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   858篇
  免费   51篇
  国内免费   3篇
电工技术   15篇
综合类   3篇
化学工业   221篇
金属工艺   20篇
机械仪表   14篇
建筑科学   49篇
矿业工程   36篇
能源动力   29篇
轻工业   56篇
水利工程   22篇
无线电   54篇
一般工业技术   186篇
冶金工业   124篇
原子能技术   3篇
自动化技术   80篇
  2023年   13篇
  2022年   14篇
  2021年   30篇
  2020年   17篇
  2019年   18篇
  2018年   27篇
  2017年   25篇
  2016年   25篇
  2015年   30篇
  2014年   33篇
  2013年   50篇
  2012年   46篇
  2011年   63篇
  2010年   49篇
  2009年   36篇
  2008年   42篇
  2007年   47篇
  2006年   41篇
  2005年   33篇
  2004年   25篇
  2003年   28篇
  2002年   7篇
  2001年   9篇
  2000年   12篇
  1999年   12篇
  1998年   41篇
  1997年   17篇
  1996年   13篇
  1995年   11篇
  1994年   9篇
  1993年   10篇
  1992年   5篇
  1991年   8篇
  1990年   5篇
  1989年   2篇
  1987年   5篇
  1986年   6篇
  1985年   2篇
  1983年   4篇
  1982年   2篇
  1981年   4篇
  1980年   3篇
  1979年   3篇
  1976年   6篇
  1970年   5篇
  1931年   1篇
  1928年   1篇
  1921年   2篇
  1920年   4篇
  1913年   1篇
排序方式: 共有912条查询结果,搜索用时 15 毫秒
21.
Scoring and double-sided due diligence processes employed with vendor selection for IT infrastructure outsourcing Outsourcing opens the procurement of semi-finished products from business partners that are able to provide the respective processes in the required quality but at lower prices, e. g. because of bundling effects and specialization advantages. In particular, services that are not based on core-processes of an enterprise are well-suited for outsourcing. The evaluation of IT service outsourcing is difficult, because of its strategic position in enterprises. Against this background, this article describes a method to select a suitable vendor for IT infrastructure outsourcing employing scoring and double-sided due diligence processes. Our findings are based on experiences when selecting the vendor for outsourcing the European Information Technology Infrastructure (IT/I) area of the Deutsche Bank AG.  相似文献   
22.
23.
Locales are a module system for managing theory hierarchies in a theorem prover through theory interpretation. They are available for the theorem prover Isabelle. In this paper, their semantics is defined in terms of local theories and morphisms. Locales aim at providing flexible means of extension and reuse. Theory modules (which are called locales) may be extended by definitions and theorems. Interpretation to Isabelle’s global theories and proof contexts is possible via morphisms. Even the locale hierarchy may be changed if declared relations between locales do not adequately reflect logical relations, which are implied by the locales’ specifications. By discussing their design and relating it to more commonly known structuring mechanisms of programming languages and provers, locales are made accessible to a wider audience beyond the users of Isabelle. The discussed mechanisms include ML-style functors, type classes and mixins (the latter are found in modern object-oriented languages).  相似文献   
24.
25.
26.
27.
γ-Alumina extrudates for chemical-looping combustion in fluidized bed reactors were shaped by varying acetic acid concentrations between 0.07 and 3.76 M. Influence of pseudo-boehmite peptization on structural properties, microstructure, chemical phases and attrition resistance was determined. With addition of acetic acid, the d90 of boehmite agglomerates after 1 h kneading decreased from 134 to 40 μm at pH 4. Due to this, the extrusion diameter was reduced from 1500 to 200 μm, as well as median pore radii (from 30.1 to 5.3 nm). Porosity was about 70%. Addition of more than 1.87 M acid lead to a slight increase in mesopore sizes caused by some pore blocking caused by the formation of aluminium acetate salts. A small micropore surface was determined with t-layer model from Harkins and Jura. Higher attrition resistance was observed for samples peptized with lower acid concentration because of the closer contact between particles after decomposition.  相似文献   
28.
Solid solution-strengthened ductile iron (DI) exhibits outstanding mechanical properties due to the high silicon content. The strengthening by silicon addition is limited since additions above 4.3?wt-% lead to embrittlement. For a further improvement of mechanical properties, other alloying elements need to be considered. In the present work, the effect of various copper additions on the microstructure and the mechanical properties of solid solution-strengthened DI were investigated. The results show that no appreciable strengthening can be achieved by copper addition without the formation of pearlite in the matrix. The pearlite content increases considerably for Cu-additions above 0.23?wt-% and is independent of the cooling rate for the cooling conditions analysed.  相似文献   
29.
30.
Solid-state phase transformations and grain growth of an intermetallic γ-TiAl alloy were investigated in-situ using high-temperature laser scanning confocal microscopy (HTLSCM). During isothermal annealing in the single β-phase region, significant grain coarsening was observed. On cooling beneath the β-transus temperature with different rates, a CCT diagram was evaluated for the initiation of β to α phase transformation and changes in the morphology were observed.  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