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   677篇
  免费   22篇
  国内免费   9篇
电工技术   18篇
综合类   29篇
化学工业   154篇
金属工艺   35篇
机械仪表   15篇
建筑科学   93篇
矿业工程   30篇
能源动力   49篇
轻工业   33篇
水利工程   2篇
石油天然气   1篇
武器工业   1篇
无线电   55篇
一般工业技术   79篇
冶金工业   10篇
原子能技术   11篇
自动化技术   93篇
  2023年   12篇
  2022年   9篇
  2021年   21篇
  2020年   19篇
  2019年   21篇
  2018年   8篇
  2017年   14篇
  2016年   12篇
  2015年   8篇
  2014年   38篇
  2013年   42篇
  2012年   49篇
  2011年   73篇
  2010年   52篇
  2009年   57篇
  2008年   50篇
  2007年   44篇
  2006年   31篇
  2005年   27篇
  2004年   15篇
  2003年   15篇
  2002年   21篇
  2001年   9篇
  2000年   7篇
  1999年   6篇
  1998年   6篇
  1997年   5篇
  1996年   8篇
  1995年   5篇
  1994年   5篇
  1993年   4篇
  1992年   2篇
  1991年   2篇
  1990年   1篇
  1989年   2篇
  1988年   1篇
  1985年   3篇
  1983年   1篇
  1982年   3篇
排序方式: 共有708条查询结果,搜索用时 609 毫秒
71.
72.
房间空调器用换热器的技术进步   总被引:3,自引:0,他引:3  
本文综述了房间空调器中使用的换热器的总体结构、铜管铝翅片结构的发展和性能的提高 ,指出了换热器的性能提高对空调器能效比的改善、节能和环保 ,以及制冷剂的替代都起着重要的作用  相似文献   
73.
分析了告成煤矿井底侯罐室地臌的原因,针对性地采取了注浆堵水和以U型钢底梁、金属网为骨架的混凝土反底拱进行治理,保证地板砖的铺设,具有一定的借鉴价值。  相似文献   
74.
采用常温固相反应法在聚乙二醇2000作为分散剂条件下制备了纳米Cu O,用超声共混法制备了纳米Al/Cu O。借助X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等方法对所制备样品的性能进行表征和分析。结果表明:制备的纳米Cu O结构形貌统一,类似八面体结构,一次粒径在30nm左右,和球形的纳米Al粉混合均匀,形成纳米Al/Cu O,团聚后在100~200nm之间,差热分析(DTA)其放热量为2 798J·g-1。将纳米Al/Cu O配制成含能油墨,用喷墨打印装置实现了药室直径为0.7mm、厚度为1mm的10×10阵列装药,并研究了纳米Al/Cu O在微孔装药中的应用。结果表明,纳米Al/Cu O在微孔中能稳定燃烧,燃烧时间在微秒级,火焰长度约为2~4cm,燃速约为0.142 9m/s。  相似文献   
75.
某建筑物安装有一台无机房电梯,因受现场条件限制.原有的曳引钢丝绳平层标识达不到应急救援的要求,故综合现场实际情况。提出了一种在限速器钢丝绳上设置平层标识的新方法.通过采用该方法.使得整改后满足了应急救援要求。  相似文献   
76.
杨军志 《智能建筑》2014,(12):64-67
本文通过对BA系统在建筑物及数据中心的应用分析,分别介绍了自控系统对于冷冻机房主机台数、冷却塔控制、冷冻机组的控制,最后介绍了整个自控系统的系统构架与节能效果。  相似文献   
77.
This paper explores how programme management (as opposed to project management) can contribute to the effective design and delivery of megaprojects. Traditionally, project management is considered to be performance focused and task oriented, whilst programme management entails a more strategic focus. The programme management literature suggests that this can result in tensions between the management of the projects and the programme as a whole. This paper uses the findings of the €2.4 billion Room for the River flood protection programme in the Netherlands as a case study, because indicators about its budget, time, quality and stakeholder satisfaction suggest high programme management performance upon completion of the planning and design stage of its 39 river widening projects. Based on a literature review, document analysis and 55 face-to-face interviews, we have analysed how the programme management of the programme contributed to this result. Six attributes for effective programme management that are identified from the project and programme management literature are used to structure the research data. Consecutively, the interactions between project and programme management are analysed. The analysis of Room for the River reveals a combined strategic/performance focus at the level of both programme and project management that enables a collaborative approach between programme and project management. This particularly enables effective stakeholder collaboration, coordination and adaptation of the programme to contextual changes, newly acquired insights and the changing needs of consecutive planning stages, which positively contributes to the performance of the programme as a whole.  相似文献   
78.
A novel deposition process for nano-crystalline silicon (nc-Si) thin films was developed using neutral beam assisted chemical vapor deposition (NBaCVD) technology for the application of the thin film transistor (TFT) backplane of flexible active matrix organic light emitting diode (AMOLED). During the formation of a nc-Si thin film, the energetic particles enhance nano-sized crystalline rather microcrystalline Si in thin films. Neutral Particle Beam (NPB) affects the crystallinity in two ways: (1) NPB energy enhances nano-crystallinity through kinetic energy transfer & chemical annealing, and (2) heavier NPB (such as Ar) induces damage & amorphization through energetic particle impinging. Nc-Si thin film properties effectively can be changed by the reflector bias. As increase of NPB energy limits growing the crystalline, the performance of TFT supports this NPB behavior. The results of nc-Si TFT by NBaCVD demonstrate the technical potentials of neutral beam based processes for achieving high stability and reduced leakage in TFT backplanes for AMOLEDs.  相似文献   
79.
Most of the anodic aluminum oxide (AAO) templates are performed by potentiostatical method at 0-10 °C to inhibit the Joule's heat enhanced dissolution in aluminum oxide for well-ordered cell configuration. In this article, we propose the hybrid pulse anodization (HPA) method with effective suppression of Joule's heat generation to fabricate AAO at room temperature. Effects of purity of aluminum (Al) foils and pulse voltage on the evolution of pore characteristics have been investigated. The AAO morphology is captured by scanning electron microscope and analyzed via gray-scale imaging in order to identify the pore size distribution. The increased applied potential results in the widened pores and non-uniform cell arrangement due to the increased current density and variation. Moreover, low-purity Al foils lead to the reduced AAO distribution uniformity owing to the uneven electric field induced pits on the Al surface for inferior pore arrangement. Extending both the positive and negative pulse period from 1 s to 5 s during HPA can enhance the distribution uniformity of AAO from high-purity Al by up to about 95%. In addition, the relationship between AAO configuration and Al purity and pulse voltage is further discussed and established.  相似文献   
80.
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