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   863979篇
  免费   70727篇
  国内免费   1836篇
耳鼻咽喉   12857篇
儿科学   24672篇
妇产科学   25113篇
基础医学   124330篇
口腔科学   25511篇
临床医学   75482篇
内科学   164976篇
皮肤病学   16991篇
神经病学   70267篇
特种医学   35315篇
外国民族医学   171篇
外科学   136323篇
综合类   24635篇
现状与发展   2篇
一般理论   263篇
预防医学   67222篇
眼科学   20537篇
药学   64816篇
  14篇
中国医学   1595篇
肿瘤学   45450篇
  2018年   7363篇
  2015年   7749篇
  2014年   11144篇
  2013年   16830篇
  2012年   22770篇
  2011年   23906篇
  2010年   13902篇
  2009年   13096篇
  2008年   22621篇
  2007年   24674篇
  2006年   24548篇
  2005年   24200篇
  2004年   23754篇
  2003年   22867篇
  2002年   21957篇
  2001年   35861篇
  2000年   36502篇
  1999年   30931篇
  1998年   9232篇
  1997年   8562篇
  1996年   8489篇
  1995年   8020篇
  1994年   7731篇
  1992年   26684篇
  1991年   26138篇
  1990年   25634篇
  1989年   24701篇
  1988年   23237篇
  1987年   22907篇
  1986年   21773篇
  1985年   21111篇
  1984年   16397篇
  1983年   14003篇
  1982年   8866篇
  1981年   8208篇
  1980年   7679篇
  1979年   16743篇
  1978年   12121篇
  1977年   10191篇
  1976年   9333篇
  1975年   10153篇
  1974年   12646篇
  1973年   12146篇
  1972年   11543篇
  1971年   10693篇
  1970年   10224篇
  1969年   9916篇
  1968年   8903篇
  1967年   8232篇
  1966年   7655篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.

Purpose

Living in a cold home increases the risk of dying in winter, especially in older people. However, it is unclear which individual factors predict whether older people are living in cold homes.

Methods

Thousand four hundred two men aged 74–95 years from a U.K. population–based study reported difficulties in keeping warm during winter, answering four simple “yes/no” questions. Associations between individual's characteristics and each of the four self-reported measures of cold homes were estimated using logistic regression models. Next, we investigated whether measures of cold homes predict mortality over the subsequent 2.1 years.

Results

Manual social class, difficulties making ends meet, and not being married were each associated (P < .05) with each of the four measures of cold homes (adjusted odds ratios ranged from 1.61 to 4.68). Social isolation, poor respiratory health, and grip strength were also associated with reports of cold homes. Hundred twenty-six men died; those who reported the presence of at least three measures cold homes had increased mortality (adjusted hazard ratios 2.85 [95% confidence interval, 1.11–7.30, P = .029]).

Conclusions

Older people who find it hard to keep warm in winter, and have an elevated mortality, could be identified using a self-report questionnaire.  相似文献   
104.
105.
Maternal and Child Health Journal - Objective The association between and commonality of risk factors for poor self-rated oral health (SROH) and general health (SRGH) among new mothers has not been...  相似文献   
106.
The focus on recovery, not just symptom reduction, in mental health care brings a need for psychometrically sound measures of recovery. This study examined the factor structure and sensitivity to change of a common measure of mental health recovery, the Recovery Assessment Scale (RAS). We conducted a secondary data analysis from a randomized clinical trial of self-management for depression (n = 302). We tested both bifactor and the previously found five-factor model. Sensitivity to change was examined three ways: (1) between the intervention and control group; (2) across time in the intervention group; and (3) in those whose depression remitted. The previous five-factor model was supported. One subscale, no domination by symptoms, was particularly sensitive to change and showed sensitivity to change whereas the subscale reliance on others did not show change in any of the comparisons. Results suggest that the subscales of the RAS should be examined separately in future studies of recovery.  相似文献   
107.
108.
We introduce this supplemental issue of Prevention Science, which brings together a set of papers from leading investigators who have conducted trials testing whether intervention programs prevent adolescent depression. Using data from these trials, these papers explore a series of factors that might account for variation in intervention benefit, employing several novel methods for assessing effect heterogeneity. These studies follow two general paradigms: three papers report findings from single randomized preventive intervention trials, while the remaining papers develop and apply new methods for combining data from multiple studies to evaluate effect heterogeneity more broadly. Colleagues from NIMH and SAMHSA also provide commentaries on these studies. They conclude that synthesis of findings from multiple trials holds great promise for advancing the field, and progress will be accelerated if collaborative data sharing becomes the norm rather than the exception.  相似文献   
109.
Inhalation of ash can be of great concern for affected communities, during and after volcanic eruptions. Governmental and humanitarian agencies recommend and distribute a variety of respiratory protection (RP), most commonly surgical masks. However, there is currently no evidence on how effective such masks are in protecting wearers from volcanic ash. In Part I of this study (Mueller et al., 2018), we assessed the filtration efficiency (FE) of 17 materials from different forms of RP against volcanic ash and a surrogate, low-toxicity dust, Aloxite. Based on those results, we now present the findings from a volunteer simulation study to test the effect of facial fit through assessment of Total Inward Leakage (TIL).Four different disposable RP types that demonstrated very high median FE (≥96% for Aloxite; ≥89% for volcanic ash) were tested without provision of training on fit. These were an industry-certified mask (N95-equiv.); a surgical mask from Japan designed to filter PM2.5; a flat-fold basic mask from Indonesia; and a standard surgical mask from Mexico, which was also tested with an added medical bandage on top, as an additional intervention to improve fit.Ten volunteers (6 female, 4 male) were recruited. Each RP type was worn by volunteers under two different conditions simulating cleaning-up activities during/after volcanic ashfall. Each activity lasted 10?min and two repeats were completed for each RP type per activity. Dust (as PM2.5) concentration inside and outside the mask was measured with two TSI SidePak aerosol monitors (Models AM510 and AM520, TSI, Minnesota, USA) to calculate TIL. A questionnaire was administered after each test to collect perceptions of fit, comfort, protection and breathability.The best-performing RP type, across both activities, was the industry-certified N95-equiv. mask with 9% mean TIL. The standard surgical mask and the basic flat-fold mask both performed worst (35% TIL). With the additional bandage intervention, the surgical mask mean TIL improved to 24%. The PM2.5 surgical mask performed similarly, with 22% TIL. The N95-equiv. mask was perceived to provide the best protection, but was also perceived as being uncomfortable and more difficult to breathe through.This study provides a first objective evidence base for the effectiveness of a selection of RP types typically worn around the world during volcanic crises. The findings will help agencies to make informed decisions on the procurement and distribution of RP in future eruptions.  相似文献   
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