全文获取类型
收费全文 | 14048篇 |
免费 | 2320篇 |
国内免费 | 934篇 |
专业分类
化学 | 3064篇 |
晶体学 | 112篇 |
力学 | 2369篇 |
综合类 | 285篇 |
数学 | 6051篇 |
物理学 | 5421篇 |
出版年
2024年 | 32篇 |
2023年 | 188篇 |
2022年 | 338篇 |
2021年 | 359篇 |
2020年 | 348篇 |
2019年 | 320篇 |
2018年 | 338篇 |
2017年 | 586篇 |
2016年 | 661篇 |
2015年 | 580篇 |
2014年 | 748篇 |
2013年 | 1136篇 |
2012年 | 782篇 |
2011年 | 839篇 |
2010年 | 712篇 |
2009年 | 851篇 |
2008年 | 862篇 |
2007年 | 901篇 |
2006年 | 727篇 |
2005年 | 566篇 |
2004年 | 590篇 |
2003年 | 611篇 |
2002年 | 517篇 |
2001年 | 395篇 |
2000年 | 422篇 |
1999年 | 404篇 |
1998年 | 344篇 |
1997年 | 238篇 |
1996年 | 248篇 |
1995年 | 217篇 |
1994年 | 187篇 |
1993年 | 148篇 |
1992年 | 114篇 |
1991年 | 115篇 |
1990年 | 101篇 |
1989年 | 75篇 |
1988年 | 82篇 |
1987年 | 66篇 |
1986年 | 51篇 |
1985年 | 79篇 |
1984年 | 47篇 |
1983年 | 32篇 |
1982年 | 45篇 |
1981年 | 32篇 |
1980年 | 52篇 |
1979年 | 53篇 |
1978年 | 31篇 |
1977年 | 40篇 |
1976年 | 43篇 |
1974年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Mathematical Notes - 相似文献
102.
Decentralized iterative learning control for a class of large scale interconnected dynamical systems
Hansheng Wu 《Journal of Mathematical Analysis and Applications》2007,327(1):233-245
The problem of decentralized iterative learning control for a class of large scale interconnected dynamical systems is considered. In this paper, it is assumed that the considered large scale dynamical systems are linear time-varying, and the interconnections between each subsystem are unknown. For such a class of uncertain large scale interconnected dynamical systems, a method is presented whereby a class of decentralized local iterative learning control schemes is constructed. It is also shown that under some given conditions, the constructed decentralized local iterative learning controllers can guarantee the asymptotic convergence of the local output error between the given desired local output and the actual local output of each subsystem through the iterative learning process. Finally, as a numerical example, the system coupled by two inverted pendulums is given to illustrate the application of the proposed decentralized iterative learning control schemes. 相似文献
103.
René Meziat Diego Patiño Pablo Pedregal 《Computational Optimization and Applications》2007,38(1):147-171
We propose an alternative method for computing effectively the solution of non-linear, fixed-terminal-time, optimal control
problems when they are given in Lagrange, Bolza or Mayer forms. This method works well when the nonlinearities in the control
variable can be expressed as polynomials. The essential of this proposal is the transformation of a non-linear, non-convex
optimal control problem into an equivalent optimal control problem with linear and convex structure. The method is based on
global optimization of polynomials by the method of moments. With this method we can determine either the existence or lacking
of minimizers. In addition, we can calculate generalized solutions when the original problem lacks of minimizers. We also
present the numerical schemes to solve several examples arising in science and technology. 相似文献
104.
An effect of Berry’s phase on the NQR spectrum of the rotating powder sample is described and applied for the determination of the electric field gradient asymmetry. The proposed method involves the analysis of the frequency singularities in the NQR powder patterns of the rotating samples. The Berry’s phases for the eigenstates, associated with an adiabatically changing quadrupole hamiltonian, are calculated for nuclei with a spin I = 3/2 and I = 1 as a function of the asymmetry parameter. 相似文献
105.
Rolando Cavazos-Cadena 《Annals of Operations Research》1991,28(1):169-184
We consider a class of Markov decision processes withfinite state and action spaces which, essentially, is determined by the following condition: The state space isirreducible under the action of any stationary policy. However, except by this restriction, the transition law iscompletely unknown to the controller. In this context, we find a set of policies under which thefrequency estimators of the transition law are strongly consistent and then, this result is applied to constructadaptive asymptotically discount-optimal policies.Dedicated to Professor Truman O. Lewis, on the occasion of his sixtieth birthdayThis research was supported in part by the Third World Academy of Sciences (TWAS) under Grant TWAS RG MP 898-152, and in part by the Consejo Nacional de Ciencia y Tecnología (CONACYT) under Grant A128CCOEO550 (MT-2). 相似文献
106.
刘继成 《数学物理学报(B辑英文版)》2004,24(2)
Let X be a two parameter smooth semimartingale and (~X) be its process of the product variation. It is proved that (~X) can be approximated as D∞-limit of sums of its discrete product variations as the mesh of division tends to zero. Moreover, this result can be strengthen to yield the quasi sure convergence of sums by estimating the speed of the convergence. 相似文献
107.
108.
HT—6M闭环反馈平衡控制系统 总被引:1,自引:1,他引:0
本文描述HT-6M托卡马克装置闭环反馈平衡控制系统的结构组成,通过对各个环节的简化,得到了有效实用的数学模型,进而分析了系统稳态和动态性能。实验结果表明,该系统运行可靠;并且,将等离子体环水平位移控制在2mm以内。 相似文献
109.
This paper deals with the optimal control of a one-machine two-product manufacturing system with setup changes, operating in a continuous time dynamic environment. The system is deterministic. When production is switched from one product to the other, a known constant setup time and a setup cost are incurred. Each product has specified constant processing time and constant demand rate, as well as an infinite supply of raw material. The problem is formulated as a feedback control problem. The objective is to minimize the total backlog, inventory and setup costs incurred over a finite horizon. The optimal solution provides the optimal production rate and setup switching epochs as a function of the state of the system (backlog and inventory levels). For the steady state, the optimal cyclic schedule is determined. To solve the transient case, the system's state space is partitioned into mutually exclusive regions such that with each region, the optimal control policy is determined analytically. 相似文献
110.
壳模型计算表明,1/2+[411]出现于157Tm核的基态可能是由非轴对称形变造成的.但是新近从157Yb衰变纲图给出的157Tm低激发谱中,指认了一个建立在1/2+[411]带头上的基态转动带,并认为该带的性质是轴对称的,提取了该带的惯性参数与脱耦合参数.通过对奇ATm核1/2+[411]转动带的系统分析,强调了在157Tm核中非轴对称γ自由度效应的重要性. 相似文献