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   5791篇
  免费   770篇
  国内免费   580篇
电工技术   344篇
综合类   264篇
化学工业   226篇
金属工艺   136篇
机械仪表   1098篇
建筑科学   115篇
矿业工程   70篇
能源动力   105篇
轻工业   46篇
水利工程   94篇
石油天然气   25篇
武器工业   24篇
无线电   958篇
一般工业技术   303篇
冶金工业   59篇
原子能技术   11篇
自动化技术   3263篇
  2024年   13篇
  2023年   52篇
  2022年   78篇
  2021年   94篇
  2020年   118篇
  2019年   121篇
  2018年   151篇
  2017年   180篇
  2016年   199篇
  2015年   256篇
  2014年   380篇
  2013年   395篇
  2012年   473篇
  2011年   548篇
  2010年   407篇
  2009年   379篇
  2008年   371篇
  2007年   416篇
  2006年   334篇
  2005年   314篇
  2004年   223篇
  2003年   198篇
  2002年   175篇
  2001年   152篇
  2000年   142篇
  1999年   181篇
  1998年   138篇
  1997年   156篇
  1996年   137篇
  1995年   85篇
  1994年   47篇
  1993年   48篇
  1992年   30篇
  1991年   35篇
  1990年   22篇
  1989年   22篇
  1988年   16篇
  1987年   8篇
  1986年   5篇
  1985年   4篇
  1984年   8篇
  1983年   8篇
  1982年   2篇
  1981年   2篇
  1980年   4篇
  1979年   3篇
  1977年   2篇
  1972年   2篇
  1958年   1篇
  1955年   1篇
排序方式: 共有7141条查询结果,搜索用时 15 毫秒
11.
介绍CCD(chargecoupleddevices)传感器与激光光源、成象系统、二值化电路、电子计算机等组成的钢丝直径测试装置的工作原理、光学系统自动选择和检测电路系统及其优越的工作性能、广阔的应用前景。  相似文献   
12.
根据实际要求和目前的注油方法及装置的情况,提出了真空循环注油的思想,设计并研制成功了这种注油装置;介绍了它的工作过程原理、特点及应用情况.  相似文献   
13.
When designing a multimedia server, several things must be decided: which scheduling scheme to adopt, how to allocate multimedia objects on storage devices, and the round length with which the streams will be serviced. Several problems in the designing of large-scale multimedia servers are addressed, with the following contributions: (1) a striping scheme is proposed that minimizes the number of seeks and hence maximizes the performance; (2) a simple and efficient mechanism is presented to find the optimal striping unit size as well as the optimal round length, which exploits both the characteristics of VBR streams and the situation of resources in the system; and (3) the characteristics and resource requirements of several scheduling schemes are investigated in order to obtain a clear indication as to which scheme shows the best performance in realtime multimedia servicing. Based on our analysis and experimental results, the CSCAN scheme outperforms the other schemes. It is believed that the results ar  相似文献   
14.
Fabrication process of open surfaces by robotic fibre placement   总被引:3,自引:2,他引:3  
Composite materials are being used extensively in many industrial sectors. They offer excellent material properties compared to other structural materials available. However, the traditional fabrication process using manual hand lay-up is time consuming and labour intensive. Therefore, robotic fibre placement has been introduced to overcome these drawbacks. This approach may greatly reduce cycle time and manufacturing costs. This paper describes the overall strategy for the establishment of a flexible robotic fibre placement technique. The fabrication process planning of this new technique is presented. Three different types of fibre placement for open surfaces are discussed. These include simulation-based fibre path generation, fibre steering, and sensory-based contour following methodologies. The system architecture for the process control is also presented.  相似文献   
15.
TES microcalorimeter readout via transformer   总被引:1,自引:0,他引:1  
Readout configuration for Transition Edge Sensor (TES) electrically coupled to a low noise warm front-end via transformer is studied. The study was aimed at the implementation of the readout involved in imaging with microcalorimeter detector arrays using frequency multiplexing technique (Appl. Phys. Lett. 81(1) (2002) 159). A model describing both TES electrothermal reaction and the readout response is investigated. Contribution of electronic noise to TES energy resolution is calculated. Prospective readout architecture with TES electrical biasing from the warm readout side is introduced. The architecture allows building of large imaging detector arrays with TES. It is shown that an unprecedented combination of imaging and spectrometry features can be achieved with TES readout via transformer.  相似文献   
16.
王魁汉  吴向中  董健 《粉末冶金技术》2015,33(2):140-146,155
从粉末冶金行业的精确生产与优质高效的战略出发,简述粉末冶金行业用钨铼热电偶的特点、分类与使用。详细论述粉末冶金真空炉专用超高真空(10~5 Pa)、超高压(15 MPa)密封式热电偶及炉温均匀性测试等新型传感器。详细探讨真空炉测温准确度的影响因素:真空度、发射率、热导率、热响应时间及热电偶的插入深度、热电偶保护管的选择等;简介进口真空炉专用热电偶国产化研究,国内外温度传感器性能对比及替代进口真空炉热电偶的成功业绩。目前,对测温系统的检定,多采用分立元件法,即对构成测温系统的元件及仪表分别进行检定。此种检定方法是离线的。本文简述离线式检定方法的诸多弊端以及美国宇航标准(AMS 2750E)中,有关系统准确度校准的特点及要求。详细论述在线原位校准的最新理念,最佳的系统准确度校准方案,并开发出与其配套、行之有效的带有校准孔的热电偶及便携式在线校准仪。为了提高测温系统的准确度,建议采用在线原位校准,方便易行,现已在国内推广应用。  相似文献   
17.
The system considered is a generalized system E = Ax + Bu, Y = Cx with matrix E singular. When the impulsive modes of the system are both controllable and observable, it is shown in this paper that these modes can be eliminated by almost any constant output feedback. For a strongly controllable and observable generalized system, after its impulsive modes are eliminated, the poles of the system can be assigned arbitrarily by state feedback. Even if the states are not available, the paper adopts an efficient method to design a compensator for the system.  相似文献   
18.
为解决未知系统的PID控制问题,根据PID控制及零极点配置控制理论,详细讨论了零极点配置PID控制器、智能PID控制器的构成过程.该控制器结构简单,实用性强,控制器的阶数仅与被控系统的传递函数分子多项式阶数m有关,而与分母多项式阶数n无关,可以用低阶控制器控制高阶系统,通过大量的仿真试验研究,说明该智能控制器具有良好的自适应性和鲁棒性.  相似文献   
19.
《Ergonomics》2012,55(14):1302-1311
In this experiment all panels had four circular displays arranged in a square on a vertical surface and four controls aligned vertically to the right of the displays. Two panels had linkages between controls and displays which earlier research had shown to be compatible, the other two had incompatible linkages. Each of these four panels was tested with and without sensor lines showing the linkages between controls and displays. Ninety-six subjects each made 128 trials on one of the eight panels. A subject's task was to respond as quickly as possible by pushing the correct control to extinguish a light when it appeared in one of the displays. Sensor lines had no effect on performance with the compatible panels but impaired performance on the incompatible panels. The results also confirm again the potency of the compatibility principle: responses were faster and fewer errors were made when using the compatible panels.  相似文献   
20.
LED生产过程中的质量控制   总被引:2,自引:0,他引:2  
对LED封装过程可能出现的问题逐一指出,并提出解决的办法,着重介绍封装位置对LED发光亮度的影响。以期引起LED封装管理人员及工作人员的注意。  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