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   897篇
  免费   20篇
  国内免费   5篇
电工技术   74篇
综合类   2篇
化学工业   103篇
金属工艺   11篇
机械仪表   72篇
建筑科学   23篇
能源动力   37篇
轻工业   30篇
水利工程   14篇
无线电   158篇
一般工业技术   152篇
冶金工业   145篇
自动化技术   101篇
  2024年   2篇
  2023年   8篇
  2022年   10篇
  2021年   17篇
  2020年   9篇
  2019年   20篇
  2018年   19篇
  2017年   23篇
  2016年   18篇
  2015年   20篇
  2014年   16篇
  2013年   42篇
  2012年   37篇
  2011年   40篇
  2010年   36篇
  2009年   28篇
  2008年   43篇
  2007年   35篇
  2006年   38篇
  2005年   32篇
  2004年   30篇
  2003年   39篇
  2002年   33篇
  2001年   30篇
  2000年   25篇
  1999年   27篇
  1998年   49篇
  1997年   35篇
  1996年   16篇
  1995年   10篇
  1994年   5篇
  1993年   15篇
  1992年   13篇
  1991年   12篇
  1990年   5篇
  1989年   9篇
  1988年   8篇
  1987年   15篇
  1986年   5篇
  1985年   8篇
  1984年   7篇
  1983年   6篇
  1982年   5篇
  1981年   3篇
  1978年   6篇
  1977年   3篇
  1976年   2篇
  1971年   1篇
  1970年   1篇
  1967年   1篇
排序方式: 共有922条查询结果,搜索用时 15 毫秒
1.
Godfrey Chua   《Refocus》2003,4(6):965-28
The Asia-Pacific region is one of the fastest growing regional economies in the world today. The region is home to over half of the global population and is one of the most important markets for multinational corporations to penetrate. The wind power sector is no exception. Wind resources remain untapped and the demand for electricity continues to grow as a result of expanding and modernizing economies. Godfrey Chua, Emerging Energy Research USA reports on the current status and development of the wind industry in the region.  相似文献   
2.
Pull-out experiments have been carried out on single production fibres under carefully controlled conditions. Four parameters were determined. The interfacial yield stresses, of about 9–14 MPa, were very much smaller than the shear strengths of the bulk polymers in the case of an epoxy, whether post-cured or not, and a non-post-cured polyester. Values for the work of fracture of the interface varied from 140 to 300 Jm?2, and again were less than those of the polymer. Interface failure sometimes took place in the epoxy rather than at the fibre surface, whereas with the polyester it always took place at the fibre surface. After interface failure, pull-out was governed by friction, with maximum shear stresses of 7–10 MPa for polyester, and 21–34 MPa for epoxy, the higher values being obtained for the post-cured resins. Average frictional shear stresses were sometimes less than a half of the maximum shear stress, indicating that the fibre Poisson's shrinkage was playing an important role in the pull-out process. A silicone release agent reduced the frictional shear stresses to 2·5 MPa, with both resins.  相似文献   
3.
The cellular neural network (CNN) architecture combines the best features from traditional fully-connected analog neural networks and digital cellular automata. The network can rapidly process continuous-valued (gray-scale) input signals (such as images) and perform many computation functions which traditionally were implemented in digital form. Here, we briefly introduce the the theory of CNN circuits, provide some examples of CNN applications to image processing, and discuss work toward a CNN implementation in custom CMOS VLSI. The role of analog computer-aided design (CAD) will be briefly presented as it relates to analog neural network implementation.This work is supported in part by the Office of Naval Research under Contract N00014-89-J1402, and the National Science Foundation under grant MIP-8912639.  相似文献   
4.
5.
6.
Four experiments addressed the question of whether attention may be captured when the visual system is in the midst of an attentional blink (AB). Participants identified 2 target letters embedded among distractor letters in a rapid serial visual presentation sequence. In some trials, a square frame was inserted between the targets; as the only geometric object in the sequence, it constituted a singleton. Capture effects obtained when the AB was most severe and when it was over were compared. There were 3 main results. First, capture occurred even when the AB was crippling, suggesting that a singleton exogenously engaged attention even when processing of a previous target was continuing apace. Second, when the singleton contained the key target feature, capture effects were clearly manifest. Third, even when the singleton did not possess the key target feature, it still succeeded in capturing attention, although the effects were both feeble and fleeting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
7.
The field of single-cell analysis has advanced rapidly in the last decade and is providing new insights into the characterization of intercellular genetic heterogeneity and complexity, especially in human cancer. In this regard, analyzing single circulating tumor cells (CTCs) is becoming particularly attractive due to the easy access to CTCs from simple blood samples called “liquid biopsies”. Analysis of multiple single CTCs has the potential to allow the identification and characterization of cancer heterogeneity to guide best therapy and predict therapeutic response. However, single-CTC analysis is restricted by the low amounts of DNA in a single cell genome. Whole genome amplification (WGA) techniques have emerged as a key step, enabling single-cell downstream molecular analysis. Here, we provide an overview of recent advances in WGA and their applications in the genetic analysis of single CTCs, along with prospective views towards clinical applications. First, we focus on the technical challenges of isolating and recovering single CTCs and then explore different WGA methodologies and recent developments which have been utilized to amplify single cell genomes for further downstream analysis. Lastly, we list a portfolio of CTC studies which employ WGA and single-cell analysis for genetic heterogeneity and biomarker detection.  相似文献   
8.
The extreme conditions of high pressure and shear imposed in a lubricated sliding contact could influence tribochemical reactions that could occur over long sliding distances and time scales, possibly leading to changes in both friction and film thickness. Experiments conducted with 12 plant oils reveal for the first time, that thin lubricating films of some plant oils can grow to thicknesses much greater than what is predicted from either elastohydrodyamic theory or their adsorbed molecular heights. Some films grew as much as 25 times in thickness (unrefined canola oil), while others remained roughly unchanged (flaxseed and olive oil), or grew slightly and then collapsed during the test (safflower oil). The absence of a loss in film thickness and the viscoelastic-like behavior of the film when speeds are reduced to zero, support the view that polymerization could be the main mechanism of film growth. However, the lack of correlation between the degree of unsaturation and the film growth rate suggests that other mechanisms could also be at work.  相似文献   
9.
利用多模干涉效应和自由载流子等离子体色散效应设计和模拟了基于1.55μm波长的2×3 SiGe光开关.该光开关由两个单模输入端口、一个多模干涉区和三个单模输出端口构成.在多模干涉区,设有两个折射率调制区,可以利用来把从两个输入端口输入的光信号分别从三个输出端口输出.束传播法分析结果表明,该光开关的传输损耗小于1.43dB,串扰在-18~-32.8dB之间.  相似文献   
10.
The scattering of carriers due to dislocations is studied. Unlike semiconductors such as Si or GaAs, the major scattering mechanism for undoped or lightly doped samples is dislocation scattering instead of ionized impurity scattering. It was found that for GaN samples in the dislocation scattering region, the mobility is a function of the dislocation density and free carrier concentration, via a relationship. Temperature-variation mobility plots also indicate that a T3/2 dependence component is present, which is also attributed to dislocation scattering.  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