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   38321篇
  免费   1914篇
  国内免费   476篇
电工技术   933篇
技术理论   8篇
综合类   5175篇
化学工业   1624篇
金属工艺   210篇
机械仪表   480篇
建筑科学   21808篇
矿业工程   648篇
能源动力   806篇
轻工业   2508篇
水利工程   413篇
石油天然气   275篇
武器工业   49篇
无线电   658篇
一般工业技术   2316篇
冶金工业   763篇
原子能技术   112篇
自动化技术   1925篇
  2024年   329篇
  2023年   333篇
  2022年   657篇
  2021年   771篇
  2020年   841篇
  2019年   662篇
  2018年   518篇
  2017年   764篇
  2016年   812篇
  2015年   1033篇
  2014年   3979篇
  2013年   2272篇
  2012年   2784篇
  2011年   2872篇
  2010年   2570篇
  2009年   2770篇
  2008年   2409篇
  2007年   2805篇
  2006年   2169篇
  2005年   1841篇
  2004年   1486篇
  2003年   1204篇
  2002年   1007篇
  2001年   869篇
  2000年   680篇
  1999年   553篇
  1998年   381篇
  1997年   292篇
  1996年   221篇
  1995年   153篇
  1994年   121篇
  1993年   111篇
  1992年   94篇
  1991年   67篇
  1990年   53篇
  1989年   27篇
  1988年   23篇
  1987年   32篇
  1986年   22篇
  1985年   24篇
  1984年   16篇
  1983年   15篇
  1982年   6篇
  1981年   4篇
  1980年   20篇
  1979年   4篇
  1973年   4篇
  1961年   3篇
  1960年   3篇
  1955年   3篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
An alternative approach to understanding innovation is made using two intersecting ideas. The first is that successful innovation requires consideration of the social and organizational contexts in which it is located. The complex context of construction work is characterized by inter-organizational collaboration, a project-based approach and power distributed amongst collaborating organizations. The second is that innovations can be divided into two modes: 'bounded', where the implications of innovation are restricted within a single, coherent sphere of influence, and 'unbounded', where the effects of implementation spill over beyond this. Bounded innovations are adequately explained within the construction literature. However, less discussed are unbounded innovations, where many firms' collaboration is required for successful implementation, even though many innovations can be considered unbounded within construction's inter-organizational context. It is argued that unbounded innovations require an approach to understand and facilitate the interactions both within a range of actors and between the actors and technological artefacts. The insights from a sociology of technology approach can be applied to the multiplicity of negotiations and alignments that constitute the implementation of unbounded innovation. The utility of concepts from the sociology of technology, including 'system building' and 'heterogeneous engineering', is demonstrated by applying them to an empirical study of an unbounded innovation on a major construction project (the new terminal at Heathrow Airport, London, UK). This study suggests that 'system building' contains outcomes that are not only transformations of practices, processes and systems, but also the potential transformation of technologies themselves.  相似文献   
3.
换填法建筑地基处理的工程实录   总被引:2,自引:0,他引:2  
结合某工程的地基处理,对换填法的应用作了较详细的阐述。  相似文献   
4.
Suspension cultures of tobacco cells were studied using airlift and rotary-drum bioreactors. The effect of initial concentrations of a major substrate, sucrose, on the growth and production of a secondary metabolite, phenolic compounds, was investigated. The dry weights and total concentrations of the phenolic compounds increased with the initial sucrose concentration in both bioreactors. Both bioreactors were found to have the same tendency for the effect of initial sucrose concentration. The structured model, presented previously was modified by considering that sucrose was hydrolyzed to glucose and fructose by an enzymatic reaction. The previous and the new models were applied to the above two sets of experimental data obtained with two bioreactors, independently. The hydrolysis of sucrose was elucidated to contribute slightly to the overall kinetics of growth and secondary metabolite production in these cultures. Furthermore, the levels of shear damage in each bioreactor were quantitatively compared based on the death rate constant, ki, which is one of the model constants.  相似文献   
5.
6.
The study revealed that Fixed Price, Cost Plus and Purchased Labour contracts are the top three maintenance contracts adopted whilst Unit Price, Cost Plus A Percentage Fee contracts are alternatives used in the Kingdom. Some other types of maintenance contract were thought to be inappropriate by ministry departments.  相似文献   
7.
门式脚手架在已建高层建筑外装修中的应用   总被引:1,自引:0,他引:1  
介绍门式脚手架在已建高层建筑外排栅中的整体搭设和应用实例。  相似文献   
8.
The widening of interest and scope of property management and maintenance has attracted a greater diversity of professional disciplines into facilities management. Dr Quah, coordinator of CIB W70 on Management, Maintenance and Modernization of Building facilities, expresses her personal views on the current fascination with the subject.  相似文献   
9.
10.
A time‐dependent coefficient of heat transfer is proposed for the computation of thermal power required, so that a room temperature reaches a desired value within a given time. A mathematical formulation of the room heating transient phenomenon is constructed in a dimensionless form. Using an integral approximate solution an analytical expression for this coefficient is provided and it is verified by diagrams adopted by DIN 4701. Copyright © 2003 John Wiley & Sons, Ltd.  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