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   1192篇
  免费   100篇
  国内免费   50篇
化学   120篇
晶体学   1篇
力学   68篇
综合类   7篇
数学   471篇
物理学   675篇
  2024年   3篇
  2023年   30篇
  2022年   31篇
  2021年   21篇
  2020年   38篇
  2019年   25篇
  2018年   16篇
  2017年   33篇
  2016年   31篇
  2015年   42篇
  2014年   73篇
  2013年   108篇
  2012年   65篇
  2011年   81篇
  2010年   83篇
  2009年   87篇
  2008年   77篇
  2007年   92篇
  2006年   68篇
  2005年   51篇
  2004年   46篇
  2003年   32篇
  2002年   30篇
  2001年   19篇
  2000年   24篇
  1999年   21篇
  1998年   23篇
  1997年   24篇
  1996年   15篇
  1995年   8篇
  1994年   8篇
  1993年   5篇
  1992年   3篇
  1991年   4篇
  1990年   2篇
  1989年   4篇
  1988年   4篇
  1987年   3篇
  1986年   1篇
  1985年   2篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1979年   3篇
  1978年   1篇
  1977年   1篇
排序方式: 共有1342条查询结果,搜索用时 0 毫秒
161.
An investigation of BELENE Nuclear Power Plant (NPP) free field signal is presented in the current study. An SH wave propagation trough multilayer geological media in the region is considered. An original structural model of the geological column has been developed. The investigated layers are isotropic, with constant depth and skyline parallel. The SH rays are with an arbitrary angle as far as the layers are concerned. The seismic SH waves have been generated by a special detonation device. The main results of the study are graphically illustrated. A comparison between the original BELENE NPP experimental and the numerical surface (free field) signals (obtained by the formulated direct problem) for the investigated geological column has been carried out and its results are hereby shown.  相似文献   
162.
In this paper, we first discuss the origin of preferential attachment. Then we establish the generalized preferential attachment (GPA) which has two new properties; first, it encapsulates both the topological and weight aspects of a network, which makes it is neither entirely degree preferential nor entirely weight preferential. Second, it can tell us not only the chance that each already-existing vertex being connected but also how much weight each new edge has. The GPA can generate four power-law distributions, besides the three for vertex degrees, vertex strengths, and edge weights, it yields a new power-law distribution for the subgraph degrees.  相似文献   
163.
The distribution of patients’ lengths of stay in English hospitals is measured by using routinely collected data from 11 years. It is found to be well approximated by a power law distribution spanning over more than three decades. To explain this observation, a theoretical resource allocation model is presented. It is based on iterative long-term scheduling of hospital beds, and its main assumption is that future beds are allocated preferentially. This represents a situation where different parts of the health care system compete for resources, with bargaining powers proportional to current resource levels.  相似文献   
164.
In this paper we provide a systematic study of how the probability limit and central limit theorem for realised multipower variation changes when we add finite activity and infinite activity jump processes to an underlying Brownian semimartingale.  相似文献   
165.
Advection and dispersion in time and space   总被引:2,自引:0,他引:2  
B. Baeumer  D.A. Benson  M.M. Meerschaert   《Physica A》2005,350(2-4):245-262
Previous work showed how moving particles that rest along their trajectory lead to time-nonlocal advection–dispersion equations. If the waiting times have infinite mean, the model equation contains a fractional time derivative of order between 0 and 1. In this article, we develop a new advection–dispersion equation with an additional fractional time derivative of order between 1 and 2. Solutions to the equation are obtained by subordination. The form of the time derivative is related to the probability distribution of particle waiting times and the subordinator is given as the first passage time density of the waiting time process which is computed explicitly.  相似文献   
166.
龙永红  陈培德 《数学学报》2003,46(5):851-856
本文给出两指标点过程的跳线刻划、停止方法,论述了跳线的可测性及点过程有关的σ-域的结构和特征。  相似文献   
167.
设s(c)为双纽线|W2+c|=1的弧长,c∈「0,+∞).该文讨论了s(c)的性质,并在n=2的情况下解决了Erdos,Herzog和Piranian提出的一个猜测。  相似文献   
168.
In this paper, we present a power penalty function approach to the linear complementarity problem arising from pricing American options. The problem is first reformulated as a variational inequality problem; the resulting variational inequality problem is then transformed into a nonlinear parabolic partial differential equation (PDE) by adding a power penalty term. It is shown that the solution to the penalized equation converges to that of the variational inequality problem with an arbitrary order. This arbitrary-order convergence rate allows us to achieve the required accuracy of the solution with a small penalty parameter. A numerical scheme for solving the penalized nonlinear PDE is also proposed. Numerical results are given to illustrate the theoretical findings and to show the effectiveness and usefulness of the method. This work was partially supported by a research grant from the University of Western Australia and the Research Grant Council of Hong Kong, Grants PolyU BQ475 and PolyU BQ493.  相似文献   
169.
This note employs path counting techniques to extend recent results on bounds for odd order linear recurrences to higher dimensions. The results imply optimal zero-free polydisks for multivariable power series with 0, 1 coefficients. Among the applications is a result that states that the optimal zero-free polydisk has radius approximately 1/(v+1), for large dimensions v.  相似文献   
170.
On the Effect of Misspecifying the Density Ratio Model   总被引:1,自引:0,他引:1  
The density ratio model specifies that the log-likelihood ratio of two unknown densities is of known linear form which depends on some finite dimensional parameters. The model can be broadened to allow for m-samples in a quite natural way. Estimation of both parametric and nonparametric part of the model is carried out by the method of empirical likelihood. However the assumed linear form has an impact on the estimation and testing for the parametric part. The goal of this study is to quantify the effect of choosing an incorrect linear form and its impact to inference. The issue of misspecification is addressed by embedding the unknown linear form to some parametric transformation family which yields ultimately to its identification. Simulated examples and data analysis integrate the presentation.  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