全文获取类型
收费全文 | 3913篇 |
免费 | 685篇 |
国内免费 | 611篇 |
专业分类
化学 | 3293篇 |
晶体学 | 67篇 |
力学 | 192篇 |
综合类 | 75篇 |
数学 | 421篇 |
物理学 | 1161篇 |
出版年
2024年 | 25篇 |
2023年 | 89篇 |
2022年 | 148篇 |
2021年 | 189篇 |
2020年 | 213篇 |
2019年 | 209篇 |
2018年 | 190篇 |
2017年 | 173篇 |
2016年 | 226篇 |
2015年 | 251篇 |
2014年 | 292篇 |
2013年 | 343篇 |
2012年 | 365篇 |
2011年 | 361篇 |
2010年 | 308篇 |
2009年 | 282篇 |
2008年 | 259篇 |
2007年 | 233篇 |
2006年 | 186篇 |
2005年 | 145篇 |
2004年 | 97篇 |
2003年 | 88篇 |
2002年 | 90篇 |
2001年 | 70篇 |
2000年 | 53篇 |
1999年 | 48篇 |
1998年 | 24篇 |
1997年 | 18篇 |
1996年 | 12篇 |
1995年 | 23篇 |
1994年 | 15篇 |
1993年 | 20篇 |
1992年 | 16篇 |
1991年 | 7篇 |
1990年 | 15篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1985年 | 8篇 |
1982年 | 5篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1975年 | 9篇 |
1974年 | 8篇 |
1972年 | 11篇 |
1971年 | 6篇 |
1970年 | 5篇 |
1969年 | 5篇 |
排序方式: 共有5209条查询结果,搜索用时 15 毫秒
1.
2.
In this note, we study convergence rates in the law of large numbers for independent and identically distributed random variables under sublinear expectations. We obtain a strong L^p-convergence version and a strongly quasi sure convergence version of the law of large numbers. 相似文献
3.
Based on solving the couple mode equation numerically, the characterization of the signal power on the gate power was analyzed. And the relationship of the tolerance of the grating period and the bulk temperature on the interaction length was analyzed. 相似文献
4.
5.
Each convex planar set K has a perimeter C, a minimum width E, an area A, and a diameter D. The set of points (E,C, A1/2, D) corresponding to
all such sets is shown to occupy a cone in the non-negative orthant of R4with its vertex at the origin. Its three-dimensional cross section S in the
plane D = 1 is investigated. S lies in a rectangular parallelepiped in R3. Results of Lebesgue, Kubota, Fukasawa, Sholander, and Hemmi are used to
determine some of the boundary surfaces of S, and new results are given for the other boundary surfaces. From knowledge of S, all inequalities among
E, C ,A, and D can be found. 相似文献
6.
7.
8.
InAs/GaSb/AlSb resonant tunneling spin device concepts 总被引:1,自引:0,他引:1
David Z. -Y. Ting Xavier Cartoix 《Physica E: Low-dimensional Systems and Nanostructures》2004,20(3-4):350
We discuss device concepts for creating spin-polarized current sources without external magnetic fields, using non-magnetic 6.1 Å semiconductor resonant tunneling structures. Spin filters, spin pumps, and spin transistors that exploit structural and bulk inversion asymmetries will be examined. 相似文献
9.
Esarey E. Ting A. Sprangle P. Umstadter D. Liu X. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1993,21(1):95-104
A linearly polarized, ultraintense laser field induces transverse plasma currents which are highly relativistic and nonlinear, resulting in the generation of coherent harmonic radiation in the forward direction (i.e., copropagating with the incident laser field). A nonlinear cold fluid model, valid for ultrahigh intensities, is formulated and used to analyze relativistic harmonic generation. The plasma density response is included self-consistently and is shown to significantly reduce the current driving the harmonic radiation. Phase detuning severely limits the growth of the harmonic radiation. The effects of diffraction are considered in the mildly relativistic limit. No third-harmonic signal emerges from a uniform plasma of near-infinite extent. A finite third-harmonic signal requires the use of a semi-infinite or finite slab plasma. For an initially uniform plasma, no second-harmonic radiation is generated. Generation of even harmonics requires transverse gradients in the initial plasma density profile 相似文献
10.