全文获取类型
收费全文 | 592篇 |
免费 | 56篇 |
国内免费 | 16篇 |
专业分类
化学 | 54篇 |
晶体学 | 3篇 |
力学 | 42篇 |
综合类 | 7篇 |
数学 | 162篇 |
物理学 | 396篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 16篇 |
2019年 | 10篇 |
2018年 | 6篇 |
2017年 | 11篇 |
2016年 | 17篇 |
2015年 | 13篇 |
2014年 | 37篇 |
2013年 | 31篇 |
2012年 | 29篇 |
2011年 | 28篇 |
2010年 | 31篇 |
2009年 | 39篇 |
2008年 | 45篇 |
2007年 | 50篇 |
2006年 | 34篇 |
2005年 | 29篇 |
2004年 | 34篇 |
2003年 | 27篇 |
2002年 | 19篇 |
2001年 | 15篇 |
2000年 | 12篇 |
1999年 | 16篇 |
1998年 | 16篇 |
1997年 | 18篇 |
1996年 | 11篇 |
1995年 | 9篇 |
1994年 | 14篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有664条查询结果,搜索用时 15 毫秒
91.
Erdős has conjectured that every subgraph of the n‐cube Qn having more than (1/2 + o(1))e(Qn) edges will contain a 4‐cycle. In this note we consider ‘layer’ graphs, namely, subgraphs of the cube spanned by the subsets of sizes k − 1, k and k + 1, where we are thinking of the vertices of Qn as being the power set of {1,…, n}. Observe that every 4‐cycle in Qn lies in some layer graph. We investigate the maximum density of 4‐cycle free subgraphs of layer graphs, principally the case k = 2. The questions that arise in this case are equivalent to natural questions in the extremal theory of directed and undirected graphs. © 2000 John Wiley & Sons, Inc. J Graph Theory 33: 66–82, 2000 相似文献
92.
For a positive integer d, the usual d‐dimensional cube Qd is defined to be the graph (K2)d, the Cartesian product of d copies of K2. We define the generalized cube Q(Kk, d) to be the graph (Kk)d for positive integers d and k. We investigate the decomposition of the complete multipartite graph K into factors that are vertex‐disjoint unions of generalized cubes Q(Kk, di), where k is a power of a prime, n and j are positive integers with j ≤ n, and the di may be different in different factors. We also use these results to partially settle a problem of Kotzig on Qd‐factorizations of Kn. © 2000 John Wiley & Sons, Inc. J Graph Theory 33: 144–150, 2000 相似文献
93.
A cube factorization of the complete graph on n vertices, Kn, is a 3‐factorization of Kn in which the components of each factor are cubes. We show that there exists a cube factorization of Kn if and only if n ≡ 16 (mod 24), thus providing a new family of uniform 3‐factorizations as well as a partial solution to an open problem posed by Kotzig in 1979. © 2004 Wiley Periodicals, Inc. 相似文献
94.
梁小艳 《纯粹数学与应用数学》1997,13(1):78-83
得到了En+1^+上的BMO函数在插值序列上取值的特征,它是单位圆盘上的相应结果在高维空间的推广。 相似文献
95.
96.
We describe the construction of a collection of quadrature formulae suitable for the efficient discretization of certain boundary integral equations on a very general class of two-dimensional domains with corner points. The resulting quadrature rules allow for the rapid high-accuracy solution of Dirichlet boundary value problems for Laplace’s equation and the Helmholtz equation on such domains under a mild assumption on the boundary data. Our approach can be adapted to other boundary value problems and certain aspects of our scheme generalize to the case of surfaces with singularities in three dimensions. The performance of the quadrature rules is illustrated with several numerical examples. 相似文献
97.
98.
The generalized theory of double-mode electrostatic dispersing prism for time-domain compressing electron pulse is presented. The fundamental difference between the two modes of o mode and e mode lies in the dispersive dependence of electron's time of flight on its initial kinetic energy at prism entrance: the electrons with higher initial axial energy definitely have longer time of flight for o mode, while not the case for e mode, which results from the electron pulse's U-shaped motion in the prism. The dispersive dependence of time of flight constitutes the mechanism of electron pulse compression for each mode. An example is given to demonstrate the issue of parameter choosing for the prism and to verify its tunable performance of compression. 相似文献
99.
We investigate some topological properties of a normal functorH introduced earlier by Radul which is some functorial compactification of the Hartman-Mycielski construction HM. We prove
that the pair (H X, HMY) is homeomorphic to the pair (Q, σ) for each nondegenerated metrizable compactumX and each denseσ-compact subsetY. 相似文献