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   206168篇
  免费   2416篇
  国内免费   565篇
电工技术   3531篇
综合类   141篇
化学工业   31874篇
金属工艺   10267篇
机械仪表   7017篇
建筑科学   3998篇
矿业工程   2161篇
能源动力   4643篇
轻工业   12880篇
水利工程   2921篇
石油天然气   7726篇
武器工业   22篇
无线电   21519篇
一般工业技术   45193篇
冶金工业   34468篇
原子能技术   6623篇
自动化技术   14165篇
  2021年   2054篇
  2019年   2001篇
  2018年   3680篇
  2017年   3719篇
  2016年   4003篇
  2015年   2234篇
  2014年   3787篇
  2013年   8750篇
  2012年   5688篇
  2011年   7221篇
  2010年   5860篇
  2009年   6501篇
  2008年   6619篇
  2007年   6501篇
  2006年   5573篇
  2005年   5124篇
  2004年   4631篇
  2003年   4562篇
  2002年   4369篇
  2001年   4475篇
  2000年   4186篇
  1999年   4211篇
  1998年   10213篇
  1997年   7205篇
  1996年   5510篇
  1995年   4146篇
  1994年   3602篇
  1993年   3845篇
  1992年   2987篇
  1991年   2996篇
  1990年   2894篇
  1989年   2857篇
  1988年   2868篇
  1987年   2512篇
  1986年   2570篇
  1985年   2855篇
  1984年   2689篇
  1983年   2560篇
  1982年   2301篇
  1981年   2272篇
  1980年   2345篇
  1979年   2359篇
  1978年   2384篇
  1977年   2488篇
  1976年   2882篇
  1975年   2190篇
  1974年   2070篇
  1973年   2166篇
  1972年   1940篇
  1971年   1757篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
The chromium (Cr) evaporation behavior of several different types of iron (Fe)-based AFA alloys and benchmark Cr2O3-forming Fe-based 310 and Ni-based 625 alloys was investigated for 500 h exposures at 800 °C to 900 °C in air with 10% H2O. The Cr evaporation rates from alumina-forming austenitic (AFA) alloys were ~5 to 35 times lower than that of the Cr2O3-forming alloys depending on alloy and temperature. The Cr evaporation behavior was correlated with extensive characterization of the chemistry and microstructure of the oxide scales, which also revealed a degree of quartz tube Si contamination during the test. Long-term oxidation kinetics were also assessed at 800 to 1000 °C for up to 10,000 h in air with 10% H2O to provide further guidance for SOFC BOP component alloy selection.  相似文献   
72.
Power Technology and Engineering - The monitoring of hydraulic structures as high-risk facilities is discussed. Monitoring should ensure the reliability and functioning of a hydraulic structure...  相似文献   
73.
Theoretical Foundations of Chemical Engineering - A choline chloride–sulfosalicylic acid deep eutectic solvent (DES) is proposed for dissolving the oxides Co(II), Cu(II), Zn(II), Fe(III),...  相似文献   
74.
Atomic Energy - The results of calculations and experimental determination of the neutronics characteristics of the IRT-T research reactor are presented. The IRT-T reactor is a pool reactor with...  相似文献   
75.
Journal of Inorganic and Organometallic Polymers and Materials - The reaction of potassium tetracyanocupprate(I) with triethyltin bromide in presence of phenanthroline (Phen) and quinoxaline (Qox)...  相似文献   
76.
Strength of Materials - The paper addresses the investigation of high-strain rate compressive behavior of Al foams subjected to impact at the intermediate striking velocity ranged from 40 to...  相似文献   
77.
78.
Potentiometric sensors with plasticized poly(vinyl chloride) membranes based on β-lactam–tetraalkylammonium ion associates sensitive to penicillin antibiotics are proposed. The physicochemical characteristics (solubility product constants and dissociation constants) of active membrane components and the electrode, transport, and selective properties of the membranes of liquidand solid-contact sensors have been studied. The quantitative characteristics of membrane transport (penetrability, ion flux, and transport rate) have been evaluated. The main charge carriers in the membranes and at the membrane/solution interface have been determined from the membrane transport characteristics. The potentiometric sensors are shown to be applicable to the determination of penicillin antibiotics in biological fluids (blood serum and oral fluid) from patients with urinary tract infection.  相似文献   
79.
80.
The authors have developed a procedure and a test bench for studying evolution of various nature physical fields in modeling geomedium fracture by fluids. The test bench performs synchronous recording of macro- and micro-deformation, heat and acoustic emission induced in physical models of geomedium under loading to discontinuity. The experimental procedure has been trialed. The analysis of the synchronized test data allows a conclusion on the existence of time–space relationship between different nature physical fields induced during failure of solids.  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