全文获取类型
收费全文 | 6412篇 |
免费 | 787篇 |
国内免费 | 221篇 |
专业分类
化学 | 615篇 |
晶体学 | 5篇 |
力学 | 605篇 |
综合类 | 71篇 |
数学 | 4715篇 |
物理学 | 1409篇 |
出版年
2023年 | 53篇 |
2022年 | 54篇 |
2021年 | 135篇 |
2020年 | 183篇 |
2019年 | 186篇 |
2018年 | 185篇 |
2017年 | 207篇 |
2016年 | 234篇 |
2015年 | 160篇 |
2014年 | 243篇 |
2013年 | 633篇 |
2012年 | 293篇 |
2011年 | 302篇 |
2010年 | 284篇 |
2009年 | 306篇 |
2008年 | 306篇 |
2007年 | 298篇 |
2006年 | 279篇 |
2005年 | 285篇 |
2004年 | 226篇 |
2003年 | 245篇 |
2002年 | 370篇 |
2001年 | 240篇 |
2000年 | 243篇 |
1999年 | 164篇 |
1998年 | 164篇 |
1997年 | 132篇 |
1996年 | 90篇 |
1995年 | 86篇 |
1994年 | 85篇 |
1993年 | 54篇 |
1992年 | 69篇 |
1991年 | 62篇 |
1990年 | 55篇 |
1989年 | 44篇 |
1988年 | 43篇 |
1987年 | 36篇 |
1986年 | 40篇 |
1985年 | 58篇 |
1984年 | 49篇 |
1983年 | 18篇 |
1982年 | 35篇 |
1981年 | 25篇 |
1980年 | 23篇 |
1979年 | 29篇 |
1978年 | 16篇 |
1977年 | 25篇 |
1976年 | 28篇 |
1974年 | 10篇 |
1973年 | 7篇 |
排序方式: 共有7420条查询结果,搜索用时 31 毫秒
41.
In this note we study uncertainty sequencing situations, i.e., one-machine sequencing situations in which no initial order
is specified. We associate cooperative games with these sequencing situations, study their core, and provide links with the
classic sequencing games introduced by Curiel et al. (Eur J Oper Res 40:344–351, 1989). Moreover, we propose and characterize
two simple cost allocation rules for uncertainty sequencing situations with equal processing times. 相似文献
42.
Using an infinite-horizon two-player differential game, we derive and compare Bertrand and Cournot equilibria for a differentiated duopoly engaging in the process of R&D competition. The main findings of this study are as follows. First, Bertrand competition is more efficient if either R&D productivity is low or products are very different. Second, Cournot competition is more efficient provided that R&D productivity is high, products are close substitutes, and spillovers are not close to zero. This last result is different from what has been obtained in the literature. Hence, this shows that considering a dynamic model and more general investment costs does have an impact on the efficiency results. 相似文献
43.
In this article, we define stochastic dynamics for a system coupled to reservoirs. The rules for forward and backward transitions are related by a generalized detailed balance identity involving the system and its reservoirs. We compare the variation of information and of entropy. We define the Carnot dissipation and prove that it can be expressed in terms of cyclic transformations. Lower bounds for partial dissipations are also studied, as well as the effect of switching off certain reservoirs. We also study the near degeneracy of the stochastic matrix, relate it to phase transitions and we show that the reduced dynamics on the set of phases is a permutation. Finally, we relate these concepts to heat, work and more generally to the dissipation and creation of resources, in general systems. 相似文献
44.
We study the stationary measure for the two-dimensional Boussinesq equation with random forcing. We prove the ergodicity for the two-dimensional stochastically forced Boussinesq equation. We also study the Galerkin truncations of the three-dimensional Boussinesq equations under degenerate stochastic forcing. We follow closely the previous results on the stochastically forced Navier–Stokes equations. 相似文献
45.
46.
应用广义胞映射方法研究了参激和外激共同作用的Duffing-van der Pol振子的随机分岔.以 系统参数通过某一临界值时,如果系统的随机吸引子或随机鞍的形态发生突然变化,则认为 系统发生随机分岔为定义,分析了参激强度和外激强度的变化对于随机分岔的影响.揭示了 随机分岔的发生主要是由于系统的随机吸引子与系统的随机鞍碰撞产生的.分析表明,广义 胞映射方法是分析随机分岔的有力工具,这种全局分析方法可以清晰地给出随机分岔的发生 和发展.
关键词:
随机分岔
全局分析
广义胞映射方法
随机吸引子
随机鞍 相似文献
47.
吴臻 《数学物理学报(B辑英文版)》2004,24(1):91-99
The existence and uniqueness results of fully coupled forward-backward stochastic differential equations with stopping time (unbounded) is obtained. One kind of comparison theorem for this kind of equations is also proved. 相似文献
48.
P. Q. Khanh 《Journal of Optimization Theory and Applications》1995,87(2):359-378
We prove the Kuhn-Tucker sufficient optimality condition, the Wolfe duality, and a modified Mond-Weir duality for vector optimization problems involving various types of invex-convexlike functions. The class of such functins contains many known generalized convex functions. As applications, we demonstrate that, under invex-convexlikeness assumptions, the Pontryagin maximum principle is a sufficient optimality condition for cooperative differential games. The Wolfe duality is established for these games.The author is indebted to the referees and Professor W. Stadler for valuable remarks and comments, which have been used to revise considerably the paper. 相似文献
49.
本文针对单件小批量生产系统 ,建立了模糊优化的动态随机投入产出模型 ,同时给出了该模型的递推解法 ,并用此模型对某单件小批企业在生产计划期的商品量进行了规划 相似文献
50.
Olav Kallenberg 《Stochastic Processes and their Applications》1992,40(2):199-223
From the predictable reduction of a marked point process to Poisson, we derive a similar reduction theorem for purely discontinuous martingales to processes with independent increments. Both results are then used to examine the existence of stochastic integrals with respect to stable Lévy processes, and to prove a variety of time change representations for such integrals. The Knight phenomenon, where possibly dependent but orthogonal processes become independent after individual time changes, emerges as a general principle. 相似文献