全文获取类型
收费全文 | 9205篇 |
免费 | 809篇 |
国内免费 | 342篇 |
专业分类
化学 | 1231篇 |
晶体学 | 51篇 |
力学 | 624篇 |
综合类 | 67篇 |
数学 | 5631篇 |
物理学 | 2752篇 |
出版年
2023年 | 85篇 |
2022年 | 103篇 |
2021年 | 195篇 |
2020年 | 258篇 |
2019年 | 223篇 |
2018年 | 222篇 |
2017年 | 199篇 |
2016年 | 239篇 |
2015年 | 186篇 |
2014年 | 329篇 |
2013年 | 917篇 |
2012年 | 376篇 |
2011年 | 412篇 |
2010年 | 374篇 |
2009年 | 476篇 |
2008年 | 498篇 |
2007年 | 566篇 |
2006年 | 455篇 |
2005年 | 379篇 |
2004年 | 299篇 |
2003年 | 334篇 |
2002年 | 345篇 |
2001年 | 324篇 |
2000年 | 346篇 |
1999年 | 263篇 |
1998年 | 275篇 |
1997年 | 175篇 |
1996年 | 134篇 |
1995年 | 131篇 |
1994年 | 131篇 |
1993年 | 90篇 |
1992年 | 104篇 |
1991年 | 87篇 |
1990年 | 79篇 |
1989年 | 74篇 |
1988年 | 58篇 |
1987年 | 74篇 |
1986年 | 48篇 |
1985年 | 96篇 |
1984年 | 70篇 |
1983年 | 40篇 |
1982年 | 56篇 |
1981年 | 26篇 |
1980年 | 29篇 |
1979年 | 35篇 |
1978年 | 22篇 |
1977年 | 35篇 |
1976年 | 24篇 |
1974年 | 15篇 |
1973年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
The F- F+-photoconversion in oxygen-deficient corundum, induced by 210 nm irradiation at different temperatures, was analyzed. It was shown that the dosimetric trap and known deep trap contribute little to these transformations. The dose dependencies of detectors in initial and sensitized states were studied. The interactive processes between different traps in TLD-500 were examined directly. 相似文献
32.
The control of piecewise-deterministic processes is studied where only local boundedness of the data is assumed. Moreover the discount rate may be zero. The value function is shown to be solution to the Bellman equation in a weak sense; however the solution concept is strong enough to generate optimal policies. Continuity and compactness conditions are given for the existence of nonrelaxed optimal feedback controls. 相似文献
33.
K. Kubilius 《Acta Appl Math》2003,78(1-3):233-242
We consider the integral equation driven by a standard Brownian motion and by a fractional Brownian motion. Sufficient conditions under which the equation has a weak solution are obtained. 相似文献
34.
35.
36.
37.
A. Debussche 《Journal de Mathématiques Pures et Appliquées》1998,77(10):967-988
The notion of random attractor for a dissipative stochastic dynamical system has recently been introduced. It generalizes the concept of global attractor in the deterministic theory. It has been shown that many stochastic dynamical systems associated to a dissipative partial differential equation perturbed by noise do possess a random attractor. In this paper, we prove that, as in the case of the deterministic attractor, the Hausdorff dimension of the random attractor can be estimated by using global Lyapunov exponents. The result is obtained under very natural assumptions. As an application, we consider a stochastic reaction-diffusion equation and show that its random attractor has finite Hausdorff dimension. 相似文献
38.
该文利用算子半群的方法给出了取值于具有左不变度量的完备可分群的齐次Levy过程是复合Poisson过程的弱极限这一结论. 相似文献
39.
集值Lebesgue—Stieltjes积分 总被引:8,自引:2,他引:6
本文首先刻划了B(R_ )上的集值测度,其次建立了(R_ B(R_ ))上的集值Lebesgue-Stieltjes积分.最后,进—步建立了集值随机Lebesgue-Stietjes积分的理论. 相似文献
40.
We develop a production policy that controls work-in-process (WIP) levels and satisfies demand in a multistage manufacturing system with significant uncertainty in yield, rework, and demand. The problem addressed in this paper is more general than those in the literature in three aspects: (i) multiple products are processed at multiple workstations, and the capacity of each workstation is limited and shared by multiple operations; (ii) the behavior of a production policy is investigated over an infinite-time horizon, and thus the system stability can be evaluated; (iii) the representation of yield and rework uncertainty is generalized. Generalizing both the system structure and the nature of uncertainty requires a new mathematical development in the theory of infinite-horizon stochastic dynamic programming. The theoretical contributions of this paper are the existence proofs of the optimal stationary control for a stochastic dynamic programming problem and the finite covariances of WIP and production levels under the general expression of uncertainty. We develop a simple and explicit sufficient condition that guarantees the existence of both the optimal stationary control and the system stability. We describe how a production policy can be constructed for the manufacturing system based on the propositions derived. 相似文献