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   30314篇
  免费   740篇
  国内免费   39篇
电工技术   367篇
综合类   15篇
化学工业   6361篇
金属工艺   558篇
机械仪表   535篇
建筑科学   1271篇
矿业工程   336篇
能源动力   702篇
轻工业   2059篇
水利工程   248篇
石油天然气   249篇
无线电   2011篇
一般工业技术   4549篇
冶金工业   7498篇
原子能技术   295篇
自动化技术   4039篇
  2022年   253篇
  2021年   433篇
  2020年   277篇
  2019年   361篇
  2018年   455篇
  2017年   403篇
  2016年   513篇
  2015年   420篇
  2014年   651篇
  2013年   1763篇
  2012年   1004篇
  2011年   1326篇
  2010年   1001篇
  2009年   1049篇
  2008年   1263篇
  2007年   1165篇
  2006年   1051篇
  2005年   962篇
  2004年   819篇
  2003年   787篇
  2002年   783篇
  2001年   556篇
  2000年   456篇
  1999年   540篇
  1998年   816篇
  1997年   657篇
  1996年   652篇
  1995年   547篇
  1994年   560篇
  1993年   533篇
  1992年   482篇
  1991年   322篇
  1990年   459篇
  1989年   448篇
  1988年   393篇
  1987年   449篇
  1986年   375篇
  1985年   503篇
  1984年   510篇
  1983年   426篇
  1982年   400篇
  1981年   329篇
  1980年   329篇
  1979年   403篇
  1978年   342篇
  1977年   280篇
  1976年   285篇
  1975年   269篇
  1974年   251篇
  1973年   251篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
The author describe their incorporation of IDDQ testing into the design of the PA-7100LC PA-RISC microprocessor. They also discuss design guidelines, measurement techniques, results after fabrication and volume production, and suggested improvement. Their 900,000-transistor custom design supports IDDQ testing to ensure high quality without compromising 100-MHz-plus performance  相似文献   
52.
Examined the 10 most cited articles published in the Psychological Bulletin over the past 4 decades. Seven of the 10 articles were methodologically oriented. A survey of the authors revealed that highly cited articles have an important message that goes beyond momentary fads, are broad in topic and intended audience, accessible, and well written. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
53.
54.
Determination of temperatures associated with room fires provides a means of assessing an important aspect of fire hazard: the likelihood of the occurrence of flashover. Layer temperatures in excess of 600°C have been associated with the occurrence of flashover. A data correlation has previously been presented to estimate layer temperatures for fires burning in the center of rooms. For fires in corners and along walls, restricted entrainment results in higher layer temperatures than predicted by the previous correlation. Modification factors for the previous correlation are developed to extend its applicability to wall and corner burning geometries. The present analysis suggests that a fire in a corner may cause flashover with only half the heat release rate necessary for a fire burning in the center of a room. Reference: Frederick Mowrer and Robert Williamson, Estimating Room Temperatures from Fires along Walls and in Corners,Fire Technology, Vol. 23, May 1987, pp. 133–145.  相似文献   
55.
Railway Engineering Science - Electrified railways are becoming a popular transport medium and these consume a large amount of electrical energy. Environmental concerns demand reduction in energy...  相似文献   
56.
The author’s previously published partial pressures of tellurium over tellurium-rich CdTe are reanalyzed to yield new solidus points as well as temperatures and partial pressures for compositions within the homogeneity range. Although the results are qualitatively the same as before, they are more satisfactory in that some thermodynamic inconsistencies have been removed. The composition range of the CdTe phase extends slightly beyond the equal atom fraction,X Te=0.5, to a Te-rich composition of (X Te−0.5)=(1 to 7)×10−5. The data are in fair agreement with that obtained from total pressure measurements at generally higher compositions. Since both types of measurement are near the limits of attainable accuracy, their agreement would seem to confirm the essential correctness of both.  相似文献   
57.
An interactive computer program is introduced in order to make a simultaneous graphical presentation of phase boundaries and their corresponding free energy curves. The program, which uses a graphics display terminal, is a useful tool in teaching thermodynamic concepts involved in phase diagrams, especially for undergraduate students.  相似文献   
58.
In normal vision, eye movements cause the image to move on the retina. Special apparatus can stabilize the image on the retina so it cannot move, and vision fades away. Previous methods for stabilizing the image were either optical systems or complex computer-controlled feedback systems. A simpler feedback system is presented which detects eye motion and rotates a mirror through which the target is viewed, to exactly compensate for eye motion. Unlike previous optical systems, this new system has no lenses in either the viewing or the image-forming path to limit the spatial resolution.  相似文献   
59.
A multiplexing, demodulating, and recording telemetry system designed to process multiple pulse-coded temperature channels is described. The system provides complete control of recording and multiplexing sequences and timing, and gives a single analog signal in response to each sample of pulse-coded data. It identifies all channels and indicates to a computer when a new data sample is to be processed. The system is self-calibrating to maintain accuracy over extended data collection periods, and is inexpensive.  相似文献   
60.
The triplet-triplet spectra of three commercial anthraquinone vat dyes (C.I. 67300, C.I. 59100 and C.I. 60515) were studied in solution at room temperature using laser photolysis. The triplet states of these dyes react with oxygen, and the rate constants for the quenching process were measured, together with the rates of energy transfer from the triplet state to anthracene. These observations are considered in relation to the photoreactivity of these dyes.  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