全文获取类型
收费全文 | 10533篇 |
免费 | 1797篇 |
国内免费 | 632篇 |
专业分类
化学 | 2337篇 |
晶体学 | 82篇 |
力学 | 913篇 |
综合类 | 151篇 |
数学 | 4883篇 |
物理学 | 4596篇 |
出版年
2024年 | 11篇 |
2023年 | 99篇 |
2022年 | 178篇 |
2021年 | 303篇 |
2020年 | 302篇 |
2019年 | 351篇 |
2018年 | 311篇 |
2017年 | 407篇 |
2016年 | 443篇 |
2015年 | 371篇 |
2014年 | 529篇 |
2013年 | 887篇 |
2012年 | 591篇 |
2011年 | 644篇 |
2010年 | 570篇 |
2009年 | 624篇 |
2008年 | 728篇 |
2007年 | 632篇 |
2006年 | 578篇 |
2005年 | 490篇 |
2004年 | 417篇 |
2003年 | 436篇 |
2002年 | 411篇 |
2001年 | 361篇 |
2000年 | 322篇 |
1999年 | 307篇 |
1998年 | 236篇 |
1997年 | 214篇 |
1996年 | 166篇 |
1995年 | 166篇 |
1994年 | 110篇 |
1993年 | 83篇 |
1992年 | 73篇 |
1991年 | 69篇 |
1990年 | 65篇 |
1989年 | 60篇 |
1988年 | 39篇 |
1987年 | 48篇 |
1986年 | 40篇 |
1985年 | 59篇 |
1984年 | 40篇 |
1983年 | 25篇 |
1982年 | 30篇 |
1981年 | 27篇 |
1980年 | 12篇 |
1979年 | 21篇 |
1978年 | 19篇 |
1977年 | 17篇 |
1976年 | 12篇 |
1974年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
Jonathan M. Levin Lawrence L. Wald Marc J. Kaufman Marjorie H. Ross Luis C. Maas Perry F. Renshaw 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1998,130(2):292-295
Residual effects of an initial bolus of gadolinium contrast agent have been previously demonstrated in sequential dynamic susceptibility contrast MR experiments. While these residual effects quickly reach a saturation steady state, their etiology is uncertain, and they can lead to spurious estimates of hemodynamic parameters in activation experiments. The possible influence ofT1effects is now investigated with experiments in whichT1weighting is varied as well as with serial regionalT1measurements. Little evidence for significant residualT1effects is found, suggesting instead that susceptibility effects underlie these observations. An initial saturation dose of contrast agent minimizes this effect. 相似文献
12.
The radiation emitted by charged, scalar particles in a Schwarzschild field with maximal acceleration corrections is calculated classically and in the tree approximation of quantum field theory. In both instances the particles emit radiation that has characteristics similar to those of gamma-ray bursters. 相似文献
13.
14.
LI Yu-qiong SUN Zhen-rong ZHANG Shi-an YANG Xi-hua WANG Zu-geng. Key Laboratory of Optical Magnetic Resonance Spectroscopy 《光谱学与光谱分析》2006,26(8):1395-1395
The authors achieved the temporal coherent control in an Er^3+ doped telluride glass, one kind of disordered solids. The upconversion at 670 nm was modulated and the dephasing time was simulated as 300 fs. Moreover, the photon echo signal gave the dephasing time due to the phonon interaction. The agreement between the two data indicates that the interaction between the wavepacket and the phonon leads to the fast disappearance of wavepackets interference, which is helpful for the tech- nique to be applied to the disordered solids. 相似文献
15.
16.
17.
带干扰的多险种风险模型 总被引:2,自引:0,他引:2
由于保险公司风险经营规模不断扩大,用单一险种的模型来描述风险过程存在局限性,本文讨论了带干扰多险种风险模型,应用鞅论方法,得出伦德伯格不等式和最终破产概率公式。 相似文献
18.
Blaise Faugeras Jé rô me Pousin Franck Fontvieille. 《Mathematics of Computation》2006,75(253):209-222
A numerical scheme based on an operator splitting method and a dense output event location algorithm is proposed to integrate a diffusion-dissolution/precipitation chemical initial-boundary value problem with jumping nonlinearities. The numerical analysis of the scheme is carried out and it is proved to be of order 2 in time. This global order estimate is illustrated numerically on a test case.
19.
Benjamin J. K. Evans Susan M. Scott Antony C. Searle 《General Relativity and Gravitation》2002,34(10):1675-1684
We have developed a new tool for numerical work in General Relativity: GRworkbench. We discuss how GRworkbench's implementation of a numerically-amenable analogue to Differential Geometry facilitates the development of robust and chart-independent numerical algorithms. We consider, as an example, geodesic tracing on two charts covering the exterior Schwarzschild space-time. 相似文献
20.