首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1102篇
  免费   95篇
  国内免费   45篇
化学   116篇
晶体学   1篇
力学   68篇
综合类   7篇
数学   382篇
物理学   668篇
  2024年   1篇
  2023年   30篇
  2022年   28篇
  2021年   22篇
  2020年   36篇
  2019年   24篇
  2018年   15篇
  2017年   31篇
  2016年   32篇
  2015年   43篇
  2014年   70篇
  2013年   91篇
  2012年   63篇
  2011年   79篇
  2010年   79篇
  2009年   78篇
  2008年   70篇
  2007年   81篇
  2006年   66篇
  2005年   46篇
  2004年   45篇
  2003年   30篇
  2002年   27篇
  2001年   16篇
  2000年   22篇
  1999年   22篇
  1998年   22篇
  1997年   18篇
  1996年   14篇
  1995年   4篇
  1994年   6篇
  1993年   5篇
  1992年   3篇
  1991年   4篇
  1990年   1篇
  1989年   4篇
  1988年   4篇
  1987年   2篇
  1986年   2篇
  1985年   1篇
  1984年   1篇
  1979年   2篇
  1978年   1篇
  1977年   1篇
排序方式: 共有1242条查询结果,搜索用时 15 毫秒
101.
In this paper, we present a power penalty function approach to the linear complementarity problem arising from pricing American options. The problem is first reformulated as a variational inequality problem; the resulting variational inequality problem is then transformed into a nonlinear parabolic partial differential equation (PDE) by adding a power penalty term. It is shown that the solution to the penalized equation converges to that of the variational inequality problem with an arbitrary order. This arbitrary-order convergence rate allows us to achieve the required accuracy of the solution with a small penalty parameter. A numerical scheme for solving the penalized nonlinear PDE is also proposed. Numerical results are given to illustrate the theoretical findings and to show the effectiveness and usefulness of the method. This work was partially supported by a research grant from the University of Western Australia and the Research Grant Council of Hong Kong, Grants PolyU BQ475 and PolyU BQ493.  相似文献   
102.
利用PIC (particle-in-cell) 方法,结合实验装置的几何结构和实验结果,采用动态开关模型,对微秒等离子体断路开关和电感负载间的功率流特性进行了研究。模拟得到了与实验结果符合较好的开关电压和负载电流波形,并给出了开关下游出现的稀薄等离子体的密度(约1012 cm-3)和速度(约1 cm/ns), 同时也得到了开关下游的空间电流分布。模拟结果表明,开关下游的结构应避免阻抗突变以减少电流损失,同时提高开关阻抗可有利于提高负载上的最大功率。  相似文献   
103.
糖尿病患者的自我监测是减少由糖尿病引发并发症的重要手段。无创血糖监测的近红外光谱分析方法是最具有应用前景的一种,葡萄糖近红外光谱则是研究无损血糖检测基础。本文通过实验采集了葡萄糖粉末的近红外光谱,并对结果作了详细分析。  相似文献   
104.
机械阻抗测量的一种新方法   总被引:3,自引:0,他引:3       下载免费PDF全文
明瑞森 《应用声学》1997,16(1):13-17,12
本文介绍了一种新的机械阻抗测量方法-声强法,由定义出发将机械阻抗表为功率流和加速度响应谱的函数,应用结构声强技术测量功率流,声强法不需要测量作用力信号,可以用于测量任意结构中的各类机械阻抗,实验结果表明,声强获得的测量值与直接获得的测量值相近,声强法能较准确地测量一维和二维匀质结构中机械阻抗。  相似文献   
105.
设s(c)为双纽线|W2+c|=1的弧长,c∈「0,+∞).该文讨论了s(c)的性质,并在n=2的情况下解决了Erdos,Herzog和Piranian提出的一个猜测。  相似文献   
106.
A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.  相似文献   
107.
Two algorithms for the synthesis of a microwave beam with desired characteristics are discussed. The beam is composed by an array of either identical or non-identical antennas. In an example, the application of those algorithms for wireless power transmission is demonstrated.  相似文献   
108.
In this paper we provide a systematic study of how the probability limit and central limit theorem for realised multipower variation changes when we add finite activity and infinite activity jump processes to an underlying Brownian semimartingale.  相似文献   
109.
Generation scheduling (GS) in power systems is a tough optimisation problem which continues to present a challenge for efficient solution techniques. The solution is to define on/off decisions and generation levels for each electricity generator of a power system for each scheduling interval. The solution procedure requires simultaneous consideration of binary decision and continuous variables. In recent years researchers have focused much attention on developing new hybrid approaches using evolutionary and traditional exact methods for this type of mixed-integer problems. This paper investigates how the optimum or near optimum solution for the GS problem may be quickly identified. A design is proposed which uses a variety of metaheuristic, heuristics and mathematical programming techniques within a hybrid framework. The results obtained for two case studies are promising and show that the hybrid approach offers an effective alternative for solving the GS problems within a realistic timeframe.  相似文献   
110.
This paper presents results of research into the use of the Bellman–Zadeh approach to decision making in a fuzzy environment for solving multicriteria optimization problems. Its application conforms to the principle of guaranteed result and provides constructive lines in obtaining harmonious solutions on the basis of analyzing associated maxmin problems. The use of the Bellman–Zadeh approach has served as a basis for solving a problem of multicriteria allocation of resources (or their shortages) and developing a corresponding adaptive interactive decision making system (AIDMS1). AIDMS1 includes procedures for considering linguistic variables to reflect conditions that are difficult to formalize as well as procedures for constructing and correcting vectors of importance factors for goals. The use of these procedures permits one to realize an adaptive approach to processing information of a decision maker to provide successive improvment in solution quality. The results of the paper are universally applicable and are already being used to solve power engineering problems. It is illustrated by considering problems of multicriteria power and energy shortage allocation and multicriteria power system operation.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号