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   2132篇
  免费   107篇
  国内免费   201篇
化学   43篇
晶体学   1篇
力学   21篇
综合类   17篇
数学   1040篇
物理学   168篇
综合类   1150篇
  2024年   3篇
  2023年   25篇
  2022年   17篇
  2021年   22篇
  2020年   46篇
  2019年   40篇
  2018年   48篇
  2017年   52篇
  2016年   39篇
  2015年   49篇
  2014年   121篇
  2013年   176篇
  2012年   91篇
  2011年   150篇
  2010年   121篇
  2009年   166篇
  2008年   174篇
  2007年   160篇
  2006年   153篇
  2005年   114篇
  2004年   92篇
  2003年   87篇
  2002年   94篇
  2001年   67篇
  2000年   55篇
  1999年   47篇
  1998年   34篇
  1997年   41篇
  1996年   23篇
  1995年   20篇
  1994年   16篇
  1993年   10篇
  1992年   12篇
  1991年   13篇
  1990年   6篇
  1989年   14篇
  1988年   5篇
  1987年   4篇
  1986年   4篇
  1985年   8篇
  1984年   5篇
  1982年   3篇
  1981年   1篇
  1979年   2篇
  1978年   1篇
  1977年   2篇
  1975年   2篇
  1974年   2篇
  1957年   1篇
  1936年   1篇
排序方式: 共有2440条查询结果,搜索用时 9 毫秒
971.
We give a rather sharp upper bound for the degree of a binomial Thue--Mahler equation in terms of the coefficients and the primes involved. Further, we establish explicit lower bounds for the greatest prime factor of a binomial binary form at integral points. Our estimates considerably generalize and improve the earlier results obtained in this direction.  相似文献   
972.
LetA e be the algebra obtained by adjoining identity to a non-unital Banach algebra (A, ∥ · ∥). Unlike the case for aC*-norm on a Banach *-algebra,A e admits exactly one uniform norm (not necessarily complete) if so doesA. This is used to show that the spectral extension property carries over fromA to A e . Norms onA e that extend the given complete norm ∥ · ∥ onA are investigated. The operator seminorm ∥ · ∥op onA e defined by ∥ · ∥ is a norm (resp. a complete norm) iffA has trivial left annihilator (resp. ∥ · ∥op restricted toA is equivalent to ∥ · ∥).  相似文献   
973.
Graded analogs of (n,k,r)-Lie algebras (in particular, of Nambu–Lie algebras), introduced by the authors, are defined and their general property are studied.  相似文献   
974.
利用DvornicichR和ViolaC关于ξ(2)=和ξ(3)=无理性测量的证明方法,给出了一个关于log2的无理性测量的新的证明方法.  相似文献   
975.
A unified treatment is presented here of compounding with the bivariate Poisson distribution. Exploiting the exponential nature of its probability generating function, it is shown that the pgf of the compound distribution is the moment generating function of the compounding random variable. This relationship leads to rather interesting general results. Particularly, the development of the conditional distribution is simplified. Four cases are presented in detail.  相似文献   
976.
Define coefficients (κλ) by Cλ(Ip + Z)/Cλ(Ip) = Σk=0l Σ?∈Pk (?λ) Cκ(Z)/Cκ(Ip), where the Cλ's are zonal polynomials in p by p matrices. It is shown that C?(Z) etr(Z)/k! = Σl=k Σλ∈Pl (?λ) Cλ(Z)/l!. This identity is extended to analogous identities involving generalized Laguerre, Hermite, and other polynomials. Explicit expressions are given for all (?λ), ? ∈ Pk, k ≤ 3. Several identities involving the (?λ)'s are derived. These are used to derive explicit expressions for coefficients of Cλ(Z)l! in expansions of P(Z), etr(Z)k! for all monomials P(Z) in sj = tr Zj of degree k ≤ 5.  相似文献   
977.
本文对蚕种检验中的超几何分布用“f二项近似式”进行计算,既方便,又准确率高。  相似文献   
978.
In this paper, we deal with a class of non-stationary multiresolution analysis and wavelets generated by certain radial basis functions. These radial basis functions are noted for their effectiveness in terms of projection, such as interpolation and least-squares approximation, particularly when the data structure is scattered or the dimension of s is large. Thus projecting a functionf onto a suitable multiresolution space is relatively easy here. The associated multiresolution spaces approximate sufficiently smooth functions exponentially fast. The non-stationary wavelets satisfy the Littlewood-Paley identity so that perfect reconstruction of wavelet decompositions is achieved. For the univariate case, we give a detailed analysis of the time-frequency localization of these wavelets. Two numerical examples for the detection of singularities with analytic wavelets are provided.Supported by NSF Grant #DMS-92-06928, Air Force Grant #F49620-92-J-0403DEF and NATO Grant #CR-900158.  相似文献   
979.
拟除虫菊酯分子设计中的生物同一性   总被引:3,自引:0,他引:3  
讨论了在拟除虫菊酯分子设计中利用生物同一性,对先导化合物进行一系列化 学改造和修饰,以获得新的拟除虫菊酯。  相似文献   
980.
In this note, the GI/M/ queue with batch arrivals of constant sizek is investigated. It is shown that the stationary probabilities that an arriving batch findsi customers in the system can be computed in terms of the corresponding binomial moments (Jordan's formula), which are determined by a recursive relation. This generalizes well-known results by Takács [12] for GI/M/. Furthermore, relations between batch arrival- and time-stationary probabilities are given.  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