全文获取类型
收费全文 | 27359篇 |
免费 | 4244篇 |
国内免费 | 2408篇 |
专业分类
化学 | 5736篇 |
晶体学 | 150篇 |
力学 | 3362篇 |
综合类 | 684篇 |
数学 | 14216篇 |
物理学 | 9863篇 |
出版年
2024年 | 37篇 |
2023年 | 279篇 |
2022年 | 421篇 |
2021年 | 629篇 |
2020年 | 724篇 |
2019年 | 694篇 |
2018年 | 669篇 |
2017年 | 987篇 |
2016年 | 1106篇 |
2015年 | 874篇 |
2014年 | 1472篇 |
2013年 | 2014篇 |
2012年 | 1454篇 |
2011年 | 1700篇 |
2010年 | 1518篇 |
2009年 | 1693篇 |
2008年 | 1889篇 |
2007年 | 1953篇 |
2006年 | 1614篇 |
2005年 | 1481篇 |
2004年 | 1375篇 |
2003年 | 1174篇 |
2002年 | 1190篇 |
2001年 | 983篇 |
2000年 | 871篇 |
1999年 | 808篇 |
1998年 | 701篇 |
1997年 | 617篇 |
1996年 | 501篇 |
1995年 | 461篇 |
1994年 | 311篇 |
1993年 | 273篇 |
1992年 | 204篇 |
1991年 | 241篇 |
1990年 | 153篇 |
1989年 | 115篇 |
1988年 | 140篇 |
1987年 | 100篇 |
1986年 | 79篇 |
1985年 | 92篇 |
1984年 | 76篇 |
1983年 | 46篇 |
1982年 | 50篇 |
1981年 | 50篇 |
1980年 | 38篇 |
1979年 | 44篇 |
1978年 | 29篇 |
1977年 | 16篇 |
1976年 | 15篇 |
1973年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
71.
R. S. Martynov Yu. M. Nechepurenko 《Computational Mathematics and Mathematical Physics》2006,46(7):1155-1167
For a discrete linear stochastic dynamical system, computation of the response matrix to the external action from a subspace using given observational data is examined. An algorithm is proposed and substantiated that makes it possible to improve the numerical accuracy and to reduce the amount of observational data compared to the general case where an arbitrary external action is allowed. As an illustration, a discrete system arising in the analysis of a linear stochastic dynamical continuous-time system is considered more thoroughly. Some numerical results are presented. 相似文献
72.
P. E. Cladis 《Journal of statistical physics》1991,62(5-6):899-925
We first discuss nonlinear aspects of phase transition theory applied to a particular liquid crystal phase transition. A simple derivation is given to show how two coupled Goldstone modes (one appearing as gauge fluctuations of the ordered phase) can force a phase transition, against all expectations, to take place discontinuously (theory of Halperin, Lubensky, and Ma)-but the discontinuity may be immeasurably small. Then, we describe a new dynamical test of phase transition order, developed by Cladiset al., that turns out to be more sensitive than x-ray diffraction and adiabatic calorimetry. Quantitative data found by this new method are in excellent agreement with the measurements of adiabatic calorimetry and x-ray diffraction as well as expectations implicit in the predictions of HLM.This is the text of an after-banquet talk given at the CNLS Workshop on the Dynamics of Concentrated Systems. 相似文献
73.
Harel and Puri (1989, J. Multivariate Anal. 29) studied the asymptotic behavior of the U-statistic and the one-sample rank order statistic for nonstationary absolutely regular processes. In this note, we present some applications of these results for Markov processes as well as ARMA processes. 相似文献
74.
Thierry de la Rue 《Bulletin of the Brazilian Mathematical Society》2006,37(4):503-521
V.A. Rohlin asked in 1949 whether 2-fold mixing implies 3-fold mixing for a stationary process (ξi )i2ℤ, and the question remains open today. In 1978, F. Ledrappier exhibited a counterexample to the 2-fold mixing implies 3-fold
mixing problem, the socalled 3-dot system, but in the context of stationary random fields indexed by ℤ2.
In this work, we first present an attempt to adapt Ledrappier's construction to the onedimensional case, which finally leads
to a stationary process which is 2-fold but not 3-fold mixing conditionally to the σ-algebra generated by some factor process. Then, using arguments coming from the theory of joinings, we will give some strong obstacles proving that Ledrappier's counterexample
can not be fully adapted to one-dimensional stationary processes. 相似文献
75.
76.
77.
基于校园网的实验管理系统的设计 总被引:2,自引:1,他引:1
主要讨论了应用实验室管理系统的必要性,并从用户需求分析、系统总体设计、功能模块的设计等方面对B/S实验室管理系统的开发进行了详细的阐述。 相似文献
78.
本文对系统dxdt=-y(1-ax2n)(1-bx2n) δx-lx4n 1dydt=x2n-1(1-cx2n)(1-bx2n)进行定性分析,得出其极限环的存在性,不存在性及唯一性的一系列充分条件. 相似文献
79.
ON THE UNIQUENESS OF THE WEAK SOLUTIONS OF A QUASILINEAR HYPERBOLIC SYSTEM WITH A SINGULAR SOURCE TERM 下载免费PDF全文
This paper is a continuation of the authors'previous paper[1].In this paper the authorsprove,assuming additional conditions on the initial data,some results about the existence anduniqueness of the entropy weak solutions of the Cauchy problem for the singular hyperbolicsystem a_t+(au)_x_2au/x=0,u_t+1/2(a~2+u~2)_x=0,x>0,t≥0. 相似文献
80.
本文给出Riccati方程及另外一类具有代表性微分方程的亚纯解(n,1)级的上界估计,在一定条件下确立了文[2]中的猜测的正确性。 相似文献