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   177篇
  免费   10篇
  国内免费   19篇
化学   13篇
力学   15篇
综合类   1篇
数学   155篇
物理学   22篇
  2022年   1篇
  2021年   1篇
  2020年   1篇
  2019年   2篇
  2018年   4篇
  2017年   9篇
  2016年   7篇
  2015年   8篇
  2014年   3篇
  2013年   11篇
  2012年   7篇
  2011年   9篇
  2010年   11篇
  2009年   9篇
  2008年   15篇
  2007年   11篇
  2006年   11篇
  2005年   9篇
  2004年   7篇
  2003年   6篇
  2002年   6篇
  2001年   11篇
  2000年   6篇
  1999年   5篇
  1998年   3篇
  1997年   8篇
  1996年   4篇
  1995年   3篇
  1993年   2篇
  1991年   5篇
  1990年   2篇
  1989年   2篇
  1987年   2篇
  1985年   2篇
  1984年   2篇
  1982年   1篇
排序方式: 共有206条查询结果,搜索用时 218 毫秒
191.
Let D be a domain obtained by a holomorphic motion of a domain D p M p n–1 along a complex curve P in a complex space form M n . We prove that, if n= 2, the volume of D depends only on the geometry of D p and the intrinsic geometry of P, but not on the extrinsic geometry of P. When M is closed (compact without boundary), then the dependence on P is only through its topology. When n > 2, and for arbitrary domains D p, a similar result holds only for Frenet motions, but when D p has certain integral symmetries (and only in this case) this result is still true for any motion .  相似文献   
192.
The character of holomorphic functions on the space of pure spinors in 10, 11 and 12 dimensions is calculated. From this character formula, we derive in a manifestly covariant way various central charges which appear in the pure spinor formalism for the superstring. We also derive in a simple way the zero momentum cohomology of the pure spinor BRST operator for the D=10 and D=11 superparticle Mathematics Subject Classifications (2000): 81T30, 83E30, 83E50  相似文献   
193.
高恒珊 《数学学报》2003,46(3):463-468
设WMμ为系统MIPC*全部公式的集,再设г∪{A} WMμ,则гMIPC* A意义明显.而 M A指гM-蕴涵A.以前已证明гM A гMIPC*A,即MIPC*为强完全的.本文证明其逆定理成立,即гMIPC*A гM A.是为MIPC*的可靠性定理.  相似文献   
194.
曲面到复Grassmann流形调和映照的若干结果   总被引:1,自引:0,他引:1  
吴炳烨 《数学学报》2003,46(2):291-296
本文讨论曲面到复Grassmann流形调和映照的若干问题,得到了调和映照 为(?)'-不可约或(?)"-不可约的等价条件,给出了显式计算调和映照迷向阶的方法.  相似文献   
195.
Optimal Configurations of Finite Sets in Riemannian 2-Manifolds   总被引:1,自引:0,他引:1  
  相似文献   
196.
We introduce a new weighted wavelet-like transform, generated by the Poisson integral and a “wavelet measure.” By making use of the relevant Calderón-type reproducing formula, we obtain an explicit inversion formula for the Flett potentials which are interpreted as negative fractional powers of the operator (E+Λ), where Λ=(−Δ)1/2, Δ is the Laplacian and E is the identity operator.  相似文献   
197.
This paper studies a discrete-time Geo/G/1 retrial queue where the server is subject to starting failures. We analyse the Markov chain underlying the regarded queueing system and present some performance measures of the system in steady-state. Then, we give two stochastic decomposition laws and find a measure of the proximity between the system size distributions of our model and the corresponding model without retrials. We also develop a procedure for calculating the distributions of the orbit and system size as well as the marginal distributions of the orbit size when the server is idle, busy or down. Besides, we prove that the M/G/1 retrial queue with starting failures can be approximated by its discrete-time counterpart. Finally, some numerical examples show the influence of the parameters on several performance characteristics. This work is supported by the DGINV through the project BFM2002-02189.  相似文献   
198.
A theorem concerning a product of a general class of polynomials and theH-function of several complex variables is given. Using this theorem certain integrals and expansion formula have been obtained. This general theorem is capable of giving a number of new, interesting and useful integrals, expansion formulae as its special cases.  相似文献   
199.
A close study of Heisenberg uncertainty principles reveals many significant facts, and all four major physical quantities, energy, time, momentum and length, have both lower and upper limits. Now, many questions come up. What are these limits? Some answers may lead to the understanding of the development of our universe. What is the shortest limit of time? At the beginning of big bang, there exists a tremendously short time, the Planck time. This may be just the shortest time limit in our universe. The longest time limit might be the lifetime of our universe. The longest length might be the final diameter of our expanding universe. All these lead to a finite universe. Two more coupling formulae are formed for the other two pairs of physical quantities, mass and speed, thermal energy and temperature. These four physical quantities must also have limits. We already knew that speed has upper limit and temperature has lower limit. By these two formulae, Planck and Einstein equations are derived directly. Since most other physical quantities are somewhat related to these major physical quantities, it seems that there exists a principle of limitation of physical quantities. A quantitative sketch of big bang is described. It also shows that our universe will contract back to another big bang. The principle of limitation opens up some fields of investigation. It may bring nature back to the harmony and determined world described by classical physics.  相似文献   
200.
In this paper, we expand asymptotically the general representation formulae for (C o) m-parameter operator semigroups. When we consider special semigroups, our results yield the asymptotic expansions for multivariate Feller operators. In particular, the asymptotic expansions for univariate and multivariate Bernstein operators are reobtained. See the related examples at the end.  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