全文获取类型
收费全文 | 9579篇 |
免费 | 911篇 |
国内免费 | 962篇 |
专业分类
化学 | 3922篇 |
晶体学 | 36篇 |
力学 | 374篇 |
综合类 | 171篇 |
数学 | 5520篇 |
物理学 | 1429篇 |
出版年
2024年 | 9篇 |
2023年 | 100篇 |
2022年 | 133篇 |
2021年 | 163篇 |
2020年 | 266篇 |
2019年 | 263篇 |
2018年 | 273篇 |
2017年 | 320篇 |
2016年 | 294篇 |
2015年 | 257篇 |
2014年 | 421篇 |
2013年 | 1263篇 |
2012年 | 384篇 |
2011年 | 474篇 |
2010年 | 417篇 |
2009年 | 515篇 |
2008年 | 541篇 |
2007年 | 581篇 |
2006年 | 563篇 |
2005年 | 484篇 |
2004年 | 430篇 |
2003年 | 399篇 |
2002年 | 1004篇 |
2001年 | 288篇 |
2000年 | 289篇 |
1999年 | 232篇 |
1998年 | 229篇 |
1997年 | 144篇 |
1996年 | 143篇 |
1995年 | 125篇 |
1994年 | 97篇 |
1993年 | 60篇 |
1992年 | 46篇 |
1991年 | 28篇 |
1990年 | 31篇 |
1989年 | 21篇 |
1988年 | 24篇 |
1987年 | 20篇 |
1986年 | 25篇 |
1985年 | 21篇 |
1984年 | 15篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1957年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
Norman Biggs 《Journal of Combinatorial Theory, Series B》2004,92(2):359
An explicit formula for the chromatic polynomials of certain families of graphs, called bracelets', is obtained. The terms correspond to irreducible representations of symmetric groups. The theory is developed using the standard bases for the Specht modules of representation theory, and leads to an effective means of calculation. 相似文献
92.
Richard Arratia Bla Bollobs Gregory B. Sorkin 《Journal of Combinatorial Theory, Series B》2004,92(2):199-233
Motivated by circle graphs, and the enumeration of Euler circuits, we define a one-variable “interlace polynomial” for any graph. The polynomial satisfies a beautiful and unexpected reduction relation, quite different from the cut and fuse reduction characterizing the Tutte polynomial.It emerges that the interlace graph polynomial may be viewed as a special case of the Martin polynomial of an isotropic system, which underlies its connections with the circuit partition polynomial and the Kauffman brackets of a link diagram. The graph polynomial, in addition to being perhaps more broadly accessible than the Martin polynomial for isotropic systems, also has a two-variable generalization that is unknown for the Martin polynomial. We consider extremal properties of the interlace polynomial, its values for various special graphs, and evaluations which relate to basic graph properties such as the component and independence numbers. 相似文献
93.
94.
95.
Ioan Tomescu 《Journal of Graph Theory》2003,43(3):210-222
In the set of graphs of order n and chromatic number k the following partial order relation is defined. One says that a graph G is less than a graph H if ci(G) ≤ ci(H) holds for every i, k ≤ i ≤ n and at least one inequality is strict, where ci(G) denotes the number of i‐color partitions of G. In this paper the first ? n/2 ? levels of the diagram of the partially ordered set of connected 3‐chromatic graphs of order n are described. © 2003 Wiley Periodicals, Inc. J Graph Theory 43: 210–222, 2003 相似文献
96.
Summary By employing a novel idea and simple techniques, we substantially generalize the Turán type inequality for rational functions
with real zeros and prescribed poles established by Min [5] to include Lpspaces for 1≤p≤∞<span style='font-size:10.0pt'>while loosing the restriction ρ > 2 at the same time. 相似文献
97.
Multiple-zero multiple-pole optical filter transfer functions may be implemented more efficiently in an integrated optics architecture if higher order N × M optical couplers are utilized. For example, a coherent ring resonator made from two 3×3 couplers offers some advantages over the three mirror Fabry-Perot etalon, which is its analog. To this end we develop the formalism for obtaining the transfer functions and scattering matrices of ring resonators made from two N × M couplers. We then present a methodology for analyzing serial and parallel systems of N × M optical coupler ring resonators. 相似文献
98.
SINGLE MACHINE SCHEDULING WITH CONTROLLABLE PROCESSING TIMES AND COMPRESSION COSTS (PART I:EQUAL TIMES AND COSTS) 总被引:1,自引:0,他引:1
Most papers in scheduling research have treated individual job processing times as fixed parameters. However, in many practical situations, a manager may control processing time by realloeating resources. In this paper, authors consider a machine scheduling problemwith controllable processing times. In the first part of this paper, a special case where the pro-cessing times and compression costs are uniform among jobs is discussed. Theoretical results are derived that aid in developing an O(n^2) algorithm to slove the problem optimally. In the second part of this paper, authors generalize the discussion to general case, An effective heuristic to the genera/ problem will be presented. 相似文献
99.
C. Scheidenberger K. Beckert P. Beller F. Bosch C. Brandau D. Boutin L. Chen B. Franzke H. Geissel R. Knöbel C. Kozhuharov J. Kurcewicz S. A. Litvinov Yu. A. Litvinov M. Mazzocco G. Münzenberg F. Nolden W. R. Plaß M. Steck B. Sun H. Weick M. Winkler 《Hyperfine Interactions》2006,173(1-3):61-66
One important goal of the ILIMA project at FAIR is the study of masses and decay properties of relativistic isomeric beams
stored and cooled in the planned storage-ring complex. A new scheme is described, where a storage-cooler ring is used for
high-resolution mass separation. Experimental results on the separation of the isobaric pair 140Pr-140Ce are presented.
P. Beller, deceased. 相似文献
100.
卢琳璋 《高等学校计算数学学报(英文版)》1994,(1)
The unit circle problem is the problem of finding the number of eigenvalues of a non-Hermitian matrix inside and outside the unit circle . To reduce the cost of computing eigenvalues for the problem, a direct method, which is analogous to that given in [5], is proposed in this paper. 相似文献