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   1077489篇
  免费   73569篇
  国内免费   3354篇
耳鼻咽喉   13542篇
儿科学   34915篇
妇产科学   29112篇
基础医学   158627篇
口腔科学   28797篇
临床医学   103873篇
内科学   206950篇
皮肤病学   21173篇
神经病学   89775篇
特种医学   38679篇
外国民族医学   293篇
外科学   147123篇
综合类   23021篇
现状与发展   1篇
一般理论   365篇
预防医学   91616篇
眼科学   23239篇
药学   79352篇
  31篇
中国医学   2569篇
肿瘤学   61359篇
  2021年   8935篇
  2019年   9780篇
  2018年   13093篇
  2017年   9929篇
  2016年   10695篇
  2015年   12141篇
  2014年   16607篇
  2013年   25613篇
  2012年   35453篇
  2011年   37376篇
  2010年   21726篇
  2009年   19857篇
  2008年   34234篇
  2007年   36056篇
  2006年   36104篇
  2005年   34760篇
  2004年   33185篇
  2003年   31546篇
  2002年   30441篇
  2001年   48767篇
  2000年   50006篇
  1999年   41833篇
  1998年   11660篇
  1997年   10647篇
  1996年   10582篇
  1995年   9982篇
  1994年   9349篇
  1993年   8732篇
  1992年   33387篇
  1991年   32710篇
  1990年   31608篇
  1989年   29881篇
  1988年   27792篇
  1987年   26870篇
  1986年   25713篇
  1985年   24513篇
  1984年   18343篇
  1983年   15650篇
  1982年   9454篇
  1979年   16589篇
  1978年   11805篇
  1977年   9667篇
  1976年   9485篇
  1975年   9629篇
  1974年   11853篇
  1973年   11652篇
  1972年   10708篇
  1971年   9981篇
  1970年   9197篇
  1969年   8299篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.

Objective

We performed a systematic review to look for an association between progestin-only contraception and depression.

Methods

We searched PubMed, Ovid and Web of Science for English-language articles including progestin-only contraception and depression from database inception to September 2016. We evaluated study quality with the procedures guiding reviews for the United States Preventive Services Task Force and the Cochrane Risk of Bias Tools. We included studies that evaluated progestin-only contraception and depression, focusing on externally validated depression measures. We excluded case studies, review articles and other psychiatric disorders.

Results

We identified 26 studies that met the inclusion criteria, including 5 randomized controlled trials, 11 cohort studies and 10 cross-sectional studies. We found minimal association between progestin-only methods and depression. No correlation with depression was found in five low-quality, high-risk-of-bias progestin subdermal implant studies and four out of five varying-quality and medium-risk-of-bias levonorgestrel intrauterine device studies. Three medroxyprogesterone acetate intramuscular injection trials with varying levels of quality and bias show no difference in depression. Two progestin-only contraceptive pill studies with varying levels of quality and bias indicate no increase in depression scores, while one good-quality, medium-bias study shows an association between progestin-only pills, the intrauterine device and depression.

Conclusion

Despite perceptions in the community of increased depression following the initiation of progestin contraceptives, the preponderance of evidence does not support an association based on validated measures (mostly level II-1 evidence, moderate quality, low risk of bias).  相似文献   
82.
Veterans are at an increased risk of being injured or killed in motor vehicle crashes, potentially due to their proclivity to engage in risky driving behaviors. However, most research in this area has focused on driving behaviors of veterans who have recently returned home after deployment. No research has focused on risky driving behaviors of older veterans (aged 65 or older) and if risky driving behaviors extend beyond the time period immediately following return from deployment. The purpose of this research is to determine if differences exist in risky driving behaviors of veterans and non-veterans aged 65 or older. This study used data from the 2011 National Health and Aging Trend Study (NHATS), a nationally representative, longitudinal survey of community-dwelling, Medicare beneficiaries aged 65 or older. Binary logistic regression analyses were conducted in 2017 to determine if veteran’s status was predictive of specific risky driving behaviors. Veteran’s status was found to be predictive of specific driving behaviors for adults aged 65 and older, with non-veterans significantly more likely than veterans to: not currently drive; avoid driving at night; avoid driving alone; avoid driving on busy roads or highways; and avoid driving in bad weather. The results of this study highlight the need to further understand the effects of veteran’s status on risky driving behaviors among older adults, specifically, whether veteran’s status compounds driving-related risks associated with aging-related physical and mental changes.  相似文献   
83.
84.
85.
While colorectal cancer (CRC) screening rates have been increasing in the general population, rates are considerably lower in Federally Qualified Health Centers (FQHCs), which serve a large proportion of uninsured and medically vulnerable patients. Efforts to screen eligible patients must be accelerated if we are to reach the national screening goal of 80% by 2018 and beyond. To inform this work, we conducted a survey of key informants at FQHCs in eight states to determine which evidence-based interventions (EBIs) to promote CRC screening are currently being used, and which implementation strategies are being employed to ensure that the interventions are executed as intended. One hundred and forty-eight FQHCs were invited to participate in the study, and 56 completed surveys were received for a response rate of 38%. Results demonstrated that provider reminder and recall systems were the most commonly used EBIs (44.6%) while the most commonly used implementation strategy was the identification of barriers (84.0%). The mean number of EBIs that were fully implemented at the centers was 2.4 (range 0–7) out of seven. Almost one-quarter of respondents indicated that their FQHCs were not using any EBIs to increase CRC screening. Full implementation of EBIs was correlated with higher CRC screening rates. These findings identify gaps as well as the preferences and needs of FQHCs in selecting and implementing EBIs for CRC screening.  相似文献   
86.
87.
Point-of-Care Ultrasound is a method of performing a rapid clinical ultrasound, with the aim of responding to a clinical question immediately. This is not an ultrasound performed systematically as the radiologists do, nor does it pretend to replace it. It is useful in some kind of screening (abdominal aortic aneurysm) and is of special interest in ultrasound-guided procedures (joint infiltration by injection).It allows to adapt the derivations, minimising the uncertainty, ruling out certain pathologies due to its high diagnostic precision. It can also lead to overdiagnosis, if the examinations carried out are not limited to the organs on which our clinical suspicion is based.Ultrasound is one tool more in the diagnostic process, but its use must be limited to certain clinical situations. Its use in early detection of prevalent diseases in Primary Care should be properly evaluated. On the other hand with more evidence of a high diagnostic accuracy in a large list of pathological conditions.  相似文献   
88.
89.
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