全文获取类型
收费全文 | 126405篇 |
免费 | 10828篇 |
国内免费 | 2455篇 |
出版年
2023年 | 652篇 |
2022年 | 1645篇 |
2021年 | 3472篇 |
2020年 | 2088篇 |
2019年 | 2605篇 |
2018年 | 2831篇 |
2017年 | 2304篇 |
2016年 | 3733篇 |
2015年 | 6010篇 |
2014年 | 6845篇 |
2013年 | 7851篇 |
2012年 | 10014篇 |
2011年 | 9775篇 |
2010年 | 6052篇 |
2009年 | 5546篇 |
2008年 | 7431篇 |
2007年 | 7240篇 |
2006年 | 6766篇 |
2005年 | 6410篇 |
2004年 | 6055篇 |
2003年 | 5688篇 |
2002年 | 5273篇 |
2001年 | 1701篇 |
2000年 | 1359篇 |
1999年 | 1673篇 |
1998年 | 1660篇 |
1997年 | 1278篇 |
1996年 | 1181篇 |
1995年 | 1041篇 |
1994年 | 994篇 |
1993年 | 971篇 |
1992年 | 992篇 |
1991年 | 899篇 |
1990年 | 792篇 |
1989年 | 643篇 |
1988年 | 654篇 |
1987年 | 540篇 |
1986年 | 458篇 |
1985年 | 584篇 |
1984年 | 638篇 |
1983年 | 506篇 |
1982年 | 581篇 |
1981年 | 545篇 |
1980年 | 468篇 |
1979年 | 367篇 |
1978年 | 389篇 |
1977年 | 327篇 |
1976年 | 310篇 |
1975年 | 243篇 |
1974年 | 272篇 |
排序方式: 共有10000条查询结果,搜索用时 828 毫秒
31.
32.
Silvio Antoniak Erica M. Sparkenbaugh Michael Tencati Mauricio Rojas Nigel Mackman Rafal Pawlinski 《PloS one》2013,8(11)
Heart failure is a major clinical problem worldwide. Previous studies have demonstrated an important role for G protein-coupled receptors, including protease-activated receptors (PARs), in the pathology of heart hypertrophy and failure. Activation of PAR-2 on cardiomyocytes has been shown to induce hypertrophic growth in vitro. PAR-2 also contributes to myocardial infarction and heart remodeling after ischemia/reperfusion injury. In this study, we found that PAR-2 induced hypertrophic growth of cultured rat neonatal cardiomyocytes in a MEK1/2 and p38 dependent manner. In addition, PAR-2 activation on mouse cardiomyocytes increased expression of the pro-fibrotic chemokine MCP-1. Furthermore, cardiomyocyte-specific overexpression of PAR-2 in mice induced heart hypertrophy, cardiac fibrosis, inflammation and heart failure. Finally, in a mouse model of myocardial infarction induced by permanent ligation of the left anterior descending coronary artery, PAR-2 deficiency attenuated heart remodeling and improved heart function independently of its contribution to the size of the initial infarct. Taken together, our data indicate that PAR-2 signaling contributes to the pathogenesis of hypertrophy and heart failure. 相似文献
33.
34.
Yunfan Sun Liang Wu Yu Zhong Kaiqian Zhou Yong Hou Zifei Wang Zefan Zhang Jiarui Xie Chunqing Wang Dandan Chen Yaling Huang Xiaochan Wei Yinghong Shi Zhikun Zhao Yuehua Li Ziwei Guo Qichao Yu Liqin Xu Jia Fan 《Cell》2021,184(2):404-421.e16
- Download : Download high-res image (233KB)
- Download : Download full-size image
35.
Michael Lenhard 《Current biology : CB》2012,22(19):R838-R840
36.
37.
Expression of tracheal differentiated functions in serum-free hormone-supplemented medium 总被引:18,自引:0,他引:18
Most dissociated airway epithelial cells in culture express few of their in vivo functions and only to a limited degree. In this report, we demonstrate that hamster tracheal epithelial (HTE) cells cultured on a collagen gel substratum in a serum-free hormone-supplemented medium differentiate to cilia-beating and mucus-secreting cell types. The medium is Ham's F-12 supplemented with insulin, epidermal growth factor, transferrin, hydrocortisone, cholera toxin, bovine hypothalamus extract, and vitamin A. Under these culture conditions, HTE cells exhibit a growth rate of 24 h/population doubling and reach confluency, at a density of 2-5 X 10(4) cells/cm2, within 2 weeks. Both the collagen gel substratum and vitamin A of this culture system are important to the growth and differentiation of HTE cells in vitro. Evidence of HTE cell differentiation has been obtained at both the ultrastructural and the histochemical levels. In addition, a variety of biochemical studies (gel filtration, ion exchange column chromatography, enzyme digestion, nitrous acid treatment, and composition analysis) indicate the production of mucin-like glycoprotein in the HTE cultures. The levels of mucin-like glycoprotein were found to closely correlate with the histochemically quantitated levels of the mucous cell type. Kinetic studies demonstrate that HTE cells rapidly lose their differentiated features during the attachment stage of primary culture but redifferentiation occurs after the cultures reach confluency. The ability of HTE cells to grow and differentiate in this serum-free culture system in the absence of other cell types should greatly facilitate the study of mucociliary functions in vitro. 相似文献
38.
39.
40.
The cost of interspecific competition in two gerbil species 总被引:5,自引:1,他引:4