全文获取类型
收费全文 | 5125篇 |
免费 | 341篇 |
国内免费 | 499篇 |
专业分类
化学 | 396篇 |
晶体学 | 4篇 |
力学 | 280篇 |
综合类 | 120篇 |
数学 | 4860篇 |
物理学 | 305篇 |
出版年
2024年 | 2篇 |
2023年 | 59篇 |
2022年 | 68篇 |
2021年 | 93篇 |
2020年 | 105篇 |
2019年 | 113篇 |
2018年 | 130篇 |
2017年 | 128篇 |
2016年 | 131篇 |
2015年 | 102篇 |
2014年 | 201篇 |
2013年 | 355篇 |
2012年 | 225篇 |
2011年 | 287篇 |
2010年 | 258篇 |
2009年 | 353篇 |
2008年 | 346篇 |
2007年 | 326篇 |
2006年 | 325篇 |
2005年 | 259篇 |
2004年 | 225篇 |
2003年 | 262篇 |
2002年 | 223篇 |
2001年 | 204篇 |
2000年 | 173篇 |
1999年 | 171篇 |
1998年 | 171篇 |
1997年 | 149篇 |
1996年 | 91篇 |
1995年 | 68篇 |
1994年 | 55篇 |
1993年 | 48篇 |
1992年 | 36篇 |
1991年 | 25篇 |
1990年 | 19篇 |
1989年 | 13篇 |
1988年 | 13篇 |
1987年 | 11篇 |
1986年 | 9篇 |
1985年 | 24篇 |
1984年 | 20篇 |
1983年 | 12篇 |
1982年 | 21篇 |
1981年 | 16篇 |
1980年 | 18篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1974年 | 3篇 |
排序方式: 共有5965条查询结果,搜索用时 15 毫秒
101.
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
102.
103.
研究了乘积空间中严格集压缩减算子不动点存在唯一性问题,在弱连续的条件下,得到了不动点的存在唯一性和迭代收敛性.并给出了它的应用. 相似文献
104.
CONE-DIRECTED CONTINGENT DERIVATIVES AND GENERALIZED PREINVEX SET-VALUED OPTIMIZATION 总被引:2,自引:0,他引:2
丘京辉 《数学物理学报(B辑英文版)》2007,27(1):211-218
By using cone-directed contingent derivatives, the unified necessary and suffi-cient optimality conditions are given for weakly and strongly minimal elements respectively in generalized preinvex set valued optimization. 相似文献
105.
Curtis Bennett Kathy J. Dempsey Bruce E. Sagan 《Journal of Algebraic Combinatorics》1994,3(3):261-283
We construct a family of partially ordered sets (posets) that are q-analogs of the set partition lattice. They are different from the q-analogs proposed by Dowling [5]. One of the important features of these posets is that their Whitney numbers of the first and second kind are just the q-Stirling numbers of the first and second kind, respectively. One member of this family [4] can be constructed using an interpretation of Milne [9] for S[n, k] as sequences of lines in a vector space over the Galois field F
q. Another member is constructed so as to mirror the partial order in the subspace lattice. 相似文献
106.
The solvability of a class of forward-backward stochastic differential equations (SDEs for short) over an arbitrarily prescribed time duration is studied. The authors design a stochastic relaxed control problem, with both drift and difftusion all being controlled, so that the solvability problem is converted to a problem of finding the nodal set of the viscosity solution to a certain Hamilton-Jacobi-Bellman equation. This method overcomes the fatal difficulty encountered in the traditional contraction mapping approach to the existence theorem of such SDEs. 相似文献
107.
108.
An interval-parameter fuzzy linear programming method (IFMOLP) is proposed in this study for multiple objective decision-making
under uncertainty. As a hybrid of interval-parameter and fuzzy methodologies, the IFMOLP incorporates interval-parameter linear
programming and fuzzy multiobjective programming approaches to form an integrated optimization system. The method inherits
advantages of interval-parameter programming, and allows uncertainties and decision-makers’ aspirations to be effectively
communicated into its programming processes and resulting solutions. Membership functions for both objectives and constraints
are formulated to reflect uncertainties in different system components and their interrelationships. An interactive solution
procedure has been developed based on solution approaches of the interval-parameter and fuzzy programming techniques, plus
necessary measures for handling the multiobjective feature. A didactic example is provided in the paper to illustrate the
detailed solution process. Possibilities of further improvements by seeking Pareto optimum and incorporating flexible preference
within constraints are also discussed. 相似文献
109.
张昌斌 《纯粹数学与应用数学》1998,14(3):21-24,71
借助于文(1)中的结论研究了仿紧集上的拟-似变分不等式,统一和发展了文(2-6)中的相应结果。 相似文献
110.
We show that the problem of deciding whether anN-free ordered set has dimension at most 3 is NP-complete.Both authors supported by Office of Naval Research contract N00014-85K-0494. 相似文献