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   10914篇
  免费   1221篇
  国内免费   1160篇
  2024年   23篇
  2023年   127篇
  2022年   393篇
  2021年   568篇
  2020年   494篇
  2019年   532篇
  2018年   556篇
  2017年   415篇
  2016年   518篇
  2015年   698篇
  2014年   808篇
  2013年   805篇
  2012年   949篇
  2011年   856篇
  2010年   582篇
  2009年   477篇
  2008年   571篇
  2007年   496篇
  2006年   456篇
  2005年   361篇
  2004年   374篇
  2003年   374篇
  2002年   366篇
  2001年   243篇
  2000年   163篇
  1999年   185篇
  1998年   119篇
  1997年   109篇
  1996年   97篇
  1995年   96篇
  1994年   80篇
  1993年   58篇
  1992年   56篇
  1991年   48篇
  1990年   44篇
  1989年   42篇
  1988年   27篇
  1987年   20篇
  1986年   19篇
  1985年   10篇
  1984年   12篇
  1983年   14篇
  1982年   13篇
  1981年   11篇
  1980年   6篇
  1979年   7篇
  1978年   3篇
  1977年   4篇
  1974年   2篇
  1972年   2篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
Abstract This paper deals in detail with the morphology of the larva of Neopsylla specialis specialis Jordan, 1932. It may be distinguished from other larvae of 5 species or subspecies of Neopsylla by two fine setae lying on outside of each posterior long seta on the ventral plates of the first to third thoracic segments, ratio of the length and width of the egg burster, number and shape of mandibular teeth, number and length of the setae in the anterior and posterior row on dorsal side of head, and number of the setae of anal comb and the strut setae. The sense organs on the 10th tergite are discussed.  相似文献   
5.
The aim of the study was to explore the mechanism of mesenchymal stem cell‐derived exosomes (MSC‐EXO) to protect against experimentally induced pulmonary hypertension (PH). Monocrotaline (MCT)‐induced rat model of PH was successfully established by a single intraperitoneal injection of 50 mg/kg MCT, 3 weeks later the animals were treated with MSC‐EXO via tail vein injection. Post‐operation, our results showed that MSC‐EXO could significantly reduce right ventricular systolic pressure (RVSP) and the right ventricular hypertrophy index, attenuate pulmonary vascular remodelling and lung fibrosis in vivo. In vitro experiment, the hypoxia models of pulmonary artery endothelial cell (PAEC) and pulmonary vascular smooth muscle cell (PASMC) were used. We found that the expression levels of Wnt5a, Wnt11, BMPR2, BMP4 and BMP9 were increased, but β‐catenin, cyclin D1 and TGF‐β1 were decreased in MSC‐EXO group as compared with MCT or hypoxia group in vivo or vitro. However, these increased could be blocked when cells were transfected with Wnt5a siRNA in vitro. Taken together, these results suggested that the mechanism of MSC‐EXO to prevent PH vascular remodelling may be via regulation of Wnt5a/BMP signalling pathway.  相似文献   
6.
Hyperthermic treatment at 43 degrees C suppressed the growth of Ehrlich ascites tumor (EAT) cells in vitro. Incubation of EAT cells at 43 degrees C for as little as 1.5 h totally abolished the transplantability of the tumor. At the same time, the rate of cellular glucose uptake, the density of glucose transporter on the cells as well as the extent of thymidine, uridine and leucine incorporation were significantly reduced.  相似文献   
7.
8.
9.
Diabetic nephropathy (DN), a major cause of end-stage chronic renal failure, is histologically characterized by glomerulosclerosis. To investigate the molecular mechanisms of DN, it is important to establish a stable model of glomerulosclerosis in mice, because genomic manipulation techniques (such as gene destruction or transgene insertion) are well established in rodent species. In this study, we found that repeated administrations of streptozotocin led to early onset of glomerular sclerotic lesions in C57BL/6 mice, accompanied with renal dysfunction. During the natural course of DN, glomerular endothelial cells decreased at 10 weeks after the start of streptozotocin-injections, whereas myofibroblastic mesangial cells became evident. Our results provide an animal tool to elucidate the molecular mechanisms of DN, for example to investigate vascular pathology in diabetic glomerular diseases.  相似文献   
10.
The chemical reaction of cleavaging territrem B to give 3,4,5-trimethoxy benzoic acid by alkaline hydrogen peroxide was investigated. The method was applied for confirmation of the chemical structure of the aromatic moiety of territrem A, A’, B, and B’. The physicochemical properties of the aromatic cleavage product of territrem Aindicated the structure as 3,4-methylendioxy, 5-methoxy benzoic acid (or 4-methoxy, 6-carboxy, 1, 3-benzodioxole). The experiment also gave the evidences that territrem A and A’, on the other hand territrem B and B’ have the identical aromatic moieties on their structures.  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