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   564篇
  免费   67篇
  国内免费   70篇
化学   31篇
力学   32篇
综合类   9篇
数学   504篇
物理学   125篇
  2024年   2篇
  2023年   12篇
  2022年   19篇
  2021年   14篇
  2020年   25篇
  2019年   22篇
  2018年   18篇
  2017年   14篇
  2016年   20篇
  2015年   16篇
  2014年   24篇
  2013年   50篇
  2012年   25篇
  2011年   20篇
  2010年   13篇
  2009年   34篇
  2008年   25篇
  2007年   44篇
  2006年   35篇
  2005年   23篇
  2004年   31篇
  2003年   28篇
  2002年   30篇
  2001年   26篇
  2000年   18篇
  1999年   18篇
  1998年   16篇
  1997年   26篇
  1996年   10篇
  1995年   11篇
  1994年   3篇
  1993年   2篇
  1992年   5篇
  1991年   4篇
  1990年   2篇
  1989年   2篇
  1988年   6篇
  1987年   1篇
  1986年   1篇
  1984年   1篇
  1983年   1篇
  1982年   2篇
  1978年   2篇
排序方式: 共有701条查询结果,搜索用时 0 毫秒
1.
We examine several interesting relationships and expressions involving Fourier-Feynman transform, convolution product and first variation for functionals in the Fresnel class F(B) of an abstract Wiener space B. We also prove a translation theorem and Parseval's identity for the analytic Feynman integral. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   
2.
The PDE-preserving operators O on the space of nuclearly entire functions of bounded type HNb(E) on a Banach space E are characterized. An operator is PDE-preserving when it preserves homogenous solutions to homogeneous convolution equations. We establish a one to one correspondence between O and a set Σ of sequences of entire functionals, i.e. exponential type functions. In this way, algebraic structures on Σ, such as ring structures, can be carried over to O and vice versa. In particular, it follows that O is a non-commutative ring (algebra) with unity with respect to composition and the convolution operators form a commutative subring (subalgebra). We discuss range and kernel properties, for the operators in O, and characterize the projectors (onto polynomial spaces) in O by determining the corresponding elements in Σ. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   
3.
Functional central limit theorems for triangular arrays of rowwise independent stochastic processes are established by a method replacing tail probabilities by expectations throughout. The main tool is a maximal inequality based on a preliminary version proved by P. Gaenssler and Th. Schlumprecht. Its essential refinement used here is achieved by an additional inequality due to M. Ledoux and M. Talagrand. The entropy condition emerging in our theorems was introduced by K. S. Alexander, whose functional central limit theorem for so-calledmeasure-like processeswill be also regained. Applications concern, in particular, so-calledrandom measure processeswhich include function-indexed empirical processes and partial-sum processes (with random or fixed locations). In this context, we obtain generalizations of results due to K. S. Alexander, M. A. Arcones, P. Gaenssler, and K. Ziegler. Further examples include nonparametric regression and intensity estimation for spatial Poisson processes.  相似文献   
4.
In this note, we characterize the regular probability measures satisfying the Choquet-Deny convolution equation =* on Abelian topological semigroups for a given probability measure .  相似文献   
5.
Let ( t ) t0 be a -semistable convolution semigroup of probability measures on a Lie groupG whose idempotent 0 is the Haar measure on some compact subgroupK. Then all the measures 1 are supported by theK-contraction groupC K() of the topological automorphism ofG. We prove here the structure theoremC K()=C()K, whereC() is the contraction group of . Then it turns out that it is sufficient to study semistable convolution semigroups on simply connected nilpotent Lie groups that have Lie algebras with a positive graduation.  相似文献   
6.
二维卷积在动力学分析中的应用   总被引:2,自引:0,他引:2  
沈卫阳  朱建育 《分析化学》1995,23(4):404-406
本文用计算机模拟和二维卷积研究了稀土与间乙酰基偶氮氯膦的显色反应,选择不同的模型参数可描述这类反应的细节,二维卷积则增强对叠合二维谱的分辨。  相似文献   
7.
We consider hypergroups associated with Jacobi functions () (x), (–1/2). We prove the existence of a dual convolution structure on [0,+[i(]0,s 0]{{) =++1,s 0=min(,–+1). Next we establish a Lévy-Khintchine type formula which permits to characterize the semigroup and the infinitely divisible probabilities associated with this dual convolution, finally we prove a central limit theorem.  相似文献   
8.
Let μ be a measure in a Banach spaceE, f be an even function onR. We consider the potentialg(a)=f E f(‖x?a‖)dμ(x). The question is as follows: For whichf does the potentialg determine μ uniquely? In this article we give answers in the cases whereE=l n and wheref(t)=|t| p andE is a finite dimensional Banach space with symmetric analytic norm. Calculating the Fourier transform of the functionf(‖x‖ ) we give a new proof of the J. Misiewicz's result that the functionf(‖x‖ ) is positive definite only iff is a constant function.  相似文献   
9.
Transformation of impedance spectra into relaxation time spectra (RTS) is used for determining contributions of individual processes of the oxygen electroreduction reaction (OER) to the polarization resistance of the electrochemical cell. The transformation technique involves the solution of the convolution equation found with the aid of a modified Van Cittert iteration algorithm checked on model impedance spectra. The technique, when used to analyze impedance spectra of electrochemical cells air|Pt|YSZ|YSZ + Pt|air, shows that the conversion of a globular structure of the YSZ + Pt cermet layer to a columnar one is accompanied by a change of peak amplitudes in RTS. The revealed RTS dynamics when heated to 750°C is compared with peculiarities of individual processes in OER.  相似文献   
10.
二阶导数卷积伏安法应用于水稻中痛量雌雄激素的检测,具有快速,灵敏,干扰少的特点。本文以光周期敏感核不育水稻农垦58S为材料,以农垦58作对照,了叶焉和穗中雌,雄性激素的含量,研究了不同光周期条件下两类激素的变化。  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