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   578917篇
  免费   12829篇
  国内免费   4104篇
电工技术   13035篇
技术理论   8篇
综合类   4150篇
化学工业   87944篇
金属工艺   22844篇
机械仪表   18430篇
建筑科学   16605篇
矿业工程   3772篇
能源动力   16232篇
轻工业   50469篇
水利工程   6308篇
石油天然气   12162篇
武器工业   682篇
无线电   66554篇
一般工业技术   108224篇
冶金工业   106282篇
原子能技术   11246篇
自动化技术   50903篇
  2022年   4953篇
  2021年   7329篇
  2020年   5287篇
  2019年   6059篇
  2018年   9479篇
  2017年   9399篇
  2016年   9535篇
  2015年   7811篇
  2014年   11907篇
  2013年   27439篇
  2012年   18156篇
  2011年   23870篇
  2010年   19066篇
  2009年   20868篇
  2008年   21120篇
  2007年   20639篇
  2006年   18412篇
  2005年   16618篇
  2004年   15384篇
  2003年   14973篇
  2002年   14268篇
  2001年   14326篇
  2000年   13154篇
  1999年   13896篇
  1998年   33919篇
  1997年   23849篇
  1996年   18215篇
  1995年   13670篇
  1994年   11759篇
  1993年   11380篇
  1992年   8223篇
  1991年   7671篇
  1990年   7438篇
  1989年   7185篇
  1988年   6603篇
  1987年   5847篇
  1986年   5738篇
  1985年   6336篇
  1984年   5931篇
  1983年   5195篇
  1982年   4936篇
  1981年   4998篇
  1980年   4722篇
  1979年   4625篇
  1978年   4416篇
  1977年   5348篇
  1976年   6990篇
  1975年   3807篇
  1974年   3560篇
  1973年   3679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.
67.
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   
68.
69.
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   
70.
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   
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