全文获取类型
收费全文 | 7210篇 |
免费 | 876篇 |
国内免费 | 611篇 |
专业分类
化学 | 234篇 |
晶体学 | 4篇 |
力学 | 810篇 |
综合类 | 170篇 |
数学 | 6162篇 |
物理学 | 1317篇 |
出版年
2024年 | 12篇 |
2023年 | 60篇 |
2022年 | 75篇 |
2021年 | 104篇 |
2020年 | 155篇 |
2019年 | 167篇 |
2018年 | 190篇 |
2017年 | 213篇 |
2016年 | 255篇 |
2015年 | 156篇 |
2014年 | 279篇 |
2013年 | 566篇 |
2012年 | 323篇 |
2011年 | 376篇 |
2010年 | 349篇 |
2009年 | 402篇 |
2008年 | 454篇 |
2007年 | 453篇 |
2006年 | 438篇 |
2005年 | 413篇 |
2004年 | 379篇 |
2003年 | 320篇 |
2002年 | 351篇 |
2001年 | 237篇 |
2000年 | 281篇 |
1999年 | 226篇 |
1998年 | 195篇 |
1997年 | 183篇 |
1996年 | 135篇 |
1995年 | 157篇 |
1994年 | 103篇 |
1993年 | 108篇 |
1992年 | 90篇 |
1991年 | 63篇 |
1990年 | 76篇 |
1989年 | 48篇 |
1988年 | 31篇 |
1987年 | 28篇 |
1986年 | 40篇 |
1985年 | 24篇 |
1984年 | 32篇 |
1983年 | 13篇 |
1982年 | 22篇 |
1981年 | 14篇 |
1980年 | 13篇 |
1979年 | 15篇 |
1978年 | 18篇 |
1977年 | 18篇 |
1974年 | 7篇 |
1973年 | 9篇 |
排序方式: 共有8697条查询结果,搜索用时 359 毫秒
141.
142.
本文讨论定义于Banach空间的多目标数学规划,得到一些ε-最优解和(弱)有效解的必要条件,充分条件和必要充分条件。 相似文献
143.
讨论带有对合反自同构*有单位元的结合环R上矩阵的广义Moore-Penrose 逆,给出了环R上矩阵的广义Moore-Penrose逆存在的几个充要条件.特别,得到了环 R上矩阵A的关于M和N的广义Moore-Penrose逆存在的充要条件是A有分解A= GDH,其中D2=D,(MD)*=MD,(GD)*MGD+M(I-D)和DHN-1(DH)*+ (I-D)M-1均可逆. 相似文献
144.
In the present paper,we investigate the well-posedness of the global solution for the Cauchy problem of generalized long-short wave equations.Applying Kato's method for abstract quasi-linear evolution equations and a priori estimates of solution,we get the existence of globally smooth solution. 相似文献
145.
框式约束凸二次规划问题的内点算法 总被引:4,自引:0,他引:4
张艺 《高等学校计算数学学报》2002,24(2):163-168
In this paper,a primal-dual interior point algorithm for convex quadratic progromming problem with box constrains is presented.It can be started at any primal-dual interior feasible point.If the initial point is close to the central path,it becomes a central path-following alogorithm and requires a total of O(√nL)number of iterations,where L is the input length. 相似文献
146.
147.
Keith Warren Julien C. Sprott Raymond C. Hawkins 《Nonlinear dynamics, psychology, and life sciences》2002,6(1):55-70
In recent years there has been considerable interest in the construction of nonlinear models of the dynamics of human behavior. In this exploratory article we argue that attempts at controlling problematic thoughts, emotions, or behaviors can lead to nonlinearity in mental/behavioral dynamics. We illustrate our model by fitting threshold autoregression models to self-recorded time series of the daily highs in intensity of anxiety and obsessive ruminations, kept by an individual in therapy for this problem. In our discussion, we raise the possibility that bifurcations that occur in this nonlinear model may offer insight into mental control paradoxes. 相似文献
148.
对四分块矩阵A=A(︿) A(︿,︿′)A(︿′,︿) A(︿′)来说 ,如果 A和 A(︿)都是非奇异的 ,则A- 1 (︿′) =(A/︿) - 1 ,这里 A/ ︿=A(︿′) -A(︿′,︿) A(︿) - 1 A(︿,︿′)是 A(︿)在 A中的 Schur补 .王伯英教授指出上述等式 ,对半正定的 Hermitian矩阵而言 ,一般也是不能推广到 Moore-Penrose逆上去的 .在某些限制条件下 ,我们证明了广义逆的主子矩阵与广义 Schur补的关系是密切的 ,它使经典结果成为特例 相似文献
149.
In 1991, one of the authors showed the existence of quadratic transformations between the Painlevé VI equations with local monodromy differences (1/2, a, b, ±1/2) and (a, a, b, b). In the present paper we give concise forms of these transformations. They are related to the quadratic transformations obtained by Manin and Ramani–Grammaticos–Tamizhmani via Okamoto transformations. To avoid cumbersome expressions with differentiation, we use contiguous relations instead of the Okamoto transformations. The 1991 transformation is particularly important as it can be realized as a quadratic‐pull back transformation of isomonodromic Fuchsian equations. The new formulas are illustrated by derivation of explicit expressions for several complicated algebraic Painlevé VI functions. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
150.
COSEARCH: A Parallel Cooperative Metaheuristic 总被引:1,自引:0,他引:1
In order to design a well-balanced metaheuristic for robustness, we propose the COSEARCH approach which manages the cooperation
of complementary heuristic methods via an adaptive memory which contains a history of the search already done. In this paper,
we present the idiosyncrasies of the COSEARCH approach and its application for solving large scale instances of the quadratic
assignment problem (QAP). We propose an original design of the adaptive memory in order to focus on high quality regions of
the search and avoid attractive but deceptive areas. For the QAP, we have hybridized three heuristic agents of complementary
behaviours: a Tabu Search is used as the main search algorithm, a Genetic Algorithm is in charge of the diversification and
a Kick Operator is applied to intensify the search. The evaluations have been executed on large scale network of workstations
via a parallel environment which supports fault tolerance and adaptive dynamic scheduling of tasks. 相似文献