全文获取类型
收费全文 | 185237篇 |
免费 | 27618篇 |
国内免费 | 12000篇 |
出版年
2023年 | 1735篇 |
2022年 | 2162篇 |
2021年 | 7238篇 |
2020年 | 6907篇 |
2019年 | 9499篇 |
2018年 | 9353篇 |
2017年 | 8082篇 |
2016年 | 10077篇 |
2015年 | 13242篇 |
2014年 | 14665篇 |
2013年 | 16107篇 |
2012年 | 16472篇 |
2011年 | 14935篇 |
2010年 | 11147篇 |
2009年 | 9097篇 |
2008年 | 9567篇 |
2007年 | 8270篇 |
2006年 | 7262篇 |
2005年 | 6018篇 |
2004年 | 5194篇 |
2003年 | 4695篇 |
2002年 | 4071篇 |
2001年 | 3533篇 |
2000年 | 3284篇 |
1999年 | 2962篇 |
1998年 | 1754篇 |
1997年 | 1680篇 |
1996年 | 1635篇 |
1995年 | 1460篇 |
1994年 | 1379篇 |
1993年 | 1085篇 |
1992年 | 1585篇 |
1991年 | 1230篇 |
1990年 | 1033篇 |
1989年 | 938篇 |
1988年 | 747篇 |
1987年 | 674篇 |
1986年 | 573篇 |
1985年 | 559篇 |
1984年 | 359篇 |
1983年 | 349篇 |
1982年 | 207篇 |
1981年 | 199篇 |
1980年 | 140篇 |
1979年 | 220篇 |
1978年 | 131篇 |
1977年 | 151篇 |
1975年 | 166篇 |
1974年 | 168篇 |
1973年 | 131篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
2.
3.
The activation of endothelial cells is essential to repair damage caused by atherosclerosis via endothelial cell proliferation and migration. Overexpression of VEGF (vascular endothelial growth factor) and the downstream gene, B-cell lymphoma-2 (BCL-2) could result in apoptosis-resistant endothelial cells, which are responsible for aggravated hyperplasia and instable plaques generation. Previous studies have shown that miRNA126 could regulate the expression of VEGF. Here, we verified the existence of a miRNA126 binding site in VEGF’s 3’UTR. Additionally, VEGF regulated BCL-2 expression via AP1 (Activator Protein 1) binding site in BCL-2’s promoter. Next, we established an apoptosis-resistant endothelial cell line and constructed a lentiviral vector to express miRNA126 under the control of the BCL-2 promoter to investigate whether conditional expression of miRNA126 could modulate VEGF and BCL-2 expression in apoptosis-resistant endothelial cells. This lentiviral system specifically expressed miRNA126 in cells with high BCL-2 levels, downregulated VEGF expression, inhibited MAPK pathway activation and downregulated BCL-2 expression via suppression of AP1, and as a whole, reduced apoptosis-resistant endothelial cells, while the effects of miRNA126 on normal endothelial cells were relatively small. Our results demonstrate that conditional miRNA126 overexpression under the control of the downstream BCL-2 promoter provides a flexible regulatory strategy for reducing the apoptosis-resistant endothelial cells without having a significant impact on normal endothelial cells. 相似文献
4.
Xiaobin Chen Hugo Giambini Ephraim Ben-Abraham Kai-Nan An Ahmad Nassr Chunfeng Zhao 《PloS one》2015,10(10)
IntroductionAn increased bone mineral density (BMD) in the proximity to tendon insertion can improve rotator cuff repair and healing. However, how a decrease of BMD in the humeral head affects the biomechanical properties of the rotator cuff tendon is still unclear. Previous studies have demonstrated ovariectomy in animals to lead to osteoporosis and decreased BMD, and Teriparatide (PTH) administration to improve BMD and strength of bone. This study aimed to explore the correlation between humeral head BMD and infraspinatus (ISP) tendon insertion strength, and if an increase in bone quantity of the humeral head can improve the strength of the rotator cuff.ResultsSignificant differences were observed in the measured humeral head BMD of the Control and OVX-PTH groups compared to the OVX-Saline group (P = 0.0004 and P = 0.0024, respectively). No significant difference was found in failure stress among the three groups, but an expected trend with the control group and OVX-PTH group presenting higher failure strength compared to the OVX-Saline group. BMD at the humeral head showed a positive linear correlation with stress (r2 = 0.54). Histology results showed the superiority in OVX-PTH group ISP enthesis compared to the OVX-Saline group.ConclusionBone loss of the humeral head leads to decreased tendon/bone insertion strength of the infraspinatus tendon enthesis. Teriparatide administration can increase bone density of the humeral head and may improve the mechanical properties of the infraspinatus tendon enthesis. 相似文献
5.
6.
Detection and genotyping of group A rotaviruses isolated from sewage samples in Monastir,Tunisia between April 2007 and April 2010 下载免费PDF全文
7.
8.
9.