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   11565篇
  免费   402篇
  国内免费   175篇
电工技术   130篇
技术理论   5篇
综合类   120篇
化学工业   2263篇
金属工艺   584篇
机械仪表   305篇
建筑科学   454篇
矿业工程   126篇
能源动力   1196篇
轻工业   798篇
水利工程   115篇
石油天然气   157篇
武器工业   70篇
无线电   1014篇
一般工业技术   1935篇
冶金工业   317篇
原子能技术   125篇
自动化技术   2428篇
  2024年   24篇
  2023年   421篇
  2022年   254篇
  2021年   346篇
  2020年   447篇
  2019年   410篇
  2018年   185篇
  2017年   573篇
  2016年   662篇
  2015年   619篇
  2014年   865篇
  2013年   741篇
  2012年   597篇
  2011年   592篇
  2010年   511篇
  2009年   588篇
  2008年   352篇
  2007年   541篇
  2006年   462篇
  2005年   296篇
  2004年   157篇
  2003年   219篇
  2002年   268篇
  2001年   259篇
  2000年   152篇
  1999年   201篇
  1998年   163篇
  1997年   87篇
  1996年   87篇
  1995年   74篇
  1994年   77篇
  1993年   40篇
  1992年   39篇
  1991年   44篇
  1990年   44篇
  1989年   38篇
  1988年   107篇
  1987年   194篇
  1986年   169篇
  1985年   50篇
  1984年   31篇
  1983年   18篇
  1982年   14篇
  1981年   19篇
  1980年   17篇
  1979年   22篇
  1978年   25篇
  1976年   12篇
  1974年   5篇
  1971年   6篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
171.
Basing on the Gordon model perspective and applying multiple criteria decision making (MCDM), this research explores the influential factors and relative weight of dividend, discount rate, and dividend growth rate. The purpose is to establish an investment decision model and provides investors with a reference/selection of stocks most suitable for investing effects to achieve the greatest returns. Taking full consideration of the interrelation effect among variables of the decision model, this paper introduced analytical network process (ANP) and examined leading electronics companies spanning the hottest sectors of lens, solar, and handset by experts. Empirical findings indicated that dividend was affected by industry outlook, earnings, operating cash flow, and dividend payout rate; discount rate was affected by market β and risk-free rate; and dividend growth rate was affected by earnings growth rate and dividend payout growth rate. Also, according to literatures, discount rate possessed a self-effect relationship. Among the eight evaluation criteria, market β was the most important factor influencing investment decisions, followed by dividend growth rate and risk-free rate. In stock evaluations, leadership companies in the solar industry outperformed those in handset and lens, becoming investors’ favorite stock group at the time that this research was conducted.  相似文献   
172.
邢熠  叶新铭 《计算机工程》2009,35(24):36-38
针对一致性测试中的静态需求测试通常采用手工方法而产生的效率低问题,提出一种基于统计学习的方法,包括静态需求的关联规则表示,并对采样的协议数据进行关联规则挖掘,如果得到的规则与需求规则一致,静态需求就可以得到统计上的测试检验。该方法在OSPFv3协议测试中取得了较好的效果。  相似文献   
173.
174.
175.
176.
随着流媒体应用需求的日益增加,不断改进和完善现有流媒体系统性能势在必行,将云计算引入流媒体系统成为未来流媒体系统的一大趋势.本文简单分析了云计算、CDN(ContentDeliveryNetwork)St]P2P(PeertoPeer)网络的优缺点和研究现状.主要讨论并分析了云环境下的P2P流媒体传输系统所面临的带宽问题、流媒体数据处理、服务质量问题和系统中的关键技术——虚拟化技术、存储管理技术、调度技术和复制技术.此外,从搭建云计算实验环境角度。本文列举了目前比较流行的5种仿真实验手段.  相似文献   
177.
The violent free-surface motions and the corresponding impact loads are numerically simulated by using the Moving Particle Semi-implicit (MPS) method, which was originally proposed by Koshizuka and Oka [10] for incompressible flows. In the original MPS method, there were several defects including non-optimal source term, gradient and collision models, and search of free-surface particles, which led to less-accurate fluid motions and non-physical pressure fluctuations. In the present study, how those defects can be remedied is illustrated by step-by-step improvements in the respective processes of the revised MPS method. For illustration, two examples are studied; (i) dam breaking problem and (ii) liquid sloshing inside a rectangular tank. The improvement of each step is explained and numerically demonstrated. The numerical results are also compared against the experimental results of Martin and Moyce [12] for dam-breaking problem and Kishev et al. [9] for sloshing problem. The numerical results for violent free-surface motions and impact pressures are in good agreement with their experimental data.  相似文献   
178.
This paper addresses a very important question—how to select the right products to promote in order to maximize promotional benefit. We set up a framework to incorporate promotion decisions into the data-mining process, formulate the profit maximization problem as an optimization problem, and propose a heuristic search solution to discover the right products to promote. Moreover, we are able to get access to real supermarket data and apply our solution to help achieve higher profits. Our experimental results on both synthetic data and real supermarket data demonstrate that our framework and method are highly effective and can potentially bring huge profit gains to a marketing campaign.  相似文献   
179.
When multimedia information is transported over a packet-switched network, the quality of presentation can be degraded due to network delay variation or jitter. This paper presents a dejittering scheme that can be used in the transport of MPEG-4 and MPEG-2 video to absorb any introduced network jitter, thus preserving the presentation quality of transported media streams. The dejittering scheme is based on the statistical approximation of delay variation in the arrival times of video packets carrying encoded clock reference values and a filtering and re-stamping mechanism. In addition, a brief overview of the MPEG-4 system is presented.  相似文献   
180.
This paper develops a framework for the consideration of internal markets as an alternative to information systems (IS) outsourcing. It is based on an assessment of the pros and cons of both outsourcing and of insourcing based on the internal markets approach. It is formulated in terms of the operational, tactical, and strategic impacts of the choice among the alternatives. The framework, and the propositions that are developed from it, should be useful both for researchers, who can use it for developing testable research hypotheses, and for practitioners, who may use it as a basis for developing a comprehensive set of criteria for the evaluation of these sourcing options.  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