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   1557391篇
  免费   31041篇
  国内免费   9790篇
电工技术   38497篇
技术理论   9篇
综合类   11035篇
化学工业   283533篇
金属工艺   67722篇
机械仪表   46858篇
建筑科学   52314篇
矿业工程   13399篇
能源动力   52323篇
轻工业   114509篇
水利工程   16195篇
石油天然气   41692篇
武器工业   669篇
无线电   204524篇
一般工业技术   289534篇
冶金工业   152278篇
原子能技术   34653篇
自动化技术   178478篇
  2021年   18450篇
  2020年   13987篇
  2019年   16401篇
  2018年   17403篇
  2017年   17051篇
  2016年   23178篇
  2015年   20035篇
  2014年   32347篇
  2013年   92057篇
  2012年   39589篇
  2011年   51813篇
  2010年   46430篇
  2009年   54631篇
  2008年   47849篇
  2007年   44797篇
  2006年   48427篇
  2005年   42488篇
  2004年   43335篇
  2003年   43144篇
  2002年   41934篇
  2001年   38653篇
  2000年   37373篇
  1999年   36418篇
  1998年   42116篇
  1997年   37920篇
  1996年   34939篇
  1995年   30962篇
  1994年   29012篇
  1993年   28534篇
  1992年   26590篇
  1991年   23536篇
  1990年   23738篇
  1989年   22707篇
  1988年   21228篇
  1987年   19443篇
  1986年   18823篇
  1985年   22068篇
  1984年   22346篇
  1983年   20289篇
  1982年   19243篇
  1981年   19300篇
  1980年   17875篇
  1979年   18487篇
  1978年   17703篇
  1977年   17206篇
  1976年   17744篇
  1975年   15969篇
  1974年   15540篇
  1973年   15590篇
  1972年   13042篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
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   
22.
23.
24.
25.
26.
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   
27.
28.
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   
29.
The viability and β‐galactosidase activity of four Lactobacillus strains in milk drink containing gums during 28 days of refrigerated storage at 4 °C were assessed. The population of Lactobacillus rhamnosus GGB101 and Lactobacillus rhamnosus GGB103 were maintained, whereas the population of Lactobacillus reuteri DSM20016 and Lactobacillus reuteri SD2112 significantly decreased. The recommended level of 6 log CFU g?1 was exceeded for all tested trains throughout storage. The highest viable number of Lactobacillus rhamnosus GGB103 (8.76 ± 0.03 log CFU mL?1) was obtained in the product containing carrageenan–maltodextrin. The addition of guar–locust bean–carrageenan led to 20‐fold increase in the level of β‐galactosidase activity for L. rhamnosus GGB101 (1208 ± 2.12 Miller units mL?1) compared to the control (61 ± 2.83 Miller units mL?1). Our results suggested that gums could be added to milk to improve viability and enhance β‐galactosidase activity of Lactobacillus.  相似文献   
30.
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