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   140500篇
  免费   10671篇
  国内免费   5216篇
电工技术   7292篇
技术理论   13篇
综合类   8279篇
化学工业   23876篇
金属工艺   7609篇
机械仪表   8646篇
建筑科学   10975篇
矿业工程   4078篇
能源动力   3835篇
轻工业   8260篇
水利工程   2233篇
石油天然气   8239篇
武器工业   902篇
无线电   17004篇
一般工业技术   17619篇
冶金工业   7477篇
原子能技术   1559篇
自动化技术   18491篇
  2024年   540篇
  2023年   2246篇
  2022年   3727篇
  2021年   5122篇
  2020年   4016篇
  2019年   3307篇
  2018年   3874篇
  2017年   4294篇
  2016年   3794篇
  2015年   4962篇
  2014年   6281篇
  2013年   7988篇
  2012年   8377篇
  2011年   9027篇
  2010年   7900篇
  2009年   7802篇
  2008年   7664篇
  2007年   7264篇
  2006年   7620篇
  2005年   6738篇
  2004年   4553篇
  2003年   4004篇
  2002年   3575篇
  2001年   3374篇
  2000年   3542篇
  1999年   4163篇
  1998年   3595篇
  1997年   3162篇
  1996年   2815篇
  1995年   2367篇
  1994年   1903篇
  1993年   1483篇
  1992年   1167篇
  1991年   892篇
  1990年   715篇
  1989年   602篇
  1988年   470篇
  1987年   348篇
  1986年   258篇
  1985年   199篇
  1984年   130篇
  1983年   97篇
  1982年   105篇
  1981年   68篇
  1980年   52篇
  1979年   33篇
  1978年   25篇
  1977年   25篇
  1976年   40篇
  1973年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Cao  Zehui  Zhao  Jing  Sun  Shiliang 《Neural Processing Letters》2021,53(1):339-353
Neural Processing Letters - The beta processes (BP) is a powerful nonparametric tool in feature learning, which is often used as the prior of Bernoulli process for choosing features from a feature...  相似文献   
102.
103.
104.
Advanced biogas power generation technology has been attracting attentions, which contributes to the waste disposal and the mitigation of greenhouse gas emissions. This work proposes and models a novel biogas-fed hybrid power generation system consisting of solid oxide fuel cell, water gas shift reaction, thermal swing adsorption and proton exchange membrane fuel cell (SOFC-WGS-TSA-PEMFC). The thermodynamic, exergetic, and thermo-economic analyses of this hybrid system for power generation were conducted to comprehensively evaluate its performance. It was found that the novel biogas-fed hybrid system has a gross energy conversion efficiency of 68.63% and exergy efficiency of 65.36%, indicating high efficiency for this kind of hybrid power technology. The market sensitivity analysis showed that the hybrid system also has a low sensitivity to market price fluctuation. Under the current subsidy level for the distributed biogas power plant, the levelized cost of energy can be lowered to 0.02942 $/kWh for a 1 MW scale system. Accordingly, the payback period and annual return on investment can reach 1.4 year and about 20%, respectively. These results reveal that the proposed hybrid system is promising and economically feasible as a distributed power plant, especially for the small power scale (no more than 2 MW).  相似文献   
105.
The support flux was first investigated as a separate influencing factor for its effect on performances of ceramic filtration membranes. Three pre-membranes were prepared by tape-casting and then transfer-coated to supports to form dual-layer ceramic membranes after sintering. Experiments demonstrated that membrane layers with almost the same properties were obtained despite the huge difference in support flux. When the support flux increases from 3.120 to 97.53 m3m?2h?1, the flux of these three membrane series have increased by 75%, 186% and 228%, respectively. Experimental rules can provide structural design and evaluation from the perspective of permeability. The limit membrane flux of a certain system was derived according to the resistance distribution law of internal membrane structure and the Darcy's theorem. On this basis, a method for designing support flux was proposed. Furthermore, we present a criterion to quickly and easily evaluate the match between the support and the top layer, which is the ratio of membrane resistance to total resistance. Finally, the filtration resistance of penetration caused by suction of membrane particles into the support was measured for the first time, taking the advantage of the transfer-coating method that inherently free of penetration. Our works are expected to deepen the understanding of the ceramic membrane structure and provided guidance for its rational design and optimization.  相似文献   
106.
107.
108.
109.
Computational fluid dynamics (CFD) models were employed to investigate flow conditions inside a model reactor in which yield stress non‐Newtonian liquid is mobilized using submerged recirculating jets. The simulation results agree well with the experimental results of active volume in the reactor obtained using flow visualization by the authors in a previous study. The models developed are capable of predicting a critical jet velocity (vc) that determines the extent of active volume obtained due to jet mixing. The vc values are influenced both by the rheological properties of the liquid and the nozzle orientation. The liquid with higher effective viscosity leads to higher vc for a downward facing injection nozzle. However, an upward facing injection nozzle along with a downward facing suction nozzle generates enhanced complementary flow fields which overcome the rheological constraints of the liquid and lead to lower vc.  相似文献   
110.
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