全文获取类型
收费全文 | 4669391篇 |
免费 | 381807篇 |
国内免费 | 16032篇 |
专业分类
耳鼻咽喉 | 67036篇 |
儿科学 | 146444篇 |
妇产科学 | 124450篇 |
基础医学 | 704163篇 |
口腔科学 | 130734篇 |
临床医学 | 422466篇 |
内科学 | 853003篇 |
皮肤病学 | 110507篇 |
神经病学 | 395930篇 |
特种医学 | 186080篇 |
外国民族医学 | 1154篇 |
外科学 | 712919篇 |
综合类 | 135927篇 |
现状与发展 | 23篇 |
一般理论 | 2708篇 |
预防医学 | 393210篇 |
眼科学 | 110511篇 |
药学 | 331508篇 |
24篇 | |
中国医学 | 12301篇 |
肿瘤学 | 226132篇 |
出版年
2021年 | 56059篇 |
2019年 | 58889篇 |
2018年 | 74289篇 |
2017年 | 56856篇 |
2016年 | 63350篇 |
2015年 | 76268篇 |
2014年 | 111017篇 |
2013年 | 176461篇 |
2012年 | 129174篇 |
2011年 | 134700篇 |
2010年 | 126558篇 |
2009年 | 128589篇 |
2008年 | 121917篇 |
2007年 | 130102篇 |
2006年 | 138481篇 |
2005年 | 133881篇 |
2004年 | 134428篇 |
2003年 | 125028篇 |
2002年 | 115405篇 |
2001年 | 174187篇 |
2000年 | 170926篇 |
1999年 | 156220篇 |
1998年 | 73646篇 |
1997年 | 69401篇 |
1996年 | 67229篇 |
1995年 | 62973篇 |
1994年 | 57031篇 |
1993年 | 52876篇 |
1992年 | 116516篇 |
1991年 | 111661篇 |
1990年 | 106849篇 |
1989年 | 103975篇 |
1988年 | 96757篇 |
1987年 | 94992篇 |
1986年 | 90553篇 |
1985年 | 88265篇 |
1984年 | 73080篇 |
1983年 | 64810篇 |
1982年 | 50627篇 |
1981年 | 46829篇 |
1980年 | 44116篇 |
1979年 | 65135篇 |
1978年 | 51609篇 |
1977年 | 45415篇 |
1976年 | 42332篇 |
1975年 | 42282篇 |
1974年 | 48060篇 |
1973年 | 46080篇 |
1972年 | 43326篇 |
1971年 | 39764篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
891.
Oga Emmanuel. A. Peters Erica. N. Mark Katrina Trocin Kathleen Coleman-Cowger Victoria. H. 《Maternal and child health journal》2019,23(2):250-257
Maternal and Child Health Journal - Background Prenatal substance use screening is recommended. The 4 P’s Plus screener includes questions on perceived problematic substance use in parents... 相似文献
892.
893.
894.
895.
896.
897.
898.
899.
Understanding the contribution of endothelial cells to the progenitor pools of adult tissues has the potential to inform therapies for human disease.To address whether endothelial cells transdifferentiate into non-vascular cell types,we performed cell lineage tracing analysis using transgenic mice engineered to express a fluorescent marker following activation by tamoxifen in vascular endothelial cadherin promoter-expressing cells(VEcad-CreERT2;B6 Cg-Gt(ROSA)26Sortm9(CAG-tdTomato)Hze).Activation of target-cell labeling following 1.5 months of ad libitum feeding with tamoxifen-laden chow in 4–5 month-old mice resulted in the tracing of central nervous system and peripheral cells that include:cerebellar granule neurons,ependymal cells,skeletal myocytes,pancreatic beta cells,pancreatic acinar cells,tubular cells in the renal cortex,duodenal crypt cells,ileal crypt cells,and hair follicle stem cells.As Nestin expression has been reported in a subset of endothelial cells,Nes-CreERT2 mice were also utilized in these conditions.The tracing of cells in adult Nes-CreERT2 mice revealed the labeling of canonical progeny cell types such as hippocampal and olfactory granule neurons as well as ependymal cells.Interestingly,Nestin tracing also labeled skeletal myocytes,ileal crypt cells,and sparsely marked cerebellar granule neurons.Our findings provide support for endothelial cells as active contributors to adult tissue progenitor pools.This information could be of particular significance for the intravenous delivery of therapeutics to downstream endothelial-derived cellular targets.The animal experiments were approved by the Boise State University Institute Animal Care and Use Committee(approval No.006-AC15-018)on October 31,2018. 相似文献
900.
Elizabeth A. Mosley PhD MPH Amy J. Schulz PhD MPH MSW Lisa H. Harris MD PhD Barbara A. Anderson PhD 《Women & health》2020,60(7):806-820
ABSTRACT Abortion is legal in South Africa, but negative abortion attitudes remain common and are poorly understood. We used nationally representative South African Social Attitudes Survey data to analyze abortion attitudes in the case of fetal anomaly and in the case of poverty from 2007 to 2016 (n = 20,711; ages = 16+). We measured correlations between abortion attitudes and these important predictors: religiosity, attitudes about premarital sex, attitudes about preferential hiring and promotion of women, and attitudes toward family gender roles. Abortion acceptability for poverty increased over time (b = 0.05, p < .001), but not for fetal anomaly (b = ?0.008, p = .284). Highly religious South Africans reported lower abortion acceptability in both cases (Odds Ratio (OR)anomaly = 0.85, p = .015; ORpoverty = 0.84, p = .02). Premarital sex acceptability strongly and positively predicted abortion acceptability (ORanomaly = 2.63, p < .001; ORpoverty = 2.46, p < .001). Attitudes about preferential hiring and promotion of women were not associated with abortion attitudes, but favorable attitudes about working mothers were positively associated with abortion acceptability for fetal anomaly ((ORanomaly = 1.09, p = .01; ORpoverty = 1.02, p = .641)). Results suggest negative abortion attitudes remain common in South Africa and are closely tied to religiosity, traditional ideologies about sexuality, and gender role expectations about motherhood. 相似文献