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   808篇
  免费   110篇
  国内免费   55篇
化学   44篇
力学   33篇
综合类   19篇
数学   735篇
物理学   142篇
  2023年   8篇
  2022年   13篇
  2021年   8篇
  2020年   20篇
  2019年   16篇
  2018年   14篇
  2017年   22篇
  2016年   27篇
  2015年   12篇
  2014年   46篇
  2013年   61篇
  2012年   27篇
  2011年   49篇
  2010年   57篇
  2009年   54篇
  2008年   68篇
  2007年   57篇
  2006年   68篇
  2005年   41篇
  2004年   35篇
  2003年   30篇
  2002年   27篇
  2001年   25篇
  2000年   31篇
  1999年   22篇
  1998年   20篇
  1997年   20篇
  1996年   21篇
  1995年   13篇
  1994年   7篇
  1993年   3篇
  1992年   6篇
  1991年   6篇
  1990年   2篇
  1989年   4篇
  1988年   8篇
  1987年   2篇
  1986年   2篇
  1985年   6篇
  1984年   3篇
  1982年   1篇
  1981年   3篇
  1979年   2篇
  1978年   1篇
  1977年   1篇
  1976年   2篇
  1973年   2篇
排序方式: 共有973条查询结果,搜索用时 93 毫秒
51.
In this paper we give new and purely analytical proofs of a number of classical results on the asymptotic behavior of large random matrices of complex Wigner type (the GUE-case) or of complex Wishart type: Wigner's semi-circle law, the Harer-Zagier recursion formula, the Marchenko-Pastur law, the Geman-Silverstein results on the largest and smallest eigenvalues and other related results. Our approach is based on the derivation of explicit formulae for the moment generating functions for random matrices of the two considered types.  相似文献   
52.
In this paper, we give precise formulas for the general two-dimensional recursion sequences by generating function method, and make use of the multivariate generating functions asymptotic estimation technique to compute their asymptotic values.  相似文献   
53.
We show that every unitary representation π of a connected Lie group G is characterized up to quasi-equivalence by its complete moment set.Moreover, irreducible unitary representations π of G are characterized by their moment sets.  相似文献   
54.
李炜  柳向东 《应用数学》2007,20(3):500-504
设{xn,n≥1}是同分布的两两NQD列,记Sn=∑i=1Xi^n.本文讨论了max |Si|/i(n≥1)的分布函数的上下界.作为应用,获得了随机变量supn≥|Sn|/n型的1阶矩及p(〉1)阶矩分别存在有限的充分必要条件,这是一个与独立同分布场合相一致的结果.  相似文献   
55.
A connection between Romanovski polynomials and those polynomials that solve the one-dimensional Schrödinger equation with the trigonometric Rosen-Morse and hyperbolic Scarf potential is established. The map is constructed by reworking the Rodrigues formula in an elementary and natural way. The generating function is summed in closed form from which recursion relations and addition theorems follow. Relations to some classical polynomials are also given.  相似文献   
56.
An urn has balls of colors C1 and C2. It is replenished (R) by balls of both colors and then depleted by (D) the same number; this constitutes a cycle. When R = D, the system is closed and equilibrium will be reached after many cycles. The ultimate distribution is found only when the replenishment is the same for each color. Asymptotic normal and asymptotic binomial distributions arise when the parameters reach extreme values. For the multicolor urn an expression is given for the correlation between the number of balls of any two colors.  相似文献   
57.
The convexification of a noninferior frontier can be achieved in an appropriate equivalent objective space for general nonconvex multiobjective optimization problems. Specifically, this paper proves that taking the exponentials of the objective functions can act as a convexification scheme. This convexification scheme further leads to the exponential generating method that guarantees the identification of the entire set of noninferior solutions.  相似文献   
58.
We consider a single server retrial queueing system in which each customer (primary or retrial customer) has discrete service times taking on value Dj with probability , and . An arriving primary customer who finds the server busy tries later. Moreover, each retrial customer has its own orbit, and the retrial customers try to enter the service independently of each other. We call this retrial queue an M/{Dn}/1 retrial queue. A necessary and sufficient condition for this system stability is given. In the steady state, we derive the joint distribution of the state of the server and the number of customers in the retrial orbits. The explicit expressions of some performance measures are given. In addition, the steady-state distribution of the waiting time is discussed.  相似文献   
59.
60.
Single line queue with repeated demands   总被引:2,自引:0,他引:2  
We analyze a model of a queueing system in which customers can only call in to request service: if the server is free, the customer enters service immediately, but if the service system is occupied, the unsatisfied customer must break contact and reinitiate his request later. Such a customer is said to be in “orbit”. In this paper we consider three models characterized by the discipline governing the order of re-request of service from orbit. First, all customers in orbit can reapply, but are discouraged and reduce their rate of demand as more customers join the orbit. Secondly, the FCFS discipline operates for the unsatisfied customers in orbit. Finally, the LCFS discipline governs the customers in orbit and the server takes an exponentially distributed vacation after each service is completed. We calculate several characteristics quantities of such systems, assuming a general service-time distribution and different exponential distributions for the times between arrivals of first and repeat requests.  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