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   2288篇
  免费   80篇
  国内免费   5篇
电工技术   37篇
综合类   6篇
化学工业   663篇
金属工艺   59篇
机械仪表   49篇
建筑科学   130篇
矿业工程   9篇
能源动力   47篇
轻工业   210篇
水利工程   6篇
无线电   140篇
一般工业技术   383篇
冶金工业   190篇
原子能技术   29篇
自动化技术   415篇
  2023年   20篇
  2022年   37篇
  2021年   67篇
  2020年   37篇
  2019年   36篇
  2018年   40篇
  2017年   38篇
  2016年   76篇
  2015年   54篇
  2014年   68篇
  2013年   99篇
  2012年   117篇
  2011年   155篇
  2010年   117篇
  2009年   99篇
  2008年   119篇
  2007年   98篇
  2006年   112篇
  2005年   79篇
  2004年   81篇
  2003年   53篇
  2002年   44篇
  2001年   43篇
  2000年   41篇
  1999年   44篇
  1998年   59篇
  1997年   49篇
  1996年   33篇
  1995年   34篇
  1994年   27篇
  1993年   21篇
  1992年   28篇
  1991年   24篇
  1990年   22篇
  1989年   20篇
  1988年   15篇
  1987年   16篇
  1985年   16篇
  1984年   10篇
  1983年   12篇
  1982年   13篇
  1981年   11篇
  1980年   15篇
  1979年   13篇
  1977年   12篇
  1976年   12篇
  1975年   16篇
  1974年   17篇
  1959年   16篇
  1958年   10篇
排序方式: 共有2373条查询结果,搜索用时 0 毫秒
11.
12.
13.
14.
Composite materials with vibrations damping qualities can be made of two steel sheets enclosing a viscoelastic plasticcorelayer. These sandwich sheets often need to be formed. Material parameters are determined to describe the forming process. Based on these parameters, pilot studies are carried out in order to develop recommendations for forming this class of material.  相似文献   
15.
16.
UNICORE is a European Grid Technology with more than 10 years of history. Originating from the Supercomputing domain, the latest version UNICORE 6 has turned into a general-purpose Grid technology that follows established standards and offers a rich set of features to its users. The paper starts with an architectural insight into UNICORE 6, highlighting the workflow features, standards and the different clients. Next, the current state of advancement is presented by describing recent developments. The paper closes with an outlook on future planned developments.  相似文献   
17.
We present an interdigitated back‐contact silicon heterojunction system designed for liquid‐phase crystallized thin‐film (~10 µm) silicon on glass. The preparation of the interdigitated emitter (a‐Si:H(p)) and absorber (a‐Si:H(n)) contact layers relies on the etch selectivity of doped amorphous silicon layers in alkaline solutions. The etch rates of a‐Si:H(n) and a‐Si:H(p) in 0.6% NaOH were determined and interdigitated back‐contact silicon heterojunction solar cells with two different metallizations, namely Al and ITO/Ag electrodes, were evaluated regarding electrical and optical properties. An additional random pyramid texture on the back side provides short‐circuit current density (jSC) of up to 30.3 mA/cm2 using the ITO/Ag metallization. The maximum efficiency of 10.5% is mainly limited by a low of fill factor of 57%. However, the high jSC, as well as VOC values of 633 mV and pseudo‐fill factors of 77%, underline the high potential of this approach. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
18.
19.
We study the behavior of feedback bridging faults with non-zero bridge resistance in both combinational and sequential circuits. We demonstrate that a test vector may detect the fault, not detect the fault or lead to oscillation, depending on bridge resistance. Moreover, the resistance intervals in which a particular behavior is observed are not necessarily contiguous. We demonstrate non-trivial behavior for situations in which a detection seems impossible, namely disabled loops going through a gate with controlling values on its side inputs.We outline the multiple strengths problem which arises due to the fact that a critical bridge resistance depends on the strengths of the signals driving the bridge, which in turn are functions of the number of the on-transistors, these again depending on the bridge resistance, making such a fault very hard to resolve. For sequential circuits, we describe additional difficulties caused by the need to account for implications on bridge behavior, which have originated in the previous time frames. We conclude that the complexity of resistive feedback bridging fault simulation accurate enough to resolve such situations will probably be prohibitively high and propose possible simplifying assumptions. We present simulation results for ISCAS benchmarks using these assumptions with and without taking oscillation into account.This revised version was published online in March 2005 with corrections to the cover date.  相似文献   
20.
This article investigates the short‐term relationship between media coverage, stock prices, and trading volumes of eight listed German companies. A content analysis of news reports about the selected companies and a secondary analysis of the daily changes in closing prices and the trading volumes of these companies were combined in a time‐series design. After ARIMA‐modeling each of them, the results suggest that media coverage rather reflects than shapes the development at stock exchanges from a short‐term perspective (2 months). There were almost no hints for a widespread media effect, that is, an impact on so many investors that it will result in a measurable change in stock prices or trading volumes. Finally, theoretical and methodological consequences for exploring widespread media effects are discussed.  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