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   424526篇
  免费   6076篇
  国内免费   1949篇
电工技术   8449篇
技术理论   4篇
综合类   1351篇
化学工业   63497篇
金属工艺   17269篇
机械仪表   14374篇
建筑科学   9895篇
矿业工程   2572篇
能源动力   12105篇
轻工业   29814篇
水利工程   4561篇
石油天然气   8598篇
武器工业   99篇
无线电   51289篇
一般工业技术   85916篇
冶金工业   77332篇
原子能技术   9474篇
自动化技术   35952篇
  2022年   2983篇
  2021年   4494篇
  2020年   3379篇
  2019年   4242篇
  2018年   7012篇
  2017年   7013篇
  2016年   7429篇
  2015年   4936篇
  2014年   7908篇
  2013年   21253篇
  2012年   12467篇
  2011年   16499篇
  2010年   13128篇
  2009年   14802篇
  2008年   15060篇
  2007年   14819篇
  2006年   13455篇
  2005年   11870篇
  2004年   11258篇
  2003年   11204篇
  2002年   10801篇
  2001年   10535篇
  2000年   9704篇
  1999年   10034篇
  1998年   24712篇
  1997年   17070篇
  1996年   13134篇
  1995年   9811篇
  1994年   8624篇
  1993年   8634篇
  1992年   6263篇
  1991年   5823篇
  1990年   5817篇
  1989年   5446篇
  1988年   5172篇
  1987年   4542篇
  1986年   4401篇
  1985年   4920篇
  1984年   4520篇
  1983年   4091篇
  1982年   3717篇
  1981年   3804篇
  1980年   3490篇
  1979年   3377篇
  1978年   3405篇
  1977年   3801篇
  1976年   4888篇
  1975年   2889篇
  1974年   2702篇
  1973年   2763篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Four weaning food formulations prepared from 70% 72-hr germinated rice/corn and 30% 48-hr germinated mungbean/cowpea were studied for tocopherol constituents and compared to ungerminated controls. γ-TocopheroIs were the major constituents of the mungbean-supplemented samples. The cowpea-supplemented foods contained a predominance of δ-tocopherols followed closely by γ-tocopherols, α-Tocopherols were comparatively higher in corn- than in rice-formulations. Tocopherols in the weaning foods decreased due to germination especially the γ-tocopherols of germinated corn-mungbean.  相似文献   
993.
Among functional properties studied, water- anf fat-holding capacities were higher for puffed grain flour. Gelation was not affected, while foaming was adversely affected by puffing. A decrease in viscosity of flour pastes also resulted due to puffing.  相似文献   
994.
For heat treating cylindrical metal billets, their lay-out in a furnace usually resembles that of an in-line heat-exchanger tube bank, with the air flows orthogonal to the billets. For maximum effectiveness of transferring thermal energy from the forced convecting air to the billets, the optimal horizontal pitch-to-diameter ratio for the billets should be 1·33 ± 0·05. For this same purpose it is advantageous to employ a vertical spacing (between the billets) as large as can be permitted for a given load of billets.  相似文献   
995.
After investigating the financial feasibility (and so abandoning the idea) of providing self-generated electricity using hydro-power, it was recommended that the top priority should be the direct connection of an electricity supply, from the mains grid to the building; this would cost £8800. Thereby, the theatre would receive a relatively unrestricted supply of electricity at cheaper unit tariffs. This improvement should be followed by the most urgent repairs being carried out to the building fabric, at an estimated cost of £6990. These repairs are necessary to ensure the continued integrity of the building's structure, thereby inhibiting the on-going deterioration.

The energy and financial appraisal also suggested a priority listing of overall improvements to the building in order to achieve a significant, economically justifiable reduction in energy demand; the recommended options are estimated to cost in total £39819. However, the capital cost of such an upgrading would only be recouped, and the theatre achieve a sustainable future, if the building were to be used more intensively and for a wider range of activities than at present in order to increase its revenue significantly.

All prices as stated are those at August 1991.  相似文献   

996.
997.
998.
A reinforcement learning algorithm based on supervised learning is described. It uses associative search to discover and learn actions that make the system perform a desired task. One problem with associative search is that the system's actions are often inconsistent. In the searching process, the system's actions are always decided stochastically, so the system cannot perform learned actions more than once, even if they have been determined to be suitable actions for the desired task. To solve this problem, a neural network that can predict an evaluation of an action and control the influence of the stochastic element is used. Results from computer simulations using the algorithms to control a mobile robot are described  相似文献   
999.
1000.
Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 12, pp. 15–16, December, 1992.  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