全文获取类型
收费全文 | 38081篇 |
免费 | 3449篇 |
国内免费 | 23篇 |
出版年
2023年 | 169篇 |
2022年 | 404篇 |
2021年 | 842篇 |
2020年 | 451篇 |
2019年 | 603篇 |
2018年 | 730篇 |
2017年 | 597篇 |
2016年 | 1087篇 |
2015年 | 1831篇 |
2014年 | 1921篇 |
2013年 | 2309篇 |
2012年 | 2974篇 |
2011年 | 3010篇 |
2010年 | 1903篇 |
2009年 | 1581篇 |
2008年 | 2364篇 |
2007年 | 2331篇 |
2006年 | 2304篇 |
2005年 | 2031篇 |
2004年 | 2017篇 |
2003年 | 1816篇 |
2002年 | 1746篇 |
2001年 | 386篇 |
2000年 | 302篇 |
1999年 | 363篇 |
1998年 | 398篇 |
1997年 | 299篇 |
1996年 | 269篇 |
1995年 | 231篇 |
1994年 | 225篇 |
1993年 | 224篇 |
1992年 | 206篇 |
1991年 | 219篇 |
1990年 | 194篇 |
1989年 | 171篇 |
1988年 | 152篇 |
1987年 | 123篇 |
1986年 | 133篇 |
1985年 | 170篇 |
1984年 | 165篇 |
1983年 | 150篇 |
1982年 | 175篇 |
1981年 | 161篇 |
1980年 | 155篇 |
1979年 | 125篇 |
1978年 | 105篇 |
1977年 | 101篇 |
1976年 | 111篇 |
1975年 | 102篇 |
1974年 | 97篇 |
排序方式: 共有10000条查询结果,搜索用时 61 毫秒
41.
Summary Osteogenesis imperfecta (OI) is a phenotype with clinical and biochemical heterogeneity. We report here that expression of the OI phenotype extends to the level of dermal fibroblast morphology in vitro. Growth characteristics and morphology of control (n=6) and OI cell strains (n=10, representing the four major OI categories, Sillence classification) were compared by measuring the following: (i) days required in culture to reach confluence after plating at uniform density; (ii) cell density at confluence; (iii) width and length of cells (measured on phase contrast micrographs at 300xmagnification). Our results show that: (i) OI fibroblasts take longer (11–27 days, mean 20 days) than control cells (10–19 days, mean 16 days) to reach stationary phase; (ii) all OI phenotypes achieve a lower cell density (0.87x106 cells/P60, range 0.3–1.6x106) at stationary phase relative to control cells (2.2x106 cells/P60, range 1.7–2.6x106; F4,77=56.1, p<0.01, indicating that OI cells are larger than normal). Cell shape (expressed as the width: length ratio) was also abnormal in OI cells. (F4,730=37.6, p<0.01), types I and II OI cells have significantly increased ratios (p<0.01) relative to control, type III, and type IV cells. Intra-group phenotypic heterogeneity was also apparent in the OI categories and also within the control population. These findings confirm deviant morphologic phenotypes in OI dermal fibroblasts and further demonstrate interindividual heterogeneity in the expression of genes that determine size and shape of dermal fibroblasts in both OI and normal donors.Publication No. 84013 from the Montreal Children's Hospital Research Institute 相似文献
42.
Andrew Leask 《Journal of cell communication and signaling》2010,4(1):73-74
Connective tissue growth factor (CTGF/CCN2) is overexpressed in diabetes. Diabetic rats possess myocardial and cardiomyocyte hypertrophy. In a recent report, Wang and colleagues (Am J Physiol Cell Physiol. 2009 Jul 22. [Epub ahead of print]) show that CCN2 directly mediates cardiomyocyte hypertrophy as well as that induced by high glucose and fatty acid. CCN2 acted via the TrkA receptor. These data are the subject of this commentary, and emphasize that CCN2 may be an excellent target for therapy in diabetes. 相似文献
43.
44.
45.
46.
47.
The kinetics of DNA replication were analyzed in the second S phase following UV irradiation of Chinese hamster ovary cells synchronized at the beginning of S phase. The cells were synchronized by treating cells selected in mitosis with hydroxyurea for 9 h. Following UV irradiation, the cells were allowed to progress until the next mitosis; at which time they were resynchronized at the beginning of the second S phase by the same procedure. The kinetics of DNA replication were determined by measuring the proportion of DNA which achieved hybrid buoyant density on CsCl density gradients as a function of the time of incubation in the presence of 5-bromodeoxyuridine.The results of these experiments showed that even though the rate of DNA replication is substantially depressed during the first S phase following UV irradiation with a fluence of 5 J/m2, the rate has recovered to the extent that it is indistinguishable from the unirradiated control by the time the cells have entered their second S phase. It was concluded from these observations that the lesions in DNA which caused the rate of DNA replication to be initially depressed during the first S phase have been either removed or modified such that they no longer are able to cause a reduction in the rate of DNA replication in the second S phase following UV irradiation. 相似文献
48.
49.
50.