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   543703篇
  免费   8896篇
  国内免费   1480篇
电工技术   9926篇
综合类   585篇
化学工业   82914篇
金属工艺   20448篇
机械仪表   15613篇
建筑科学   13633篇
矿业工程   2400篇
能源动力   14840篇
轻工业   49738篇
水利工程   5344篇
石油天然气   9356篇
武器工业   37篇
无线电   61122篇
一般工业技术   106860篇
冶金工业   104045篇
原子能技术   10717篇
自动化技术   46501篇
  2022年   3318篇
  2021年   5317篇
  2020年   3852篇
  2019年   4900篇
  2018年   8497篇
  2017年   8327篇
  2016年   8737篇
  2015年   6207篇
  2014年   10034篇
  2013年   25622篇
  2012年   15535篇
  2011年   21242篇
  2010年   16741篇
  2009年   18583篇
  2008年   19089篇
  2007年   18695篇
  2006年   16191篇
  2005年   14742篇
  2004年   14051篇
  2003年   13860篇
  2002年   13086篇
  2001年   13172篇
  2000年   12135篇
  1999年   12845篇
  1998年   33046篇
  1997年   23132篇
  1996年   17641篇
  1995年   13186篇
  1994年   11439篇
  1993年   11098篇
  1992年   8032篇
  1991年   7529篇
  1990年   7352篇
  1989年   7095篇
  1988年   6543篇
  1987年   5847篇
  1986年   5736篇
  1985年   6453篇
  1984年   6076篇
  1983年   5277篇
  1982年   5009篇
  1981年   5094篇
  1980年   4822篇
  1979年   4697篇
  1978年   4501篇
  1977年   5410篇
  1976年   7052篇
  1975年   3872篇
  1974年   3615篇
  1973年   3739篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Micro Aerial Vehicles (MAVs) have great potentials to be applied for indoor search and rescue missions. In this paper, we propose a modular lightweight design of an autonomous MAV with integrated hardware and software. The MAV is equipped with the 2D laser scanner, camera, mission computer and flight controller, running all the computation onboard in real time. The onboard perception system includes a laser‐based SLAM module and a custom‐designed visual detection module. A dual Kalman filter design provides robust state estimation by multiple sensor fusion. Specifically, the fusion module provides robust altitude measurement in the circumstance of surface changing. In addition, indoor‐outdoor transition is explicitly handled by the fusion module. In order to efficiently navigate through obstacles and adapt to multiple tasks, a task tree‐based mission planning method is seamlessly integrated with path planning and control modules. The MAV is capable of searching and rescuing victims from unknown indoor environments effectively. It was validated by our award‐winning performance at the 2017 International Micro Air Vehicle Competition (IMAV 2017), held in Toulouse, France. The performance video is available on https://youtu.be/8H19ppS_VXM .  相似文献   
62.
International Journal of Computer Vision - Anticipating future situations from streaming sensor data is a key perception challenge for mobile robotics and automated vehicles. We address the problem...  相似文献   
63.
Measurement Techniques - A comparative analysis of the results of estimation of measurement uncertainty is conducted. The results are obtained by a method described in the Handbook on the...  相似文献   
64.
65.
Strength of Materials - The paper addresses the investigation of high-strain rate compressive behavior of Al foams subjected to impact at the intermediate striking velocity ranged from 40 to...  相似文献   
66.
Electrochemical impedance spectroscopy (EIS), anodic polarization and scanning electron microscopy techniques were used to investigate the damage mechanism in the transpassive potential region of AISI ...  相似文献   
67.
68.
Potentiometric sensors with plasticized poly(vinyl chloride) membranes based on β-lactam–tetraalkylammonium ion associates sensitive to penicillin antibiotics are proposed. The physicochemical characteristics (solubility product constants and dissociation constants) of active membrane components and the electrode, transport, and selective properties of the membranes of liquidand solid-contact sensors have been studied. The quantitative characteristics of membrane transport (penetrability, ion flux, and transport rate) have been evaluated. The main charge carriers in the membranes and at the membrane/solution interface have been determined from the membrane transport characteristics. The potentiometric sensors are shown to be applicable to the determination of penicillin antibiotics in biological fluids (blood serum and oral fluid) from patients with urinary tract infection.  相似文献   
69.
The authors have developed a procedure and a test bench for studying evolution of various nature physical fields in modeling geomedium fracture by fluids. The test bench performs synchronous recording of macro- and micro-deformation, heat and acoustic emission induced in physical models of geomedium under loading to discontinuity. The experimental procedure has been trialed. The analysis of the synchronized test data allows a conclusion on the existence of time–space relationship between different nature physical fields induced during failure of solids.  相似文献   
70.
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