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   3046篇
  免费   489篇
  国内免费   153篇
化学   338篇
晶体学   37篇
力学   834篇
综合类   55篇
数学   1541篇
物理学   883篇
  2025年   23篇
  2024年   54篇
  2023年   58篇
  2022年   52篇
  2021年   54篇
  2020年   84篇
  2019年   103篇
  2018年   112篇
  2017年   102篇
  2016年   111篇
  2015年   94篇
  2014年   133篇
  2013年   236篇
  2012年   128篇
  2011年   152篇
  2010年   100篇
  2009年   117篇
  2008年   160篇
  2007年   196篇
  2006年   171篇
  2005年   150篇
  2004年   123篇
  2003年   129篇
  2002年   126篇
  2001年   114篇
  2000年   121篇
  1999年   118篇
  1998年   86篇
  1997年   49篇
  1996年   58篇
  1995年   61篇
  1994年   65篇
  1993年   36篇
  1992年   27篇
  1991年   43篇
  1990年   23篇
  1989年   18篇
  1988年   15篇
  1987年   13篇
  1986年   11篇
  1985年   13篇
  1984年   6篇
  1983年   5篇
  1982年   5篇
  1981年   6篇
  1979年   3篇
  1978年   6篇
  1977年   3篇
  1976年   8篇
  1975年   2篇
排序方式: 共有3688条查询结果,搜索用时 0 毫秒
1.
Let(X i ) be a martingale difference sequence. LetY be a standard normal random variable. We investigate the rate of uniform convergence
  相似文献   
2.
Densities and viscosities of the binary mixtures of propylene carbonate with benzene, 1,4-dimethylbenzene and ethylbenzene were measured over the entire mole fraction range at 288.15, 298.15 and 308.15?K. Using the experimental values of densities and viscosities the excess molar volumes and viscosity deviations were calculated. The results were fitted by Redlich–Kister equation. The results were discussed in terms of intermolecular interactions.  相似文献   
3.
多孔径扫描波面恢复技术的精度评定及影响因素   总被引:7,自引:2,他引:7  
程维明  林有略 《光学学报》1993,13(8):11-716
多孔径扫描波面恢复技术是一项新的高精度大孔径面形检测手段.本文从建立波面恢复精度的评价标准出发,结合实测结果进行讨论,并对影响精度的两个重要因素即拼接模式及拼接区大小进行分析.  相似文献   
4.
We continue our study of the exponential law for occurrences and returns of patterns in the context of Gibbsian random fields. For the low-temperature plus-phase of the Ising model, we prove exponential laws with error bounds for occurrence, return, waiting and matching times. Moreover we obtain a Poisson law for the number of occurrences of large cylindrical events and a Gumbel law for the maximal overlap between two independent copies. As a by-product, we derive precise fluctuation results for the logarithm of waiting and return times. The main technical tool we use, in order to control mixing, is disagreement percolation  相似文献   
5.
We consider the propagation of a combustion front resulting from the gasless combustion of a condensed state fuel. The propagation of the front, essentially a premixed laminar flame, is supported by an exothermic reaction subject to possible heat loss through a competitive endothermic reaction. The dynamics of the endothermic process inducing the heat loss strongly depend on the temperature and the local fuel concentration. Through an analysis based on high activation energy, the steady-state values of the final burnt temperature as well as the burning velocity are obtained, and the control parameters are identified. Using a linear perturbation method, we assess the stability of the propagating front and obtain a condition for oscillatory behaviour. The critical parameter values for the transition from steady to oscillatory burning speeds are identified. The results represent a generalization of those obtained by Matkowsky and Sivashinsky to include the effects of heat loss induced by a competitive endothermic reaction.  相似文献   
6.
We consider a general system of n noninteracting identical particles which evolve under a given dynamical law and whose initial microstates are a priori independent. The time evolution of the n-particle average of a bounded function on the particle microstates is then examined in the large-n limit. Using the theory of large deviations, we show that if the initial macroscopic average is constrained to be near a given value, y, then the macroscopic average at time t converges in probability as n to a value t(y) given explicitly in terms of a canonical expectation. Some general features of the graph of t(y) versus t are examined, particularly in regard to continuity, symmetry, and convergence.  相似文献   
7.
8.
An anisotropic triangular Ising model in which the first- and second-order parameters and the field parameters are functionally related is solved exactly by representing the distribution of the atom patterns in terms of a suitably constructed Markov process. The probabilities of patterns, defined as the probabilities generated by this process, are a mathematically tractable alternative to the classical representation of these probabilities in terms of the partition function. The interaction and field parameters of this Ising model, its magnetization, free energy, and its nearest neighbor correlation functions, are expressed in terms of the parameters of this Markov process. Special cases are worked out in detail and numerical examples are given.  相似文献   
9.
本文对id多指标随机变量序列{Xk;k∈Nd}(d≥2)的部分和Sn=∑k≤nXk及H(t)↑+∞,(t→+∞),提出并讨论了Порохоров的3个问题(d≥2),并讨论了多指标随机变量和的完全收敛性.  相似文献   
10.
Consider a regular diffusion process X with finite speed measure m. Denote the normalized speed measure by μ. We prove that the uniform law of large numbers holds if the class has an envelope function that is μ-integrable, or if is bounded in L p(μ) for some p>1. In contrast with uniform laws of large numbers for i.i.d. random variables, we do not need conditions on the ‘size’ of the class in terms of bracketing or covering numbers. The result is a consequence of a number of asymptotic properties of diffusion local time that we derive. We apply our abstract results to improve consistency results for the local time estimator (LTE) and to prove consistency for a class of simple M-estimators. This revised version was published online in June 2006 with corrections to the Cover Date.  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