全文获取类型
收费全文 | 1540篇 |
免费 | 27篇 |
国内免费 | 8篇 |
专业分类
化学 | 1018篇 |
晶体学 | 3篇 |
力学 | 52篇 |
数学 | 278篇 |
物理学 | 224篇 |
出版年
2020年 | 14篇 |
2019年 | 18篇 |
2016年 | 24篇 |
2015年 | 23篇 |
2014年 | 24篇 |
2013年 | 42篇 |
2012年 | 49篇 |
2011年 | 70篇 |
2010年 | 48篇 |
2009年 | 38篇 |
2008年 | 70篇 |
2007年 | 52篇 |
2006年 | 53篇 |
2005年 | 41篇 |
2004年 | 40篇 |
2003年 | 41篇 |
2002年 | 40篇 |
2001年 | 37篇 |
2000年 | 29篇 |
1999年 | 20篇 |
1998年 | 24篇 |
1997年 | 27篇 |
1996年 | 23篇 |
1995年 | 22篇 |
1994年 | 29篇 |
1993年 | 19篇 |
1992年 | 24篇 |
1991年 | 12篇 |
1990年 | 15篇 |
1989年 | 14篇 |
1988年 | 20篇 |
1987年 | 18篇 |
1986年 | 11篇 |
1985年 | 25篇 |
1984年 | 20篇 |
1983年 | 18篇 |
1982年 | 22篇 |
1981年 | 21篇 |
1980年 | 22篇 |
1979年 | 17篇 |
1978年 | 15篇 |
1977年 | 29篇 |
1976年 | 16篇 |
1975年 | 13篇 |
1974年 | 12篇 |
1973年 | 15篇 |
1972年 | 11篇 |
1970年 | 12篇 |
1967年 | 13篇 |
1926年 | 9篇 |
排序方式: 共有1575条查询结果,搜索用时 250 毫秒
1.
2.
We study a combinatorially defined double complex structure on the ordered chains of any simplicial complex. Its columns are related to the cell complex Kn whose face poset is isomorphic to the subword ordering on words without repetition from an alphabet of size n. This complex is shellable and as an application we give a representation theoretic interpretation for derangement numbers and a related symmetric function considered by Désarménien and Wachs [11].
We analyze the two spectral sequences arising from the double complex in the case of the bar resolution for a group. This spectral sequence converges to the cohomology of the group and provides a method for computing group cohomology in terms of the cohomology of subgroups. Its behavior is influenced by the complex of oriented chains of the simplicial complex of finite subsets of the group, and we examine the Ext class of this complex. 相似文献
3.
In [NR] the authors introduced the notion of superstable operators on a Banach space E using ultrapowers Eu of E. In [HR] this notion was extended to strongly continuous one-parameter semigroups again by means of ultrapowers.It is the aim of the present paper to give an equivalent intrinsic definition of superstability (without the reference to ultrapowers). This definition allows us to improve the results of [NR] as well as of [HR]. We apply our results to semigroups of positive linear operators on Banach lattices and C*-algebras, respectively. 相似文献
4.
It is known that every conformai embedding of the disk into the extended complex plane possesses a r2-quasiconformal extension across eachr-level line (the r2-property of a domain). We show here that this is a characteristic property of the disk: any simply connected domain which
is not a disk does not admit ther
2-property.
Supported by the RiP-program of the Volkswagen-Stiftung in the Mathematisches Forschungsinstitut Oberwolfach. 相似文献
5.
6.
7.
In this paper we discuss farthest-point problems in which a set or sequence S of n points in the plane is given in advance and can be preprocessed to answer various queries efficiently. First, we give a data structure that can be used to compute the point farthest from a query line segment in O(log2n) time. Our data structure needs O(nlogn) space and preprocessing time. To the best of our knowledge no solution to this problem has been suggested yet. Second, we show how to use this data structure to obtain an output-sensitive query-based algorithm for polygonal path simplification. Both results are based on a series of data structures for fundamental farthest-point queries that can be reduced to each other. 相似文献
8.
We prove for a large class of tilings that, given a finite tile set, if it is possible to tile Euclideann-space with isometric copies of this set, then there is a tiling with the ‘local isomorphism property’.
Research supported in part by NSF Grant No. DMS-9001475. 相似文献
9.
Transition temperatures (TN1) from the nematic lyotropic liquid-crystalline phase to the isotropic phase were measured for the system cetyltrimethylammonium bromide (CTAB) water in the presence of small amounts of 3-stilbene carboxylic acid (3SC), 4-stilbene carboxylic acid (4SC) and Δ2/2'-bi-(2H-l,4-benzothiazine) (BT). TNI, increases as a function of trans-3SC or trans-4SC concentration, ranging from 01 to 08 wt %, by up to 12°C. A further increase in TNI between 2 and 5°C can be achieved by photochemically converting the solubilized trans stilbene derivatives to the cis isomers. Irradiation of a trans-3SC containing sample at a temperature just above TNl leads to a light-induced phase transition to the lyotropic liquid-crystalline phase. Solubilization of trans-BT causes a slight decrease of TNI while photoisomerization to cis-BT increases TNI by 1°C. 相似文献
10.