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   401篇
  免费   28篇
  国内免费   44篇
化学   8篇
力学   20篇
综合类   3篇
数学   244篇
物理学   68篇
综合类   130篇
  2023年   2篇
  2022年   6篇
  2021年   4篇
  2020年   8篇
  2019年   7篇
  2018年   7篇
  2017年   2篇
  2016年   7篇
  2015年   5篇
  2014年   9篇
  2013年   19篇
  2012年   16篇
  2011年   18篇
  2010年   17篇
  2009年   16篇
  2008年   37篇
  2007年   32篇
  2006年   25篇
  2005年   22篇
  2004年   27篇
  2003年   26篇
  2002年   19篇
  2001年   12篇
  2000年   17篇
  1999年   15篇
  1998年   15篇
  1997年   11篇
  1996年   11篇
  1995年   10篇
  1994年   3篇
  1993年   11篇
  1992年   7篇
  1991年   3篇
  1990年   6篇
  1989年   10篇
  1987年   2篇
  1985年   3篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1980年   1篇
  1975年   1篇
  1957年   1篇
排序方式: 共有473条查询结果,搜索用时 15 毫秒
11.
利用一维离散Walsh变换的性质与结果,定义了二维离散Walsh变换及二维Walsh变换的逻辑卷积,证明了二元W系的完整性,给出二维Walsh变换的基本运算性质及二维Walsh变换下1≤p≤2时的Hausdorff-Young不等式。  相似文献   
12.
基于W alsh函数,建立一个新的函数系T n n∈N.它是一个分段线性函数序列,在0,1的子区间上其函数图像呈现三角形。并且证明了它是C[0,1]上一个完备的正交函数系。在此函数系上展成的Fourier级数有许多与三角Fourier级数相似的性质,三角形Fourier级数的部分和在作为函数的逼近工具时确实要比三角Fourier级数优越一些。  相似文献   
13.
次Mackey空间与广义次Mackey空间被引进.对于次Mackey空间E,其强对偶(E’,β(E’,E))为局部完备等价于E为C-拟桶形也等价于E为C0-拟桶形.对于广义次Mackey空间E,强对偶(E’,β(E’,E))为局部完备等价于E为C0-拟桶形.  相似文献   
14.
In this article we find some sufficient and some necessary -conditions with oracles for a model to be resplendent or chronically resplendent. The main tool of our proofs is internal arguments, that is analogues of classical theorems and model-theoretic constructions conducted inside a model of first-order Peano Arithmetic: arithmetised back-and-forth constructions and versions of the arithmetised completeness theorem, namely constructions of recursively saturated and resplendent models from the point of view of a model of arithmetic. These internal arguments are used in conjunction with Pabion’s theorem that ensures that certain oracles are coded in a sufficiently saturated model of arithmetic. Examples of applications are provided for the theories of dense linear orders and of discrete linear orders. These results are then generalised to other ω-categorical theories and theories with a unique countable recursively saturated model.   相似文献   
15.
In previous works, we presented a modification of the usual possible world semantics by introducing an independent temporal structure in each world and using accessibility functions to represent the relation among them. Different properties ofthe accessibility functions (being injective, surjective, increasing, etc.) have been considered and axiomatic systems (called functional) which define these properties have been given. Only a few ofthese systems have been proved tobe complete. The aim ofthis paper is to make a progress in the study ofcompleteness for functional systems. For this end, we use indexes as names for temporal flows and give new proofs of completeness. Specifically, we focus our attention on the system which defines injectivity, because the system which defines this property without using indexes was proved to be incomplete in previous works. The only system considered which remains incomplete is the one which defines surjectivity, even ifwe consider a sequence ofnatural extensions ofthe previous one (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
16.
Summary Using standard multiscale techniques, a first-order perturbation theory for SBS is developed. In the presence of small damping, we find that there is a stationary solution for a soliton which is a fixed point. The velocity of this soliton is determined by the damping coefficients. In addition, there is also a constant shift in the pump intensity in the region between the front of the backward moving soliton and the forward light cone of the pump.  相似文献   
17.
运用因子分析法建立教学质量评估指标体系   总被引:3,自引:1,他引:3  
在大量抽样调查的基础上,本文运用因子分析(Factor Analysis)的方法,在M—340计算机上利用ANALYST统计分析软件包中因子分析软件程序,求得因子载荷矩阵.依据因子载荷矩阵,并结合教学质量评估的特点,建立起适用于学生为参评者的教学质量评估指标体系.  相似文献   
18.
An algebra of sentences of the quite intuitionistic protothetics, that is, an intuitionistic propositional logic with quantifiers augmented by the negation of the excluded middle, is a faithful model of intuitionistic propositional logic.  相似文献   
19.
Andriyanov  G. I. 《Mathematical Notes》2002,72(5-6):742-751
We study the moment problem in a complex domain. The results obtained generalize and sharpen the well-known Kaz'min result. We also consider applications of these results to the Abel--Goncharov problem (the uniqueness and construction problem) and to the completeness problem for systems of analytic functions.  相似文献   
20.
In this study, maximal dissipative second‐order dynamic operators on semi‐infinite time scale are studied in the Hilbert space , that the extensions of a minimal symmetric operator in limit‐point case. We construct a self‐adjoint dilation of the dissipative operator together with its incoming and outgoing spectral representations so that we can determine the scattering function of the dilation as stated in the scheme of Lax‐Phillips. Moreover, we construct a functional model of the dissipative operator and identify its characteristic function in terms of the Weyl‐Titchmarsh function of a self‐adjoint second‐order dynamic operator. Finally, we prove the theorems on completeness of the system of root functions of the dissipative and accumulative dynamic operators.  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