全文获取类型
收费全文 | 921篇 |
免费 | 171篇 |
国内免费 | 100篇 |
专业分类
化学 | 164篇 |
力学 | 144篇 |
综合类 | 8篇 |
数学 | 390篇 |
物理学 | 486篇 |
出版年
2024年 | 1篇 |
2023年 | 21篇 |
2022年 | 20篇 |
2021年 | 27篇 |
2020年 | 30篇 |
2019年 | 19篇 |
2018年 | 25篇 |
2017年 | 31篇 |
2016年 | 46篇 |
2015年 | 24篇 |
2014年 | 62篇 |
2013年 | 82篇 |
2012年 | 63篇 |
2011年 | 62篇 |
2010年 | 68篇 |
2009年 | 77篇 |
2008年 | 71篇 |
2007年 | 50篇 |
2006年 | 44篇 |
2005年 | 44篇 |
2004年 | 21篇 |
2003年 | 24篇 |
2002年 | 38篇 |
2001年 | 31篇 |
2000年 | 25篇 |
1999年 | 29篇 |
1998年 | 32篇 |
1997年 | 20篇 |
1996年 | 9篇 |
1995年 | 12篇 |
1994年 | 24篇 |
1993年 | 8篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 9篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1957年 | 1篇 |
排序方式: 共有1192条查询结果,搜索用时 15 毫秒
991.
992.
The influence of fractal heterogeneity on a spiral wave in an excitable system is numerically studied based on the Barkley model. The heterogeneity is implemented by letting the diffusive coefficient in the heterogeneous area be different from the other area. The results show that fruitful transitions of the spiral tip trajectories are induced by the fractal heterogeneity. In particular, when the heterogeneity increases to a sufficiently high level the spiral tip trajectory always changes to a stable rotating trajectory (closed-circle tip trajectory), whatever transitions have been induced by a lower level of heterogeneity. We qualitatively ascribe the transitions to the attraction on the spiral tip exerted by the heterogeneous area. 相似文献
993.
Dong Shu-bao Feng Er-yin Huang Wu-ying Cui Zhi-feng 《Czechoslovak Journal of Physics》2005,55(1):27-33
Molecular reaction dynamics of Cl + H2 (D2) has been studied on the latest analytical potential energy surface called BW3 using the Monte Carlo quasi-classical trajectory method. Excitation functions, differential cross sections and angular distributions of HCl and DCl products have been calculated. The excitation functions of the Cl (2P3/2) + n-H2 and Cl(2P3/2) + n-D2 reactions are also studied. The results are compared with those of quasi-classical trajectory [M. Alagia et al.: Phys. Chem. Chem. Phys. 2 (2000); F. J. Aoiz et al.: J. Phys. Chem. 100 (1996)], quantum mechanical (QM) calculations [F. J. Aoiz et al.:J. Chem. Phys. 115 (2001)] and experimental data [S. H. Lee et al.: J. Chem. Phys. 110 (1999); F. Dong et al.: J. Chem. Phys. 115 (2001)]. Discussions are given to some new results. 相似文献
994.
Rodica Brânzei Vincenzo Scalzo 《Journal of Mathematical Analysis and Applications》2003,285(2):619-628
In this paper some new approximate fixed point theorems for multifunctions in Banach spaces are presented and a method is developed indicating how to use approximate fixed point theorems in proving the existence of approximate Nash equilibria for non-cooperative games. 相似文献
995.
Abstract
In this paper, we construct first a new concrete example
of asymmetric convex compact C
1,1-hypersurfaces
in R
2n
possessing precisely n
closed characteristics. Then we prove multiplicity results on
the closed characteristics on convex compact hypersurfaces in
R
2n
pinched by not
necessarily symmetric convex compact hypersurfaces.
*Partially supported by the 973 Program of STM,
Funds of EC of Jiangsu, the Natural Science Funds of Jiangsu (BK
2002023), the Post-doctorate Funds of China, and the NNSF of
China (10251001)
**Partially supported by the 973 Program of STM,
NNSF, MCME, RFDP, PMC Key Lab of EM of China, S. S. Chern
Foundation, and Nankai University 相似文献
996.
The quantum trajectory method was used to study the collinear reaction H + ClH′ → HCl + H′. The potential energy surface was
calculated on the QCISD(T)/6-311++G(3df,3pd) level. The reaction probabilities are in good accord with the results obtained
by solving the Schroedinger equation using the finite difference method.
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 45, No. 3, pp. 156-159, May-June, 2009. 相似文献
997.
介绍了正在研究设计的调谐强流电子束束心轨迹的计算机智能系统。根据目前正在设计建造的 “神龙一号”加速器束流输运环境,为抑制束心螺旋运动,适应束输运磁场元件无散热装置,调谐过程中应尽量减少实验次数,智能调谐方法主要采用数值模拟和计算机克隆调谐和人工调谐相结合。以束心轨迹的数值模拟为基础,对束心位置调谐过程中的核心部分二极场调谐磁元件的调谐特性曲线进行了数值模拟,并与实验获得的调谐特性曲线进行了比较。获得了数值模拟和实验的初步结果。 相似文献
998.
999.
A. Biber A. Golick M. Tomak 《International Journal of Infrared and Millimeter Waves》2002,23(6):919-930
The paper presents the extension of the time-domain mapping method applied to 2D billiard problem inside an anisotropic region bounded by ellipse [1]. In this paper, it has been considered the ray movement inside 2D anisotropic region bounded by arbitrary differentiable curve. It has been proved that the problem can be one-to-one mapped onto 2D mathemeatical billiard problem inside the region possessing isotropic properties by linear transformation of group velocity hodograph and boundary with the same coefficient, which is equal to anisotropy of the ray group velocity, simultaneously. The main features of the ray movement inside 2D anistropic region are discussed. 相似文献
1000.
一类连续体上连续映射的周期点 总被引:1,自引:0,他引:1
设X是个阶有限的遗传可分解可链连续体, f:X→X是X上的连续自映射, On(x,f)={fi(x):0≤i≤n)是f的一个返回轨道, inf(On(x,f))
相似文献