全文获取类型
收费全文 | 212960篇 |
免费 | 15880篇 |
国内免费 | 751篇 |
专业分类
耳鼻咽喉 | 2308篇 |
儿科学 | 5569篇 |
妇产科学 | 4345篇 |
基础医学 | 27550篇 |
口腔科学 | 4662篇 |
临床医学 | 20351篇 |
内科学 | 45397篇 |
皮肤病学 | 2771篇 |
神经病学 | 20575篇 |
特种医学 | 7047篇 |
外国民族医学 | 13篇 |
外科学 | 33475篇 |
综合类 | 3469篇 |
现状与发展 | 2篇 |
一般理论 | 291篇 |
预防医学 | 19360篇 |
眼科学 | 4448篇 |
药学 | 14544篇 |
1篇 | |
中国医学 | 375篇 |
肿瘤学 | 13038篇 |
出版年
2023年 | 850篇 |
2022年 | 1420篇 |
2021年 | 3458篇 |
2020年 | 2127篇 |
2019年 | 3431篇 |
2018年 | 4014篇 |
2017年 | 3248篇 |
2016年 | 3456篇 |
2015年 | 4103篇 |
2014年 | 6168篇 |
2013年 | 8920篇 |
2012年 | 13263篇 |
2011年 | 14445篇 |
2010年 | 8161篇 |
2009年 | 7375篇 |
2008年 | 13719篇 |
2007年 | 14549篇 |
2006年 | 14026篇 |
2005年 | 14516篇 |
2004年 | 13928篇 |
2003年 | 12999篇 |
2002年 | 12533篇 |
2001年 | 2012篇 |
2000年 | 1596篇 |
1999年 | 2179篇 |
1998年 | 2889篇 |
1997年 | 2475篇 |
1996年 | 2245篇 |
1995年 | 1986篇 |
1994年 | 1787篇 |
1993年 | 1682篇 |
1992年 | 1277篇 |
1991年 | 1228篇 |
1990年 | 1126篇 |
1989年 | 1012篇 |
1988年 | 1073篇 |
1987年 | 1080篇 |
1986年 | 1065篇 |
1985年 | 1146篇 |
1984年 | 1522篇 |
1983年 | 1495篇 |
1982年 | 1838篇 |
1981年 | 1668篇 |
1980年 | 1575篇 |
1979年 | 864篇 |
1978年 | 994篇 |
1977年 | 959篇 |
1976年 | 862篇 |
1975年 | 701篇 |
1974年 | 693篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Katherine M. Duszynski Nicole L. Pratt John W. Lynch Jesia G. Berry Michael S. Gold 《Vaccine》2019,37(2):280-288
Objective
To determine whether differences in combination DTaP vaccine types at 2, 4 and 6?months of age were associated with mortality (all-cause or non-specific), within 30?days of vaccination.Design
Observational nationwide cohort study.Setting
Linked population data from the Australian Childhood Immunisation Register and National Death Index.Participants
Australian infants administered a combination trivalent, quadrivalent or hexavalent DTaP vaccine (DTaP types) between January 1999 and December 2010 at 2, 4 and 6?months as part of the primary vaccination series. The study population included 2.9, 2.6, & 2.3?million children in the 2, 4 and 6?month vaccine cohorts, respectively.Main outcome measures
Infants were evaluated for the primary outcome of all-cause mortality within 30?days. A secondary outcome was non-specific mortality (unknown cause of death) within 30?days of vaccination. Non-specific mortality was defined as underlying or other cause of death codes, R95 ‘Sudden infant death syndrome’, R96 ‘Other sudden death, cause unknown’, R98 ‘Unattended death’, R99 ‘Other ill-defined and unspecified cause of mortality’ or where no cause of death was recorded.Results
The rate of 30?day all-cause mortality was low and declined from 127.4 to 59.3 deaths per 100,000 person-years between 2 and 6?month cohorts. When compared with trivalent DTaP vaccines, no elevated risk in all-cause or non-specific mortality was seen with any quadrivalent or hexavalent DTaP vaccines, for any cohort.Conclusion
Use of routine DTaP combination vaccines with differing disease antigens administered during the first six months of life is not associated with infant mortality. 相似文献32.
Keith P. Reber John D. Sivey Matthew Vollmuth Priyansh D. Gujarati 《Journal of labelled compounds & radiopharmaceuticals》2022,65(9):254-263
Parabens are antimicrobial additives found in a wide array of consumer products. However, the halogenated compounds formed from parabens during wastewater disinfection are a potential environmental concern. In order to identify these transformation products and investigate their mechanism of formation, a synthetic route to ethyl parabens labeled with the stable isotope carbon-13 at specific positions within the benzene ring was developed. This efficient two-step procedure starts from commercially available 13C-labeled phenols and involves (1) initial acylation of the phenol via a Houben–Hoesch reaction with trichloroacetonitrile followed by (2) a modified haloform reaction of the resulting trichloromethyl ketone to afford the corresponding 13C-labeled ethyl parabens in 65%–80% overall yield. The scope of the modified haloform reaction was also investigated, allowing for the synthesis of other parabens derived from primary or secondary alcohols, including 13C- and deuterium-labeled esters. In addition, 4-hydroxybenzoic acid can be formed directly from the common trichloromethyl ketone intermediate upon treatment with lithium hydroxide. This protocol complements existing methods for preparing 13C-labeled paraben derivatives and offers the specific advantages of exhibiting complete regioselectivity in the Houben–Hoesch reaction (to form the para-disubstituted product) and avoiding the need for protecting groups in the modified haloform reaction that forms the paraben esters. 相似文献
33.
