全文获取类型
收费全文 | 11725篇 |
免费 | 1345篇 |
国内免费 | 1041篇 |
专业分类
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 |
出版年
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.
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.
Fellers Gloria; McInnis Charles; Cappelli Mario; Cragg Susan; Vaillancourt Raymond 《Canadian Metallurgical Quarterly》1987,19(1):108
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.
50.