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   448316篇
  免费   7186篇
  国内免费   1452篇
电工技术   8178篇
综合类   446篇
化学工业   68990篇
金属工艺   17498篇
机械仪表   13435篇
建筑科学   11120篇
矿业工程   1953篇
能源动力   11265篇
轻工业   43276篇
水利工程   4425篇
石油天然气   6741篇
武器工业   76篇
无线电   52230篇
一般工业技术   84138篇
冶金工业   83414篇
原子能技术   8991篇
自动化技术   40778篇
  2021年   4121篇
  2020年   3182篇
  2019年   4028篇
  2018年   6829篇
  2017年   6808篇
  2016年   7235篇
  2015年   4950篇
  2014年   7783篇
  2013年   21181篇
  2012年   12693篇
  2011年   16323篇
  2010年   12989篇
  2009年   14303篇
  2008年   15125篇
  2007年   14913篇
  2006年   12926篇
  2005年   11836篇
  2004年   11396篇
  2003年   10908篇
  2002年   10528篇
  2001年   10374篇
  2000年   9833篇
  1999年   10160篇
  1998年   25487篇
  1997年   18218篇
  1996年   14001篇
  1995年   10655篇
  1994年   9236篇
  1993年   9175篇
  1992年   6896篇
  1991年   6502篇
  1990年   6190篇
  1989年   6004篇
  1988年   5798篇
  1987年   5106篇
  1986年   4947篇
  1985年   5762篇
  1984年   5373篇
  1983年   4887篇
  1982年   4539篇
  1981年   4746篇
  1980年   4429篇
  1979年   4297篇
  1978年   4090篇
  1977年   5040篇
  1976年   6532篇
  1975年   3717篇
  1974年   3679篇
  1973年   3761篇
  1972年   3041篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
This paper deals with accurate recipe implementation for abnormal condition management in a batch process using a case‐based reasoning (CBR) approach. A set of new problems can be solved by reusing proven process solutions. The proposed system integrates quantitative and qualitative parameters for adaptation of cases. A novel methodology to generate accurate recipes and to adapt to the processes is introduced during normal and abnormal conditions. In particular, the differences between current conditions and the references (recipes) should be managed to prevent any hazardous conditions arising. The processes are evaluated using their similarity to the past cases. This intelligent approach distinguishes plausible cases, generates accurate recipes, and adapts to new situations. The aim is to use the offline historical process data and safety related information in order to propose changes and adjustments in the processes.  相似文献   
102.
103.
104.
105.
106.
107.
108.
Some of the options for optical technology within the local loop environment are examined. In particular, passive shared access networks have been considered in some detail. These networks show great promise for delivering existing telephone services to small to medium business customers (4-30 lines) economically by the early 1990s. Extending fiber to the home will also be possible by virtue of a similar passive network infrastructure for customers requiring new broadband services beyond the single telephone line. For one-line plain old telephone service (POTS) customers, an intermediate approach of terminating the fiber network at the final network distribution point, with copper retained for the final leg, may be used prior to the provision of broadband services. A key feature of the passive optical network architecture is the use of wavelength-division multiplexing (WDM) as an upgrade strategy, allowing graceful upgrading from telephone services to multichannel high-definition television (HDTV) on gigabit/second bearers and full two-way switched broadband services employing wavelength routing across the network  相似文献   
109.
In the approach to a cycle-invariant state in the forced feed concentration cycling of the CO oxidation over a NiO catalyst, a very long transient has been observed lasting 80 ks or more. This transient appears to be associated only with CO pretreatment of the catalyst and is not a general phenomenon. The slow convergence to the cycle-invariant state reported in certain modelling calculations in the literature appears to have a different cause.  相似文献   
110.
The comfort diagrams and the so-called PMV-PPD values are already used today directly and indirectly in a wide field in technical practice, even at a standard level. This theory is known also in Hungary, and the PMV-PPD values have been used by us for the solution of a design problem. The task was to elaborate a calculation method, an index number suitable for the determination of the thermal confort effect in the case of occasional underheating of residential and communal buildings in winter.The results of this work are presented in this paper.  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