全文获取类型
收费全文 | 6894篇 |
免费 | 582篇 |
国内免费 | 679篇 |
专业分类
化学 | 806篇 |
晶体学 | 15篇 |
力学 | 871篇 |
综合类 | 115篇 |
数学 | 5036篇 |
物理学 | 1312篇 |
出版年
2024年 | 3篇 |
2023年 | 80篇 |
2022年 | 147篇 |
2021年 | 161篇 |
2020年 | 221篇 |
2019年 | 206篇 |
2018年 | 186篇 |
2017年 | 228篇 |
2016年 | 231篇 |
2015年 | 156篇 |
2014年 | 283篇 |
2013年 | 516篇 |
2012年 | 331篇 |
2011年 | 404篇 |
2010年 | 365篇 |
2009年 | 531篇 |
2008年 | 487篇 |
2007年 | 466篇 |
2006年 | 431篇 |
2005年 | 386篇 |
2004年 | 279篇 |
2003年 | 285篇 |
2002年 | 245篇 |
2001年 | 201篇 |
2000年 | 199篇 |
1999年 | 180篇 |
1998年 | 187篇 |
1997年 | 135篇 |
1996年 | 112篇 |
1995年 | 74篇 |
1994年 | 65篇 |
1993年 | 52篇 |
1992年 | 47篇 |
1991年 | 39篇 |
1990年 | 27篇 |
1989年 | 22篇 |
1988年 | 28篇 |
1987年 | 21篇 |
1986年 | 17篇 |
1985年 | 17篇 |
1984年 | 20篇 |
1983年 | 8篇 |
1982年 | 12篇 |
1981年 | 12篇 |
1980年 | 9篇 |
1979年 | 11篇 |
1978年 | 12篇 |
1977年 | 3篇 |
1974年 | 3篇 |
1972年 | 3篇 |
排序方式: 共有8155条查询结果,搜索用时 15 毫秒
51.
This paper proposes the Rice condition numbers for invariant subspace, singular sub-spaces of a matrix and deflating subspaces of a regular matrix pair. The first-order perturbation estimations for these subspaces are derived by applying perturbation expansions of orthogonal projection operators. 相似文献
52.
Xuechao Li 《Graphs and Combinatorics》2006,22(4):503-513
In this paper, we give new lower bounds for the size of Δ-critical graphs with Δ=8,9 which improve the partial results of
Luo [6] and Y. Zhao [12]. 相似文献
53.
L. T. Ashchepkov D. V. Davydov 《Computational Mathematics and Mathematical Physics》2006,46(11):1910-1917
Noncooperative games of a finite number of persons with interval-valued payoff functions are considered. The concept of an equilibrium situation is introduced. A reduction of such games to deterministic noncooperative games is proposed. Properties of the reduced games are discussed. Interval antagonistic and bimatrix games are examined, and illustrative examples are considered. 相似文献
54.
连通图的离散度是用s(G)来表示的,s(G)=max{ω(G-S)-|S|:ω(G-S)>1,SV(G)}.给出了两个完全图乘积的和一个完全图与路的乘积的离散度.还给出了两个完全图乘积的坚韧度. 相似文献
55.
Yuanqiu Huang 《Discrete Applied Mathematics》2007,155(3):405-409
A stable set of a graph is a vertex set in which any two vertices are not adjacent. It was proven in [A. Brandstädt, V.B. Le, T. Szymczak, The complexity of some problems related to graph 3-colorability, Discrete Appl. Math. 89 (1998) 59-73] that the following problem is NP-complete: Given a bipartite graph G, check whether G has a stable set S such thatG-Sis a tree. In this paper we prove the following problem is polynomially solvable: Given a graph G with maximum degree 3 and containing no vertices of degree 2, check whether G has a stable set S such thatG-Sis a tree. Thus we partly answer a question posed by the authors in the above paper. Moreover, we give some structural characterizations for a graph G with maximum degree 3 that has a stable set S such that G-S is a tree. 相似文献
56.
Let E
n:y
2=x
3−n
2
x denote the family of congruent number elliptic curves. Feng and Xiong (2004) equate the nontriviality of the Selmer groups
associated with E
n
to the presence of certain types of partitions of graphs associated with the prime factorization of n. In this paper, we extend the ideas of Feng and Xiong in order to compute the Selmer groups of E
n.
2000 Mathematics Subject Classification Primary—11G05; Secondary—14H52, 14H25, 05C90 相似文献
57.
This paper develops a theory for the global solution of nonconvex optimization problems with parameter-embedded linear dynamic systems. A quite general problem formulation is introduced and a solution is shown to exists. A convexity theory for integrals is then developed to construct convex relaxations for utilization in a branch-and-bound framework to calculate a global minimum. Interval analysis is employed to generate bounds on the state variables implied by the bounds on the embedded parameters. These bounds, along with basic integration theory, are used to prove convergence of the branch-and-bound algorithm to the global minimum of the optimization problem. The implementation of the algorithm is then considered and several numerical case studies are examined thoroughly 相似文献
58.
We show that the tensor product B-spline basis and the triangular Bernstein basis are in some sense best conditioned among all nonnegative bases for the spaces of tensor product splines and multivariate polynomials, respectively. We also introduce some new condition numbers which are analogs of component-wise condition numbers for linear systems introduced by Skeel. 相似文献
59.
David S. Dummit Brett A. Tangedal Paul B. van Wamelen. 《Mathematics of Computation》2004,73(247):1525-1546
Systematic computation of Stark units over nontotally real base fields is carried out for the first time. Since the information provided by Stark's conjecture is significantly less in this situation than the information provided over totally real base fields, new techniques are required. Precomputing Stark units in relative quadratic extensions (where the conjecture is already known to hold) and coupling this information with the Fincke-Pohst algorithm applied to certain quadratic forms leads to a significant reduction in search time for finding Stark units in larger extensions (where the conjecture is still unproven). Stark's conjecture is verified in each case for these Stark units in larger extensions and explicit generating polynomials for abelian extensions over complex cubic base fields, including Hilbert class fields, are obtained from the minimal polynomials of these new Stark units.
60.
介绍未确知数学方法,并用未确知数学方法分析处理物理实验数据,与传统的数据处理方法比较,未确知数学方法不必对数据作任何假设,因此更合理,也更符合实际。 相似文献