全文获取类型
收费全文 | 379223篇 |
免费 | 24872篇 |
国内免费 | 2807篇 |
专业分类
耳鼻咽喉 | 5187篇 |
儿科学 | 8205篇 |
妇产科学 | 10093篇 |
基础医学 | 53159篇 |
口腔科学 | 11787篇 |
临床医学 | 30170篇 |
内科学 | 78653篇 |
皮肤病学 | 8552篇 |
神经病学 | 27217篇 |
特种医学 | 13966篇 |
外国民族医学 | 82篇 |
外科学 | 60675篇 |
综合类 | 9963篇 |
现状与发展 | 1篇 |
一般理论 | 64篇 |
预防医学 | 17444篇 |
眼科学 | 9445篇 |
药学 | 31058篇 |
1篇 | |
中国医学 | 2197篇 |
肿瘤学 | 28983篇 |
出版年
2021年 | 2616篇 |
2019年 | 2725篇 |
2018年 | 4521篇 |
2017年 | 3437篇 |
2016年 | 3535篇 |
2015年 | 4034篇 |
2014年 | 5706篇 |
2013年 | 7382篇 |
2012年 | 10031篇 |
2011年 | 10231篇 |
2010年 | 6197篇 |
2009年 | 5859篇 |
2008年 | 9494篇 |
2007年 | 10337篇 |
2006年 | 10257篇 |
2005年 | 9310篇 |
2004年 | 8827篇 |
2003年 | 8560篇 |
2002年 | 8245篇 |
2001年 | 28309篇 |
2000年 | 28821篇 |
1999年 | 23697篇 |
1998年 | 5176篇 |
1997年 | 4257篇 |
1996年 | 3839篇 |
1995年 | 3483篇 |
1994年 | 3106篇 |
1993年 | 2858篇 |
1992年 | 16059篇 |
1991年 | 14825篇 |
1990年 | 14162篇 |
1989年 | 13969篇 |
1988年 | 12594篇 |
1987年 | 12071篇 |
1986年 | 11105篇 |
1985年 | 10327篇 |
1984年 | 6919篇 |
1983年 | 5606篇 |
1982年 | 2723篇 |
1979年 | 5482篇 |
1978年 | 3352篇 |
1977年 | 2977篇 |
1975年 | 2649篇 |
1974年 | 3075篇 |
1973年 | 2882篇 |
1972年 | 2838篇 |
1971年 | 2780篇 |
1970年 | 2516篇 |
1969年 | 2550篇 |
1968年 | 2259篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
Y. Ermias I.A. Morgan K.M. Curtis M.K. Whiteman L.G. Horton L.B. Zapata 《Contraception》2019,99(5):300-305
ObjectiveIdentify factors associated with healthcare providers' frequency of depot medroxyprogesterone acetate (DMPA) provision to adolescents.Study designWe analyzed data from surveys mailed to a nationally representative sample of public-sector providers and office-based physicians (n=1984). We estimated adjusted odds ratios (aORs) and 95% confidence intervals (CIs) of factors associated with frequent DMPA provision to adolescents in the past year.ResultsAlthough most providers (>95%) considered DMPA safe for adolescents, fewer reported frequent provision (89% of public-sector providers; 64% of office-based physicians). Among public-sector providers, factors associated with lower odds of frequent provision included working in settings without Title X funding (aOR 0.44, 95% CI 0.30–0.64), reporting primary care as their primary clinical focus versus reproductive or adolescent health (aOR 0.42, 95% CI 0.28–0.61), and providing fewer patients with family planning services. Among office-based physicians, factors associated with lower odds of frequent provision included specializing in obstetrics/gynecology (aOR 0.50, 95% CI 0.27–0.91) and family medicine (aOR 0.21, 95% CI 0.09–0.47) versus adolescent medicine, completing training ≥15 versus <5 years ago (aOR 0.27, 95% CI 0.09–0.83), and reporting that 0–24% of patients pay with Medicaid or other government healthcare assistance versus ≥50% (aOR 0.23, 95% CI 0.09–0.61). The reason most commonly reported by providers for infrequent DMPA provision was patient preference for another method.ConclusionsWhile most providers reported frequently providing DMPA to adolescents, training on evidence-based recommendations for contraception, focused on subgroups of providers with lower odds of frequent DMPA provision, may increase adolescents' access to contraception.ImplicationsAlthough >95% of providers considered depot medroxyprogesterone (DMPA) a safe contraceptive for adolescents, only 89% of public-sector providers and 64% of office-based physicians reported frequently providing DMPA to adolescents. Provider training on evidence-based recommendations for contraception counseling and provision may increase adolescents' access to DMPA and all methods of contraception. 相似文献
32.
