全文获取类型
收费全文 | 13410篇 |
免费 | 945篇 |
国内免费 | 1617篇 |
专业分类
化学 | 4349篇 |
晶体学 | 58篇 |
力学 | 1255篇 |
综合类 | 223篇 |
数学 | 7405篇 |
物理学 | 2682篇 |
出版年
2024年 | 20篇 |
2023年 | 148篇 |
2022年 | 269篇 |
2021年 | 372篇 |
2020年 | 363篇 |
2019年 | 393篇 |
2018年 | 376篇 |
2017年 | 458篇 |
2016年 | 450篇 |
2015年 | 367篇 |
2014年 | 528篇 |
2013年 | 1272篇 |
2012年 | 493篇 |
2011年 | 649篇 |
2010年 | 568篇 |
2009年 | 749篇 |
2008年 | 807篇 |
2007年 | 955篇 |
2006年 | 769篇 |
2005年 | 706篇 |
2004年 | 636篇 |
2003年 | 630篇 |
2002年 | 554篇 |
2001年 | 459篇 |
2000年 | 428篇 |
1999年 | 410篇 |
1998年 | 382篇 |
1997年 | 335篇 |
1996年 | 248篇 |
1995年 | 170篇 |
1994年 | 182篇 |
1993年 | 108篇 |
1992年 | 102篇 |
1991年 | 81篇 |
1990年 | 67篇 |
1989年 | 56篇 |
1988年 | 62篇 |
1987年 | 60篇 |
1986年 | 37篇 |
1985年 | 56篇 |
1984年 | 34篇 |
1983年 | 16篇 |
1982年 | 30篇 |
1981年 | 21篇 |
1980年 | 15篇 |
1979年 | 17篇 |
1978年 | 19篇 |
1977年 | 16篇 |
1976年 | 6篇 |
1974年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
We compute the cyclic homology of the coordinate ring A(SLq(2)) of the quantum algebraic group SL
q
(2). We observe a degeneration of the noncommutative de Rham complex. The results are also verified from the point of view of Connes' noncommutative differential geometry. 相似文献
42.
We study the system of nonlinear differential equations which expresses the constancy of the algebraic invariants of the Jacobian matrix for smooth vector fields in three-dimensional space. This system is equivalent to the equations of gas dynamics which describe the barochronous motions of a gas (the pressure and density depend only on the time). We present the results of computation of the admissible local Lie group and construction of the general solution of the system. We mention a few new problems that arise here. 相似文献
43.
David Masson 《Designs, Codes and Cryptography》2003,28(3):283-302
We study (generalized) designs supported by words of given composition. We characterize them in terms of orthogonality relations with Specht modules; we define some zonal functions for the symmetric group and we give a closed formula for them, indexed on ordered pair of semi-standard generalized tableaux: Hahn polynomials are a particular case. We derive an algorithm to test if a set is a design. We use it to search designs in some ternary self-dual codes. 相似文献
44.
We characterize all equivariant odd spectral triples for the quantum SU(2) group acting on its L
2-space and having a nontrivial Chern character. It is shown that the dimension of an equivariant spectral triple is at least three, and given any element of the K-homology group of SUq(2), there is an equivariant odd spectral triple of dimension 3 inducing that element. The method employed to get equivariant spectral triples in the quantum case is then used for classical SU(2), and we prove that for p < 4, there does not exist any equivariant spectral triple with nontrivial K-homology class and dimension p acting on the L
2-space.The first author would like to acknowledge support from the National Board of Higher Mathematics, India. 相似文献
45.
Using the techniques of approximation and factorization of convolution operators we study the problem of irregular sampling of band-limited functions on a locally compact Abelian group G. The results of this paper relate to earlier work by Feichtinger and Gröchenig in a similar way as Kluvánek's work published in 1969 relates to the classical Shannon Sampling Theorem. Generally speaking we claim that reconstruction is possible as long as there is sufficient high sampling density. Moreover, the iterative reconstruction algorithms apply simultaneously to families of Banach spaces. 相似文献
46.
The application of FRP rods as an internal or external reinforcement in new or damaged concrete structures is based on the development of design equations that take into account the mechanical properties of FRP material systems.The measurement of mechanical characteristics of FRP requires a special anchoring and protocol, since it is well known that these characteristics depend on the direction and content of fibers. In this study, an effective tensile test method is described for the mechanical characterization of FRP rods. Twelve types of glass and carbon FRP specimens with different sizes and surface characteristics were tested to validate the procedure proposed. In all, 79 tensile tests were performed, and the results obtained are discussed in this paper. Recommendations are given for specimen preparation and test setup in order to facilitate the further investigation and standardization of the FRP rods used in civil engineering. 相似文献
47.
The non-commutative torus C
*(n,) is realized as the C*-algebra of sections of a locally trivial C*-algebra bundle over S with fibres isomorphic to C
*n/S, 1) for a totally skew multiplier 1 on n/S. D. Poguntke [9] proved that A
is stably isomorphic to C(S) C(*( Zn/S, 1) C(S) A Mkl( C) for a simple non-commutative torus A and an integer kl. It is well-known that a stable isomorphism of two separable C*-algebras is equivalent to the existence of equivalence bimodule between them. We construct an A-C(S) A-equivalence bimodule. 相似文献
48.
D. A. Malinin 《Algebras and Representation Theory》2003,6(2):215-237
For a given field F of characteristic 0 we consider a normal extension E/F of finite degree d and finite Abelian subgroups GGL
n
(E) of a given exponent t. We assume that G is stable under the natural action of the Galois group of E/F and consider the fields E=F(G) that are obtained via adjoining all matrix coefficients of all matrices gG to F. It is proved that under some reasonable restrictions for n, any E can be realized as F(G), while if all coefficients of matrices in G are algebraic integers, there are only finitely many fields E=F(G) for prescribed integers n and t or prescribed n and d. 相似文献
49.
Let G be a group with a set of operators such that Z(G) is -admissible. Central -automorphisms occur in the Krull-Remak-Schmidt Theorem. We discuss the existence of a central -endomorphism of G that is not an automorphism.2000 Mathematics Subject Classification: 20E36 相似文献
50.
We consider the varieties of lattice ordered groups with the identity of commutation of the nth powers of elements. We establish that every such l-variety with n=pq, where p and q are distinct prime numbers, has a finite basis of identities. 相似文献