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   1509981篇
  免费   96842篇
  国内免费   4698篇
耳鼻咽喉   18972篇
儿科学   47966篇
妇产科学   40351篇
基础医学   221238篇
口腔科学   41338篇
临床医学   140296篇
内科学   294979篇
皮肤病学   30515篇
神经病学   125892篇
特种医学   52676篇
外国民族医学   372篇
外科学   202367篇
综合类   29768篇
现状与发展   1篇
一般理论   496篇
预防医学   132657篇
眼科学   33170篇
药学   111532篇
  41篇
中国医学   3829篇
肿瘤学   83065篇
  2021年   14485篇
  2019年   15380篇
  2018年   22478篇
  2017年   16180篇
  2016年   16617篇
  2015年   18673篇
  2014年   25156篇
  2013年   38243篇
  2012年   54287篇
  2011年   57433篇
  2010年   32683篇
  2009年   29307篇
  2008年   51389篇
  2007年   54166篇
  2006年   53774篇
  2005年   51892篇
  2004年   49234篇
  2003年   46677篇
  2002年   45062篇
  2001年   64688篇
  2000年   66761篇
  1999年   55609篇
  1998年   15470篇
  1997年   13860篇
  1996年   13687篇
  1995年   12940篇
  1994年   12032篇
  1993年   11287篇
  1992年   43474篇
  1991年   42376篇
  1990年   41144篇
  1989年   38822篇
  1988年   35969篇
  1987年   35047篇
  1986年   33454篇
  1985年   31833篇
  1984年   23908篇
  1983年   20342篇
  1982年   12139篇
  1979年   21826篇
  1978年   15501篇
  1977年   12740篇
  1976年   12517篇
  1975年   12880篇
  1974年   15763篇
  1973年   15450篇
  1972年   14319篇
  1971年   13327篇
  1970年   12333篇
  1969年   11306篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
104.

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   
105.
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   
106.
107.
108.
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   
109.
110.
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