Prevention Science - This study aimed to evaluate the effectiveness of the drug and violence resistance educational program (PROERD) on short-term secondary outcomes, such as intentions to use... 相似文献
33.
34.
35.
36.
Parallel enzyme‐linked immunosorbent assay screening for human immunodeficiency virus among blood donors in five Chinese blood centres: a retrospective analysis 下载免费PDF全文
37.
38.
Harinakshi Sanikini David C. Muller Marisa Sophiea Sabina Rinaldi Antonio Agudo Eric J. Duell Elisabete Weiderpass Kim Overvad Anne Tjønneland Jytte Halkjær Marie-Christine Boutron-Ruault Franck Carbonnel Iris Cervenka Heiner Boeing Rudolf Kaaks Tilman Kühn Antonia Trichopoulou Georgia Martimianaki Anna Karakatsani Valeria Pala Domenico Palli Amalia Mattiello Rosario Tumino Carlotta Sacerdote Guri Skeie Charlotta Rylander María-Dolores Chirlaque López Maria-Jose Sánchez Eva Ardanaz Sara Regnér Tanja Stocks Bas Bueno-de-Mesquita Roel C.H. Vermeulen Dagfinn Aune Tammy Y.N. Tong Nathalie Kliemann Neil Murphy Marc Chadeau-Hyam Marc J. Gunter Amanda J. Cross 《International journal of cancer. Journal international du cancer》2020,146(4):929-942
Obesity has been associated with upper gastrointestinal cancers; however, there are limited prospective data on associations by subtype/subsite. Obesity can impact hormonal factors, which have been hypothesized to play a role in these cancers. We investigated anthropometric and reproductive factors in relation to esophageal and gastric cancer by subtype and subsite for 476,160 participants from the European Prospective Investigation into Cancer and Nutrition cohort. Multivariable hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox models. During a mean follow-up of 14 years, 220 esophageal adenocarcinomas (EA), 195 esophageal squamous cell carcinomas, 243 gastric cardia (GC) and 373 gastric noncardia (GNC) cancers were diagnosed. Body mass index (BMI) was associated with EA in men (BMI ≥30 vs. 18.5–25 kg/m2: HR = 1.94, 95% CI: 1.25–3.03) and women (HR = 2.66, 95% CI: 1.15–6.19); however, adjustment for waist-to-hip ratio (WHR) attenuated these associations. After mutual adjustment for BMI and HC, respectively, WHR and waist circumference (WC) were associated with EA in men (HR = 3.47, 95% CI: 1.99–6.06 for WHR >0.96 vs. <0.91; HR = 2.67, 95% CI: 1.52–4.72 for WC >98 vs. <90 cm) and women (HR = 4.40, 95% CI: 1.35–14.33 for WHR >0.82 vs. <0.76; HR = 5.67, 95% CI: 1.76–18.26 for WC >84 vs. <74 cm). WHR was also positively associated with GC in women, and WC was positively associated with GC in men. Inverse associations were observed between parity and EA (HR = 0.38, 95% CI: 0.14–0.99; >2 vs. 0) and age at first pregnancy and GNC (HR = 0.54, 95% CI: 0.32–0.91; >26 vs. <22 years); whereas bilateral ovariectomy was positively associated with GNC (HR = 1.87, 95% CI: 1.04–3.36). These findings support a role for hormonal pathways in upper gastrointestinal cancers. 相似文献
39.
40.