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   238093篇
  免费   29135篇
  国内免费   7774篇
电工技术   11886篇
技术理论   14篇
综合类   11214篇
化学工业   51039篇
金属工艺   10821篇
机械仪表   12655篇
建筑科学   18030篇
矿业工程   4942篇
能源动力   6607篇
轻工业   19303篇
水利工程   3485篇
石油天然气   11114篇
武器工业   1345篇
无线电   31411篇
一般工业技术   36388篇
冶金工业   11437篇
原子能技术   2115篇
自动化技术   31196篇
  2024年   881篇
  2023年   3262篇
  2022年   5828篇
  2021年   8052篇
  2020年   7034篇
  2019年   7710篇
  2018年   8106篇
  2017年   9235篇
  2016年   9149篇
  2015年   10809篇
  2014年   12979篇
  2013年   16616篇
  2012年   14601篇
  2011年   15973篇
  2010年   13961篇
  2009年   13717篇
  2008年   12712篇
  2007年   12164篇
  2006年   12340篇
  2005年   10859篇
  2004年   7771篇
  2003年   6969篇
  2002年   6411篇
  2001年   5750篇
  2000年   5859篇
  1999年   6049篇
  1998年   5319篇
  1997年   4385篇
  1996年   3974篇
  1995年   3317篇
  1994年   2787篇
  1993年   2200篇
  1992年   1711篇
  1991年   1286篇
  1990年   1029篇
  1989年   881篇
  1988年   684篇
  1987年   501篇
  1986年   401篇
  1985年   336篇
  1984年   214篇
  1983年   202篇
  1982年   164篇
  1981年   146篇
  1980年   132篇
  1979年   97篇
  1978年   65篇
  1977年   64篇
  1976年   77篇
  1973年   39篇
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
61.
Amino acid modified polyaspartic acids were evaluated as calcium-scale inhibitors. Feasibility of scale inhibition experiments was analyzed by molecular dynamics simulation and Gaussian optimization, and the scale inhibition mechanism was theoretically analyzed. Scale inhibition performance was studied by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, static scale inhibition experiments, and electrochemical performance testing, which provided an experimental basis for the molecular dynamics simulation. The experimental results showed that Arg-SA-PASP has better scale inhibition and corrosion inhibition performance than His-SA-PASP. The scale inhibition effect increased with increasing concentration. Electrochemical tests indicated that Arg-SA-PASP is an excellent scale and corrosion inhibitor.  相似文献   
62.
63.
Since the beginning of the 21st Century, the development of microfluidic chip technology has been very rapid and has attracted the attention of more and more scholars. As an important part of the microfluidic chip, the performance of the micromixer is critical. The fractal structure in the microchannels helps to improve the mixing performance of the micromixer and improve the mixing efficiency of the micromixer. The research results of other scholars are of great significance to the research of the present paper, which mainly studies the effect of changing the baffle state on the mixing efficiency of the micromixer based on the Koch fractal principle. Through simulation analysis, it was found that the mixing efficiency of the baffles distributed on both sides of the microchannel was higher than the mixing efficiency of the baffles distributed on the microchannel side. When the distance between adjacent baffles was divided into 0.15, 0.25 and 0.35 mm, simulated data suggested that the baffle distance of 0.15 mm was best. Increasing the number of baffles from six to eight groups increased the mixing path of the fluid in the microchannel and improved mixing efficiency. A comparison of mixing efficiencies of the 0°, 15° and 30° baffle angles revealed that very significant improvement in mixing efficiency was obtained at 30°. © 2019 Society of Chemical Industry  相似文献   
64.
Wang  Lijing  Chen  Jiangzhuo  Marathe  Achla 《World Wide Web》2019,22(6):2997-3020
World Wide Web - Infectious diseases such as Influenza and Ebola pose a serious threat to everyone but certain demographics and cohorts face a higher risk of infection than others. This research...  相似文献   
65.
The use of field robots can greatly decrease the amount of time, effort, and associated risk compared to if human workers were to carryout certain tasks such as disaster response. However, transportability and reliability remain two main issues for most current robot systems. To address the issue of transportability, we have developed a lightweight modularizable platform named AeroArm. To address the issue of reliability, we utilize a multimodal sensing approach, combining the use of multiple sensors and sensor types, and the use of different detection algorithms, as well as active continuous closed‐loop feedback to accurately estimate the state of the robot with respect to the environment. We used Challenge 2 of the 2017 Mohammed Bin Zayed International Robotics Competition as an example outdoor manipulation task, demonstrating the capabilities of our robot system and approach in achieving reliable performance in the fields, and ranked fifth place internationally in the competition.  相似文献   
66.
Chen  Meng  Yu  Xiaohui  Liu  Yang 《World Wide Web》2019,22(6):2901-2920
World Wide Web - The wide spread use of positioning and photographing devices gives rise to a deluge of traffic trajectory data (e.g., vehicle passage records and taxi trajectory data), with each...  相似文献   
67.
液滴撞击干燥倾斜壁面铺展实验研究   总被引:2,自引:0,他引:2       下载免费PDF全文
通过高速摄影技术及像素分析方法对液滴撞击干燥倾斜壁面进行实验研究,分析了不同倾斜角及韦伯数(We)对液滴飞溅及铺展的影响,结果表明,倾斜角的增加有利于抑制飞溅的产生;We一定时,液滴的前铺展因子随着倾斜角的增加而增加,后铺展因子随着倾斜角的增加而减小;液滴的前后初始铺展速度均大于液滴的撞击速度,且随着倾斜角的增加而减小。   相似文献   
68.
69.
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