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   1604206篇
  免费   37141篇
  国内免费   12852篇
电工技术   42176篇
技术理论   9篇
综合类   14901篇
化学工业   289379篇
金属工艺   70554篇
机械仪表   50105篇
建筑科学   54695篇
矿业工程   14674篇
能源动力   53334篇
轻工业   117886篇
水利工程   17398篇
石油天然气   43338篇
武器工业   1183篇
无线电   209565篇
一般工业技术   294918篇
冶金工业   159792篇
原子能技术   35599篇
自动化技术   184693篇
  2022年   14279篇
  2021年   20957篇
  2020年   15832篇
  2019年   17764篇
  2018年   19798篇
  2017年   19674篇
  2016年   24954篇
  2015年   22076篇
  2014年   34399篇
  2013年   94518篇
  2012年   42835篇
  2011年   55852篇
  2010年   49729篇
  2009年   58054篇
  2008年   51079篇
  2007年   47893篇
  2006年   49963篇
  2005年   44210篇
  2004年   44745篇
  2003年   44573篇
  2002年   43704篇
  2001年   40042篇
  2000年   37984篇
  1999年   36619篇
  1998年   43625篇
  1997年   38820篇
  1996年   35470篇
  1995年   31283篇
  1994年   29225篇
  1993年   28771篇
  1992年   26549篇
  1991年   23480篇
  1990年   23723篇
  1989年   22800篇
  1988年   21150篇
  1987年   19389篇
  1986年   18724篇
  1985年   22047篇
  1984年   22239篇
  1983年   20201篇
  1982年   19221篇
  1981年   19316篇
  1980年   17962篇
  1979年   18458篇
  1978年   17666篇
  1977年   17386篇
  1976年   18078篇
  1975年   15935篇
  1974年   15441篇
  1973年   15529篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
A layer-by-layer analysis of the structures, the phase compositions, and the defect substructures of differentially hardened rails has been carried by optical and transmission electron microscopy. It is found that the material volume of the rail head fillet is cooled faster than the volume located along the central axis.  相似文献   
32.
33.
34.
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   
35.
36.
Cable‐shaped supercapacitors (SCs) have recently aroused significant attention due to their attractive properties such as small size, lightweight, and bendability. Current cable‐shaped SCs have symmetric device configuration. However, if an asymmetric design is used in cable‐shaped supercapacitors, they would become more attractive due to broader cell operation voltages, which results in higher energy densities. Here, a novel coil‐type asymmetric supercapacitor electrical cable (CASEC) is reported with enhanced cell operation voltage and extraordinary mechanical‐electrochemical stability. The CASECs show excellent charge–discharge profiles, extraordinary rate capability (95.4%), high energy density (0.85 mWh cm−3), remarkable flexibility and bendability, and superior bending cycle stability (≈93.0% after 4000 cycles at different bending states). In addition, the CASECs not only exhibit the capability to store energy but also to transmit electricity simultaneously and independently. The integrated electrical conduction and storage capability of CASECS offer many potential applications in solar energy storage and electronic gadgets.  相似文献   
37.
38.
39.
40.
Pinhão seed is an unconventional source of starch and the pines grow up in native forests of southern Latin America. In this study, pinhão starch was adjusted at 15, 20 and 25% moisture content and heated to 100, 110 and 120 °C for 1 h. A decrease in λ max (starch/iodine complex) was observed as a result of increase in temperature and moisture content of HMT. The ratio of crystalline to amorphous phase in pinhão starch was determined via Fourier transform infra red by taking 1045/1022 band ratio. A decrease in crystallinity occurred as a result of HMT. Polarised light microscopy indicated a loss of birefringence of starch granules under 120 °C at 25% moisture content. Granule size distribution was further confirmed via scanning electron microscopy which showed the HMT effects. These results increased the understanding on molecular and structural properties of HMT pinhão starch and broadened its food and nonfood industrial applications.  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