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   5790篇
  免费   158篇
  国内免费   11篇
电工技术   83篇
综合类   5篇
化学工业   1114篇
金属工艺   114篇
机械仪表   77篇
建筑科学   316篇
矿业工程   7篇
能源动力   163篇
轻工业   376篇
水利工程   44篇
石油天然气   114篇
武器工业   1篇
无线电   397篇
一般工业技术   882篇
冶金工业   1458篇
原子能技术   50篇
自动化技术   758篇
  2021年   64篇
  2020年   59篇
  2019年   59篇
  2018年   72篇
  2017年   61篇
  2016年   79篇
  2015年   82篇
  2014年   85篇
  2013年   346篇
  2012年   204篇
  2011年   235篇
  2010年   168篇
  2009年   181篇
  2008年   224篇
  2007年   226篇
  2006年   194篇
  2005年   189篇
  2004年   169篇
  2003年   155篇
  2002年   162篇
  2001年   95篇
  2000年   96篇
  1999年   111篇
  1998年   88篇
  1997年   96篇
  1996年   116篇
  1995年   85篇
  1994年   78篇
  1993年   91篇
  1992年   85篇
  1991年   63篇
  1990年   78篇
  1989年   91篇
  1988年   81篇
  1987年   89篇
  1986年   82篇
  1985年   103篇
  1984年   112篇
  1983年   85篇
  1982年   79篇
  1981年   85篇
  1980年   63篇
  1979年   99篇
  1978年   68篇
  1977年   77篇
  1976年   58篇
  1975年   68篇
  1974年   57篇
  1973年   75篇
  1972年   55篇
排序方式: 共有5959条查询结果,搜索用时 15 毫秒
1.
Abstract

Industry 4.0 aims at providing a digital representation of a production landscape, but the challenges in building, maintaining, optimizing, and evolving digital models in inter-organizational production chains have not been identified yet in a systematic manner. In this paper, various Industry 4.0 research and technical challenges are addressed, and their present scenario is discussed. Moreover, in this article, the novel concept of developing experience-based virtual models of engineering entities, process, and the factory is presented. These models of production units, processes, and procedures are accomplished by virtual engineering object (VEO), virtual engineering process (VEP), and virtual engineering factory (VEF), using the knowledge representation technique of Decisional DNA. This blend of the virtual and physical domains permits monitoring of systems and analysis of data to foresee problems before they occur, develop new opportunities, prevent downtime, and even plan for the future by using simulations. Furthermore, the proposed virtual model concept not only has the capability of Query Processing and Data Integration for Industrial Data but also real-time visualization of data stream processing.  相似文献   
2.
We investigate the challenges of building an end-to-end cloud pipeline for real-time intelligent visual inspection system for use in automotive manufacturing. Current methods of visual detection in automotive assembly are highly labor intensive, and thus prone to errors. An automated process is sought that can operate within the real-time constraints of the assembly line and can reduce errors. Components of the cloud pipeline include capture of a large set of high-definition images from a camera setup at the assembly location, transfer and storage of the images as needed, execution of object detection, and notification to a human operator when a fault is detected. The end-to-end execution must complete within a fixed time frame before the next car arrives in the assembly line. In this article, we report the design, development, and experimental evaluation of the tradeoffs of performance, accuracy, and scalability for a cloud system.  相似文献   
3.
4.
5.
Passive permeability is a key property in drug disposition and delivery. It is critical for gastrointestinal absorption, brain penetration, renal reabsorption, defining clearance mechanisms and drug-drug interactions. Passive diffusion rate is translatable across tissues and animal species, while the extent of absorption is dependent on drug properties, as well as in vivo physiology/pathophysiology. Design principles have been developed to guide medicinal chemistry to enhance absorption, which combine the balance of aqueous solubility, permeability and the sometimes unfavorable compound characteristic demanded by the target. Permeability assays have been implemented that enable rapid development of structure-permeability relationships for absorption improvement. Future advances in assay development to reduce nonspecific binding and improve mass balance will enable more accurately measurement of passive permeability. Design principles that integrate potency, selectivity, passive permeability and other ADMET properties facilitate rapid advancement of successful drug candidates to patients.  相似文献   
6.
7.
Indoor infrared communication systems is one of the possible ways of offering data rates in excess of 100 Mbit/s without the need for wiring. Multiple users can share an infrared channel by code division-multiple access (CDMA) techniques. However, the CDMA system performance is limited by both background noise and co-channel interference. In this paper we study the use of angle diversity for mitigating the effects of the noise and interference. The system considered uses on-off shift keying modulation with multibeam transmitters and imaging receivers. The overall system performance for different diversity combining techniques is evaluated and compared to a system without diversity. Numerical results for a 2-user CDMA system indicate that signal to noise and interference ratio (SNIR) improvement (over systems with no diversity) of 5 dB is obtained for at least 50% of an ensemble of 10000 sample evaluations. The generalized selection combining (GSC)--a new diversity technique yet to be implemented for infrared systems--offers the best performance even with its reduced complexity.  相似文献   
8.
An implicit assumption of several causal reasoning models is that readers adopt the goals of a narrative's protagonist during text comprehension. In apparent violation of this assumption, readers participating in Experiment 1 of the present study drew inferences relevant to a protagonist's goal even when that goal was already satisfied from the perspective of the protagonist. In Experiments 2 and 3, participants were explicitly asked to view the text situation from the point of view of the protagonist. In this case, the goals of the reader and the protagonist should be the same. In these experiments, participants focused on the goals of the protagonist only when those goals had not been satisfied from the perspective of the protagonist. These results are discussed in terms of reader- and character-based perspectives and in terms of text characteristics that cue perspective taking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
9.
Studied how 26 senior managers and 47 senior professional technical staff (recently repatriated) of 4 US owned multinational organizations viewed their international posting, specifically with respect to career path satisfaction. Results of satisfaction scales indicate that many Ss felt under-prepared for their international assignment. It is suggested that a comprehensive international employee development program should assess, provide feedback, and coach individuals on career path, culture shock and adjustment, and performance issues prior, during, and on return from the expatriate assignment. Results suggest that opportunities exist for individual and organizational intervention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
10.
Comments on the proposal by L. H. Levy et al (see record 1984-27507-001) for a new charter for clinical psychology—human services psychology. Current trends suggest that both clinical and counseling psychology are becoming eclectic and health oriented. Clinical psychology appears to be becoming more involved in community psychology and to be tempering its remedial role with the preventive role. Counseling psychology appears to be becoming less involved in its vocational and preventive roles and more involved in the remedial role. It is concluded that clinical and counseling psychology have come to be increasingly similar and could be integrated into a human services psychology. (38 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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