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   50540篇
  免费   3184篇
  国内免费   156篇
耳鼻咽喉   656篇
儿科学   1437篇
妇产科学   868篇
基础医学   5953篇
口腔科学   813篇
临床医学   5241篇
内科学   10865篇
皮肤病学   870篇
神经病学   4700篇
特种医学   2024篇
外国民族医学   1篇
外科学   8857篇
综合类   486篇
一般理论   48篇
预防医学   3198篇
眼科学   819篇
药学   3106篇
中国医学   45篇
肿瘤学   3893篇
  2023年   247篇
  2022年   419篇
  2021年   1092篇
  2020年   628篇
  2019年   1115篇
  2018年   1319篇
  2017年   960篇
  2016年   1005篇
  2015年   1186篇
  2014年   1834篇
  2013年   2338篇
  2012年   3779篇
  2011年   3944篇
  2010年   2202篇
  2009年   1875篇
  2008年   3426篇
  2007年   3616篇
  2006年   3601篇
  2005年   3511篇
  2004年   3362篇
  2003年   3127篇
  2002年   2889篇
  2001年   397篇
  2000年   292篇
  1999年   430篇
  1998年   574篇
  1997年   461篇
  1996年   357篇
  1995年   353篇
  1994年   335篇
  1993年   272篇
  1992年   225篇
  1991年   208篇
  1990年   189篇
  1989年   177篇
  1988年   181篇
  1987年   165篇
  1986年   151篇
  1985年   153篇
  1984年   187篇
  1983年   193篇
  1982年   212篇
  1981年   180篇
  1980年   129篇
  1979年   96篇
  1978年   81篇
  1977年   74篇
  1976年   45篇
  1974年   50篇
  1973年   38篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.

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   
4.
A comparative study involving bimetallic nickel catalysts designed from disubstituted N,N,N′,N′‐tetra(diphenylphosphanylmethyl)benzene diamine bridging ligands is reported. Catalyst behavior is explored in the Kumada catalyst‐transfer polymerization (KCTP) using poly(3‐hexylthiophene) (P3HT) as the model system. The success of a controlled polymerization is monitored by analyzing monomer conversion, degree of polymerization, end‐group identity, and molecular weight distribution. The characterization of P3HT obtained from KCTP initiated with the bimetallic catalysts shows chain‐growth behavior; however, the presence of Br/Br end‐groups and broader molecular weight distribution reveals a reduced controlled polymerization compared to the commonly employed Ni(dppp)Cl2. The observed increase in intermolecular chain transfer and termination processes in KCTP initiation with the bimetallic catalysts can be attributed to a weaker Ni(0)‐π‐aryl complex interaction, which is caused by increased steric crowding of the coordination sphere.  相似文献   
5.
6.
7.
8.
In the USA, the Black Church is among the most important institutions in the Black community, offering numerous spiritual, social and health benefits. Yet, the presence of homonegativity in many Black Churches may mitigate those effects for gay Black youth. This research examines the role of the Church in the lives of gay and bisexual Black youth to understand how they reconcile any tension between their religious and sexual identities. Through interviews with pastors of Black churches (n = 21) and young Black men who have sex with men (n = 30), we explored homonegativity and young men’s experiences within the Black Church. Findings reveal that despite the prevalence of homonegativity within Black churches, religious involvement remains important for young men and many remain involved in non-affirming churches. The importance of the Church for young men stems from their significant involvement as youth and the integration of religion, family and community. Young men may not be able to leave their religious homes as readily as other gay youth given the cultural relevance of the Church. As a result, young men made attempts to conceal their sexuality in church to avoid shame and gossip and find opportunities to balance their sexuality and religiosity.  相似文献   
9.
10.
PurposeTo examine what proportion of caregivers, if given a choice, would choose medical versus surgical treatment of appendicitis and what factors would be important in their decision.MethodsA survey was devised and given to the caregivers of children presenting to the pediatrician for a routine visit in community and academic pediatric clinics. The survey presented a summary of outcomes after medical (non-operative) and surgical treatment of uncomplicated appendicitis. Participants were then asked to choose medical versus surgical treatment if their child were to develop appendicitis. They were also asked to rate the importance of certain factors in their decision ? 1 being “not important” and 5 being “very important”.ResultsFour hundred surveys were distributed with an 86.2% (345/400) response rate. Six percent (21/342) of respondents reported a history of appendicitis and 49.4% (168/340) reported having known someone who had appendicitis. The majority of respondents, 85.3% (284/333), were mothers. A minority of respondents, 41.7% (95% CI: 36.7, 47.0), chose medical treatment over surgery for appendicitis. There was no statistical difference in the proportion of mothers (41.6%) versus fathers who chose medical treatment (41.3%). Caregivers who chose medical treatment were more likely to rate time in hospital (p = .008) and time out of school (p = 05) as important in decision making when compared with those who chose surgery. Those who chose surgical treatment were more likely to rate risk of recurrent appendicitis (p < .001) as important to decision making. In the multivariate analysis, those who rated time in hospital as very important had more than twice the odds of choosing medical therapy (OR 2.20, p = 0.02) when compared with those who rated it as less important. Not knowing someone who has had appendicitis was significantly associated with choosing medical therapy when compared with those who do know someone who has had appendicitis, OR 2.3, p = .002. Rating pain as very important was also significantly associated with choosing medical therapy, when compared to those rating pain 1–3, OR 3.38, p = .03.ConclusionsIn this survey of caregivers of children presenting for routine care, 41.7% would choose medical, or non-operative, therapy for their children with acute appendicitis. The risk of recurrence, time in hospital, and time out of school, pain, and knowing someone who has had appendicitis were all important factors that families may consider when making a decision. These data may be useful for surgeons counseling patients on which treatment to pursue.  相似文献   
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