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   27210篇
  免费   1863篇
  国内免费   66篇
电工技术   373篇
综合类   27篇
化学工业   6491篇
金属工艺   1072篇
机械仪表   1665篇
建筑科学   516篇
矿业工程   9篇
能源动力   1161篇
轻工业   2265篇
水利工程   106篇
石油天然气   19篇
无线电   4600篇
一般工业技术   5890篇
冶金工业   1694篇
原子能技术   377篇
自动化技术   2874篇
  2024年   27篇
  2023年   325篇
  2022年   472篇
  2021年   840篇
  2020年   618篇
  2019年   673篇
  2018年   879篇
  2017年   869篇
  2016年   973篇
  2015年   823篇
  2014年   1215篇
  2013年   1773篇
  2012年   1905篇
  2011年   2317篇
  2010年   1640篇
  2009年   1659篇
  2008年   1506篇
  2007年   1171篇
  2006年   1028篇
  2005年   903篇
  2004年   810篇
  2003年   776篇
  2002年   729篇
  2001年   648篇
  2000年   526篇
  1999年   536篇
  1998年   787篇
  1997年   484篇
  1996年   457篇
  1995年   307篇
  1994年   202篇
  1993年   171篇
  1992年   144篇
  1991年   119篇
  1990年   100篇
  1989年   116篇
  1988年   95篇
  1987年   77篇
  1986年   65篇
  1985年   59篇
  1984年   48篇
  1983年   31篇
  1982年   32篇
  1981年   28篇
  1980年   31篇
  1979年   15篇
  1977年   25篇
  1976年   36篇
  1975年   18篇
  1974年   14篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Food Science and Biotechnology - Various hilling materials (rice hulls, pine sawdust, and perlite) were compared to produce sprout vegetables using beach silvertop (Glehnia littoralis Fr. Schm. ex...  相似文献   
3.
International Journal of Information Security - Machine learning techniques have been widely used and shown remarkable performance in various fields. Along with the widespread utilization of...  相似文献   
4.
5.
6.
Antimony triselenide (Sb2Se3) nanoflake-based nitrogen dioxide (NO2) sensors exhibit a progressive bifunctional gas-sensing performance, with a rapid alarm for hazardous highly concentrated gases, and an advanced memory-type function for low-concentration (<1 ppm) monitoring repeated under potentially fatal exposure. Rectangular and cuboid shaped Sb2Se3 nanoflakes, comprising van der Waals planes with large surface areas and covalent bond planes with small areas, can rapidly detect a wide range of NO2 gas concentrations from 0.1 to 100 ppm. These Sb2Se3 nanoflakes are found to be suitable for physisorption-based gas sensing owing to their anisotropic quasi-2D crystal structure with extremely enlarged van der Waals planes, where they are humidity-insensitive and consequently exhibit an extremely stable baseline current. The Sb2Se3 nanoflake sensor exhibits a room-temperature/low-voltage operation, which is noticeable owing to its low energy consumption and rapid response even under a NO2 gas flow of only 1 ppm. As a result, the Sb2Se3 nanoflake sensor is suitable for the development of a rapid alarm system. Furthermore, the persistent gas-sensing conductivity of the sensor with a slow decaying current can enable the development of a progressive memory-type sensor that retains the previous signal under irregular gas injection at low concentrations.  相似文献   
7.
A recent development in tactile technology enables an improvement in the appreciation of the visual arts for people with visual impairment (PVI). The tactile sense, in conjunction with, or a possibly as an alternative to, the auditory sense, would allow PVIs to approach artwork in a more self‐driven and engaging way that would be difficult to achieve with just an auditory stimulus. Tactile colour pictograms (TCPs), which are raised geometric patterns, are ideographic characters that are designed to enable PVIs to identify colours and interpret information by touch. In this article, three TCPs are introduced to code colours in the Munsell colour system. Each colour pattern consists of a basic cell size of 10 mm × 10 mm to represent the patterns consistently in terms of regular shape. Each TCP consists of basic geometric patterns that are combined to create primary, secondary, and tertiary colour pictograms of shapes indicating colour hue, intensity and lightness. Each TCP represents 29 colours including six hues; they were then further expanded to represent 53 colours. Two of them did not increase the cell size, the other increased the cell size 1.5 times for some colours, such as yellow‐orange, yellow, blue, and blue‐purple. Our proposed TCPs use a slightly larger cell size compared to most tactile patterns currently used to indicate colour, but code for more colours. With user experience and identification tests, conducted with 23 visually impaired adults, the effectiveness of the TCPs suggests that they were helpful for the participants.  相似文献   
8.
9.
Food Science and Biotechnology - Aluminum based reflective nanolens arrays were developed via a series of aluminum electropolishing and anodization steps with subsequent selective dissolution of...  相似文献   
10.
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