全文获取类型
收费全文 | 496篇 |
免费 | 24篇 |
国内免费 | 28篇 |
专业分类
力学 | 16篇 |
综合类 | 8篇 |
数学 | 366篇 |
物理学 | 158篇 |
出版年
2024年 | 1篇 |
2023年 | 9篇 |
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 10篇 |
2019年 | 9篇 |
2018年 | 9篇 |
2017年 | 13篇 |
2016年 | 13篇 |
2015年 | 7篇 |
2014年 | 24篇 |
2013年 | 42篇 |
2012年 | 14篇 |
2011年 | 21篇 |
2010年 | 23篇 |
2009年 | 35篇 |
2008年 | 37篇 |
2007年 | 29篇 |
2006年 | 21篇 |
2005年 | 26篇 |
2004年 | 24篇 |
2003年 | 24篇 |
2002年 | 22篇 |
2001年 | 15篇 |
2000年 | 19篇 |
1999年 | 12篇 |
1998年 | 18篇 |
1997年 | 18篇 |
1996年 | 15篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有548条查询结果,搜索用时 31 毫秒
41.
On the basis of some works on persistent centers and weakly persistent centers, in this paper we discuss a generalized version of persistent center and weakly persistent center for complex planar differential systems, in which conjugacy of variables may not be required. We give some complex systems which have a persistent center or weakly persistent center at the origin. Then, we find all conditions of persistent center for cubic systems and all conditions of weakly persistent center for complex cubic Lotka–Volterra system. Relations between complex systems and real ones are given concerning persistent centers and weakly persistent centers. 相似文献
42.
Robert Carroll 《Acta Appl Math》2000,60(3):225-316
We sketch some of the different roles played by Whitham times in connection with averaging, adiabatic invariants, soliton theory, Hamiltonian structures, topological field theory (TFT), Seiberg–Witten (SW) theory, isomonodromy problems, Hitchin systems, WDVV and Picard–Fuchs equations, renormalization, soft supersymmetry breaking, etc. 相似文献
43.
44.
Potential Analysis - Assume that a bounded domain Ω??N (N ≥ 2) has the property that there exists a signed measure µ with compact support in Ω such that, for every... 相似文献
45.
We briefly review the recent progress in obtaining (2+1) dimensional integrable generalizations of soliton equations in (1+1)
dimensions. Then, we develop an algorithmic procedure to obtain interesting classes of solutions to these systems. In particular
using a Painlevé singularity structure analysis approach, we investigate their integrability properties and obtain their appropriate
Hirota bilinearized forms. We identify line solitons and from which we introduce the concept of ghost solitons, which are
patently boundary effects characteristic of these (2+1) dimensional integrable systems. Generalizing these solutions, we obtain
exponentially localized solutions, namely the dromions which are driven by the boundaries. We also point out the interesting
possibility that while the physical field itself may not be localized, either the potential or composite fields may get localized.
Finally, the possibility of generating an even wider class of localized solutions is hinted by using curved solitons. 相似文献
46.
R S Kaushal 《Pramana》1994,42(4):315-318
The ground state of a class of potentials described byV(x)=a
20
x
2+a
1/x
2 is investigated. This potential possesses some distinct features like that of a symmetric double-well potential, and can
be used in modelling the fusion process of two identical nuclei as well. 相似文献
47.
Chun-Li Chen Sen-Yue Lou Yi-Shen li 《Communications in Nonlinear Science & Numerical Simulation》2004,9(6):583-601
The possible solitary wave solutions for a general Boussinesq (GBQ) type fluid model are studied analytically. After proving the non-Painlevé integrability of the model, the first type of exact explicit travelling solitary wave with a special velocity selection is found by the truncated Painlevé expansion. The general solitary waves with different travelling velocities can be studied by casting the problems to the Newtonian quasi-particles moving in some proper one dimensional potential fields. For some special velocity selections, the solitary waves possess different shapes, say, the left moving solitary waves may possess different shapes and/or amplitudes with those of the right moving solitons. For some other velocities, the solitary waves are completely prohibited. There are three types of GBQ systems (GBQSs) according to the different selections of the model parameters. For the first type of GBQS, both the faster moving and lower moving solitary waves allowed but the solitary waves with“middle” velocities are prohibit. For the second type of GBQS all the slower moving solitary waves are completely prohibit while for the third type of GBQS only the slower moving solitary waves are allowed. Only the solitary waves with the almost unit velocities meet the weak non-linearity conditions. 相似文献
48.
An Invariant of Gauge Transformations of Contact Riemannian StructuresLiangXiquan(梁希泉)andLiuXimin(刘西民)(InstituteofMathematics... 相似文献
49.
We construct a family of spin chain Hamiltonians, which have the affine quantum group symmetry
. Their eigenvalues coincide with the eigenvalues of the usual spin chain Hamiltonians, but have the degeneracy of levels, corresponding to the affine
. The space of states of these spin chains is formed by the tensor product of the fully reducible representations of the quantum group.
The fermionic representations of the constructed spin chain Hamiltonians show that we have obtained new extensions of the Hubbard Hamiltonians. All of them are integrable and have the affine quantum group symmetry. The exact ground state of such type of model is presented, exhibiting superconducting behavior via the η-pairing mechanism. 相似文献
50.
This paper is devoted to studying maximal singular integrals and Marcinkiewicz integrals with rough kernels in a mixed homogeneity setting. Assuming that the kernels satisfy certain rather weak size conditions, the boundedness of such operators on the mixed radial-angular spaces are established, respectively. Meanwhile, the corresponding vector-valued versions are also given. 相似文献