 | 1039篇 |
2007年 | 879篇 |
2006年 | 816篇 |
2005年 | 668篇 |
2004年 | 561篇 |
2003年 | 449篇 |
2002年 | 513篇 |
2001年 | 387篇 |
2000年 | 321篇 |
1999年 | 333篇 |
1998年 | 261篇 |
1997年 | 228篇 |
1996年 | 209篇 |
1995年 | 179篇 |
1994年 | 149篇 |
1993年 | 158篇 |
1992年 | 103篇 |
1991年 | 103篇 |
1990年 | 84篇 |
1989年 | 81篇 |
1988年 | 71篇 |
1987年 | 41篇 |
1986年 | 39篇 |
1985年 | 47篇 |
1984年 | 28篇 |
1983年 | 18篇 |
1982年 | 24篇 |
1981年 | 12篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1973年 | 3篇 |
1972年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
We report on Raman scattering of VO2 films prepared by radio frequency magnetron sputtering under different conditions. Our investigations revealed that the dominated Raman peaks shift towards high frequency for both V-rich and O-rich VO2 films, compared with the stoichiometry VO2 films. The experimental evidence is presented and the cause for nonstoichiometry dependence of Raman spectra of VO2 films is discussed. 相似文献
122.
A one‐dimensional zinc(II) coordination polymer has been constructed from zinc(II), 4,4′‐biphenyldicarboxylate and pyridine in which each zinc(II) atom is coordinated by two pyridine ligands and two monodentate 4,4′‐biphenyldicarboxylate ligands that define a distorted tetrahedral geometry. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
123.
Triterpenoid Constituents of Huperzia miyoshiana 总被引:1,自引:0,他引:1
Thirteen triterpenoids, including three new ones, miyoshianois A (1), B (2) and C (3), were isolated from Huperzia miyoshiana. The structures of these new compounds were established as 3-O-dihydroferuloyltohogenol (1), 16-oxo-3β,21β-dihydrox-y-serrat-14-en-24-ferulate (2) and 16-oxo-3a, 21β-dihydroxy-serrat-14-en-24-ferulate (3), respectively, on the basis of their spectroscopic analysis. 相似文献
124.
125.
126.
A novel and cost-effective sol-gel process for preparation of MgAl2O4 spinel nanometer powders has been developed in this study. A solution of magnesium and aluminum nitrates in stoichiometric proportion was successfully embraced in the biology polysaccharide gel network, formed by the synergistic interaction between xanthan gum (XG) and locust bean gum (LBG) utilizing their broad-spectrum stability of salt tolerance and character of transformation from sol to gel on the condition of proper temperature and relative proportion of polymeric components. Dry gel could be obtained by vacuum dehydration of aqueous gel at low temperatures. Monolithic MgAl2O4 spinel nanometer powders were produced by calcining the dry gel above 800°C, with average crystallite size of 20 nanometers. 相似文献
127.
Brian Ingalls Eduardo D. Sontag Yuan Wang 《Proceedings of the American Mathematical Society》2003,131(2):487-499
The fundamental relaxation result for Lipschitz differential inclusions is the Filippov-Wazewski Relaxation Theorem, which provides approximations of trajectories of a relaxed inclusion on finite intervals. A complementary result is presented, which provides approximations on infinite intervals, but does not guarantee that the approximation and the reference trajectory satisfy the same initial condition.
128.
DING Xuantong YANG Qingwei YAN Long wen LIU Yi HUANG Yuan LIU Zetian HONG Wenyu SHI Peilan 《核工业西南物理研究院年报(英文版)》2004,(1):1-4
The main mission the HL-2A tokamak is of the experiments on to explore the divertor physics and to investigate the plasma confinement, transport and instabilities with high power auxiliary heating and advanced fuelling, it is necessary to develop more new diagnostics and increase the spatial and temporal resolutions of the measurements for exist system. Up to now, about 30 diagnostic systems have been moved from HL-1M to HL-2A tokamak. Other 10 diagnostic systems are being designed and installed on the device. In developed in last 2 years, will be presented. 相似文献
129.
130.