全文获取类型
收费全文 | 2656724篇 |
免费 | 194981篇 |
国内免费 | 5164篇 |
专业分类
耳鼻咽喉 | 36596篇 |
儿科学 | 88324篇 |
妇产科学 | 74751篇 |
基础医学 | 380366篇 |
口腔科学 | 76905篇 |
临床医学 | 234460篇 |
内科学 | 517175篇 |
皮肤病学 | 58937篇 |
神经病学 | 206835篇 |
特种医学 | 101745篇 |
外国民族医学 | 597篇 |
外科学 | 406688篇 |
综合类 | 59830篇 |
现状与发展 | 5篇 |
一般理论 | 775篇 |
预防医学 | 197620篇 |
眼科学 | 63069篇 |
药学 | 197725篇 |
8篇 | |
中国医学 | 6122篇 |
肿瘤学 | 148336篇 |
出版年
2018年 | 28281篇 |
2017年 | 21391篇 |
2016年 | 23780篇 |
2015年 | 27142篇 |
2014年 | 37704篇 |
2013年 | 55922篇 |
2012年 | 77202篇 |
2011年 | 81996篇 |
2010年 | 48513篇 |
2009年 | 45527篇 |
2008年 | 77225篇 |
2007年 | 82774篇 |
2006年 | 83664篇 |
2005年 | 80844篇 |
2004年 | 78054篇 |
2003年 | 74758篇 |
2002年 | 72674篇 |
2001年 | 129797篇 |
2000年 | 133166篇 |
1999年 | 111295篇 |
1998年 | 30412篇 |
1997年 | 26804篇 |
1996年 | 26968篇 |
1995年 | 25705篇 |
1994年 | 23987篇 |
1993年 | 22075篇 |
1992年 | 86822篇 |
1991年 | 84423篇 |
1990年 | 81963篇 |
1989年 | 79273篇 |
1988年 | 72950篇 |
1987年 | 71426篇 |
1986年 | 67734篇 |
1985年 | 64511篇 |
1984年 | 47648篇 |
1983年 | 40985篇 |
1982年 | 23660篇 |
1981年 | 21117篇 |
1979年 | 43667篇 |
1978年 | 30309篇 |
1977年 | 26046篇 |
1976年 | 24332篇 |
1975年 | 26248篇 |
1974年 | 31525篇 |
1973年 | 30308篇 |
1972年 | 28538篇 |
1971年 | 26401篇 |
1970年 | 24635篇 |
1969年 | 23419篇 |
1968年 | 21977篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
221.
222.
223.
224.
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
225.
Conall T. Morgan Brigitte Mueller Varsha Thakur Vitor Guerra Callaghan Jull Luc Mertens Mark Friedberg Fraser Golding Mike Seed Steven E.S. Miner Edgar T. Jaeggi Cedric Manlhiot Lynne E. Nield 《The Canadian journal of cardiology》2019,35(4):453-461
Background
The purpose of the study was to evaluate the association between fetal echocardiographic measurements and the need for intervention (primary coarctation repair, staged coarctation repair, or catheter intervention) in prenatally diagnosed coarctation of the aorta.Methods
A single-centre retrospective cohort study (2005-2015) of 107 fetuses diagnosed with suspected coarctation of the aorta in the setting of an apex-forming left ventricle and antegrade flow across the mitral and aortic valves.Results
Median gestational age at diagnosis was 32 weeks (interquartile range, 23-35 weeks). Fifty-six (52%) did not require any neonatal intervention, 51 patients (48%) underwent a biventricular repair. In univariable analysis, an increase in ascending aorta (AAo) peak Doppler flow velocity (odds ratio [OR], 1.40 [95% confidence interval [CI], 1.05-1.91] per 20 cm/s; P = 0.03) was associated with intervention. No intervention was associated with larger isthmus size (OR, 0.23; P < 0.001), transverse arch diameter (OR, 0.23; P < 0.001), and aortic (OR, 0.72; P = 0.02), mitral (OR, 0.58; P = 0.001), and AAo (OR, 0.53; P < 0.001) z-scores. In multivariable analysis, higher peak AAo Doppler (OR, 2.51 [95% CI, 1.54-4.58] per 20 cm/s; P = 0.001) and younger gestational age at diagnosis (OR, 0.81 [95% CI, 0.70-0.93] per week; P = 0.005) were associated with intervention, whereas a higher AAo z-score (OR, 0.65 [95% CI, 0.43-0.94] per z; P = 0.029) and transverse arch dimension (OR, 0.44 [95% CI, 0.18-0.97]; P = 0.05) decreased the risk of intervention.Conclusions
In prenatally suspected coarctation, the variables associated with intervention comprised smaller AAo and transverse arch size, earlier gestational age at diagnosis, and the additional finding of a higher peak AAo Doppler. 相似文献226.
Ramya Deepthi Vinnakota Allan S. Brett 《The American journal of the medical sciences》2019,357(2):160-163
Iron deficiency anemia is often listed among potential adverse effects of gastric acid-suppressive medications, given that gastric acidity promotes intestinal absorption of nonheme iron. Additionally, the antacid calcium carbonate can inhibit iron absorption. However, there is little direct clinical evidence that proton-pump inhibitors, histamine-2 receptor antagonists, or calcium carbonate cause iron deficiency anemia. Most case reports have had substantial limitations (e.g., minimal follow-up and presence of other causes of iron deficiency), and retrospective cohort studies have lacked sufficient patient-specific detail to make strong causal inferences. We present 2 cases—both with detailed, prospective 10-year follow-up—in which combinations of proton-pump inhibitors, histamine-2 receptor antagonists and calcium carbonate were clearly associated with development of iron deficiency anemia. Overt iron-deficiency anemia is probably uncommon in patients who use acid-modifying medications and who have no other conditions that predispose to iron deficiency. Nevertheless, clinicians should be aware of this potential complication, given widespread use of these agents. 相似文献
227.
228.
229.
230.
A. Cattapan K. Browne D.M. Halperin A. Di Castri P. Fullsack J. Graham J.M. Langley B.A. Taylor S.A. McNeil S.A. Halperin 《Vaccine》2019,37(2):289-295