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   113138篇
  免费   20410篇
  国内免费   4052篇
电工技术   4980篇
技术理论   1篇
综合类   6907篇
化学工业   28828篇
金属工艺   4372篇
机械仪表   5492篇
建筑科学   6722篇
矿业工程   1627篇
能源动力   3041篇
轻工业   13645篇
水利工程   1755篇
石油天然气   2831篇
武器工业   545篇
无线电   16044篇
一般工业技术   19490篇
冶金工业   4298篇
原子能技术   1100篇
自动化技术   15922篇
  2024年   229篇
  2023年   842篇
  2022年   1607篇
  2021年   2448篇
  2020年   3086篇
  2019年   4523篇
  2018年   4638篇
  2017年   5122篇
  2016年   5604篇
  2015年   6333篇
  2014年   7243篇
  2013年   9236篇
  2012年   7718篇
  2011年   7887篇
  2010年   7767篇
  2009年   7592篇
  2008年   7159篇
  2007年   6758篇
  2006年   6411篇
  2005年   5374篇
  2004年   4654篇
  2003年   4283篇
  2002年   4801篇
  2001年   4189篇
  2000年   3195篇
  1999年   2051篇
  1998年   1279篇
  1997年   1048篇
  1996年   891篇
  1995年   751篇
  1994年   574篇
  1993年   422篇
  1992年   334篇
  1991年   272篇
  1990年   240篇
  1989年   164篇
  1988年   144篇
  1987年   127篇
  1986年   87篇
  1985年   87篇
  1984年   67篇
  1983年   61篇
  1982年   27篇
  1981年   40篇
  1980年   39篇
  1979年   25篇
  1978年   22篇
  1977年   31篇
  1976年   40篇
  1975年   16篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
The aim of this exploratory study has been to investigate the fire properties and environmental aspects of different upholstery material combinations, mainly for domestic applications. An analysis of the sustainability and circularity of selected textiles, along with lifecycle assessment, is used to qualitatively evaluate materials from an environmental perspective. The cone calorimeter was the primary tool used to screen 20 different material combinations from a fire performance perspective. It was found that textile covers of conventional fibres such as wool, cotton and polyester, can be improved by blending them with fire resistant speciality fibres. A new three‐dimensional web structure has been examined as an alternative padding material, showing preliminary promising fire properties with regard to ignition time, heat release rates and smoke production.  相似文献   
13.
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   
14.
The germline carrier of the BRCA1 pathogenic mutation has been well proven to confer an increased risk of breast and ovarian cancer. Despite BRCA1 biallelic pathogenic mutations being extremely rare, they have been reported to be embryonically lethal or to cause Fanconi anemia (FA). Here we describe a patient who was a 48-year-old female identified with biallelic pathogenic mutations of the BRCA1 gene, with no or very subtle FA-features. She was diagnosed with ovarian cancer and breast cancer at the ages of 43 and 44 and had a strong family history of breast and gynecological cancers.  相似文献   
15.
16.
17.
18.
19.
20.
Lobster krill (Munida genus) represents an under‐valued crustacean frequently caught on European fishing banks. In this work, its sensory, microbiological and biochemical qualities were evaluated during chilled storage. Additionally, the effects of a prestorage antimelanosic treatment consisting of soaking in sodium metabisulphite (SMB) solutions at two different concentrations (0.25% and 0.75%) were also studied. SMB prestorage treatment provided lobster specimens that still exhibited acceptable sensory quality after 10 days of storage, while control specimens were unacceptable at that time. SMB treatment also resulted in a significant (P < 0.05) inhibition of microbial growth, mainly of Enterobacteriaceae, psychrotrophes and proteolytic bacteria. Low lipid oxidation levels were observed for all batches; however, a significantly higher (P < 0.05) retention of polyunsaturated fatty acids was found in SMB‐treated lobster, especially in the 0.75% SMB batch. The results presented here open the way to the potential commercialisation of currently under‐utilised lobster krill as a chilled product.  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