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   12647篇
  免费   918篇
  国内免费   218篇
电工技术   484篇
技术理论   1篇
综合类   500篇
化学工业   2360篇
金属工艺   351篇
机械仪表   474篇
建筑科学   667篇
矿业工程   214篇
能源动力   383篇
轻工业   1100篇
水利工程   179篇
石油天然气   482篇
武器工业   52篇
无线电   1087篇
一般工业技术   2238篇
冶金工业   1199篇
原子能技术   75篇
自动化技术   1937篇
  2024年   29篇
  2023年   173篇
  2022年   207篇
  2021年   423篇
  2020年   312篇
  2019年   315篇
  2018年   377篇
  2017年   396篇
  2016年   409篇
  2015年   423篇
  2014年   580篇
  2013年   835篇
  2012年   844篇
  2011年   949篇
  2010年   755篇
  2009年   717篇
  2008年   757篇
  2007年   668篇
  2006年   648篇
  2005年   503篇
  2004年   393篇
  2003年   355篇
  2002年   325篇
  2001年   275篇
  2000年   233篇
  1999年   243篇
  1998年   299篇
  1997年   225篇
  1996年   176篇
  1995年   150篇
  1994年   127篇
  1993年   100篇
  1992年   73篇
  1991年   48篇
  1990年   44篇
  1989年   39篇
  1988年   35篇
  1987年   39篇
  1986年   28篇
  1985年   41篇
  1984年   19篇
  1983年   20篇
  1982年   29篇
  1981年   28篇
  1980年   10篇
  1979年   12篇
  1977年   18篇
  1976年   19篇
  1975年   10篇
  1974年   11篇
排序方式: 共有10000条查询结果,搜索用时 328 毫秒
91.
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   
92.
93.
Linear Modulated Frequency (LMF) Costas Stepped Frequency Radar (SFR) signal is introduced. Its ambiguity function is derived and analyzed in detail and its feasibility is validated in theory. The scheme of the proposed signal processing is also presented. The results of theoretic analysis and simulation show that, by using the proposed signal and increasing the bandwidth of the total stepped frequency, the ambiguity sidelobe is well suppressed and the range-velocity coupling in the stepped frequency radar is also greatly weakened.  相似文献   
94.
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   
95.
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   
96.
穆紫 《国外塑料》2002,20(4):14-16
详细介绍了一种新型装饰工艺-模内贴箔工艺的自动化过程及生产要求。  相似文献   
97.
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   
98.
In this introduction to a special issue of Computers and Composition, the authors critically review current literature on computer-assisted writing pedagogies that grapple with issues of sexuality. Although this body of work is small, it points to provocative ways to develop our students’ critical and rhetorical sensibilities about the constructions of sexuality in our culture. Further, such work innovatively addresses the place of networked communication technologies in the interrogation of such constructions. The authors conclude with both an introduction of the work in this special issue that addresses the intersection of sexuality studies and computer-assisted writing studies and with a call for additional work in this field.  相似文献   
99.
The dielectric properties of a ceramic powder (BaTiO3) filled thermoplastic elastomer (EPDM TPE) were investigated for use in a flexible electromagnetic crystal. Materials were produced that had a high dielectric constant (approximately 9) and low loss tangent (less than 0.01). Materials were extruded and injection molded so as to povide low‐cost processing. Mechanical and electromagnetic test results showed the effect of processing conditions on the final quality of the composite. The shear rate during processing and the number of mixing cycles were found to affect the final material characteristics significantly. An electromagnetic crystal woven from extruded rods showed good reflectivity in the 10–15 GHz region.  相似文献   
100.
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