全文获取类型
收费全文 | 502篇 |
免费 | 20篇 |
国内免费 | 71篇 |
专业分类
化学 | 22篇 |
力学 | 40篇 |
综合类 | 3篇 |
数学 | 395篇 |
物理学 | 133篇 |
出版年
2023年 | 6篇 |
2022年 | 6篇 |
2021年 | 6篇 |
2020年 | 14篇 |
2019年 | 11篇 |
2018年 | 8篇 |
2017年 | 15篇 |
2016年 | 5篇 |
2015年 | 13篇 |
2014年 | 17篇 |
2013年 | 45篇 |
2012年 | 11篇 |
2011年 | 17篇 |
2010年 | 21篇 |
2009年 | 27篇 |
2008年 | 31篇 |
2007年 | 20篇 |
2006年 | 37篇 |
2005年 | 29篇 |
2004年 | 28篇 |
2003年 | 38篇 |
2002年 | 24篇 |
2001年 | 20篇 |
2000年 | 17篇 |
1999年 | 19篇 |
1998年 | 16篇 |
1997年 | 25篇 |
1996年 | 15篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1980年 | 1篇 |
1978年 | 3篇 |
1976年 | 1篇 |
1969年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有593条查询结果,搜索用时 31 毫秒
151.
Alexander Yong 《Proceedings of the American Mathematical Society》2003,131(9):2649-2655
Fulton and Woodward have recently identified the smallest degree of that appears in the expansion of the product of two Schubert classes in the (small) quantum cohomology ring of a Grassmannian. We present a combinatorial proof of this result, and provide an alternative characterization of this smallest degree in terms of the rim hook formula for the quantum product.
152.
Scott Jeremy Baldridge 《Transactions of the American Mathematical Society》2003,355(4):1669-1697
The main result of this paper is a formula for calculating the Seiberg-Witten invariants of 4-manifolds with fixed-point-free circle actions. This is done by showing under suitable conditions the existence of a diffeomorphism between the moduli space of the 4-manifold and the moduli space of the quotient 3-orbifold. Two corollaries include the fact that } 1$"> -manifolds with fixed-point-free circle actions are simple type and a new proof of the equality . An infinite number of -manifolds with whose Seiberg-Witten invariants are still diffeomorphism invariants is constructed and studied.
153.
Ursula Hamenstädt 《Geometriae Dedicata》2002,93(1):163-176
Let PSL(2,) be a torsion free function group. We discuss some aspects of the asymptotic relation between the geometry of the hyperbolic manifold H3/ and the geometry of the boundary of its convex core. This leads to a characterization of Fuchsian function groups by dynamical invariants. 相似文献
154.
Hans-Jürgen Hoehnke 《Acta Appl Math》1998,52(1-3):277-283
Group theoretical constructions usually terminate in the problem to decide whether two groups are isomorphic. In the case of arbitrary finite groups the calculation of ordinary group characters is not sufficient to decide about it. R. Brauer posed the problem, to find suitable additional group invariants. Applying the theory of norm-type forms of associative algebras, specialized to group algebras, we found, that the 1-, 2-, and 3-characters in the nonmodular case (with some restrictions on the characteristic), especially over the field of complex numbers, are necessary and sufficient for the finite groups. This sharpens a recent result of E. Formanek and D. Sibley on group determinants. Detailed proofs will be given elsewhere. Here we give an overview on recent related results and add a remark concerning calculations in the modular group case. 相似文献
155.
Varghese Mathai Melvin Rothenberg 《Proceedings of the American Mathematical Society》1998,126(3):887-897
We prove the homotopy invariance of torsion for covering spaces, whenever the covering transformation group is either residually finite or amenable. In the case when the covering transformation group is residually finite and when the cohomology of the covering space vanishes, the homotopy invariance was established by Lück. We also give some applications of our results.
156.
M.L. Thakur 《Commentarii Mathematici Helvetici》1999,74(2):297-305
Let k be a field with characteristic different from 2 and 3. Let B be a central simple algebra of degree 3 over a quadratic extension K/k, which admits involutions of second kind. In this paper, we prove that if the Albert algebras and have same and invariants, then they are isotopic. We prove that for a given Albert algebra J, there exists an Albert algebra J' with , and . We conclude with a construction of Albert division algebras, which are pure second Tits' constructions.
Received: December 9, 1997. 相似文献
157.
A numerical scheme based on the piecewise parabolic method on a local stencil (PPML) is proposed for solving the ideal magnetohydrodynamic (MHD) equations. The method makes use of the conservation of Riemann invariants along the characteristics of the MHD equations. As a result, a local stencil can be used to construct a numerical solution. This approach improves the dissipative properties of the numerical scheme and is convenient in the case of adaptive grids. The basic stages in the design of the scheme are illustrated in the two-dimensional case. The conservation of the solenoidal property of the magnetic field is discussed. The scheme is tested using several typical MHD problems. 相似文献
158.
159.
D. V. van Coevorden M. H. Ernst R. Brito J. A. Somers 《Journal of statistical physics》1994,74(5-6):1085-1115
FCHC lattice gases are the basic models for studying flow problems in three-dimensional systems. This paper presents a self-contained theoretical analysis and some computer simulations of such lattice gases, extended to include an arbitrary number of rest particles, with special emphasis on non-semi-detailed balance (NSDB) models. The special FCHC lattice symmetry guarantees isotropy of the Navier-Stokes equations, and enumerates the 12 spurious conservation laws (staggered momenta). The kinetic theory is based on the mean field approximation or the nonlinear Boltzmann equation. It is shown how calculation of the eigenvalues of the linearized Boltzmann equation offers a simple alternative to the Chapman-Enskog method or the multi-time-scale methods for calculating transport coefficients and relaxation rates. The simulated values for the speed of sound in NSDB models slightly disagree with the Boltzmann prediction. 相似文献
160.
Effat A. Saied 《Journal of statistical physics》1996,82(3-4):951-962
We consider the way in which a solution to a class of nonlinear partial differential equationsS(u)u
t=(K(u)ux)x approaches the similarity form. The problem we solve is chosen for two main reasons: first the equation above is of widespread use in modeling physical situations and second it provides a tractable but significant example of a free boundary problem. 相似文献