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   831585篇
  免费   12307篇
  国内免费   2482篇
电工技术   15057篇
综合类   840篇
化学工业   125832篇
金属工艺   30159篇
机械仪表   23472篇
建筑科学   22039篇
矿业工程   3238篇
能源动力   22688篇
轻工业   76194篇
水利工程   7499篇
石油天然气   10891篇
武器工业   49篇
无线电   98477篇
一般工业技术   155960篇
冶金工业   164315篇
原子能技术   14449篇
自动化技术   75215篇
  2021年   6945篇
  2020年   5003篇
  2019年   6384篇
  2018年   10590篇
  2017年   10380篇
  2016年   11093篇
  2015年   8145篇
  2014年   13331篇
  2013年   39151篇
  2012年   21699篇
  2011年   30366篇
  2010年   23812篇
  2009年   26753篇
  2008年   27863篇
  2007年   27713篇
  2006年   24577篇
  2005年   22560篇
  2004年   21707篇
  2003年   21387篇
  2002年   20419篇
  2001年   20303篇
  2000年   18785篇
  1999年   20086篇
  1998年   49872篇
  1997年   35476篇
  1996年   27520篇
  1995年   21067篇
  1994年   18533篇
  1993年   18094篇
  1992年   13156篇
  1991年   12444篇
  1990年   12092篇
  1989年   11728篇
  1988年   11027篇
  1987年   9678篇
  1986年   9484篇
  1985年   11110篇
  1984年   10404篇
  1983年   9143篇
  1982年   8578篇
  1981年   8608篇
  1980年   8154篇
  1979年   7990篇
  1978年   7552篇
  1977年   9076篇
  1976年   12136篇
  1975年   6458篇
  1974年   6135篇
  1973年   6136篇
  1972年   4993篇
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
71.
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   
72.
Machine Learning - We propose a set of highly scalable algorithms for the combinatorial data analysis problem of seriating similarity matrices. Seriation consists of finding a permutation of data...  相似文献   
73.
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   
74.
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   
75.
Mobile Networks and Applications - Public cloud system offers Infrastructure-as-a-Service (IaaS) to deliver the computational resources on demand. Resource requirements of a cloud environment are...  相似文献   
76.
77.
When solving a mathematical problem, students who do not have sufficient conceptual understanding may perform poorly and exhibit misconceptions. This study was aimed to examine students' conceptual understanding and significant misconceptions when solving number sense‐related problems. An online three‐tier diagnostic test was administered to 125 fifth‐grade students with varied socio‐economic backgrounds in Hong Kong. Only 14.40% of the students exhibited high performance with high confidence, indicating that these students had a profound conceptual understanding of number sense. In addition, the majority of the students (66.40%) did not demonstrate number sense; these students exhibited several significant misconceptions and could solve the questions only by using a rule‐based method or guessing. Accordingly, most students performed unsatisfactorily on number sense‐related problems. This study is imperative in identifying early predictors and provides information for further compatible interventions in the teaching and learning of number sense in Hong Kong in particular and worldwide in general.  相似文献   
78.
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   
79.
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   
80.
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