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   1918篇
  免费   92篇
  国内免费   5篇
电工技术   26篇
综合类   18篇
化学工业   581篇
金属工艺   30篇
机械仪表   33篇
建筑科学   147篇
矿业工程   4篇
能源动力   27篇
轻工业   176篇
水利工程   11篇
石油天然气   4篇
无线电   121篇
一般工业技术   381篇
冶金工业   80篇
原子能技术   18篇
自动化技术   358篇
  2024年   6篇
  2023年   36篇
  2022年   52篇
  2021年   74篇
  2020年   45篇
  2019年   49篇
  2018年   44篇
  2017年   41篇
  2016年   51篇
  2015年   47篇
  2014年   73篇
  2013年   98篇
  2012年   90篇
  2011年   157篇
  2010年   100篇
  2009年   113篇
  2008年   102篇
  2007年   85篇
  2006年   87篇
  2005年   74篇
  2004年   68篇
  2003年   55篇
  2002年   51篇
  2001年   44篇
  2000年   43篇
  1999年   43篇
  1998年   31篇
  1997年   30篇
  1996年   18篇
  1995年   20篇
  1994年   27篇
  1993年   19篇
  1992年   11篇
  1991年   24篇
  1990年   13篇
  1989年   14篇
  1988年   7篇
  1987年   7篇
  1986年   4篇
  1985年   8篇
  1984年   10篇
  1983年   8篇
  1981年   3篇
  1980年   4篇
  1978年   4篇
  1977年   5篇
  1976年   5篇
  1974年   2篇
  1967年   2篇
  1931年   3篇
排序方式: 共有2015条查询结果,搜索用时 15 毫秒
161.
European Food Research and Technology - The volatile constituents of cape gooseberry (Physalis peruviana L.) were characterized using liquid/liquid extraction and fractionation of the flavour...  相似文献   
162.
This paper presents a non-ideality analysis of the wideband frequency synthesizer, and proposes a new digital architecture for signal modulation and quantization. Using error masking strategy, this method can offer smaller routing area and less power consumption without sacrificing any system performance. Simulation results confirm the theoretical predictions. Finally, the design guidelines are derived to fulfill the customized synthesizer specifications.  相似文献   
163.
A hybrid approach for the realization of In‐free transparent conductive layers based on a composite of a mesh of silver nanowires (NWs) and a conductive metal‐oxide is demonstrated. As metal‐oxide room‐temperature‐processed sol–gel SnOx or Al:ZnO prepared by low‐temperature (100 °C) atomic layer deposition is used, respectively. In this concept, the metal‐oxide is intended to fuse the wires together and also to “glue” them to the substrate. As a result, a low sheet resistance down to 5.2 Ω sq‐1 is achieved with a concomitant average transmission of 87%. The adhesion of the NWs to the substrate is significantly improved and the resulting composites withstand adhesion tests without loss in conductivity. Owing to the low processing temperatures, this concept allows highly robust, highly conductive, and transparent coatings even on top of temperature sensitive objects, for example, polymer foils, organic devices. These Indium‐ and PEDOT:PSS‐free hybrid layers are successfully implemented as transparent top‐electrodes in efficient all‐solution‐processed semitransparent organic solar cells. It is obvious that this approach is not limited to organic solar cells but will generally be applicable in devices which require transparent electrodes.  相似文献   
164.
165.
Design of 5.9 ghz dsrc-based vehicular safety communication   总被引:3,自引:0,他引:3  
The automotive industry is moving aggressively in the direction of advanced active safety. Dedicated short-range communication (DSRC) is a key enabling technology for the next generation of communication-based safety applications. One aspect of vehicular safety communication is the routine broadcast of messages among all equipped vehicles. Therefore, channel congestion control and broadcast performance improvement are of particular concern and need to be addressed in the overall protocol design. Furthermore, the explicit multichannel nature of DSRC necessitates a concurrent multichannel operational scheme for safety and non-safety applications. This article provides an overview of DSRC based vehicular safety communications and proposes a coherent set of protocols to address these requirements  相似文献   
166.
The fundamental nature of charge transport in highly ordered organic semiconductors is under constant debate. At cryogenic temperatures, effects within the semiconductor such as traps or the interaction of charge carriers with the insulating substrate (dipolar disorder or Fröhlich polarons) are known to limit carrier motion. In comparison, at elevated temperatures, where charge carrier mobility often also decreases as function of temperature, phonon scattering or dynamic disorder are frequently discussed mechanisms, but the exact microscopic cause that limits carrier motion is debated. Here, the mobility in the temperature range between 200 and 420 K as function of carrier density is explored in highly ordered perylene‐diimide from 3 to 9 nm thin films. It is observed that above room temperature increasing the gate electric field or decreasing the semiconducting film thickness leads to a suppression of the charge carrier mobility. Via X‐ray diffraction measurements at various temperatures and electric fields, changes of the thin film structure are excluded as cause for the observed mobility decrease. The experimental findings point toward scattering sites or traps at the semiconductor–dielectric interface, or in the dielectric as limiting factor for carrier mobility, whose role is usually neglected at elevated temperatures.  相似文献   
167.
本文在解释电池板不匹配现象的基础上分析了电池参数的微小变化影响PV陈列系统性能的原因。此外,文章深入剖析了用于解决电池板不匹配问题的电源优化器技术,并列举了与集中式最大功率点跟踪(MPPT)和传统解决方案相比,电源优化器支持的分布式MPPT的潜在优点。  相似文献   
168.
Carbon hard mask structures have been used to etch a variety of materials typically used in sub 90 nm DRAM manufacture. The results indicate that carbon hard masks can be used very effectively to structure oxide, nitride and metal films giving the CD performance required for the technologies being investigated.  相似文献   
169.
An overview on RF-front-end architectures and technologies for future reconfigurable mobile communication is given. A favourable solution for fourth mobile generation is an extension of traditional cellular parameters by OFDM-based systems like WLAN. Therefore, an approach for widely reconfigurable receivers considering a variety of different standards, with the example of combining WCDMA and WLAN front-end into one architecture, is presented in this paper. RF-front-end key components like low noise amplifiers, mixers, and frequency synthesizers, as well as baseband variable gain amplifiers and filters are treated, particularly with regard to reconfigurable systems.  相似文献   
170.
Ralf  Briest  张斌 《电力电子》2006,4(3):35-38
过去几年里,中小功率的UPS电源设计已经越来越多的采用无变压器电路原理,这不仅使得成本进一步优化,而且将给制造技术带来全新的面貌。随着UPS电源向高功率领域扩展,这一电路原理还不能完全的适用,还需要增添新的原理。本文介绍了关于这一新的电路原理及其控制结构,它使无变压器UPS电源的新潜力得以发挥。文章给出了这一技术的基本层面,并展示了一系列高功率UPS电源的新的研究成果。  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