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   5690篇
  免费   439篇
  国内免费   112篇
电工技术   244篇
综合类   202篇
化学工业   967篇
金属工艺   198篇
机械仪表   198篇
建筑科学   348篇
矿业工程   53篇
能源动力   315篇
轻工业   463篇
水利工程   96篇
石油天然气   182篇
武器工业   4篇
无线电   663篇
一般工业技术   836篇
冶金工业   366篇
原子能技术   22篇
自动化技术   1084篇
  2024年   20篇
  2023年   96篇
  2022年   168篇
  2021年   226篇
  2020年   178篇
  2019年   174篇
  2018年   228篇
  2017年   206篇
  2016年   243篇
  2015年   216篇
  2014年   235篇
  2013年   449篇
  2012年   337篇
  2011年   423篇
  2010年   347篇
  2009年   352篇
  2008年   281篇
  2007年   241篇
  2006年   238篇
  2005年   191篇
  2004年   131篇
  2003年   150篇
  2002年   197篇
  2001年   144篇
  2000年   103篇
  1999年   59篇
  1998年   89篇
  1997年   67篇
  1996年   57篇
  1995年   59篇
  1994年   51篇
  1993年   39篇
  1992年   22篇
  1991年   8篇
  1990年   16篇
  1989年   9篇
  1988年   16篇
  1987年   14篇
  1986年   13篇
  1985年   10篇
  1984年   22篇
  1983年   10篇
  1982年   13篇
  1981年   12篇
  1980年   6篇
  1979年   9篇
  1978年   10篇
  1977年   10篇
  1976年   13篇
  1975年   7篇
排序方式: 共有6241条查询结果,搜索用时 15 毫秒
111.
文章的设计是采用内部互联一分二功分器的方法来实现多路功分器,因为实际制作中很难将一分二功分器直接相连,所以在一分二功分器之间需要采用传输线进行连接,本文主要研究了内部互联多路多节功分器的性能以及传输线对内部互联多路多节功分器的影响.  相似文献   
112.
一、辽宁省农村水电发展现状 1.水能资源概况 辽宁省农村水电资源主要分布在东部的鸭绿江水系、辽河水系的浑河和太子河等,另有西部的大凌河和青龙河等。根据2003年全国水力资源普查结果表明,全省河流水能资源理论蕴藏量为202万千瓦(单站500千瓦装机以上)。  相似文献   
113.
一种病毒进化型遗传算法   总被引:13,自引:0,他引:13  
本文提出一种病毒进化型遗传算法VEGA。此算法在一般遗传算法的基础上,通过对病毒个体和宿主体行为及相互关系的模拟,使进化个体的多样性大大提高,算法更易趋于全局极化。模拟实验验证了VEGA的优良性能。  相似文献   
114.
Within the field of Information Systems, a good proportion of research is concerned with the work organisation and this has, to some extent, restricted the kind of application areas given consideration. Yet, it is clear that information and communication technology deployments beyond the work organisation are acquiring increased importance in our lives. With this in mind, we offer a field study of the appropriation of an online play space known as Habbo Hotel. Habbo Hotel, as a site of media convergence, incorporates social networking and digital gaming functionality. Our research highlights the ethical problems such a dual classification of technology may bring. We focus upon a particular set of activities undertaken within and facilitated by the space—scamming. Scammers dupe members with respect to their ‘Furni’, virtual objects that have online and offline economic value. Through our analysis we show that sometimes, online activities are bracketed off from those defined as offline and that this can be related to how the technology is classified by members—as a social networking site and/or a digital game. In turn, this may affect members’ beliefs about rights and wrongs. We conclude that given increasing media convergence, the way forward is to continue the project of educating people regarding the difficulties of determining rights and wrongs, and how rights and wrongs may be acted out with respect to new technologies of play online and offline.
Ben LightEmail:

Marie Griffiths   moved from the IT industry into academia and is now based at the University of Salford as an EPSRC Academic Fellow. She has, and continues to research gender and ICTs. Recently she has embarked upon the study “Cybercitizens and their Virtual Pursuits” to understand the consequence of growing up and living in a technologically saturated environment. Her work has been published in journals such as Gender, Work and Organization, the European Journal of Information Systems and Information Communication and Society. Ben Light   is Professor of Technology and Society at the University of Salford. His research concerns the appropriation of configurable technologies within work, organisations and society. This has led him to explore the use of large-scale enterprise resource planning packages, call centre technologies, social networking sites and digital games. He has published in journals such as Communications of the ACM, Information Systems Journal, New Technology, Work and Employment, the European Journal of Information Systems and the Journal of Information Technology.  相似文献   
115.
Ben 《电脑》2014,(10)
正火爆的眼球之争作为有史以来最火爆的亲子节目,《爸爸去哪儿》成为了全民狂欢的游戏,同时也拉动了一系列相关品牌的关注度飙升。比如去年"仅"以2800万"捡"得冠名权的999感冒灵,年销量飙升40%。惹得各路豪强眼红不已,第二季冠名权立马硬生生杀到3.1个亿,各大品牌在节目中争相露脸,你方唱罢我登场,不挤爆观众眼球不罢休。  相似文献   
116.
