全文获取类型
| 收费全文 | 2296001篇 |
| 免费 | 172006篇 |
| 国内免费 | 3354篇 |
学科分类
| 医药卫生 | 2471361篇 |
出版年
| 2018年 | 24002篇 |
| 2017年 | 18206篇 |
| 2016年 | 19957篇 |
| 2015年 | 22860篇 |
| 2014年 | 31619篇 |
| 2013年 | 48512篇 |
| 2012年 | 66423篇 |
| 2011年 | 70789篇 |
| 2010年 | 41585篇 |
| 2009年 | 39884篇 |
| 2008年 | 67165篇 |
| 2007年 | 71990篇 |
| 2006年 | 71850篇 |
| 2005年 | 70217篇 |
| 2004年 | 68125篇 |
| 2003年 | 65576篇 |
| 2002年 | 64074篇 |
| 2001年 | 105010篇 |
| 2000年 | 108180篇 |
| 1999年 | 91844篇 |
| 1998年 | 25804篇 |
| 1997年 | 23273篇 |
| 1996年 | 23910篇 |
| 1995年 | 22603篇 |
| 1994年 | 21264篇 |
| 1993年 | 19801篇 |
| 1992年 | 73298篇 |
| 1991年 | 71927篇 |
| 1990年 | 69856篇 |
| 1989年 | 67264篇 |
| 1988年 | 62179篇 |
| 1987年 | 61216篇 |
| 1986年 | 57684篇 |
| 1985年 | 55049篇 |
| 1984年 | 41702篇 |
| 1983年 | 35626篇 |
| 1982年 | 20993篇 |
| 1981年 | 19177篇 |
| 1979年 | 38388篇 |
| 1978年 | 27597篇 |
| 1977年 | 23179篇 |
| 1976年 | 21693篇 |
| 1975年 | 23321篇 |
| 1974年 | 27820篇 |
| 1973年 | 27223篇 |
| 1972年 | 25423篇 |
| 1971年 | 23454篇 |
| 1970年 | 22042篇 |
| 1969年 | 20528篇 |
| 1968年 | 18969篇 |
排序方式： 共有10000条查询结果，搜索用时 0 毫秒
1.
2.
3.
4.
5.
6.
7.
Emma J. Walker Noni E. MacDonald Nehal Islam Nicole Le Saux Karina A. Top Deshayne B. Fell 《Vaccine》2019,37(13):1725-1735
Objective
To systematically review literature on uptake and timeliness of diphtheria-tetanus-pertussis, measles-mumps-rubella, and/or polio-containing vaccines in infants who were born preterm, with a low birth weight, and/or with chronic health conditions that were diagnosed within the first 6?months of life.Methods
Using a standardized search strategy developed by a medical librarian, records were extracted from MEDLINE, Embase, Database of Abstracts of Reviews of Effects, and CINAHL up to May 8, 2018.Results
Out of the 1997 records that were screened, we identified 21 studies that met inclusion criteria. Eleven studies assessed vaccine coverage and/or timeliness in preterm infants, 6 in low birth weight infants, and 7 in children with chronic health conditions. Estimates of coverage in these populations were highly variable, ranging from 40% to 100% across the vaccines and population groups.Conclusions
There is a lack of studies reporting coverage and timeliness of routine immunizations in special populations of children.Policy implications
Our review suggests a need for improved surveillance of immunization status in special populations of infants, as well as a need for standardization of reporting practices. 相似文献8.
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9.
M. Iachina P.M. Ljungdalh R.G. Sørensen L. Kaerlev J. Blaakær O. Trosko N. Qvist B.M. Nørgård 《Clinical oncology (Royal College of Radiologists (Great Britain))》2019,31(2):115-123
