首页 | 官方网站   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   48482篇
  免费   4351篇
  国内免费   1965篇
工业技术   54798篇
  2024年   101篇
  2023年   856篇
  2022年   1199篇
  2021年   1897篇
  2020年   1523篇
  2019年   1285篇
  2018年   1449篇
  2017年   1610篇
  2016年   1432篇
  2015年   1999篇
  2014年   2370篇
  2013年   2889篇
  2012年   2932篇
  2011年   3306篇
  2010年   2964篇
  2009年   2822篇
  2008年   3020篇
  2007年   2519篇
  2006年   2599篇
  2005年   2286篇
  2004年   1436篇
  2003年   1349篇
  2002年   1213篇
  2001年   1081篇
  2000年   1185篇
  1999年   1410篇
  1998年   1099篇
  1997年   925篇
  1996年   828篇
  1995年   758篇
  1994年   624篇
  1993年   465篇
  1992年   352篇
  1991年   256篇
  1990年   213篇
  1989年   147篇
  1988年   131篇
  1987年   81篇
  1986年   56篇
  1985年   29篇
  1984年   25篇
  1983年   25篇
  1982年   22篇
  1981年   14篇
  1980年   11篇
  1979年   4篇
  1978年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
The CO_2 sensing of PrFeO_3 and NdFeO_3 sensors were investigated. Experimental results show that the resistances for PrFeO_3 and NdFeO_3 in CO_2 gas are larger than those in air and the responses for PrFeO_3and NdFeO_3 sensors increase with an increase in room-temperature relative humidity. When exposed to1000 ppm CO_2, the response of PrFeO_3 thick film based on nano-powders annealed at 700℃can reach8.44 at 160℃for the background of wet air with 58%of room-temperature relative humidity (RH),which is much larger than the corresponding value (3.03) in wet air with 25%RH. The sensing response S of NdFeO_3 thick-film sensor based on nano-powders annealed at 600℃to 3000 ppm CO_2 at the operating temperature 200℃can reach 2.36 for the background of wet air with 72%RH, which is larger than the corresponding value (1.83) in the air with 25%RH. Compared with other CO_2 sensing materials, the PrFeO_3 sensor has larger response at lower operating temperature for CO_2 gas and may be used as a new CO_2 sensing material.  相似文献   
54.
Shang  Tao  Zhao  Pei  Gao  Yan  Liu  Yuanhao 《Telecommunication Systems》2019,70(1):81-96
Telecommunication Systems - In a wireless sensor network (WSN) where positioning information is not assumed or is partially available, efficient data access is a very challenging issue especially...  相似文献   
55.
Zhan  Furui  Yao  Nianmin  Gao  Zhenguo  Lu  Zhimao  Chen  Bingcai 《Wireless Networks》2019,25(2):611-624
Wireless Networks - Key generation leveraging wireless channel reciprocity can establish secret keys from unauthenticated broadcast channels and thus protect the communication of wireless networks....  相似文献   
56.
For rechargeable wireless sensor networks, limited energy storage capacity, dynamic energy supply, low and dynamic duty cycles cause that it is unpractical to maintain a fixed routing path for packets delivery permanently from a source to destination in a distributed scenario. Therefore, before data delivery, a sensor has to update its waking schedule continuously and share them to its neighbors, which lead to high energy expenditure for reestablishing path links frequently and low efficiency of energy utilization for collecting packets. In this work, we propose the maximum data generation rate routing protocol based on data flow controlling technology. For a sensor, it does not share its waking schedule to its neighbors and cache any waking schedules of other sensors. Hence, the energy consumption for time synchronization, location information and waking schedule shared will be reduced significantly. The saving energy can be used for improving data collection rate. Simulation shows our scheme is efficient to improve packets generation rate in rechargeable wireless sensor networks.  相似文献   
57.
Shen  Liang  Shen  Hao  Gao  Mingming  Liu  Yajuan  Huang  Xia 《Neural Processing Letters》2019,49(1):1-18
Neural Processing Letters - This paper is concerned with the global Mittag-Leffler synchronization schemes for the Caputo type fractional-order BAM neural networks with multiple time-varying delays...  相似文献   
58.
59.
The Pythagorean fuzzy set (PFS) is characterized by two functions expressing the degree of membership and the degree of nonmembership, which square sum of them is equal or less than 1. It was proposed as a generalization of a fuzzy set to deal with indeterminate and inconsistent information. In this study, we shall present some novel Dice similarity measures of PFSs and the generalized Dice similarity measures of PFSs and indicates that the Dice similarity measures and asymmetric measures (projection measures) are the special cases of the generalized Dice similarity measures in some parameter values. Then, we propose the generalized Dice similarity measures-based multiple attribute group decision-making models with Pythagorean fuzzy information. Then, we apply the generalized Dice similarity measures between PFSs to multiple attribute group decision making. Finally, an illustrative example is given to demonstrate the efficiency of the similarity measures for selecting the desirable ERP system.  相似文献   
60.
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-23

京公网安备 11010802026262号