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   5935篇
  免费   140篇
  国内免费   2篇
电工技术   69篇
综合类   3篇
化学工业   802篇
金属工艺   117篇
机械仪表   122篇
建筑科学   182篇
矿业工程   11篇
能源动力   100篇
轻工业   531篇
水利工程   41篇
石油天然气   20篇
无线电   652篇
一般工业技术   793篇
冶金工业   2070篇
原子能技术   64篇
自动化技术   500篇
  2021年   41篇
  2020年   45篇
  2019年   50篇
  2018年   56篇
  2017年   61篇
  2016年   77篇
  2015年   49篇
  2014年   63篇
  2013年   249篇
  2012年   108篇
  2011年   170篇
  2010年   122篇
  2009年   133篇
  2008年   157篇
  2007年   150篇
  2006年   135篇
  2005年   119篇
  2004年   156篇
  2003年   145篇
  2002年   125篇
  2001年   126篇
  2000年   113篇
  1999年   156篇
  1998年   582篇
  1997年   353篇
  1996年   240篇
  1995年   175篇
  1994年   178篇
  1993年   178篇
  1992年   95篇
  1991年   100篇
  1990年   98篇
  1989年   82篇
  1988年   77篇
  1987年   86篇
  1986年   84篇
  1985年   86篇
  1984年   65篇
  1983年   75篇
  1982年   73篇
  1981年   66篇
  1980年   54篇
  1979年   55篇
  1978年   55篇
  1977年   78篇
  1976年   164篇
  1975年   48篇
  1974年   42篇
  1973年   37篇
  1970年   25篇
排序方式: 共有6077条查询结果,搜索用时 125 毫秒
941.
Studied cross-cultural communication with Canadian university students who identified themselves as French-speaking or English-speaking. Ss were divided into 36 French-English pairs (18 of which were tested in a French setting and 18 in an English setting) and 36 same-ethnic pairs. The pairs performed an experimental task under 1 of 3 instructional sets in which Ss were forced to communicate, communication was optional, or no communication set was provided. Each condition was followed by an unstructured period where Ss were free to communicate. Following the communication task, Ss completed a questionnaire which assessed their attitudes about communicating with their partner. Results were analyzed in terms of patterns of communication, content of communication, and languages used for communication. Findings suggest that effective cross-cultural communication is possible and that, at least in a dyadic situation, members of 2 ethnic groups are motivated to communicate. (French summary) (21 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
942.
Rheological properties and swelling were examined in a series of concentrations of particles of crosslinked polyacrylate gels in water or salt solutions. The modulus during steady shear Gs = 2τ2/P11-P22 was determined from shear stress τ and primary normal force difference P11-P22 in a cone-and-plate rheometer. Gs was nearly constant with shear rate for the gel particles in the closely packed condition. The dynamic storage modulus G′ determined by ecentric rotating disc rheometry increased with increasing frequency for all concentrations. The apparent equilibrium shear modulus Ge determined by stress relaxation agreed closely at all concentrations and ionic strengths with the corresponding values of Gs, and hence Gs is considered a good estimate of equilibrium shear modulus for this gel material.  相似文献   
943.
2 conferences, one in August 1955 and the other in August 1957, on "The Identification of Creative Scientific Talent" were supported financially by the National Science Foundation. Titles of research reports and authors are presented. Reports of special committees at each conference are summarized. "A multiplicity of hypotheses and problems needing research… emerged throughout both conferences. It is hoped that concurrent attacks on problems of creativity will be undertaken by researchers in industry, government, universities, and school systems." (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
944.
The sample consisted of 190 Utah physicians fully certified as specialists by an American Board. 80 scores relevant to the performance of these physicians were intercorrelated and factor analyzed using the principal components solution based on eigenvalues and eigenvectors. The 29 factors which had an eigenvalue greater than 1.00 were rotated by the varimax procedure and interpreted. The most important finding was the great criterion complexity for this group of medical specialists. This complexity suggests that one cannot adequately measure physician performance on the basis of a single score or a few scores. Instead, one must obtain a relatively large number of scores. Performance in poth premedical and medical education was independent of performance as a physician. (19 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
945.
The compatibility of mixtures of poly(2,3-dichloro-1-propyl acrylate) and poly(glycidyl methacrylate–co–ethyl acrylate) has been investigated by measurement of the following properties: density, light transmission, glass transition temperature, vapor absorption, and NMR relaxation times. To varying degrees, all results provided evidence supporting the contention that these mixtures are compatible.  相似文献   
946.
This paper suggests that under certain conditions attitudes may be measured as validly and as reliably with a single "attitude report question" as with a multi-item attitude scale. 84 physicans responded to 8 Guttman scales, and also rated their attitudes on 8 comparable graphic rating scales. These data were factor analyzed, and the communalities used as an estimate of the minimal scale reliability. In general, the graphic rating scales proved as reliable as the Guttman scales. An examination of the interscale correlations showed that similar conclusions would be drawn from either technique. It is suggested that a single graphic rating may usefully substitute for a multi-item attitude scale when the attitude continuum is unidimensional. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
947.
Intensive research and development in Computational Fluid Dynamics (CFD) has recently produced many powerful CFD codes to simulate complex aerodynamic phenomena. However, in order to enhance the usefulness of these CFD codes for design practice, development of design sensitivity equations compatible to these codes becomes very important. This paper represents a part of such an effort to develop a sensitivity analysts methodology that enables the sensitivity equations to be implemented into existing CFD codes with minimal code modification. The methodology is based upon a pre-elimination procedure which accounts for consistently linearized boundary conditions. Formulations of both the direct differentiation and the adjoint variable methods will be presented in the paper.  相似文献   
948.
Passive mode locking in the previously uncovered 705-798 nm spectral region has been achieved with a simple flashlamp-pumped dye laser using rhodamine 700 as the active medium with DCI (1, 1'- Diethyl-4, 4'-carbocyanine iodide) and DDCI (1, 1' Diethyl-2, 2'-dicarbocyanine iodide) as saturable absorbers. Pulses having duration in the range 4-7 ps with peak powers up to 10 MW have been produced. Several other saturable absorbers have also been shown to operate successfully in this wavelength range.  相似文献   
949.
950.
The United States Lines' 15 690-ton commercial-container ship, "American Alliance," was selected as lead ship for an onboard EMI survey prior to installation of 1535-1645-MHz (L-Band) shipboard terminals for communication via a maritime satellite. Three maritime communications satellites are currently in orbit: Marisat-1, over the Atlantic Ocean at 15° W. longitude, Marisat-B, over the Pacific Ocean at 176.5 E. longitude, and Marisat-C, over the Indian Ocean at 73° E. longitude. In general, the EMI survery revealed tolerable interference levels onboard ship: radiometer measurements indicate antenna-noise temperatures less than 70 K, at elevation angles of 5° and greater, at 1559 MHz, at the output terminals of the 1.2-m diametci, parabolic-dish antenna for the L-band shipboard terminal. Other EMI measurements include field intensity from 3-cm and 10-cm wavelength pulse radars, and conducted-emission tests of primary power lines to both onboard radars. This information should be helpful to designers of maritune L-band shipboard terminals.  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