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   1493382篇
  免费   26016篇
  国内免费   7005篇
电工技术   35139篇
综合类   6461篇
化学工业   272991篇
金属工艺   65982篇
机械仪表   44219篇
建筑科学   45607篇
矿业工程   11770篇
能源动力   50329篇
轻工业   107853篇
水利工程   15098篇
石油天然气   38593篇
武器工业   151篇
无线电   198343篇
一般工业技术   284534篇
冶金工业   144621篇
原子能技术   34445篇
自动化技术   170267篇
  2021年   15661篇
  2020年   11910篇
  2019年   14650篇
  2018年   18402篇
  2017年   18112篇
  2016年   22506篇
  2015年   17680篇
  2014年   28872篇
  2013年   88313篇
  2012年   35572篇
  2011年   49377篇
  2010年   44787篇
  2009年   53354篇
  2008年   45629篇
  2007年   43296篇
  2006年   43669篇
  2005年   39898篇
  2004年   41291篇
  2003年   40908篇
  2002年   39854篇
  2001年   36169篇
  2000年   34812篇
  1999年   33604篇
  1998年   38253篇
  1997年   35358篇
  1996年   32645篇
  1995年   29070篇
  1994年   27460篇
  1993年   27397篇
  1992年   25800篇
  1991年   22763篇
  1990年   23217篇
  1989年   22329篇
  1988年   20761篇
  1987年   19099篇
  1986年   18441篇
  1985年   21751篇
  1984年   22116篇
  1983年   20060篇
  1982年   19110篇
  1981年   19205篇
  1980年   17796篇
  1979年   18353篇
  1978年   17608篇
  1977年   17152篇
  1976年   17658篇
  1975年   15935篇
  1974年   15457篇
  1973年   15542篇
  1972年   13011篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
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   
22.
23.
24.
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   
25.
26.
27.
28.
Here we report some recent biophysical issues on the preparation of solute-filled lipid vesicles and their relevance to the construction of “synthetic cells.” First, we introduce the “semi-synthetic minimal cells” as the liposome-based cell-like systems, which contain a minimal number of biomolecules required to display simple and complex biological functions. Next, we focus on recent aspects related to the construction of synthetic cells. Emphasis is given to the interplay between the methods of synthetic cell preparation and the physics of solute encapsulation. We briefly introduce the notion of structural and compositional “diversity” in synthetic cell populations.  相似文献   
29.
30.
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