全文获取类型
收费全文 | 5051篇 |
免费 | 619篇 |
国内免费 | 356篇 |
专业分类
化学 | 792篇 |
晶体学 | 23篇 |
力学 | 684篇 |
综合类 | 66篇 |
数学 | 2594篇 |
物理学 | 1867篇 |
出版年
2024年 | 5篇 |
2023年 | 49篇 |
2022年 | 73篇 |
2021年 | 123篇 |
2020年 | 117篇 |
2019年 | 127篇 |
2018年 | 101篇 |
2017年 | 162篇 |
2016年 | 194篇 |
2015年 | 127篇 |
2014年 | 270篇 |
2013年 | 372篇 |
2012年 | 262篇 |
2011年 | 299篇 |
2010年 | 296篇 |
2009年 | 290篇 |
2008年 | 315篇 |
2007年 | 356篇 |
2006年 | 280篇 |
2005年 | 241篇 |
2004年 | 262篇 |
2003年 | 225篇 |
2002年 | 177篇 |
2001年 | 150篇 |
2000年 | 139篇 |
1999年 | 144篇 |
1998年 | 106篇 |
1997年 | 100篇 |
1996年 | 79篇 |
1995年 | 96篇 |
1994年 | 70篇 |
1993年 | 54篇 |
1992年 | 49篇 |
1991年 | 40篇 |
1990年 | 32篇 |
1989年 | 28篇 |
1988年 | 32篇 |
1987年 | 29篇 |
1986年 | 13篇 |
1985年 | 25篇 |
1984年 | 17篇 |
1983年 | 16篇 |
1982年 | 9篇 |
1981年 | 14篇 |
1980年 | 12篇 |
1979年 | 10篇 |
1978年 | 7篇 |
1977年 | 10篇 |
1976年 | 7篇 |
1975年 | 4篇 |
排序方式: 共有6026条查询结果,搜索用时 15 毫秒
81.
82.
Quantization consists in studying the L
r
-error induced by the approximation of a random vector X by a vector (quantized version) taking a finite number n of values. We investigate this problem for Gaussian random vectors in an infinite dimensional Banach space and in particular, for Gaussian processes. A precise link proved by Fehringer(4) and Dereich et al.
(3) relates lower and upper bounds for small ball probabilities with upper and lower bounds for the quantization error, respectively. We establish a complete relationship by showing that the same holds for the direction from the quantization error to small ball probabilities. This allows us to compute the exact rate of convergence to zero of the minimal L
r
-quantization error from logarithmic small ball asymptotics and vice versa. 相似文献
83.
This paper is concerned with processes which are max-plus counterparts of
Markov diffusion processes governed by Ito sense stochastic differential
equations. Concepts of max-plus martingale and max-plus stochastic differential
equation are introduced. The max-plus counterparts of backward and forward
PDEs for Markov diffusions turn out to be first-order PDEs of
Hamilton–Jacobi–Bellman type. Max-plus additive integrals and a max-plus
additive dynamic programming principle are considered. This leads to
variational inequalities of Hamilton–Jacobi–Bellman type. 相似文献
84.
本文介绍概率抽样法在钢球生产过程中的应用,通过此法确定钢球生产中各工序质量监测的最佳抽检方案,以确保产品被接受的概率最大。 相似文献
85.
The determination of the sensitivity of the acoustical characteristics of vibrating systems with respect to the variation of the design parameters predicting these characteristics is a necessary and important step of the acoustic design and optimization process. Acoustic design sensitivity analysis includes the computation and evaluation of the sensitivity information required for this procedure. In this study, a boundary element code performing the sensitivity analysis of the acoustic pressure by using the matrix sensitivities with respect to different design variables has been developed. The effect of the precision of boundary element discretization on the acoustic pressure sensitivity is examined via this code. The formulation is applied to a multi-source system and the dimension sensitivity analysis of near field pressures of two-dilating-spherical source is performed. The last application is devoted to a real sound source: a washing machine sitting on the floor. Sensitivity of the field pressures to the machine’s dimensions (size), surface velocity and frequency is examined on the bases of the boundary element model of the machine and half-space condition. The impacts of these variables are compared; and a limiting speed for the machine responding both the acoustical and operational requirements is determined. 相似文献
86.
Petr Lachout 《Acta Appl Math》2003,78(1-3):243-250
The paper introduces an extension of the epi-convergence, the lower semicontinuous approximation and the epi-upper semicontinuous approximation of random real functions in distribution. The new notions could be helpful tools for sensitivity analyzes of stochastic optimization problems. The research is evoked by S. Vogel and continues the research started by Vogel and the author. 相似文献
87.
基于错误概率达到最小的原则,该文在罐子模型序贯试验中构造了一种渐近最优设计。在这种设计下,不仅能使病员以较多机会分配到较好的处理,而且能使估计量的统计效率在一定意义下达到最优。 相似文献
88.
89.
Influence of relaxation effects on probabilities of the 2s2p35S2-2s22p2 3P1,2 intercombination transitions in NII 下载免费PDF全文
Transition probabilities of the 2s2p^3 {}^5S_2-2s^22p^2 {}^3P_{1,2} intercombination transitions in NII have been calculated by using a large-scale multiconfiguration Dirac-Fock method. In the calculation the most important effects of relativity, correlation, and relaxation are considered. From the calculated transition probabilities, the lifetime of the 2s2p^3 {}^5S_2 metastable state is derived. The result is in excellent agreement with the latest experimental result. In the meantime the influence of anomalously strong relaxation effects on probabilities of the 2s2p^3 {}^5S_2-2s^22p^2 {}^3P_{1,2} lines in NII have been found. 相似文献
90.
Su-Yun Huang Chuhsing Kate Hsiao Ching-Wei Chang 《Annals of the Institute of Statistical Mathematics》2003,55(3):655-670
The article provides a refinement for the volume-corrected Laplace-Metropolis estimator of the marginal likelihood of DiCiccioet al. The correction volume of probability α in DiCiccioet al. is fixed and suggested to take the value α=0.05. In this article α is selected based on an asymptotic analysis to minimize
the mean square relative error (MSRE). This optimal choice of α is shown to be invariant under linear transformations. The
invariance property leads to easy implementation for multivariate problems. An implementation procedure is provided for practical
use. A simulation study and a real data example are presented. 相似文献