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   333031篇
  免费   8494篇
  国内免费   3032篇
电工技术   6844篇
综合类   5135篇
化学工业   50536篇
金属工艺   16967篇
机械仪表   12083篇
建筑科学   8970篇
矿业工程   3635篇
能源动力   6888篇
轻工业   22597篇
水利工程   5058篇
石油天然气   9261篇
武器工业   486篇
无线电   34655篇
一般工业技术   66556篇
冶金工业   41891篇
原子能技术   7428篇
自动化技术   45567篇
  2022年   3048篇
  2021年   4502篇
  2020年   3369篇
  2019年   3540篇
  2018年   19507篇
  2017年   18524篇
  2016年   15397篇
  2015年   5005篇
  2014年   6518篇
  2013年   12333篇
  2012年   12103篇
  2011年   19605篇
  2010年   16829篇
  2009年   14591篇
  2008年   15768篇
  2007年   16318篇
  2006年   7531篇
  2005年   7819篇
  2004年   6923篇
  2003年   6675篇
  2002年   5912篇
  2001年   5405篇
  2000年   4899篇
  1999年   4745篇
  1998年   11707篇
  1997年   8189篇
  1996年   6184篇
  1995年   4493篇
  1994年   3901篇
  1993年   4157篇
  1992年   3098篇
  1991年   3121篇
  1990年   2973篇
  1989年   2943篇
  1988年   2957篇
  1987年   2581篇
  1986年   2646篇
  1985年   2938篇
  1984年   2736篇
  1983年   2592篇
  1982年   2354篇
  1981年   2336篇
  1980年   2408篇
  1979年   2390篇
  1978年   2405篇
  1977年   2583篇
  1976年   3054篇
  1975年   2200篇
  1974年   2084篇
  1973年   2178篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
Indium separation using ion exchange resins from acidic polymetallic and very diluted solutions are investigated. Since the selectivity of commercial ion exchange resins have proven to be too low for an effective separation from solutions with high content of other metals, Lewatit® TP 208 was impregnated with common extractants to enhance its properties. By resin impregnation with D2EHPA and Cyanex 272, not only the selective indium recovery was reached but also the resin capacity was increased approx. two times. The best loading and elution performance were shown by Cyanex 272-impregnated Lewatit® TP 208, increasing the indium purity in the eluate from 0.75 % to 85 %.  相似文献   
102.
For decades now, Douglas Crimp’s landmark 1980 essay ‘The Photographic Activity of Postmodernism’ has shaped our understanding of modernism’s aftermath, at least as it unfolded in North America and Western Europe. Less remembered, however, is the degree to which the procedures of disjunction, copying, appropriation, and outright theft that he highlighted were epitomised not just by contemporary photography, but by photomontage in particular. This article recovers the debates that led critics such as Crimp, Abigail Solomon-Godeau, Christopher Phillips, Benjamin Buchloh and others to turn to photomontage as one of their principal objects of concern in what became known as the postmodern critique of photography. Why was montage tasked to perform this critical function, particularly by people around the journal October who had not otherwise devoted the balance of their writing to photography’s history? The article suggests that these men and women, along with the contemporary artists they foregrounded, manifested what Mary Anne Doane has called a ‘desire for signification’, a reaction in the late 1970s against the mute theatricality of minimalist and conceptual art. Photomontage reintroduced representation to contemporary art and to the canon of art history. But unlike the reemerging illusionism in painting that also manifested this desire, montage guarded against an uncomplicated realism by highlighting and critiquing operations of representation in a manner that painting no longer could.  相似文献   
103.
Refractories and Industrial Ceramics - Results of studying the rheotechnological properties of moldable refractory mixes based on bauxite suspensions plasticized with refractory clay are presented....  相似文献   
104.
105.
Power Technology and Engineering - The major results from the survey and geotechnical monitoring during the leveling of the model foundation of the Zagorsk PSP-2 in test site No. 3 are presented....  相似文献   
106.
Journal of Communications Technology and Electronics - Approximate formulas for calculating the coefficient of reflection from an artificial magnetic conductor (AMC) based on a capacitive lattice...  相似文献   
107.
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   
108.
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   
109.
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   
110.
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   
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