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   330308篇
  免费   19648篇
  国内免费   1853篇
电工技术   6357篇
技术理论   5篇
综合类   1186篇
化学工业   64821篇
金属工艺   11948篇
机械仪表   9059篇
建筑科学   9211篇
矿业工程   1744篇
能源动力   7145篇
轻工业   37634篇
水利工程   3478篇
石油天然气   6186篇
武器工业   250篇
无线电   35402篇
一般工业技术   65496篇
冶金工业   56001篇
原子能技术   5761篇
自动化技术   30125篇
  2021年   3613篇
  2020年   3834篇
  2019年   6044篇
  2018年   7455篇
  2017年   7650篇
  2016年   8535篇
  2015年   7366篇
  2014年   9341篇
  2013年   18694篇
  2012年   12222篇
  2011年   14243篇
  2010年   12108篇
  2009年   12418篇
  2008年   12735篇
  2007年   12464篇
  2006年   10824篇
  2005年   9404篇
  2004年   8610篇
  2003年   8071篇
  2002年   7963篇
  2001年   7750篇
  2000年   7340篇
  1999年   6791篇
  1998年   15352篇
  1997年   11240篇
  1996年   8384篇
  1995年   6191篇
  1994年   5585篇
  1993年   5554篇
  1992年   4172篇
  1991年   3973篇
  1990年   3996篇
  1989年   3947篇
  1988年   3700篇
  1987年   3164篇
  1986年   3191篇
  1985年   3566篇
  1984年   3448篇
  1983年   3169篇
  1982年   2835篇
  1981年   3072篇
  1980年   2821篇
  1979年   2924篇
  1978年   2824篇
  1977年   3140篇
  1976年   4305篇
  1975年   2507篇
  1974年   2339篇
  1973年   2384篇
  1972年   2006篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Urbano  Cristóbal  Ardanuy  Jordi 《Scientometrics》2020,124(1):575-602
Scientometrics - The interdisciplinary nature of library and information science (LIS) research has been highlighted for some time now. The term “interdisciplinary” is used primarily in...  相似文献   
52.
Russian Journal of Non-Ferrous Metals - Rolling bearing rings comprise a large reserve for expanding powder metallurgy production. This reserve is being incompletely implemented. The hot forging of...  相似文献   
53.
Metallurgical and Materials Transactions B - The process of obtaining titanium tetrachloride (TiCl4) from the quartz-leucoxene concentrate (QLC) from the Yaregskoe oil-titanium field was studied....  相似文献   
54.
55.
56.
57.
RCAS1 is a protein that participates in regulation of the tumor microenvironment and its immune responses, all in order to evade the immune system. The aim of this study was to analyze RCAS1 expression in urothelial bladder cancer cells (and in fibroblasts and macrophages of the tumor stroma) and its relationship with the histological pattern of malignancy. Eighty-three postcystectomy patients were enrolled. We analyzed the histological maturity (grade), progress (pT stage), tissue invasion type (TIT), nonclassic differentiation number (NDN), and the ability to metastasize (pN). The expression of RCAS1 protein was analyzed by immunohistochemistry. Indicators of histological malignancy were observed solely in association with the RCAS1 expression in cells in the border parts (BPs) of the tumor. Histological malignancy of the tumor, indicated by the pT and pN, and metastasis-free survival time, correlated significantly with RCAS1 expression in tumor neoplastic cells, whereas malignancy determined by grade, TIT, and NDN correlated with RCAS1 expression in fibroblasts and macrophages in the tumor microenvironment. These findings suggest that the increased RCAS1 expression depends on its cellular source and that RCAS1 expression itself is a component of various signaling pathways. The immune escape occurs within the tumor BPs, where the increase in the RCAS1 expression occurs within tumor cells and stromal cells in its microenvironment. We conclude that the histological pattern of tumor malignancy, indicated by grade, TIT, NDN, pT, and pN is a morphological indicator of immune escape.  相似文献   
58.
59.
60.
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