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   309056篇
  免费   7312篇
  国内免费   1314篇
电工技术   5470篇
综合类   358篇
化学工业   49694篇
金属工艺   12247篇
机械仪表   8407篇
建筑科学   8527篇
矿业工程   675篇
能源动力   7887篇
轻工业   35048篇
水利工程   2450篇
石油天然气   1576篇
武器工业   10篇
无线电   33931篇
一般工业技术   56734篇
冶金工业   61803篇
原子能技术   4223篇
自动化技术   28642篇
  2022年   1554篇
  2021年   3234篇
  2020年   2381篇
  2019年   2936篇
  2018年   4676篇
  2017年   4559篇
  2016年   4983篇
  2015年   3919篇
  2014年   5682篇
  2013年   15870篇
  2012年   9130篇
  2011年   11710篇
  2010年   9481篇
  2009年   9971篇
  2008年   10496篇
  2007年   10334篇
  2006年   9017篇
  2005年   8157篇
  2004年   7765篇
  2003年   7646篇
  2002年   7556篇
  2001年   7299篇
  2000年   6704篇
  1999年   7318篇
  1998年   20198篇
  1997年   14098篇
  1996年   10645篇
  1995年   7717篇
  1994年   6763篇
  1993年   6651篇
  1992年   4434篇
  1991年   4368篇
  1990年   3875篇
  1989年   3812篇
  1988年   3738篇
  1987年   3171篇
  1986年   3066篇
  1985年   3754篇
  1984年   3349篇
  1983年   2963篇
  1982年   2792篇
  1981年   2864篇
  1980年   2695篇
  1979年   2438篇
  1978年   2410篇
  1977年   3232篇
  1976年   4998篇
  1975年   2030篇
  1974年   1897篇
  1973年   1918篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
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   
63.
64.
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   
65.
Metallurgical and Materials Transactions B - The quality requirements of aluminum products are steadily increasing, and the presence of non-metallic inclusions have a large impact on the quality of...  相似文献   
66.
67.
68.
69.
70.
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