34.
35.
Evaluation of training nurses to perform semi‐automated three‐dimensional left ventricular ejection fraction using a customised workstation‐based training protocol 下载免费PDF全文
36.
Sharisse M. Arnold Rehring Liza M. Reifler Jennifer H. Seidel Karen A. Glenn John F. Steiner 《Academic pediatrics》2019,19(5):572-580
ObjectiveClinical specialty societies recommend long-acting reversible contraceptives (LARCs) as first-line contraception for adolescent women. We evaluated whether a combined educational and process improvement intervention enhanced LARC placement in primary care within an integrated health care system.MethodsThe intervention included journal clubs, live continuing education, point-of-care guidelines, and new patient materials. We conducted a retrospective cohort study across 3 time periods: baseline (January 2013?September 2015), early implementation (October 2015–March 2016), and full implementation (April 2016–June 2017). The primary outcome was the proportion of LARCs placed by primary care clinicians among women aged 13 to 18 years compared with gynecology clinicians.ResultsKaiser Foundation Health Plan of Colorado cared for approximately 20,000 women aged 13 to 18 years in each calendar quarter between 2013 and 2017. Overall, LARC placement increased from 7.0 per 1000 members per quarter at baseline to 13.0 per 1000 during the full intervention. Primary care clinicians placed 6.2% of all LARCs in 2013, increasing to 32.1% by 2017 (P < .001), including 45.5% of contraceptive implants. Clinicians who attended educational sessions were more likely to adopt LARCs than those who did not (17.9% vs 6.4% respectively, P = .009). Neither overall LARC placement rates (relative risk, 1.9; 95% confidence interval, 0.7?5.6) nor contraceptive implant rates (relative risk, 3.0; 95% confidence interval, 0.9?9.8) increased significantly in clinicians who attended educational activities.ConclusionsThis multimodal intervention was associated with increased LARC placement for adolescent women in primary care. The combination of education and process improvement is a promising strategy to promote clinician behavior change. 相似文献
37.
38.
John Lennon Silva Cunha Amanda Almeida Leite Thamiris de Castro Abrantes Lorena Passoni Vervloet Thayn Melo de Lima Morais Gerson de Oliveira Paiva Neto Tatiana Nayara Librio Kimura Snia Maria Soares Ferreira Ricardo Luiz Cavalcanti de Albuquerque‐Júnior Aline Corrêa Abraho Mario Jos Romaach Bruno Augusto Benevenuto de Andrade Oslei Paes de Almeida Ciro Dantas Soares 《Journal of cutaneous pathology》2021,48(1):24-33
39.
Altan Ahmed John A. Stauffer Jordan D. LeGout Justin Burns Kristopher Croome Ricardo Paz-Fumagalli Gregory Frey Beau Toskich 《Journal of gastrointestinal oncology.》2021,12(2):751
BackgroundNeoadjuvant yttrium-90 transarterial radioembolization (TARE) is increasingly being used as a strategy to facilitate resection of otherwise unresectable tumors due to its ability to generate both tumor response and remnant liver hypertrophy. Perioperative outcomes after the use of neoadjuvant lobar TARE remain underinvestigated.MethodsA single center retrospective review of patients who underwent lobar TARE prior to major hepatectomy for primary or metastatic liver cancer between 2007 and 2018 was conducted. Baseline demographics, radioembolization parameters, pre- and post-radioembolization volumetrics, intra-operative surgical data, adverse events, and post-operative outcomes were analyzed.ResultsTwenty-six patients underwent major hepatectomy after neoadjuvant lobar TARE. The mean age was 58.3 years (17–88 years). 62% of patients (n=16) had primary liver malignancies while the remainder had metastatic disease. Liver resection included right hepatectomy or trisegmentectomy, left or extended left hepatectomy, and sectorectomy/segmentectomy in 77% (n=20), 8% (n=2), and 15% (n=4) of patients, respectively. The mean length of stay was 8.3 days (range, 3–33 days) and there were no grade IV morbidities or 90-day mortalities. The incidence of post hepatectomy liver failure (PHLF) was 3.8% (n=1). The median time to progression after resection was 4.5 months (range, 3.3–10 months). Twenty-three percent (n=6) of patients had no recurrence. The median survival was 28.9 months (range, 16.9–46.8 months) from major hepatectomy and 37.6 months (range, 25.2–53.1 months) from TARE.ConclusionsMajor hepatectomy after neoadjuvant lobar radioembolization is safe with a low incidence of PHLF. 相似文献