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   11725篇
  免费   1345篇
  国内免费   1041篇
电工技术   806篇
综合类   1632篇
化学工业   190篇
金属工艺   112篇
机械仪表   581篇
建筑科学   640篇
矿业工程   265篇
能源动力   249篇
轻工业   165篇
水利工程   360篇
石油天然气   181篇
武器工业   187篇
无线电   1121篇
一般工业技术   804篇
冶金工业   791篇
原子能技术   46篇
自动化技术   5981篇
  2024年   38篇
  2023年   138篇
  2022年   237篇
  2021年   325篇
  2020年   359篇
  2019年   347篇
  2018年   319篇
  2017年   353篇
  2016年   375篇
  2015年   432篇
  2014年   603篇
  2013年   843篇
  2012年   689篇
  2011年   780篇
  2010年   708篇
  2009年   696篇
  2008年   752篇
  2007年   907篇
  2006年   755篇
  2005年   678篇
  2004年   586篇
  2003年   540篇
  2002年   506篇
  2001年   388篇
  2000年   282篇
  1999年   260篇
  1998年   205篇
  1997年   169篇
  1996年   122篇
  1995年   121篇
  1994年   129篇
  1993年   85篇
  1992年   54篇
  1991年   48篇
  1990年   51篇
  1989年   31篇
  1988年   25篇
  1987年   18篇
  1986年   10篇
  1985年   10篇
  1984年   13篇
  1983年   17篇
  1982年   14篇
  1981年   6篇
  1980年   8篇
  1979年   8篇
  1978年   6篇
  1966年   11篇
  1965年   8篇
  1955年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Results from applying the model on a sample of contractors, the majority of whom were international and operating in Egypt, reinforces the credibility of the developed methodology, claim the authors.  相似文献   
42.
以有效的技改投资决策理念指导企业技改投资,加快了企业技术进步,促进了企业跨越式发展,使三钢的产能从1996年年产钢50万t钢规模发展到目前的200万t钢水平,且优化了产业结构,技术经济指标从全国同行业的中下游上升到领先水平,增强了企业实力。但是,在取得显著成绩的同时,周边民营钢铁企业异军突起,面对严峻的挑战,三钢力争两年内依靠技改使产能达到300万t钢规模,并筹谋更远大的发展。  相似文献   
43.
Two experiments involving 99 undergraduate participants sought to examine the influence of mood states on encoding speed within lexical decision and pronunciation tasks. Mood states were measured naturalistically in Experiment 1 and manipulated in Experiment 2. Stimuli consisted of nouns representing useful (e.g., food) and nonuseful (e.g., lint) objects. Mood states had no implications for initial encoding speed. However, when the same words were presented a 2nd time (i.e., repeated), happy individuals displayed a tendency to encode useful words faster than nonuseful ones. Thus, mood states influenced repetition priming on the basis of stimulus valence. The authors propose that happiness sensitizes individuals to useful or rewarding objects, which in turn creates a stronger memory trace for such stimuli in the future. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
44.
The development of autonomous mobile machines to perform useful tasks in real work environments is currently being impeded by concerns over effectiveness, commercial viability and, above all, safety. This paper introduces a case study of a robotic excavator to explore a series of issues around system development, navigation in unstructured environments, autonomous decision making and changing the behaviour of autonomous machines to suit the prevailing demands of users. The adoption of the Real-Time Control Systems (RCS) architecture (Albus, 1991) is proposed as a universal framework for the development of intelligent systems. In addition it is explained how the use of Partially Observable Markov Decision Processes (POMDP) (Kaelbling et al., 1998) can form the basis of decision making in the face of uncertainty and how the technique can be effectively incorporated into the RCS architecture. Particular emphasis is placed on ensuring that the resulting behaviour is both task effective and adequately safe, and it is recognised that these two objectives may be in opposition and that the desired relative balance between them may change. The concept of an autonomous system having “values” is introduced through the use of utility theory. Limited simulation results of experiments are reported which demonstrate that these techniques can create intelligent systems capable of modifying their behaviour to exhibit either ‘safety conscious’ or ‘task achieving’ personalities.  相似文献   
45.
雒海潮 《现代电子技术》2004,27(6):63-64,67
介绍了神经网络与线性分组码之间的关系,并在文献[1]的基础上证明了软判决译码与求解能量函数最大值之间的等价性,然后以(7,4,3)汉明码为例介绍了神经网络在循环码硬判决、软判决译码中的应用。  相似文献   
46.
Product optimization involves selecting design, manufacturing, and support attributes that can produce the best system. Producibility or manufacturability is the term often used to describe the relative ease of manufacturing a product. In complex systems, productibility optimization is a very difficult process, particularly when the values of many attributes are restricted by constraints. One challenge is to develop more universal producibility metrics for the conceptual design phase when design information is limited and drawings are nondimensional. This paper develops a new method for producibility optimization in conceptual design based on a combination of both decision theoretic and expert system techniques. Decision theoretic techniques provide the means to model the design for producibility problem in a manner that can deal with risk, uncertainty, and user (or corporate) preferences, and can effectively integrate diverse factors to provide a measure of the overall worth of a design. The particular decision theoretic approach employed is based on multi-attribute utility theory. An illustrative example of the methodology is applied to the conceptual design of a structural composite part.  相似文献   
47.
The WAIS-R Information subtest was combined with 21 potential substitute Canadian content items and group-administered to 119 high school students ranging in age from 16 to 19 years. Seven acceptable substitute items were identified. Mean scores on the American items for the 16-17 and 18-19 age groups suggested that Canadians of these ages are not penalized by American content with respect to either Verbal or Full Scale IQ. Nevertheless, the research identified eight Information items, four easier and four more difficult than the standard WAIS-R implies. Similar results were noted in two previous studies of the WAIS-R, and indicate the extreme caution required for the clinical interpretation of intra test scatter. There is also evidence that item difficulty within the Information subtest may vary with the age of the subject. These results were considered indicative of the necessity for Canadian content Information items and the development of Canadian norms for an adapted WAIS-R Information subtest. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
48.
通用的自然语言词法分析机制   总被引:4,自引:1,他引:3  
本文提出了一种通用的自然语言词法分析技术,其处理机构不仅可以独立于具体自然语言,而且又具有适合于未来智能计算机直接处理的规则形式和实现过程.文中还详细讨论了独立于自然语言的词法分析技术,以及我们在IMT/EC系统中实现的词法分析机制的工作原理.  相似文献   
49.
针对影响钢制储罐寿命的因素具有复杂性、非确定性以及时变性的特点,提出了用动态二级模糊综合评判的方法对其寿命进行评估,建立了评估的数学模型和评估流程。在对某石油库油罐的寿命分析中,考虑到保留所有评判因素的影响,采用了乘、加型模糊算子,并用层次分析法来确定评价指标权重。计算结果表明,该方法能够解决储罐寿命评估中的一些复杂因素的处理问题,具有一定的实际工程意义。  相似文献   
50.
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