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   221967篇
  免费   18378篇
  国内免费   9082篇
电工技术   12677篇
技术理论   15篇
综合类   12746篇
化学工业   37958篇
金属工艺   11551篇
机械仪表   12977篇
建筑科学   17886篇
矿业工程   5369篇
能源动力   6319篇
轻工业   14225篇
水利工程   3653篇
石油天然气   11856篇
武器工业   1564篇
无线电   27705篇
一般工业技术   28873篇
冶金工业   11531篇
原子能技术   2344篇
自动化技术   30178篇
  2024年   1027篇
  2023年   3653篇
  2022年   6560篇
  2021年   8734篇
  2020年   6479篇
  2019年   5564篇
  2018年   6012篇
  2017年   6851篇
  2016年   6296篇
  2015年   8093篇
  2014年   10451篇
  2013年   13356篇
  2012年   13439篇
  2011年   15103篇
  2010年   12775篇
  2009年   12497篇
  2008年   11852篇
  2007年   11449篇
  2006年   11794篇
  2005年   10318篇
  2004年   7077篇
  2003年   6319篇
  2002年   5976篇
  2001年   5365篇
  2000年   5252篇
  1999年   5978篇
  1998年   5489篇
  1997年   4535篇
  1996年   4115篇
  1995年   3434篇
  1994年   2858篇
  1993年   2280篇
  1992年   1791篇
  1991年   1326篇
  1990年   1054篇
  1989年   906篇
  1988年   699篇
  1987年   512篇
  1986年   405篇
  1985年   344篇
  1984年   220篇
  1983年   205篇
  1982年   168篇
  1981年   146篇
  1980年   134篇
  1979年   98篇
  1978年   63篇
  1977年   63篇
  1976年   77篇
  1975年   38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.
The basic structural and functional unit of a living organism is a single cell. To understand the variability and to improve the biomedical requirement of a single cell, its analysis has become a key technique in biological and biomedical research. With a physical boundary of microchannels and microstructures, single cells are efficiently captured and analyzed, whereas electric forces sort and position single cells. Various microfluidic techniques have been exploited to manipulate single cells through hydrodynamic and electric forces. Digital microfluidics (DMF), the manipulation of individual droplets holding minute reagents and cells of interest by electric forces, has received more attention recently. Because of ease of fabrication, compactness and prospective automation, DMF has become a powerful approach for biological application. We review recent developments of various microfluidic chips for analysis of a single cell and for efficient genetic screening. In addition, perspectives to develop analysis of single cells based on DMF and emerging functionality with high throughput are discussed.  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