全文获取类型
收费全文 | 1234篇 |
免费 | 109篇 |
国内免费 | 56篇 |
专业分类
化学 | 18篇 |
力学 | 9篇 |
综合类 | 13篇 |
数学 | 1306篇 |
物理学 | 53篇 |
出版年
2023年 | 21篇 |
2022年 | 35篇 |
2021年 | 19篇 |
2020年 | 62篇 |
2019年 | 47篇 |
2018年 | 49篇 |
2017年 | 43篇 |
2016年 | 26篇 |
2015年 | 23篇 |
2014年 | 55篇 |
2013年 | 117篇 |
2012年 | 58篇 |
2011年 | 95篇 |
2010年 | 76篇 |
2009年 | 146篇 |
2008年 | 121篇 |
2007年 | 51篇 |
2006年 | 91篇 |
2005年 | 48篇 |
2004年 | 34篇 |
2003年 | 25篇 |
2002年 | 31篇 |
2001年 | 20篇 |
2000年 | 17篇 |
1999年 | 24篇 |
1998年 | 12篇 |
1997年 | 12篇 |
1996年 | 3篇 |
1995年 | 5篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有1399条查询结果,搜索用时 562 毫秒
991.
《Photonics and Nanostructures》2014,12(5):437-446
The concept of a perfect electromagnetic conductor (PEMC) was introduced to generalize and unify two well-known and apparently disjoint concepts in electromagnetics: the perfect electric conductor (PEC) and the perfect magnetic conductor (PMC). Although the PEMC has proven a fertile tool in electromagnetic analyses dealing with new and complex boundaries, its corresponding definition as a medium has, nevertheless, raised several problems. In fact, according to its initial 3D definition, the PEMC cannot be considered a unique and well-defined medium: it leads to extraneous fields without physical meaning. By using a previously published generalization of a PEMC that regards this concept both as a boundary and as a medium – which was dubbed an MIM (Minkowskian isotropic medium) and acts, in practice, as an actual electromagnetic conductor (EMC) – it is herein presented a straightforward analysis of waveguides containing PEMCs that readily and systematically follows from the general framework of waveguides containing EMCs. 相似文献
992.
ON EQUITABLE VERTEX DISTINGUISHING EDGE COLORINGS OF TREES 总被引:1,自引:0,他引:1
993.
We present a detailed and elementary construction of the inverse perfection of a scheme and discuss some of its main properties. We also establish a number of auxiliary results (for example, on inverse limits of schemes) which do not seem to appear in the literature. 相似文献
994.
提出了图的D(β)点可区别星边染色及D(β)点可区别星边色数的概念,并用Lovasz局部引理证明了在β=2时,若G=(V,E)是一个最小度为δ(G)>3的简单无向图,则X_(2-vds)(G)≤24△2/3]。 相似文献
995.
996.
997.
E. C. Sewell 《Mathematical Programming》1996,75(3):467-476
Several recent papers have shown that some properties of the maximum weight stable set problem hold true in the more general
setting of binary integer programs with two variables per inequality. In this paper, we show that in fact the two problems
are equivalent by using the transitive closure of the binary integer program and (possibly) reducing the number of variables
by fixing, complementing, or identifying them. We use this equivalence to prove two conjectures made by Johnson and Padberg
regarding the perfection of bidirected graphs. 相似文献
998.
In [9] Mundici introduced a categorical equivalence Γ between the category of MV-algebras and the category of abelian ??-groups with strong unit. Using Mundici's functor Γ, in [8] the authors established an equivalence between the category of perfect MV-algebras and the category of abelian ??-groups. Aim of the present paper is to use the above functors to provide Yosida like representations (see [4]) of a large class of MV-algebras. Mathematics Subject Classification: 03G20, 03B50, 06D30, 06F20. 相似文献
999.
If a connected component of perfect equilibria of a two-player game contains a stable set as defined by Mertens, then the
component is itself stable. Thus the stable sets maximal under inclusion are connected components of perfect equilibria.
Received: October 1999/Revised: February 2001 相似文献
1000.
The strong chromatic index of a class of graphs 总被引:1,自引:0,他引:1
Jianzhuan Wu 《Discrete Mathematics》2008,308(24):6254-6261
The strong chromatic index of a graph G is the minimum integer k such that the edge set of G can be partitioned into k induced matchings. Faudree et al. [R.J. Faudree, R.H. Schelp, A. Gyárfás, Zs. Tuza, The strong chromatic index of graphs, Ars Combin. 29B (1990) 205-211] proposed an open problem: If G is bipartite and if for each edge xy∈E(G), d(x)+d(y)≤5, then sχ′(G)≤6. Let H0 be the graph obtained from a 5-cycle by adding a new vertex and joining it to two nonadjacent vertices of the 5-cycle. In this paper, we show that if G (not necessarily bipartite) is not isomorphic to H0 and d(x)+d(y)≤5 for any edge xy of G then sχ′(G)≤6. The proof of the result implies a linear time algorithm to produce a strong edge coloring using at most 6 colors for such graphs. 相似文献