首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2012篇
  免费   877篇
  国内免费   191篇
化学   137篇
晶体学   2篇
力学   139篇
综合类   69篇
数学   1392篇
物理学   1341篇
  2024年   6篇
  2023年   22篇
  2022年   49篇
  2021年   51篇
  2020年   50篇
  2019年   50篇
  2018年   59篇
  2017年   76篇
  2016年   93篇
  2015年   76篇
  2014年   153篇
  2013年   197篇
  2012年   197篇
  2011年   184篇
  2010年   198篇
  2009年   168篇
  2008年   206篇
  2007年   199篇
  2006年   153篇
  2005年   157篇
  2004年   121篇
  2003年   93篇
  2002年   91篇
  2001年   69篇
  2000年   51篇
  1999年   62篇
  1998年   44篇
  1997年   45篇
  1996年   33篇
  1995年   21篇
  1994年   12篇
  1993年   10篇
  1992年   10篇
  1991年   13篇
  1990年   2篇
  1989年   7篇
  1988年   6篇
  1987年   6篇
  1986年   4篇
  1985年   8篇
  1984年   6篇
  1983年   3篇
  1982年   3篇
  1981年   2篇
  1980年   3篇
  1979年   2篇
  1978年   2篇
  1959年   1篇
  1957年   1篇
  1936年   1篇
排序方式: 共有3080条查询结果,搜索用时 15 毫秒
991.
两个网络间的相互同步   总被引:1,自引:1,他引:1  
本文研究了两个耦合网络的相互同步,利用线性化方法,我们给出了两个具有相同拓扑结构的网络实现同步的定理,最后用数值例子来验证得到的理论结果。  相似文献   
992.
主要考虑非对称耦合复杂网络的脉冲同步问题.通过构造Lyapunov泛函,设计合适的脉冲控制器,并利用时滞脉冲系统理论,给出了网络脉冲同步新的判别准则.数值模拟表明所得结果是正确的.  相似文献   
993.
Quality of service guarantees are an important and much discussed aspect of ATM network design. However, there is no standard definition of quality of service. Moreover, some often-used criteria seem quite crude. We consider call admission to a bufferless ATM multiplexer with on/off sources. A new criterion for a guarantee on average cell loss is proposed. This criterion represents the quality of service from the point of view of the user, and is thus more reliable. We calculate the optimal policy that minimizes blocking subject to the guarantee, when there is only one type of user.The measure of cell-loss we propose is applicable to a wide range of models. It gives rise to a mathematical programming formulation, which we derive explicitly for our case.  相似文献   
994.
In this paper we investigate the possibility of a regular embedding of a lattice ordered group into a completely distributive vector lattice.  相似文献   
995.
Generalized function projective (lag, anticipated and complete) synchronization between two different complex networks with nonidentical nodes is investigated in this paper. Based on Barbalat’s lemma, some sufficient synchronization criteria are derived by applying the nonlinear feedback control. Although previous work studied function projective synchronization on complex dynamical networks, the dynamics of the nodes are coupled partially linear chaotic systems. In our work, the dynamics of the nodes of the complex networks are any chaotic systems without the limitation of the partial linearity. In addition, each network can be undirected or directed, connected or disconnected, and nodes in either network may have identical or different dynamics. The proposed strategy is applicable to almost all kinds of complex networks. Numerical simulations further verify the effectiveness and feasibility of the proposed synchronization method. Numeric evidence shows that the synchronization rate is sensitively influenced by the feedback strength, the time delay, the network size and the network topological structure.  相似文献   
996.
This paper investigates the projective synchronization (PS) of different fractional order chaotic systems while the derivative orders of the states in drive and response systems are unequal. Based on some essential properties on fractional calculus and the stability theorems of fractional-order systems, we propose a general method to achieve the PS in such cases. The fractional operators are introduced into the controller to transform the problem into synchronization problem between chaotic systems with identical orders, and the nonlinear feedback controller is proposed based on the concept of active control technique. The method is both theoretically rigorous and practically feasible. We present two examples that illustrate the effectiveness and applications of the method, which include the PS between two 3-D commensurate fractional-order chaotic systems and the PS between two 4-D fractional-order hyperchaotic systems with incommensurate and commensurate orders, respectively. Abundant numerical simulations are given which agree well with the analytical results. Our investigations show that PS can also be achieved between different chaotic systems with non-identical orders. We have further reviewed and compared some relevant methods on this topic reported in several recent papers. A discussion on the physical implementation of the proposed method is also presented in this paper.  相似文献   
997.
Based on the modified system approach the generalized synchronization (GS) in two bidirectionally coupled discrete dynamical systems is classified into several types, and under some conditions, the existence, Lipschitz smoothness and Hölder continuity of two kinds of GS therein are derived and theoretically proved. In addition, numerical simulations validate the present theory.  相似文献   
998.
In the paper, the analog of Vahlen's theorem for Minkowski bases of three-dimensional lattices is sharpened.  相似文献   
999.
In this paper, we study the chaotic numbers of complete bipartite graphs and complete tripartite graphs. For the complete bipartite graphs, we find closed-form formulas of the chaotic numbers and characterize all chaotic mappings. For the complete tripartite graphs, we develop an algorithm running in O(n 4 3) time to find the chaotic numbers, with n 3 the number of vertices in the largest partite set.Research supported by NSC 90-2115-M-036-003.The author thanks the authors of Ref. 6, since his work was motivated by their work. Also, the author thanks the referees for helpful comments which made the paper more readable.  相似文献   
1000.
We study homogeneous chains of infinite order (ξt)tZ with the set of states taken to be X=(N\{0,1})x{-1,1}. Our approach is to interpret the half-infinite sequence ..., ξ?n,..., ξ?1, ξ0, where ξt=(it, εt) ∈ X, t ∈ Z as the continued fraction to the nearer integer expansion (read inversely) of a y ? [?12,12]. Thus, we are led to study certain Y-valued Markov chains, where Y = [?12, 12] and then by making use of their properties we establish the existence of denumerable chains of infinite order under conditions different from those given in Theorem 2.3.8 of Iosifescu-Theodorescu (1969). A (weak) variant of mixing is proved as well.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号