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   162699篇
  免费   2117篇
  国内免费   668篇
电工技术   3328篇
综合类   191篇
化学工业   26356篇
金属工艺   6062篇
机械仪表   5147篇
建筑科学   4943篇
矿业工程   469篇
能源动力   4236篇
轻工业   17717篇
水利工程   1208篇
石油天然气   666篇
武器工业   6篇
无线电   22166篇
一般工业技术   30444篇
冶金工业   25680篇
原子能技术   2505篇
自动化技术   14360篇
  2021年   891篇
  2018年   1175篇
  2017年   1225篇
  2016年   1390篇
  2015年   1185篇
  2014年   1982篇
  2013年   7318篇
  2012年   3400篇
  2011年   4936篇
  2010年   3865篇
  2009年   4496篇
  2008年   4946篇
  2007年   5188篇
  2006年   4656篇
  2005年   4398篇
  2004年   4273篇
  2003年   4153篇
  2002年   4192篇
  2001年   4222篇
  2000年   3982篇
  1999年   3944篇
  1998年   7013篇
  1997年   5525篇
  1996年   4753篇
  1995年   3940篇
  1994年   3600篇
  1993年   3413篇
  1992年   3022篇
  1991年   2893篇
  1990年   2840篇
  1989年   2839篇
  1988年   2636篇
  1987年   2336篇
  1986年   2266篇
  1985年   2692篇
  1984年   2469篇
  1983年   2305篇
  1982年   2186篇
  1981年   2125篇
  1980年   1971篇
  1979年   1991篇
  1978年   1878篇
  1977年   2201篇
  1976年   2693篇
  1975年   1679篇
  1974年   1506篇
  1973年   1523篇
  1972年   1285篇
  1971年   1186篇
  1970年   1026篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The Kyoto Protocol to the United Nationsl Framework Convention on Climate Change gives a target for the reduction of greenhouse gases in the EU and most associated states of 8% from 1990 levels to 2010. The European Commissions Whitebook on Renewable Energy is setting a target of doubling the share of Renewable Energy from 6% now to 12% in 2010 for the European Union. There is no contradiction between these targets.  相似文献   
102.
An improved accelerated cable life test is described. Through the use of programmable logic controllers (PLCs), very precise and consistent control of the accelerated aging process has been achieved. A computer has been utilized to make continuous real-time acquisition and storage of key operating parameters possible. This precise control and monitoring methodology has permitted the study of the synergistic effects of voltage and temperature on the accelerated aging of full-sized cables in the laboratory  相似文献   
103.
104.
Group communication supports information transfer between a set of participants. It is becoming more and more relevant in distributed environments. For distributed or replicated data, it provides efficient communication without overloading the network. For some types of multimedia applications, it is the only way to control data transmission to group members. This paper surveys protocol functions and mechanisms for data transmission within a group, from multicast routing problems up to end-to-end multipoint transmission control. We provide a bibliography which is organized by topic  相似文献   
105.
Nuclear magnetic resonance imaging (MRI), calorimetry, and temperature measurements were used to monitor cylindrical potato sections frozen at -11C and -42C. MRI showed the advance of the nonsymmetric freezing zone and loss of signal intensity as liquid water turned to ice. Differential calorimetry was used to follow heat removal during transient freezing. Measured times to 95% enthalpy change were 24 min (-42C) and 49 min (-11C), as compared to modeled values of 29 min (-42C) and 100 min (-11C). Times to 95% change in the NMR signal, integrated over the area of the image, were 21 min (-42C) and 56 min (-11C). Changes in NMR signal intensity could be correlated with the amount of unfrozen water remaining after a steady-state had been reached. At -42C, NMR indicated 25% unfrozen water remaining as compared to 26% by calorimetry, and 22% by modeling. At -11C, NMR measured 67% unfrozen water remaining as compared to 48% by calorimetry, and 25% by equilibrium modeling.  相似文献   
106.
The authors present a successful model of industry/university cooperation in establishing a strong power system curriculum in both the graduate and undergraduate level. Numerous long-term and short-term research projects have been developed to satisfy the university mission and to tackle challenging problems facing the power industry. A unique structure for the Clemson University Electric Power Research Association (CUEPRA) has been established to promote electric power system research and to meet the need for a working communication link between the power industry and the academic community. The power industries involvements in the power program at Clemson University and the strategic improvements that have been accomplished in research and education are outlined  相似文献   
107.
The authors describe and discuss the new technique, multistep adaptive flux interpolation (MAFI), and its application to image data for coding. When applied to an image, MAFI produces an output which is also in an image form, but which has a more uniform feature density and a greatly reduced size. MAFI warps the input image by removing those rows and columns which contain a majority of redundant pixels. The side information required for reconstruction is minimal, and the image can be further compressed using conventional coders, making the compression ratio even higher. Because of its warped nature, the MAFI output's statistics are also more consistent with the properties assumed by block-based discrete cosine transform (DCT) methods  相似文献   
108.
Dynamic Programming (DP) applies to many signal and image processing applications including boundary following, the Viterbi algorithm, dynamic time warping, etc. This paper presents an array processor implementation of generic dynamic programming. Our architecture is a SIMD array attached to a host computer. The processing element of the architecture is based on an ASIC design opting for maximum speed-up. By adopting a torus interconnection network, a dual buffer structure, and a multilevel pipeline, the performance of the DP chip is expected to reach the order of several GOPS. The paper discusses both the dedicated hardware design and the data flow control of the DP chip and the total array.This work was supported in part by the NATO, Scientific and Environmental Affairs Division, Collaborative Research Grant SA.5-2-05(CRG.960201)424/96/JARC-501.  相似文献   
109.
  相似文献   
110.
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