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   808635篇
  免费   12691篇
  国内免费   2475篇
电工技术   14870篇
综合类   864篇
化学工业   118577篇
金属工艺   29797篇
机械仪表   23082篇
建筑科学   20916篇
矿业工程   2948篇
能源动力   22308篇
轻工业   74039篇
水利工程   7362篇
石油天然气   10467篇
武器工业   57篇
无线电   97553篇
一般工业技术   153572篇
冶金工业   160426篇
原子能技术   14274篇
自动化技术   72689篇
  2021年   6687篇
  2020年   4888篇
  2019年   6186篇
  2018年   10374篇
  2017年   10201篇
  2016年   10810篇
  2015年   7975篇
  2014年   13085篇
  2013年   38157篇
  2012年   21313篇
  2011年   29810篇
  2010年   23364篇
  2009年   26244篇
  2008年   27294篇
  2007年   27198篇
  2006年   24070篇
  2005年   22071篇
  2004年   21283篇
  2003年   20972篇
  2002年   20017篇
  2001年   20013篇
  2000年   18579篇
  1999年   19815篇
  1998年   49663篇
  1997年   35102篇
  1996年   26093篇
  1995年   20606篇
  1994年   18072篇
  1993年   17643篇
  1992年   12686篇
  1991年   12075篇
  1990年   11671篇
  1989年   11232篇
  1988年   10604篇
  1987年   9242篇
  1986年   9118篇
  1985年   10679篇
  1984年   9977篇
  1983年   8742篇
  1982年   8191篇
  1981年   8286篇
  1980年   7812篇
  1979年   7639篇
  1978年   7253篇
  1977年   8809篇
  1976年   11879篇
  1975年   6223篇
  1974年   5913篇
  1973年   5908篇
  1972年   4825篇
排序方式: 共有10000条查询结果,搜索用时 640 毫秒
91.
92.
93.
94.
95.
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   
96.
97.
98.
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   
99.
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   
100.
Metallurgical and Materials Transactions A - The influence of the chemical composition on the crystallization process, amorphous phase formation, and the anticorrosion properties of Al-Zr-Ni-Fe-Y...  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