全文获取类型
收费全文 | 311篇 |
免费 | 9篇 |
国内免费 | 55篇 |
专业分类
化学 | 29篇 |
晶体学 | 3篇 |
力学 | 4篇 |
综合类 | 8篇 |
数学 | 322篇 |
物理学 | 9篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 8篇 |
2017年 | 10篇 |
2016年 | 7篇 |
2015年 | 4篇 |
2014年 | 9篇 |
2013年 | 26篇 |
2012年 | 9篇 |
2011年 | 14篇 |
2010年 | 8篇 |
2009年 | 12篇 |
2008年 | 29篇 |
2007年 | 27篇 |
2006年 | 28篇 |
2005年 | 18篇 |
2004年 | 17篇 |
2003年 | 19篇 |
2002年 | 17篇 |
2001年 | 12篇 |
2000年 | 10篇 |
1999年 | 15篇 |
1998年 | 15篇 |
1997年 | 11篇 |
1996年 | 11篇 |
1995年 | 1篇 |
1994年 | 6篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有375条查询结果,搜索用时 31 毫秒
61.
Julio C. García 《Mathematical Notes》1999,65(2):159-167
The paper suggests a constructive characterization of unbounded completely positive maps introduced earlier by Chebotarev
for the theory of quantum dynamical semigroups. We prove that such cones are generated by a positive self-adjoint “reference”
operator ΛεB(H) as follows: for any completely positive unbounded map Ф(·)εCPn*(F) these exists a completely positive normal bounded mapR(·)εCPn(H) such that ϕ(·)=ΛR(·)Λ. The class contains mappings that are unclosable sesquilinear forms.
Translated fromMatematicheskie Zametki, Vol. 65, No. 2, pp. 194–205, February, 1999. 相似文献
62.
63.
Xinwen Zhu 《Advances in Mathematics》2009,221(2):570-600
Let G be a simple algebraic group defined over C and T be a maximal torus of G. For a dominant coweight λ of G, the T-fixed point subscheme of the Schubert variety in the affine Grassmannian GrG is a finite scheme. We prove that for all such λ if G is of type A or D and for many of them if G is of type E, there is a natural isomorphism between the dual of the level one affine Demazure module corresponding to λ and the ring of functions (twisted by certain line bundle on GrG) of . We use this fact to give a geometrical proof of the Frenkel-Kac-Segal isomorphism between basic representations of affine algebras of A,D,E type and lattice vertex algebras. 相似文献
64.
Let and be the algebras of all bounded linear operators on infinite dimensional complex Banach spaces X and Y, respectively. We characterize additive maps from onto preserving different quantities such as the nullity, the defect, the ascent, and the descent of operators. 相似文献
65.
66.
The isomorphism of polynomials(IP),one of the hard problems in multivariate public key cryptography induces an equivalence relation on a set of systems of polynomials.Then the enumeration problem of IP consists of counting the numbers of different classes and counting the cardinality of each class that is highly related to the scale of key space for a multivariate public key cryptosystem.In this paper we show the enumeration of the equivalence classes containing ∑n-1 i=0 aiX2qi when char(Fq) = 2,which implies that these polynomials are all weak IP instances.Moreover,we study the cardinality of an equivalence class containing the binomial aX 2q i + bX 2qj(i=j) over Fqn without the restriction that char(Fq) = 2,which gives us a deeper understanding of finite geometry as a tool to investigate the enumeration problem of IP. 相似文献
67.
68.
69.
We study a noisy graph isomorphism problem, where the goal is to perfectly recover the vertex correspondence between two edge‐correlated graphs, with an initial seed set of correctly matched vertex pairs revealed as side information. We show that it is possible to achieve the information‐theoretic limit of graph sparsity in time polynomial in the number of vertices n. Moreover, we show the number of seeds needed for perfect recovery in polynomial‐time can be as low as in the sparse graph regime (with the average degree smaller than ) and in the dense graph regime, for a small positive constant . Unlike previous work on graph matching, which used small neighborhoods or small subgraphs with a logarithmic number of vertices in order to match vertices, our algorithms match vertices if their large neighborhoods have a significant overlap in the number of seeds. 相似文献
70.
In the paper, the notion of F function, i.e., a partial recursive function whose resemblance type consists of one isomorphism type, is generalized. 相似文献