全文获取类型
收费全文 | 7408篇 |
免费 | 1126篇 |
国内免费 | 811篇 |
学科分类
数理化 | 9345篇 |
出版年
2024年 | 26篇 |
2023年 | 153篇 |
2022年 | 290篇 |
2021年 | 265篇 |
2020年 | 291篇 |
2019年 | 310篇 |
2018年 | 244篇 |
2017年 | 233篇 |
2016年 | 336篇 |
2015年 | 368篇 |
2014年 | 395篇 |
2013年 | 488篇 |
2012年 | 623篇 |
2011年 | 684篇 |
2010年 | 417篇 |
2009年 | 377篇 |
2008年 | 434篇 |
2007年 | 402篇 |
2006年 | 405篇 |
2005年 | 308篇 |
2004年 | 240篇 |
2003年 | 217篇 |
2002年 | 169篇 |
2001年 | 166篇 |
2000年 | 169篇 |
1999年 | 187篇 |
1998年 | 157篇 |
1997年 | 143篇 |
1996年 | 131篇 |
1995年 | 124篇 |
1994年 | 113篇 |
1993年 | 77篇 |
1992年 | 76篇 |
1991年 | 88篇 |
1990年 | 56篇 |
1989年 | 34篇 |
1988年 | 35篇 |
1987年 | 33篇 |
1986年 | 20篇 |
1985年 | 20篇 |
1984年 | 9篇 |
1983年 | 19篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1971年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有9345条查询结果,搜索用时 0 毫秒
1.
We consider concentrated vorticities for the Euler equation on a smooth domain in the form of supported on well-separated vortical domains , , of small diameters . A conformal mapping framework is set up to study this free boundary problem with being part of unknowns. For any given vorticities and small , through a perturbation approach, we obtain such piecewise constant steady vortex patches as well as piecewise smooth Lipschitz steady vorticities, both concentrated near non-degenerate critical configurations of the Kirchhoff–Routh Hamiltonian function. When vortex patch evolution is considered as the boundary dynamics of , through an invariant subspace decomposition, it is also proved that the spectral/linear stability of such steady vortex patches is largely determined by that of the 2N-dimensional linearized point vortex dynamics, while the motion is highly oscillatory in the 2N-codim directions corresponding to the vortical domain shapes. 相似文献
2.
3.
曾六川 《高等学校计算数学学报(英文版)》2003,12(1)
The purpose of this paper is to investigate the problem of approximating fixed points of non-Lipschitizian asymptotically pseudocontractive mappings in an arbitrary real Banach space by the modified Ishikawa iterative sequences with errors. 相似文献
4.
5.
A Note on Topological Entropy of Maps 总被引:1,自引:0,他引:1
For a given collection of subsets of a compact metric space X which cover X,the entropies,hm(f)and hi(f),are introduced for a continuous map f of X to itseif. Also the concept of shadowing property with same end point (SPSEP for short) is introduced. The main results are,(1)H(f)≤hi(f)+hm(f)and,(2)h(f)=hm(f)whenever f has SPSEP,where h(f) is the topological entropy of f. Moreover,several corollaries are obtained. 相似文献
6.
利用指数二分性和泛函分析方法,我们研究了当未扰动系统不具有异宿流形的退化异宿分支.我们利用Melnikov型向量给出了系统在退化情形下的横截异宿轨道存在的充分条件. 相似文献
7.
8.
Jie Xue Liang Chen Li Zhou Zhifeng Jia Yanping Wang Xinyuan Zhu Deyue Yan 《Journal of Polymer Science.Polymer Physics》2006,44(15):2050-2057
α‐Cyclodextrin (α‐CD) has been complexed with various poly(ethylene glycol) (PEG) derivatives in aqueous solution. It has been found that the end groups of PEG derivatives affect the complexation kinetics greatly, but have only a little influence on the thermodynamic behavior. By increasing the hydrophobicity of end groups, the complexation speeds up rapidly. On the other hand, the bulky end groups slow down the threading of polymeric guests into the cavity of CD. By changing the hydrophobicity and the size of end groups, the complexation rate can be adjusted in the range of several orders of magnitudes, which should be quite useful in the design of new supramolecular systems. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2050–2057, 2006 相似文献
9.
Analysis of a type of nonsmooth dynamical systems 总被引:1,自引:0,他引:1
Guofeng Zhang Guanrong Chen Tongwen Chen Yanping Lin 《Chaos, solitons, and fractals》2006,30(5):1153-1164
In this paper, a class of nonsmooth dynamical systems is analyzed. Extensive simulations reveal the chaotic behavior in these systems. By introducing a parameter, a chain of systems with one end being a linear stable system and the other being a chaotic system is constructed. Then the phase transition process through the chain is investigated as the parameter varies. Difficulties involved in analyzing this class of systems are also discussed. 相似文献
10.
Pingan Zeng Jiaquan Liu Yuxia Guo 《Journal of Mathematical Analysis and Applications》2004,300(1):102-128
In this paper, by using the Morse index theory for strongly indefinite functionals developed in [Nonlinear Anal. TMA, in press], we compute precisely the critical groups at the origin and at infinity, respectively. The abstract theorems are used to study the existence (multiplicity) of nontrivial periodical solutions for asymptotically wave equation and beam equation with resonance both at infinity and at zero. 相似文献