全文获取类型
收费全文 | 713篇 |
免费 | 50篇 |
国内免费 | 75篇 |
专业分类
化学 | 36篇 |
晶体学 | 1篇 |
力学 | 35篇 |
综合类 | 20篇 |
数学 | 698篇 |
物理学 | 48篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 15篇 |
2021年 | 12篇 |
2020年 | 26篇 |
2019年 | 26篇 |
2018年 | 24篇 |
2017年 | 25篇 |
2016年 | 21篇 |
2015年 | 16篇 |
2014年 | 23篇 |
2013年 | 46篇 |
2012年 | 26篇 |
2011年 | 26篇 |
2010年 | 36篇 |
2009年 | 60篇 |
2008年 | 44篇 |
2007年 | 36篇 |
2006年 | 57篇 |
2005年 | 32篇 |
2004年 | 23篇 |
2003年 | 34篇 |
2002年 | 31篇 |
2001年 | 24篇 |
2000年 | 24篇 |
1999年 | 28篇 |
1998年 | 23篇 |
1997年 | 19篇 |
1996年 | 14篇 |
1995年 | 13篇 |
1994年 | 8篇 |
1993年 | 9篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 5篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1974年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有838条查询结果,搜索用时 15 毫秒
101.
102.
103.
In this paper, we employed lattice model to describe the three internally vertex-disjoint paths that span the vertex set of the generalized Petersen graph . We showed that the is 3-spanning connected for odd . Based on the lattice model, five amalgamated and one extension mechanisms are introduced to recursively establish the 3-spanning connectivity of the . In each amalgamated mechanism, a particular lattice trail was amalgamated with the lattice trails that was dismembered, transferred, or extended from parts of the lattice trails for , where a lattice tail is a trail in the lattice model that represents a path in . 相似文献
104.
《Discrete Mathematics》2020,343(10):112015
A long standing open problem in extremal graph theory is to describe all graphs that maximize the number of induced copies of a path on four vertices. The character of the problem changes in the setting of oriented graphs, and becomes more tractable. Here we resolve this problem in the setting of oriented graphs without transitive triangles. 相似文献
105.
I. Fabrici J. Harant T. Madaras S. Mohr R. Soták C. T. Zamfirescu 《Journal of Graph Theory》2020,95(1):125-137
A graph is 1-planar if it has a drawing in the plane such that each edge is crossed at most once by another edge. Moreover, if this drawing has the additional property that for each crossing of two edges the end vertices of these edges induce a complete subgraph, then the graph is locally maximal 1-planar. For a 3-connected locally maximal 1-planar graph G, we show the existence of a spanning 3-connected planar subgraph and prove that G is Hamiltonian if G has at most three 3-vertex-cuts, and that G is traceable if G has at most four 3-vertex-cuts. Moreover, infinitely many nontraceable 5-connected 1-planar graphs are presented. 相似文献
106.
107.
本文研究了围长为2的n阶本原极小强连通有向图的1-指数集,证明了:当n(≥4)为偶数时,E(1)={4,5,6,7,…,2n-4),无缺数段。 相似文献
108.
109.
The vertex‐deleted subgraph G?v, obtained from the graph G by deleting the vertex v and all edges incident to v, is called a card of G. The deck of G is the multiset of its unlabelled vertex‐deleted subgraphs. The number of common cards of G and H (or between G and H) is the cardinality of the multiset intersection of the decks of G and H. In this article, we present infinite families of pairs of graphs of order n ≥ 4 that have at least \begin{eqnarray*}2\lfloor\frac{1}{3}(n-1)\rfloor\end{eqnarray*} common cards; we conjecture that these, along with a small number of other families constructed from them, are the only pairs of graphs having this many common cards, for sufficiently large n. This leads us to propose a new stronger version of the Reconstruction Conjecture. In addition, we present an infinite family of pairs of graphs with the same degree sequence that have \begin{eqnarray*}\frac{2}{3}(n+5-2\sqrt{3n+6})\end{eqnarray*} common cards, for appropriate values of n, from which we can construct pairs having slightly fewer common cards for all other values of n≥10. We also present infinite families of pairs of forests and pairs of trees with \begin{eqnarray*}2\lfloor\frac{1}{3}(n-4)\rfloor\end{eqnarray*} and \begin{eqnarray*}2\lfloor\frac{1}{3}(n-5)\rfloor\end{eqnarray*} common cards, respectively. We then present new families that have the maximum number of common cards when one graph is connected and the other disconnected. Finally, we present a family with a large number of common cards, where one graph is a tree and the other unicyclic, and discuss how many cards are required to determine whether a graph is a tree. © 2009 Wiley Periodicals, Inc. J Graph Theory 63: 146–163, 2010 相似文献
110.
As the definition of free class of differential modules over a commutative ring in [1], we define DG free class for semifree DG modules over an Adams connected DG algebra A. For any DG A-modules M, we define its cone length as the least DG free classes of all semifree resolutions of M. The cone length of a DG A-module plays a similar role as projective dimension of a module over a ring does in homological ring theory. The left (resp., right) global dimension of an Adams connected DG algebra A is defined as the supremum of the set of cone lengths of all DG A-modules (resp., A op -modules). It is proved that the definition is a generalization of that of graded algebras. Some relations between the global dimension of H(A) and the left (resp. right) global dimension of A are discovered. When A is homologically smooth, we prove that the left (right) global dimension of A is finite and the dimension of D(A) and D c (A) are not bigger than the DG free class of a minimal semifree resolution X of the DG A e -module A. 相似文献