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   152106篇
  免费   1889篇
  国内免费   658篇
电工技术   3117篇
综合类   188篇
化学工业   24144篇
金属工艺   5784篇
机械仪表   4946篇
建筑科学   4435篇
矿业工程   378篇
能源动力   3930篇
轻工业   17330篇
水利工程   1143篇
石油天然气   618篇
武器工业   5篇
无线电   20517篇
一般工业技术   28903篇
冶金工业   23776篇
原子能技术   2350篇
自动化技术   13089篇
  2019年   837篇
  2018年   1081篇
  2017年   1132篇
  2016年   1275篇
  2015年   1064篇
  2014年   1799篇
  2013年   6581篇
  2012年   3194篇
  2011年   4614篇
  2010年   3601篇
  2009年   4158篇
  2008年   4654篇
  2007年   4920篇
  2006年   4354篇
  2005年   4110篇
  2004年   4003篇
  2003年   3906篇
  2002年   3937篇
  2001年   3985篇
  2000年   3742篇
  1999年   3697篇
  1998年   6647篇
  1997年   5234篇
  1996年   4468篇
  1995年   3712篇
  1994年   3364篇
  1993年   3187篇
  1992年   2788篇
  1991年   2697篇
  1990年   2630篇
  1989年   2616篇
  1988年   2462篇
  1987年   2171篇
  1986年   2117篇
  1985年   2563篇
  1984年   2321篇
  1983年   2202篇
  1982年   2071篇
  1981年   1997篇
  1980年   1863篇
  1979年   1880篇
  1978年   1773篇
  1977年   2087篇
  1976年   2571篇
  1975年   1587篇
  1974年   1437篇
  1973年   1457篇
  1972年   1200篇
  1971年   1117篇
  1970年   949篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
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   
102.
  相似文献   
103.
104.
Symmetrically substituted 1,3-diynes containing hydroxyalkyl ( 1a-d ), bromoalkyl ( 1e-h ) (diphenylphosphinyl) ( 1i-k ) and carboxyalkyl ( 2a-d ) substituents have been prepared and characterised; the phosphine derivative ( 1k ) has been converted with alkyl iodides ( RI ; R = Me, Et) into bis(phosphonium) salts ( 1l and m ). During preparation of the diynedioic acid. ( 2a ), the non-centrosymmetrical diyne, HO2CCH2C?C—C?C(CH2)2OH ( 3 ), was also isolated. 60Co γ-Irradiation of diacetylene monomers ( 2a – d ) and 10,12-tricosadiyn-1-oic acid gave the corresponding polydiacetylene derivatives ( 4a – d and 5 ), respectively. Rubidium salts of ( 4c ) and ( 4d ), a barium salt of ( 4c ), and a potassium salt of ( 5 ) were prepared and isolated; soluble potassium salts of the carboxylic acid polymers ( 4 ) were generated in aqueous solution. The effects of changes in pH on the UV/visible absorption spectra of aqueous solutions of selected carboxylic acid polydiacetylenes have been recorded, and are discussed.  相似文献   
105.
Dimensionless material balance equations describing an uninhibited enzyme hydrolysis process in a semi-batch reactor (i.e. fed-batch reactor) are formulated; numerical solution of these equations provided concentration profiles of the enzyme-substrate complex by using published kinetic parameters. The unrestricted values obtained are compared with estimates based separately on the reaction steady state and stationary state assumptions. Results are discussed in terms of the enzyme/substrate inventory used and it is found that the reaction steady state is a satisfactory approximation only when this ratio is sufficiently small. The stationary state may be a better approximation at other values, particularly when enzyme is added to substrate or when an empty tank is being filled. Reaction yields from semi-batch and batch operations are compared. Processing takes longer in the semi-batch operations and complete conversions are only practical in this mode when enzyme is added to substrate.  相似文献   
106.
Susceptibility testing with antifungal agents, e. g., minimum inhibitory concentration (MIC) determination, is performed to obtain reliable data that permit selection of the most suitable agents for treatment of an infective condition. To determine the drugs that provide maximum effectiveness against oral candidiasis, the MICs of various antifungal agents were determined. Also, synergism between two chosen antifungal agents was evaluated, and the effect of benzocaine, an anesthetic, and hydrocortisone, an antiinflammatory agent, on their MICs was examined. It was observed that among all the drugs tested, clotrimazole was the most promising candidate for use as an oral local antifungal. The combination of clotrimazole and chlorhexidine resulted in a decrease in the MIC. While the addition of hydrocortisone to this combination resulted in a slight increase in the MIC, the inclusion of benzocaine resulted in a substantial decrease in the MIC of the antifungal agent combination.  相似文献   
107.
108.
In order to control a project, construction management requires project information. This is obtained through accounting, estimating, cost management and scheduling functions which produce project reports. These reports are best obtained by subdividing the project into small parts. The ways in which each of these functions subdivides a project in order to produce its reports is discussed, together with a means of interrelating this information with a technique known as the work breakdown structure.  相似文献   
109.
110.
A mathematical model was developed to describe the removal of volatile organic compounds from drinking water in aeration basins. The model was used to simulate removal under a range of expected treatment conditions using the Continuous Systems Modeling Program. Results indicated that temperature and air-to-water ratio are the major factors influencing the removal of chloroform from water in an aeration basin. Bubble diameter was a lesser factor while liquid residence time had the smallest effect of the variables examined.  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