垂直互连技术具有互连路径短、空间利用率高、速度快等诸多优点,对星载、舰载、弹载等实现微型化、轻量化、多功能化具有重要战略意义。毛纽扣连接器作为一种弹性连接器,常用于低矮化多层印制板间的垂直互连,其自身体积小、微波性能好、工作频段宽、易拆卸、低延迟,且可以有效抑制连接器内部信号的互感效应,减小信号传输的路径长度和高频信号的趋肤效应,在射频微波领域具有重要用途。重点综述了材料类型及电镀金厚度对毛纽扣连接器性能的影响,归纳了通过建立理论模型分析毛纽扣连接器的电学性能及力学本构模型的方法,并揭示了高、低温(-55~85℃)冲击下毛纽扣连接器的可靠性,总结了其在印制电路板和微型连接器中的应用。总体来说,我国对毛纽扣垂直互连技术研究较少,特别是在宇航领域,还需积极地进行技术攻关,确保其在真空、温度交变、辐射及原子氧等苛刻复杂的宇航服役环境中的可靠性。对此,综述了基于毛纽扣连接器的垂直互连技术的基本原理,以及影响毛纽扣性能及可靠性的服役环境,分析了近年来国内外在毛纽扣连接器领域取得的研究进展,并展望了毛纽扣连接器的发展方向,可为基于毛纽扣连接器的垂直互连技术的发展提供有益的参考和启示。  相似文献   
117.
The color of polymer solar cells using an opaque electrode is given by the reflected light, which depends on the composition and thickness of each layer of the device. Metal‐oxide‐based optical spacers are intensively studied in polymer solar cells aiming to optimize the light absorption. However, the low conductivity of materials such as ZnO and TiO2 limits the thickness of such optical spacers to tenths of nanometers. A novel synthesis route of cluster‐free Al‐doped ZnO (AZO) nanocrystals (NCs) is presented for solution processing of highly conductive layers without the need of temperature annealing, including thick optical spacers on top of polymer blends. The processing of 80 nm thick optical spacers based on AZO nanocrystal solutions on top of 200 nm thick polymer blend layer is demonstrated leading to improved photocurrent density of 17% compared to solar cells using standard active layers of 90 nm in combination with thin ZnO‐based optical spacers. These AZO NCs also open new opportunities for the processing of high‐efficiency color tuned solar cells. For the first time, it is shown that applying solution‐processed thick optical spacer with polymer blends of different thicknesses can process solar cells of similar efficiency over 7% but of different colors.  相似文献   
118.
对一种新型InGaAs-GaAs脊波导分布式Bragg反射(DBR)半导体激光器双模运行特性进行了研究.该激光器由1个普通增益区和2个DBR区组成,两DBR区采用均匀蚀刻的Bragg光栅,中间加入50~100 μm的分隔区,以减小两DBR区间的热作用影响.实验发现,在增益区偏置电流强度满足双模(双波长)运行条件的情况下,在分隔区施加一电流Ispace,会对双模调谐特性产生非常大的影响.结果表明:施加适当的Ispace可使双波长的可调谐间隔显著增加,并同时提高2个激射模的边模抑制比;在一定的范围内,较大的Ispace对应较好的双模运行参数.测量了3种几何尺寸样品在多种偏置电流下的双模运行特性,对分隔区长度、Ispace以及两者组合对双模调谐特性的影响作了深入研究.研究结果对改善双波长DBR半导体激光器双模运行特性给出了有用的信息.  相似文献   
119.
Light emission of 2‐(2,6‐bis((E)‐4‐(diphenylamino)styryl)‐4H‐pyran‐4‐ylidene)malononitrile (TPA‐DCM) is weakened by aggregate formation. Attaching tetraphenylethene (TPE) units as terminals to TPA‐DCM dramatically changes its emission behavior: the resulting fluorogen, 2‐(2,6‐bis((E)‐4‐(phenyl(4′‐(1,2,2‐triphenylvinyl)‐[1,1′‐biphenyl]‐4‐yl)amino)styryl)‐4H‐pyran‐4‐ylidene)malononitrile (TPE‐TPA‐DCM), is more emissive in the aggregate state, showing the novel phenomenon of aggregation‐induced emission (AIE). Formulation of TPE‐TPA‐DCM using bovine serum albumin (BSA) as the polymer matrix yields uniformly sized protein nanoparticles (NPs) with high brightness and low cytotoxicity. Applications of the fluorogen‐loaded BSA NPs for in vitro and in vivo far‐red/near‐infrared (FR/NIR) bioimaging are successfully demonstrated using MCF‐7 breast‐cancer cells and a murine hepatoma‐22 (H22)‐tumor‐bearing mouse model, respectively. The AIE‐active fluorogen‐loaded BSA NPs show an excellent cancer cell uptake and a prominent tumor‐targeting ability in vivo due to the enhanced permeability and retention effect.  相似文献   
120.
ATM switch, the core technology of an ATM networking system, is one of the major products in Fujitsu telecommunication business. However, current gate–level design methodology can no longer satisfy its stringent time–to–market requirement. It becomes necessary to exploit high–level methodology to specify and synthesize the design at an abstraction level higher than logic gates. This paper presents our prototyping experience on domain–specific high–level modeling and synthesis for Fujitsu ATM switch design. We propose a high–level design methodology using VHDL, where ATM switch architectural features are considered during behavior modeling, and a high–level synthesis compiler, MEBS, is prototyped to synthesize the behavior model down to a gate–level implementation. Since the specific ATM switch architecture is incorporated into both modeling and synthesis phases, a high–quality design is efficiently derived. The synthesis results shows that given the design constraints, the proposed high–level design methodology can produce a gate–level implementation by MEBS with about 15 percent area reduction in shorter design cycle when compared with manual design.  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