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   5575篇
  免费   327篇
  国内免费   8篇
电工技术   68篇
综合类   8篇
化学工业   1032篇
金属工艺   61篇
机械仪表   82篇
建筑科学   205篇
矿业工程   7篇
能源动力   169篇
轻工业   405篇
水利工程   56篇
石油天然气   37篇
无线电   457篇
一般工业技术   1318篇
冶金工业   970篇
原子能技术   21篇
自动化技术   1014篇
  2023年   60篇
  2022年   102篇
  2021年   155篇
  2020年   125篇
  2019年   139篇
  2018年   133篇
  2017年   149篇
  2016年   172篇
  2015年   151篇
  2014年   202篇
  2013年   368篇
  2012年   331篇
  2011年   404篇
  2010年   318篇
  2009年   295篇
  2008年   332篇
  2007年   267篇
  2006年   232篇
  2005年   207篇
  2004年   166篇
  2003年   152篇
  2002年   151篇
  2001年   80篇
  2000年   73篇
  1999年   93篇
  1998年   120篇
  1997年   114篇
  1996年   93篇
  1995年   68篇
  1994年   67篇
  1993年   66篇
  1992年   58篇
  1991年   28篇
  1990年   41篇
  1989年   25篇
  1988年   25篇
  1987年   38篇
  1986年   30篇
  1985年   35篇
  1984年   22篇
  1983年   10篇
  1982年   19篇
  1981年   27篇
  1980年   10篇
  1979年   11篇
  1977年   18篇
  1976年   21篇
  1975年   9篇
  1973年   14篇
  1970年   9篇
排序方式: 共有5910条查询结果,搜索用时 15 毫秒
41.
Ss studied faces in a full- or a divided-attention condition and then received a recognition test that included old faces, new faces constructed by combining facial features from previously studied faces ("conjunction faces"), and partly or completely new faces. Full- but not divided attention Ss responded "old" more often to old than to conjunction faces; all Ss responded "old" to these faces more often than to partially or completely new faces. Thus it is less attentionally demanding to encode facial features than it is to encode their interrelations. Dividing attention had identical effects on an incidental and an intentional learning group. Exp 3 demonstrated that dividing attention primarily affected explicit recollection rather than stimulus familiarity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
42.
The scaphoid test described by Watson has generally been accepted as the definitive test for scaphoid instability and uses pressure against the scaphoid tubercle as the wrist moves from ulnar to radial deviation for the evaluation. This article describes a stress test done with the wrist in neutral position, which actively provokes scaphoid instability. Variations in stability can be used to grade scaphoid laxity.  相似文献   
43.
44.
MKT1 is required for m aintenance of K2 above 30°C in strains with the L-A-HN variant of the L-A double-stranded RNA virus of Saccharomyces cerevisiae. We report that MKT1 encodes a 92 979 Da protein with serine-rich regions and the retroviral protease signature, DTG, but with no substantial homology to proteins presently in the databases. This sequence is available from GenBank under Accession Number U09129.  相似文献   
45.
Remote delivery of video services using mm-waves and optics   总被引:2,自引:0,他引:2  
Advantages of a radio-based final drop for video delivery are outlined and spectral availability constraints that lead to the identification of the mm-wave region of the radio spectrum as the most appropriate for this application are discussed. The possibility of simultaneously supporting other broadband services, such as B-ISDN and traffic information systems (IVHS), enhance the attractiveness of a radio link. A large number of antenna units need to be served due to the limited propagation distances achievable at mm-wave frequencies, and therefore, a low-cost generation and delivery method has to be developed. In this paper, alternatives for the optical generation and distribution of mm-wave signals are reviewed and a new method is proposed that eases the bandwidth, and hence the cost, of the required optoelectronic components. An assessment of the relative merits of the methods is given  相似文献   
46.
A dual read-out model of context effects in letter perception is described that predicts forced-choice accuracy in the Reicher paradigm and its relation to word reportability. It is hypothesized that a correct choice to a letter in a word context is made when either the correct letter representation or a word representation containing the correct letter in the correct position reaches a response threshold (a criterion level of activation). This hypothesis was implemented using the basic architecture of the interactive activation model (J. L. McClelland & D. E. Rumelhart, 1981) in its semistochastic variant (A. M. Jacobs & J. Grainger, 1992). The model successfully captures the data of J. C. Johnston (1978), otherwise thought to be critically damaging for this type of model, and accurately predicts performance in a series of new experiments using the Reicher paradigm. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
47.
Presents an obituary of R. Fine, a psychologist-psychoanalyst who also excelled in chess. Fine worked for the government during World War II as a mathematician and consultant to the US Armed Forces, earned a PhD in clinical psychology in 1948, and was one of the founders of the National Psychological Association for Psychoanalysis. Fine also organized several centers for psychoanalytic training and was the founder of the American Psychological Association's Division 29, Psychotherapy. He wrote more than 100 articles and some 20 books on psychoanalysis, with an emphasis on love and work. (0 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
48.
This paper argues that the several models of neighbourhood change developed in the United States are generally not applicable to Canadian cities due to differences in urban form, socioeconomic characteristics, and a host of institutional factors. A simple model is presented which extends the arbitrage model of neighbourhood dynamics. Several hypotheses are advanced and then tested on a data base covering three Vancouver, B.C. neighbourhoods from 1955 to 1981 by estimating several hedonic price equations. The hypotheses receive partial support. Implications for policymakers are then discussed.We wish to thank Jim Fitzsimmons and Judy Fountain for their computer assistance and the British Columbia Assessment Authority for providing us with data. Helpful comments on an earlier version of this paper were provided by Lawrence Jones and Douglas Diamond. We also like to acknowledge the financial support of the Canada Mortgage and Housing Corporation, the Real Estate Council of British Columbia, the University of British Columbia and the British Columbia Youth Employment Program.  相似文献   
49.
Laboratory ultraviolet (UV) chambers are widely used to obtain weathering data for a wide range of commercial polymer products including coatings, textiles, elastomers, plastics, and polymeric composites. Although numerous improvements have been made in the design of UV chambers over the last 80 years, the reproducibility of the exposure results from these chambers has remained elusive. This lack of reproducibility is attributed to systematic errors in their design, operation, and control which prevent direct comparisons of the performance of materials exposed in the same environment, comparisons of the performance of the same material exposed in different laboratories, and the comparison of field and laboratory results. This paper describes an innovative UV chamber design based on integrating sphere technology that greatly reduces the magnitude of these errors, as well as provides additional experimental capabilities. Presented at the 79th Annual Meeting of the Federation of Societies for Coatings Technology, on November 4–7, 2001, in Atlanta, GA. Building Materials Division. Gaithersburg, MD. Freeport, TX.  相似文献   
50.
A method for machine interpretation of architectural (or other) schematic drawings is presented. The central problem is to build an efficient drawing parser (i.e., a program that identifies the semantic entities, characteristics, and relationships that are represented in the drawing). The parser is built from specifications of the drawing grammar and an underlying spatial model. The grammar describes what to look for, and the spatial model enables the parser to find it quickly. Coupled with existing optical recognition technology, this technique enables the use of drawings directly as: (1) a database to drive various Architecture-Engineering-Construction (AEC) applications; (2) a communication protocol to integrate CAD systems; (3) a traditional user interface.  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