全文获取类型
收费全文 | 9730篇 |
免费 | 1181篇 |
国内免费 | 461篇 |
专业分类
化学 | 879篇 |
晶体学 | 17篇 |
力学 | 1078篇 |
综合类 | 343篇 |
数学 | 6202篇 |
物理学 | 2853篇 |
出版年
2024年 | 21篇 |
2023年 | 94篇 |
2022年 | 297篇 |
2021年 | 286篇 |
2020年 | 205篇 |
2019年 | 227篇 |
2018年 | 249篇 |
2017年 | 363篇 |
2016年 | 458篇 |
2015年 | 305篇 |
2014年 | 571篇 |
2013年 | 667篇 |
2012年 | 513篇 |
2011年 | 579篇 |
2010年 | 466篇 |
2009年 | 615篇 |
2008年 | 630篇 |
2007年 | 639篇 |
2006年 | 517篇 |
2005年 | 473篇 |
2004年 | 415篇 |
2003年 | 372篇 |
2002年 | 331篇 |
2001年 | 284篇 |
2000年 | 247篇 |
1999年 | 222篇 |
1998年 | 211篇 |
1997年 | 183篇 |
1996年 | 152篇 |
1995年 | 118篇 |
1994年 | 80篇 |
1993年 | 94篇 |
1992年 | 82篇 |
1991年 | 49篇 |
1990年 | 49篇 |
1989年 | 35篇 |
1988年 | 33篇 |
1987年 | 30篇 |
1986年 | 33篇 |
1985年 | 38篇 |
1984年 | 33篇 |
1983年 | 14篇 |
1982年 | 21篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1979年 | 10篇 |
1978年 | 9篇 |
1977年 | 9篇 |
1976年 | 9篇 |
1959年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 593 毫秒
131.
The presented work offers new algorithms for phase evaluation in interferometric measurements. Several phase-shifting algorithms with an arbitrary but constant phase-shift between captured intensity frames are proposed. These phase calculation algorithms need to measure five frames of the intensity of the interference field. The algorithms are similarly derived as so called Carré algorithm. The phase evaluation process then does not depend on the linear phase shift errors. Furthermore, the detailed analysis of the algorithms with respect to most important factors, which affect interferometric measurements, is carried out. It is also studied the dependency of the evaluation algorithms on the phase shift values, and the proposed phase calculation algorithms are compared with respect to the resulting phase errors. The influence of most important factors in the measurement and evaluation process was simulated as systematic and random errors using a proposed mathematical model. 相似文献
132.
133.
Huang H. X. Liang Z. A. Pardalos P. M. 《Journal of Optimization Theory and Applications》2004,120(1):53-71
A flow search approach is presented in this paper. In the approach, each iterative process involves a subproblem, whose variables are the stepsize parameters. Every feasible solution of the subproblem corresponds to some serial search stages, the stepsize parameters in different search stages may interact mutually, and their optimal values are determined by evaluating the total effect of the interaction. The main idea of the flow search approach is illustrated via the minimization of a convex quadratic function. Based on the flow search approach, some properties of the m-step linear conjugate gradient algorithm are analyzed and new bounds on its convergence rate are also presented. Theoretical and numerical results indicate that the new bounds are better than the well-known ones. 相似文献
134.
Hiroshi Sakamoto 《Journal of Discrete Algorithms》2005,3(2-4):416-430
A linear-time approximation algorithm for the grammar-based compression is presented. This is an optimization problem to minimize the size of a context-free grammar deriving a given string. For each string of length n, the algorithm guarantees approximation ratio without suffix tree construction. 相似文献
135.
本在Glover—Klingman算法及最小费用支撑树对策的基础上,讨论了最小费用k度限制树对策问题.利用威胁、旁支付理论制订了两种规则,并利用优超、策略等价理论分别给出了在这两种规则下最小费用k度限制树对策核心中的解,从而证明了在这两种规则下其核心非空. 相似文献
136.
The authors establish the Hilbertian invariance principle for the empirical process of a stationary Markov process, by extending the forward-backward martingale decomposition of Lyons-Meyer-Zheng to the Hilbert space valued additive functionals associated with general non-reversible Markov processes. 相似文献
137.
138.
SINGLE MACHINE SCHEDULING WITH CONTROLLABLE PROCESSING TIMES AND COMPRESSION COSTS (PART I:EQUAL TIMES AND COSTS) 总被引:1,自引:0,他引:1
Most papers in scheduling research have treated individual job processing times as fixed parameters. However, in many practical situations, a manager may control processing time by realloeating resources. In this paper, authors consider a machine scheduling problemwith controllable processing times. In the first part of this paper, a special case where the pro-cessing times and compression costs are uniform among jobs is discussed. Theoretical results are derived that aid in developing an O(n^2) algorithm to slove the problem optimally. In the second part of this paper, authors generalize the discussion to general case, An effective heuristic to the genera/ problem will be presented. 相似文献
139.
Masakazu Muramatsu 《Mathematical Programming》1998,83(1-3):393-406
In this paper, we introduce an affine scaling algorithm for semidefinite programming (SDP), and give an example of a semidefinite
program such that the affine scaling algorithm converges to a non-optimal point. Both our program and its dual have interior
feasible solutions and unique optimal solutions which satisfy strict complementarity, and they are non-degenerate everywhere. 相似文献
140.
L. Mosher 《Commentarii Mathematici Helvetici》1997,72(1):16-29
The quotient of a biautomatic group by a subgroup of the center is shown to be biautomatic. The main tool used is the Neumann-Shapiro
triangulation of S
n-1, associated to a biautomatic structure on . Among other applications, a question of Gersten and Short is settled by showing that direct factors of biautomatic groups
are biautomatic.
Received: October 4, 1994 相似文献