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   24067篇
  免费   1064篇
  国内免费   147篇
电工技术   441篇
综合类   38篇
化学工业   5165篇
金属工艺   708篇
机械仪表   718篇
建筑科学   504篇
矿业工程   74篇
能源动力   1585篇
轻工业   1434篇
水利工程   163篇
石油天然气   102篇
武器工业   1篇
无线电   3041篇
一般工业技术   5308篇
冶金工业   2294篇
原子能技术   213篇
自动化技术   3489篇
  2024年   80篇
  2023年   453篇
  2022年   1014篇
  2021年   1261篇
  2020年   1000篇
  2019年   1036篇
  2018年   1332篇
  2017年   1069篇
  2016年   1027篇
  2015年   672篇
  2014年   952篇
  2013年   1838篇
  2012年   1070篇
  2011年   1305篇
  2010年   1056篇
  2009年   997篇
  2008年   925篇
  2007年   746篇
  2006年   643篇
  2005年   541篇
  2004年   416篇
  2003年   369篇
  2002年   298篇
  2001年   287篇
  2000年   253篇
  1999年   265篇
  1998年   507篇
  1997年   398篇
  1996年   330篇
  1995年   247篇
  1994年   266篇
  1993年   253篇
  1992年   187篇
  1991年   194篇
  1990年   160篇
  1989年   140篇
  1988年   140篇
  1987年   143篇
  1986年   127篇
  1985年   154篇
  1984年   131篇
  1983年   119篇
  1982年   99篇
  1981年   119篇
  1980年   88篇
  1979年   69篇
  1978年   64篇
  1977年   70篇
  1976年   81篇
  1973年   44篇
排序方式: 共有10000条查询结果,搜索用时 830 毫秒
951.
952.
Multimedia Tools and Applications - Leap motion sensor provides a new way of interaction with computers or mobile devices. With this sensor, users can write in air by moving palm or finger, thus,...  相似文献   
953.
954.
The impact of external mass transport on the biodegradation rate of phenol in a packed bed bioreactor (PBBR) was studied. A potential bacterial species, Bacillus flexus GS1 IIT (BHU), was isolated from the petroleum‐contaminated soil. Low‐density polyethylene (LDPE) immobilized with the B. flexus GS1 IIT (BHU) was used as packing material in the PBBR. The PBBR was operated by varying the inlet feed flow rate from 4 to 10 mL/min, and the corresponding degradation rate coefficients were found to be in the range of 0.119–0.157 L/g h. In addition, the highest removal rate of phenol was obtained to be 1.305 mg/g h at an inlet feed rate of 10 mL/min. The external mass transfer was studied using the model . A new empirical correlation for the biodegradation of phenol in the PBBR was developed after the evaluation at various values of K and n.  相似文献   
955.
In this paper, the performance of two solar domestic hot waters (SDHW) with drain water heat recovery (DWHR) units is investigated. Both SDHW systems are recently installed at the Archetype Sustainable Twin Houses at Kortright Center, Vaughan, Ontario. The first SDWH system in House A consists of a flat plate solar thermal collector in combination with a gas boiler and a DWHR unit. The second SDHW system in House B includes an evacuated tube solar collector, an electric tank, and a DWHR unit. Both systems are modeled in TRNSYS, and the models are validated by experimental data. The addition of the DWHR and the flat‐plate solar thermal collector would result in 1831 kWh of annual energy saving in House A. While the addition of the DWHR and the evacuated tube collector in House B would result in an annual energy saving of 1771 kWh. Subsequently, the models are used to investigate the performance of similar systems for five major Canadian cities of Halifax, Montreal, Toronto, Edmonton, and Vancouver. The conjunctions of solar thermal collectors with DWHR units are found most beneficial in Edmonton. It is also noted from experimental and simulated results that flat‐plate solar collector‐based water heater produced more thermal energy than the system based on the evacuated tube solar collector for all major Canadian cities. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
956.
957.
958.
Feature selection through optimization techniques provides an interesting approach to minimize computational time with enhanced prediction capability, and  相似文献   
959.
Wireless Personal Communications - In this paper, a patch antenna for wireless body area network (WBAN) applications is proposed. Antenna is designed for on-body to Off-body communication that aims...  相似文献   
960.
Guleria  Kalpna  Verma  Anil Kumar 《Wireless Networks》2019,25(3):1159-1183
Wireless Networks - In recent years, wireless sensor networks (WSNs) have played a major role in applications such as tracking and monitoring in remote environments. Designing energy efficient...  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