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   2004828篇
  免费   141971篇
  国内免费   4486篇
耳鼻咽喉   27763篇
儿科学   66807篇
妇产科学   55353篇
基础医学   288022篇
口腔科学   57084篇
临床医学   180240篇
内科学   380564篇
皮肤病学   46562篇
神经病学   157580篇
特种医学   78972篇
外国民族医学   497篇
外科学   302837篇
综合类   43413篇
现状与发展   1篇
一般理论   650篇
预防医学   147170篇
眼科学   46309篇
药学   153151篇
  12篇
中国医学   4546篇
肿瘤学   113752篇
  2018年   22106篇
  2017年   17376篇
  2016年   20047篇
  2015年   21899篇
  2014年   29441篇
  2013年   44798篇
  2012年   60326篇
  2011年   64545篇
  2010年   38043篇
  2009年   34672篇
  2008年   60220篇
  2007年   64220篇
  2006年   64887篇
  2005年   62249篇
  2004年   59768篇
  2003年   57614篇
  2002年   55663篇
  2001年   99304篇
  2000年   102569篇
  1999年   84923篇
  1998年   22786篇
  1997年   20053篇
  1996年   18799篇
  1995年   18845篇
  1994年   17362篇
  1993年   16317篇
  1992年   64680篇
  1991年   62627篇
  1990年   61804篇
  1989年   59579篇
  1988年   53905篇
  1987年   53401篇
  1986年   49958篇
  1985年   47834篇
  1984年   35378篇
  1983年   29805篇
  1982年   17267篇
  1981年   15324篇
  1979年   31999篇
  1978年   22325篇
  1977年   19577篇
  1976年   17716篇
  1975年   19280篇
  1974年   22811篇
  1973年   22056篇
  1972年   20642篇
  1971年   19318篇
  1970年   17828篇
  1969年   16955篇
  1968年   15426篇
排序方式: 共有10000条查询结果,搜索用时 421 毫秒
41.
42.
43.
44.
45.
46.
There is evidence that caesarean section delivery can impact on neonatal weight loss and weight gain patterns in the first 5 days of life. We conducted an integrative systematic review to examine the association of mode of delivery on early neonatal weight loss. Pubmed, Cumulative Index to Nursing and Allied Health Literature, Web of Science, Excerpta Medica dataBASE, and Medical Literature Analysis and Retrieval System Online were searched for relevant papers published before June 2019. Reference lists from the relevant papers were then backwards and forwards searched. As neonatal weight loss was reported in different formats, a meta‐analysis could not be carried out. Most studies did not distinguish between elective and emergency caesarean sections or instrumental and nonassisted vaginal deliveries. Seven papers were included. All papers except one found that caesarean section was associated with higher weight loss in the early days of life. Two papers presented data from studies on babies followed up to 1 month. One study found that on day 25, babies born by caesarean section had significantly higher weight gain than those born vaginally, while another found that by day 28, babies born vaginally gained more weight per day (11.9 g/kg/day) than those born by caesarean section (10.9 g/kg/day; p = .02). Overall, infants born by caesarean section lost more weight than those born vaginally, but due to the small number of studies included, more are needed to look at this difference and why it may occur. This discrepancy in weight between the two groups may be corrected over time, but future studies will need larger sample sizes and longer follow‐up periods to examine this.  相似文献   
47.

Objective

To examine whether a healthy weight intervention embedded in the Parents as Teachers (PAT) home visiting program, which was previously found to improve mothers’ body mass index (BMI) and obesity-related behaviors, changed the BMI of preschool children or maternal feeding practices.

Methods

This stratified randomized trial included preschool-aged children at risk for overweight whose mothers were overweight or had obesity (n?=?179). The Healthy Eating and Active Living Taught at Home (HEALTH) intervention was based on the Diabetes Prevention Program. Differences were examined using repeated-measures mixed-ANOVA models.

Results

Compared with PAT usual care, the HEALTH intervention had no effect on children's BMI or maternal feeding practices. However, combined analyses showed that children's BMI percentile decreased (P??=?.007), BMI z-scores were maintained (P??=?.19), and 3 of 8 feeding practices improved over time (P < .05).

Conclusions and Implications

Additional research is needed to assess the effectiveness of PAT to prevent preschool-age obesity using rigorous designs (eg, group-randomized trials) and to identify its active components. HEALTH is ready to be scaled up to prevent maternal weight gain through embedding within the national PAT program.  相似文献   
48.
49.

Objectives

Expedient extubation after cardiac surgery has been associated with improved outcomes, leading to postoperative extubation frequently during overnight hours. However, recent evidence in a mixed medical-surgical intensive care unit population demonstrated worse outcomes with overnight extubation. This study investigated the impact of overnight extubation in a statewide, multicenter Society of Thoracic Surgeons database.

Methods

Records from 39,812 patients undergoing coronary artery bypass grafting or valve operations (2008-2016) and extubated within 24 hours were stratified according to extubation time between 06:00 and 18:00 (day) or between 18:00 and 6:00 (overnight). Outcomes including reintubation, mortality, and composite morbidity-mortality were evaluated using hierarchical regression models adjusted for Society of Thoracic Surgeons predictive risk scores. To further analyze extubation during the night, a subanalysis stratified patients into 3 groups: 06:00 to 18:00, 18:00 to 24:00, and 24:00 to 06:00.

Results

A total of 20,758 patients were extubated overnight (52.1%) and were slightly older (median age 66 vs 65 years, P < .001) with a longer duration of ventilation (4 vs 7 hours, P < .001). Day and overnight extubation were associated with equivalent operative mortality (1.7% vs 1.7%, P = .880), reintubation (3.7% vs 3.4%, P = .141), and composite morbidity-mortality (8.2% vs 8.0%, P = .314). After risk adjustment, overnight extubation was not associated with any difference in reintubation, mortality, or composite morbidity-mortality. On subanalysis, those extubated between 24:00 and 06:00 exhibited increased composite morbidity-mortality (odds ratio, 1.18; P = .001) but no difference in reintubation or mortality.

Conclusions

Extubation overnight was not associated with increased mortality or reintubation. These results suggest that in the appropriate clinical setting, it is safe to routinely extubate cardiac surgery patients overnight.  相似文献   
50.
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