首页 | 官方网站   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   448540篇
  免费   7849篇
  国内免费   1863篇
工业技术   458252篇
  2021年   3958篇
  2020年   2825篇
  2019年   3500篇
  2018年   5400篇
  2017年   5308篇
  2016年   5866篇
  2015年   4400篇
  2014年   7240篇
  2013年   20567篇
  2012年   11993篇
  2011年   16352篇
  2010年   13053篇
  2009年   14514篇
  2008年   15018篇
  2007年   14620篇
  2006年   13373篇
  2005年   12289篇
  2004年   11868篇
  2003年   11652篇
  2002年   11478篇
  2001年   11441篇
  2000年   10582篇
  1999年   11536篇
  1998年   29603篇
  1997年   20380篇
  1996年   15938篇
  1995年   11876篇
  1994年   10363篇
  1993年   10136篇
  1992年   7133篇
  1991年   6997篇
  1990年   6555篇
  1989年   6333篇
  1988年   5996篇
  1987年   5005篇
  1986年   5009篇
  1985年   5773篇
  1984年   5132篇
  1983年   4623篇
  1982年   4209篇
  1981年   4329篇
  1980年   3964篇
  1979年   3700篇
  1978年   3649篇
  1977年   4558篇
  1976年   6504篇
  1975年   3131篇
  1974年   2982篇
  1973年   2957篇
  1972年   2482篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
The Journal of Supercomputing - Spark is one of the most widely used systems for the distributed processing of big data. Its performance bottlenecks are mainly due to the network I/O, disk I/O, and...  相似文献   
52.
53.
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.
The basic structural and functional unit of a living organism is a single cell. To understand the variability and to improve the biomedical requirement of a single cell, its analysis has become a key technique in biological and biomedical research. With a physical boundary of microchannels and microstructures, single cells are efficiently captured and analyzed, whereas electric forces sort and position single cells. Various microfluidic techniques have been exploited to manipulate single cells through hydrodynamic and electric forces. Digital microfluidics (DMF), the manipulation of individual droplets holding minute reagents and cells of interest by electric forces, has received more attention recently. Because of ease of fabrication, compactness and prospective automation, DMF has become a powerful approach for biological application. We review recent developments of various microfluidic chips for analysis of a single cell and for efficient genetic screening. In addition, perspectives to develop analysis of single cells based on DMF and emerging functionality with high throughput are discussed.  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-23

京公网安备 11010802026262号