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   568663篇
  免费   7629篇
  国内免费   1796篇
电工技术   10341篇
综合类   483篇
化学工业   85287篇
金属工艺   20505篇
机械仪表   16368篇
建筑科学   15376篇
矿业工程   2117篇
能源动力   15160篇
轻工业   55172篇
水利工程   5130篇
石油天然气   5674篇
武器工业   21篇
无线电   71463篇
一般工业技术   107699篇
冶金工业   105804篇
原子能技术   9767篇
自动化技术   51721篇
  2021年   4058篇
  2019年   3781篇
  2018年   6053篇
  2017年   6166篇
  2016年   6530篇
  2015年   4910篇
  2014年   8211篇
  2013年   26446篇
  2012年   14117篇
  2011年   19997篇
  2010年   15636篇
  2009年   17827篇
  2008年   18789篇
  2007年   19069篇
  2006年   16851篇
  2005年   15751篇
  2004年   15228篇
  2003年   14914篇
  2002年   14208篇
  2001年   14447篇
  2000年   13502篇
  1999年   14207篇
  1998年   32866篇
  1997年   23769篇
  1996年   18782篇
  1995年   14451篇
  1994年   13026篇
  1993年   12510篇
  1992年   9499篇
  1991年   9083篇
  1990年   8596篇
  1989年   8349篇
  1988年   8003篇
  1987年   6815篇
  1986年   6699篇
  1985年   8074篇
  1984年   7567篇
  1983年   6742篇
  1982年   6144篇
  1981年   6260篇
  1980年   5828篇
  1979年   5820篇
  1978年   5554篇
  1977年   6532篇
  1976年   8789篇
  1975年   4675篇
  1974年   4503篇
  1973年   4406篇
  1972年   3537篇
  1971年   3172篇
排序方式: 共有10000条查询结果,搜索用时 22 毫秒
91.
Many current implementations of protocols such as the Transmission Control Protocol/Internet Protocol (TCP/IP) are inefficient because data are often accessed more frequently than necessary. Three techniques that reduce the need for memory bandwidth are proposed. The techniques are copy-on-write, page remapping, and single-copy. Afterburner, a network-independent card that provides the services that are necessary for a single-copy protocol stack, is described. The card has 1 MByte of local buffers and provides a simple interface to a variety of network link adapters, including HIPPI and asynchronous transfer mode (ATM). Afterburner can support transfers to and from the link adapter card at rates up to 1 Gbit/s. An implementation of TCP/IP that uses the features provided by Afterburner to reduce the movement of data to a single copy is discussed. Measurements of the end-to-end performance of Afterburner and the single-copy implementation of TCP/IP are presented  相似文献   
92.
93.
Given the enormous size of the genome and that there are potentially many other types of measurements we need to do to understand it, it has become necessary to pick and choose one's targets to measure because it is still impossible to evaluate the entire genome all at once. What has emerged is a need to have rapidly customizable microarrays. There are two dominant methods to accomplish custom microarray synthesis, Affymetrix-like microarrays manufactured using light projection rather than semiconductor-like masks used by Affymetrix to mass manufacture their GeneChip/sup TM/ arrays now, or the ink-jet printing method employed by Agilent. The manufacture of these custom Affymetrix-like microarrays can now be done on a digital optical chemistry (DOC) machine developed at the University of Texas Southwestern Medical Center, and this method offers much higher feature numbers and feature density than is possible with ink-jet printed arrays. On a microarray, each feature contains a single genetic measurement. The initial DOC prototype has been described in several publications, but that has now led to a second-generation machine. This machine reliably produces a number of arrays daily, has been deployed against a number of biomedical questions, is being used in new ways and has also led to a number of spin-off technologies.  相似文献   
94.
95.
Functional Properties and Food Applications of Rapeseed Protein Concentrate   总被引:1,自引:0,他引:1  
Rapeseed protein concentrate (RC), prepared with 2% hexameta-phosphate, was tested for its functionality and performance in some foods. The RC had good nitrogen solubility, fat absorption, emulsification, and whipping capacities but poor water absorption and gelling properties. It increased the emulsion stability, and protein but lowered the fat content of wieners. It also increased the cooking yield, reduced the shrinkage and tenderized meat patties. Results were similar to soybean isolate except for the poorer color and flavor. The cooking yield of RC supplemented wieners was less than the all-meat control and soybean-supplemented wieners. A 9% RC dispersion mixed with an equal volume of eggwhite produced a meringue of comparable stability and texture to that of eggwhite alone.  相似文献   
96.
Translated from Atomnaya Énergiya, Vol. 67, No. 3, pp. 215–216, September, 1989.  相似文献   
97.
98.
J. Perahia comments on the paper by J. S. Hsu (see ibid., vol.16, p.192-7, 2001) and expands on the case of a two stator three phase squirrel cage induction machine where one stator housing is stationary and other stator housing is mounted on a worm gear assembly. The original author replies to the comments  相似文献   
99.
An investigation into the effects of pressure (helium gas) on the isothermal fluid behavior includes: (1) the effect of pressure on the rate of melting and coking as evidenced by the rate constants k(melt) and k(coke); (2) the effect of pressure on the energies of activation of melting and coking; (3) the effects of pressure on the characteristic times; (4) the effects of pressure on the maximum isothermal fluidity. Results from the effects of pressure on k(melt) revealed that it was generally the high total sulfur, low nitrogen, low reactives/mineral matter ratio, medium rank coals which show the greatest increase in k(melt), whereas the highest rank coals show the least decrease in k(coke). The energies of activation of melting and coking were not significantly affected by pressure. The investigation also reveals increases or decreases in the respective times of softening, maximum fluidity, resolidification and total time of fluid behavior under isothermal pressurized conditions. There appears the possibility that these shifts may be rank dependent. Additionally, the lower rank coals show the largest relative increase in their fluidities when subjected to pressure. Empirical relationships were derived in order to quantitatively predict the maximum isothermal fluidity for most (fluid) coals at a given pressure.  相似文献   
100.
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