全文获取类型
收费全文 | 31882篇 |
免费 | 4893篇 |
国内免费 | 16006篇 |
专业分类
化学 | 33714篇 |
晶体学 | 738篇 |
力学 | 1472篇 |
综合类 | 931篇 |
数学 | 4871篇 |
物理学 | 11055篇 |
出版年
2024年 | 302篇 |
2023年 | 1133篇 |
2022年 | 1286篇 |
2021年 | 1380篇 |
2020年 | 1231篇 |
2019年 | 1470篇 |
2018年 | 917篇 |
2017年 | 1328篇 |
2016年 | 1496篇 |
2015年 | 1621篇 |
2014年 | 2457篇 |
2013年 | 2560篇 |
2012年 | 2602篇 |
2011年 | 2570篇 |
2010年 | 2432篇 |
2009年 | 2634篇 |
2008年 | 3073篇 |
2007年 | 2879篇 |
2006年 | 3097篇 |
2005年 | 2673篇 |
2004年 | 2939篇 |
2003年 | 1887篇 |
2002年 | 1034篇 |
2001年 | 955篇 |
2000年 | 891篇 |
1999年 | 1016篇 |
1998年 | 638篇 |
1997年 | 498篇 |
1996年 | 459篇 |
1995年 | 396篇 |
1994年 | 361篇 |
1993年 | 438篇 |
1992年 | 497篇 |
1991年 | 453篇 |
1990年 | 383篇 |
1989年 | 356篇 |
1988年 | 227篇 |
1987年 | 102篇 |
1986年 | 40篇 |
1985年 | 27篇 |
1984年 | 14篇 |
1983年 | 16篇 |
1982年 | 5篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1959年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Jun-tao Chang Joerg Evers Marian O. Scully M. Suhail Zubairy 《量子光学学报》2006,12(B08):77-77
We propose a scheme to obtain the distance of two identical atoms placed inside the standing wave field by monitoring the collective resonance fluorescence spectrum emitted by the two particles. We find three different parameter ranges, depending on the distance of the atoms as compared to the transition wavelength. For large interparticle distances, dipole-dipole coupling is negligible, and the main system evolution arises from the interaction with the standing wave field. In the small-distance limit, the dynamics is dominated by the dipole-dipole interaction. Finally, in the intermediate region, a rich interplay of the various couplings arises, which however is lifted for strong driving laser fields. The present measurement procedure allows us to distinguish the three cases. In each of the cases, we show how to determine the distance of the two particles and their respective positions relative to the nodes of the standing wave field with fractional-wavelength precision. 相似文献
22.
23.
本文研究具有随机开参数集的随机场构造,获得了具有已知有穷维分布的随机场存在和唯一性条件。 相似文献
24.
25.
26.
27.
通过分析计算,设计了一种大口径宽视场折射式红外相机光学系统。该系统设计用于超长线阵扫描红外相机的地面演示成像,它能同时对短波2μm—3μm、中波3μm—4.5μm双波段成像,且同时具有24°的大视场和150mm的宽口径,成像质量接近衍射极限。该系统在航天遥感领域应用广泛。 相似文献
28.
Ennio Arimondo 《量子光学学报》2006,12(B08):59-60
Cold atoms and, more recently, Bose-Einstein condensates (BEC's) in optical lattices have attracted increasing interest since their first realization. In particular, the formal similarity between the wavefunction of a BEC inside the periodic potential of an optical lattice and of the electrons in a crystal lattice has triggered theoretical and experimental efforts alike. Many phenomena from condensed matter physics, such as Bloch oscillations and Landau-Zener tunneling have been shown to be observable also in optical lattices. An important difference between electrons in a crystal lattice and a BEC inside the periodic potential of an optical lattice is the strength of the self interaction and hence the magnitude of the nonlinearity of the system. Electrons in a metal are almost noninteracting, whereas atoms inside a BEC interact strongly. A' perturbation approach is appropriate in the former case while in the latter the full nonlinearity must be taken into account. From this feature new physics is expected. Most experiments to date have been carried out in the regime of shallow lattice depth, for which the system is well described by the mean field Gross-Pitaevskii equation with a periodic potential. Moreover, the nonlinearity induced by the mean-field of the condensate has been shown, both theoretically and experimentally, to give rise to instabilities in certain regions of the Brillouin zone. These instabilities are not present in the corresponding linear system, i.e. the electron system. Experimental and theoretical results on the subject of nonlinear Landau-Zener tunneling and nonlinearity-induced instabilities in a Bose-Einstein condensate interacting with an external periodic potential will be presented. 相似文献
29.
本文对具有有限时滞的泛函微分方程建立了关于依照两种测度的实际稳定性的Razumikhin型判定定理,其中未采用通常的辅助函数,且可运用多个含有状态变量x的部分变元的Lyapunov函数,得出部分变远实际稳定性的判定定理,从而改进了已有的结果。 相似文献
30.