首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   101048篇
  免费   7471篇
  国内免费   1910篇
耳鼻咽喉   673篇
儿科学   1813篇
妇产科学   1508篇
基础医学   7057篇
口腔科学   2121篇
临床医学   14604篇
内科学   11491篇
皮肤病学   959篇
神经病学   4566篇
特种医学   1995篇
外国民族医学   10篇
外科学   10738篇
综合类   17095篇
现状与发展   2篇
一般理论   13篇
预防医学   11060篇
眼科学   1328篇
药学   7966篇
  190篇
中国医学   11830篇
肿瘤学   3410篇
  2023年   1830篇
  2022年   2383篇
  2021年   4179篇
  2020年   4302篇
  2019年   4680篇
  2018年   4145篇
  2017年   3694篇
  2016年   3335篇
  2015年   3301篇
  2014年   6940篇
  2013年   6223篇
  2012年   5797篇
  2011年   6794篇
  2010年   6472篇
  2009年   4557篇
  2008年   4219篇
  2007年   4476篇
  2006年   4075篇
  2005年   3320篇
  2004年   2620篇
  2003年   2488篇
  2002年   1751篇
  2001年   1594篇
  2000年   1296篇
  1999年   1208篇
  1998年   909篇
  1997年   789篇
  1996年   635篇
  1995年   689篇
  1994年   634篇
  1993年   491篇
  1992年   486篇
  1991年   430篇
  1990年   353篇
  1989年   333篇
  1988年   352篇
  1986年   286篇
  1985年   851篇
  1984年   924篇
  1983年   689篇
  1982年   773篇
  1981年   770篇
  1980年   700篇
  1979年   664篇
  1978年   600篇
  1977年   433篇
  1976年   447篇
  1975年   338篇
  1974年   286篇
  1973年   281篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.

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   
83.
This paper revisits a 2003 publication in Nursing Philosophy: The need for accurate perception and informed judgement in determining the appropriate use of the nursing resource: hearing the patient's voice. The author suggests that the basic ideas and focus of this 16‐year‐old paper are still topical and relevant in considerations of nursing care. However, it is also suggested that greater attention to the importance of the nurse–patient relationship in considerations of resource allocation, and potential rationing of nursing care, would have strengthened the original paper.  相似文献   
84.
85.
86.
87.
88.
89.

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   
90.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号