全文获取类型
收费全文 | 8692篇 |
免费 | 1071篇 |
国内免费 | 592篇 |
专业分类
化学 | 821篇 |
晶体学 | 23篇 |
力学 | 847篇 |
综合类 | 178篇 |
数学 | 6391篇 |
物理学 | 2095篇 |
出版年
2024年 | 13篇 |
2023年 | 86篇 |
2022年 | 119篇 |
2021年 | 242篇 |
2020年 | 217篇 |
2019年 | 217篇 |
2018年 | 218篇 |
2017年 | 328篇 |
2016年 | 297篇 |
2015年 | 218篇 |
2014年 | 436篇 |
2013年 | 785篇 |
2012年 | 365篇 |
2011年 | 412篇 |
2010年 | 410篇 |
2009年 | 509篇 |
2008年 | 523篇 |
2007年 | 530篇 |
2006年 | 465篇 |
2005年 | 477篇 |
2004年 | 346篇 |
2003年 | 318篇 |
2002年 | 336篇 |
2001年 | 309篇 |
2000年 | 283篇 |
1999年 | 249篇 |
1998年 | 230篇 |
1997年 | 205篇 |
1996年 | 163篇 |
1995年 | 139篇 |
1994年 | 128篇 |
1993年 | 81篇 |
1992年 | 66篇 |
1991年 | 65篇 |
1990年 | 66篇 |
1989年 | 46篇 |
1988年 | 39篇 |
1987年 | 46篇 |
1986年 | 35篇 |
1985年 | 69篇 |
1984年 | 39篇 |
1983年 | 24篇 |
1982年 | 34篇 |
1981年 | 25篇 |
1980年 | 26篇 |
1979年 | 34篇 |
1978年 | 25篇 |
1977年 | 9篇 |
1976年 | 12篇 |
1974年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
ZHANG Shibin ZHANG Xinsheng & SUN Shuguang School of Management Fudan University Shanghai China Department of Mathematics Shanghai Maritime University Shanghai China 《中国科学A辑(英文版)》2006,49(9):1231-1257
The stationary Gamma-OU processes are recommended to be the volatility of the financial assets. A parametric estimation for the Gamma-OU processes based on the discrete observations is considered in this paper. The estimator of an intensity parameter A and its convergence result are given, and the simulations show that the estimation is quite accurate. Assuming that the parameter A is estimated, the maximum likelihood estimation of shape parameter c and scale parameter a, whose likelihood function is not explicitly computable, is considered. By means of the Gaver-Stehfest algorithm, we construct an explicit sequence of approximations to the likelihood function and show that it converges the true (but unkown) one. Maximizing the sequence results in an estimator that converges to the true maximum likelihood estimator and the approximation shares the asymptotic properties of the true maximum likelihood estimator. Some simulation experiments reveal that this method is still quite accurate in most of rational situations for the background of volatility. 相似文献
12.
Kasper K. Berthelsen Jesper Møller 《Bulletin of the Brazilian Mathematical Society》2002,33(3):351-367
This primer provides a self-contained exposition of the case where spatial birth-and-death processes are used for perfect
simulation of locally stable point processes. Particularly, a simple dominating coupling from the past (CFTP) algorithm and
the CFTP algorithms introduced in [13], [14], and [5] are studied. Some empirical results for the algorithms are discussed.
Received: 30 June 2002 相似文献
13.
随着图像系统的广泛应用,对图像的稳定要求也越来越高。图像的运动和不稳定是常见的,往往是由于载体的运动引起的,为了达到图像稳定的目的,就需要对其运动进行描述,然后采用相应的算法进行补偿。给出了运动对图像清晰度的影响及像偏移的估算,并对数字电子图像稳定系统进行了简单阐述。 相似文献
14.
15.
文贤章 《高校应用数学学报(A辑)》2002,17(3):291-302
利用最大值原理结合上、下解的方法,讨论了一类具有扩散的竞争-捕食的Lotka-Volterra系统静态解的存在性与持续生存。 相似文献
16.
An admissible minimax estimator of a bounded scale-parameter in a subclass of the exponential family under scale-invariant squared-error loss 总被引:3,自引:0,他引:3
Mohammad Jafari Jozani Nader Nematollahi Khalil Shafie 《Statistics & probability letters》2002,60(4):437-444
A subclass of the scale-parameter exponential family is considered and for the rth power of the scale parameter, which is lower bounded, an admissible minimax estimator under scale-invariant squared-error loss is presented. Also, an admissible minimax estimator of a lower-bounded parameter in the family of transformed chi-square distributions is given. These estimators are the pointwise limits of a sequence of Bayes estimators. Some examples are given. 相似文献
17.
We consider Markov processes built from pasting together pieces of strong Markov processes which are killed at a position
dependent rate and connected via a transition kernel. We give necessary and sufficient conditions for local absolute continuity
of probability laws for such processes on a suitable path space and derive an explicit formula for the corresponding likelihood
ratio process. The main tool is the consideration of the process between successive jumps – what we call ‘elementary experiments’
– and criteria for absolute continuity of laws of the process there. We apply our results to systems of branching diffusions
with interactions and immigrations.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
18.
Fillmore在[1]中得到一个定理:设A,T是Banach空间X上的线性变换,A有界,若Lat(A) Lat(T)且AT=TA,则T是A的多项式.在本文里,以此作为引理,讨论了Banach空间上可逆线性变换A在什么情况下,A-1可表示为A的多项式.本文最主要的结论是定理3.4:设X是Banach空间,A是X上的有界线性变换,且可逆,则A-1是A的多项式当且仅当A-1是A的局部多项式. 相似文献
19.
Statistical Inference with Fractional Brownian Motion 总被引:3,自引:1,他引:2
Kukush Alexander Mishura Yulia Valkeila Esko 《Statistical Inference for Stochastic Processes》2005,8(1):71-93
We give a test between two complex hypothesis; namely we test whether a fractional Brownian motion (fBm) has a linear trend against a certain non-linear trend. We study some related questions, like goodness-of-fit test and volatility estimation in these models. 相似文献
20.
Within the framework of a piecewise homogeneous body model, with the use of three-dimensional geometrically nonlinear exact equations of elasticity theory, a method for determining the stress—strain state in unidirectional fibrous composites with locally curved fibers is developed for the case where the interaction between the fibers is neglected. All the investigations are carried out for an infinite elastic body containing a single locally curved fiber. Numerical results illustrating the effect of geometrical nonlinearity on the distribution of the self-balanced normal and shear stresses acting on the interface and arising as a result of local curving of the fiber are presented.__________Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 41, No. 4, pp. 433–448, July–August, 2005. 相似文献