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   6866篇
  免费   747篇
  国内免费   22篇
电工技术   98篇
综合类   7篇
化学工业   1878篇
金属工艺   238篇
机械仪表   359篇
建筑科学   153篇
矿业工程   7篇
能源动力   228篇
轻工业   754篇
水利工程   43篇
石油天然气   13篇
无线电   998篇
一般工业技术   1509篇
冶金工业   316篇
原子能技术   121篇
自动化技术   913篇
  2024年   11篇
  2023年   90篇
  2022年   148篇
  2021年   274篇
  2020年   215篇
  2019年   242篇
  2018年   315篇
  2017年   303篇
  2016年   376篇
  2015年   275篇
  2014年   374篇
  2013年   522篇
  2012年   485篇
  2011年   589篇
  2010年   397篇
  2009年   423篇
  2008年   402篇
  2007年   311篇
  2006年   245篇
  2005年   184篇
  2004年   161篇
  2003年   182篇
  2002年   160篇
  2001年   129篇
  2000年   105篇
  1999年   95篇
  1998年   105篇
  1997年   73篇
  1996年   73篇
  1995年   49篇
  1994年   44篇
  1993年   35篇
  1992年   24篇
  1991年   34篇
  1990年   24篇
  1989年   21篇
  1988年   15篇
  1987年   12篇
  1986年   5篇
  1985年   18篇
  1984年   14篇
  1983年   12篇
  1982年   4篇
  1981年   6篇
  1980年   9篇
  1979年   5篇
  1977年   9篇
  1976年   8篇
  1974年   5篇
  1973年   4篇
排序方式: 共有7635条查询结果,搜索用时 395 毫秒
991.
The Journal of Supercomputing - This study proposes an efficient exact k-flexible aggregate nearest neighbor (k-FANN) search algorithm in road networks using the M-tree. The state-of-the-art...  相似文献   
992.
Surface modification of anode using surfactant has great influence on the electrical performance of a microbial fuel cell (MFC). In this study, the effect of surface‐modified exfoliated graphite used for anode fabrication on a cube‐type MFC batch reactor was examined. The surface exfoliated graphite was modified with 5‐mM anionic surfactant, sodium dodecyl sulfate. Anaerobic sludge used as inoculum containing 70% (v/v) of artificial wastewater and 30% (v/v) of seed sludge in an anode chamber and air cathode was used in cathode side. Anode modification was explored as an approach to enhance the start‐up and improve the performance of the reactor. Scanning electron microscopy was used to evaluate the morphology and activity of electrochemically active bacteria. In the study, the start‐up time of MFC required to approach stable voltage was substantially reduced, and the maximum stable voltage was higher than the control. In addition, the activation resistance of the MFC was considerably reduced, and the maximum power density (1640 mW/m2) was 20% higher than control. However, when the surface of exfoliated graphite was modified with over 10‐mM anionic surfactant, some negative effects on start‐up time, activation resistance and maximum power density were observed. This modification also enhanced the bacterial attachment and biofilm formation on the modified anode surface. The result suggested that surface modification anode with surfactant is effective for electrical responses achieved in the MFC. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
993.
Generally, the NiO composite anode becomes porous after reduction. To infiltrate additional catalysts such as Pd into the NiO-composite anode before reducing NiO to Ni, a porous NiO composite anode for protonic ceramic fuel cells (PCFCs) was fabricated in this study. The porous NiO composite was fabricated by adding graphite as a pore former along with CuO as a sintering agent. The addition of graphite increased the porosity of the NiO composite anode but resulted in poor sinterability, which was addressed by adding CuO as a sintering agent to the NiO composite anode. The Pd catalyst was added to the NiO-composite anode before reducing NiO to Ni. The composite anode for PCFC with three components, namely Ni, protonic ceramics, and a Pd catalyst, was obtained by reducing NiO to Ni during the measurement. The addition of the Pd catalyst improved the anode performance in methane fuel and hydrogen fuel by enhancing the catalytic activity for the electrochemical reaction on the surface.  相似文献   
994.
The electrochemical behavior of aluminum in tannin from Acacia mearnsii bark was evaluated by potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) in media under three different pH conditions: acid, alkaline, and neutral. A relationship among pH, polymerization grade (PG), zeta potential, surface, and electrochemical properties was observed in the inhibition performance of the tannin. At high pH, the oligomer structure of the tannin was affected, resulting in a low PG (4) and high zeta potential (−75 mV), and consequently, the inhibition efficiency decreased (68%) in comparison with that in acid (99%) and neutral media (96%). The values obtained indicate a physisorption mechanism for the aluminum corrosion inhibition in the studied conditions.  相似文献   
995.
996.
Wireless Personal Communications - The increased use of unmanned aerial vehicles (UAVs), better known as drones, by civilians has grown exponentially and their autonomous flight control systems...  相似文献   
997.
Food Science and Biotechnology - A new analytical method was developed for the simultaneous determination of seven food additives (Ponceau 4R, Allura Red AC, Amaranth, 4-hydroxymethyl benzoic acid,...  相似文献   
998.
999.
Seong Yun Cho 《ETRI Journal》2015,37(3):533-540
In wireless localization, several linear closed‐form solution (LCS) methods have been investigated as a direct result of the drawbacks that plague the existing iterative methods, such as the local minimum problem and heavy computational burden. Among the known LCS methods, both the direct solution method and the difference of squared range measurements method are considered in this paper. These LCS methods do not have any of the aforementioned problems that occur in the existing iterative methods. However, each LCS method does have its own individual error property. In this paper, a hybrid LCS method is presented to reduce these errors. The hybrid LCS method integrates the two aforementioned LCS methods by using two check points that give important information on the probability of occurrence of each LCS's individual error. The results of several Monte Carlo simulations show that the proposed method has a good performance. The solutions provided by the proposed method are accurate and reliable. The solutions do not have serious errors such as those that occur in the conventional standalone LCS and iterative methods.  相似文献   
1000.
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