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   3900篇
  免费   373篇
  国内免费   51篇
耳鼻咽喉   44篇
儿科学   160篇
妇产科学   106篇
基础医学   373篇
口腔科学   72篇
临床医学   515篇
内科学   832篇
皮肤病学   58篇
神经病学   370篇
特种医学   253篇
外科学   526篇
综合类   70篇
预防医学   446篇
眼科学   46篇
药学   237篇
  1篇
中国医学   16篇
肿瘤学   199篇
  2022年   23篇
  2021年   44篇
  2020年   32篇
  2019年   46篇
  2018年   71篇
  2017年   45篇
  2016年   62篇
  2015年   67篇
  2014年   98篇
  2013年   142篇
  2012年   161篇
  2011年   184篇
  2010年   111篇
  2009年   144篇
  2008年   164篇
  2007年   171篇
  2006年   145篇
  2005年   127篇
  2004年   130篇
  2003年   130篇
  2002年   145篇
  2001年   130篇
  2000年   102篇
  1999年   111篇
  1998年   119篇
  1997年   126篇
  1996年   80篇
  1995年   78篇
  1994年   73篇
  1993年   72篇
  1992年   88篇
  1991年   85篇
  1990年   68篇
  1989年   80篇
  1988年   88篇
  1987年   95篇
  1986年   72篇
  1985年   75篇
  1984年   44篇
  1983年   35篇
  1982年   21篇
  1981年   34篇
  1980年   30篇
  1979年   38篇
  1978年   29篇
  1977年   29篇
  1976年   23篇
  1975年   19篇
  1974年   39篇
  1973年   20篇
排序方式: 共有4324条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
75.
76.
Protected areas facilitate species' range expansions   总被引:1,自引:0,他引:1  
The benefits of protected areas (PAs) for biodiversity have been questioned in the context of climate change because PAs are static, whereas the distributions of species are dynamic. Current PAs may, however, continue to be important if they provide suitable locations for species to colonize at their leading-edge range boundaries, thereby enabling spread into new regions. Here, we present an empirical assessment of the role of PAs as targets for colonization during recent range expansions. Records from intensive surveys revealed that seven bird and butterfly species have colonized PAs 4.2 (median) times more frequently than expected from the availability of PAs in the landscapes colonized. Records of an additional 256 invertebrate species with less-intensive surveys supported these findings and showed that 98% of species are disproportionately associated with PAs in newly colonized parts of their ranges. Although colonizing species favor PAs in general, species vary greatly in their reliance on PAs, reflecting differences in the dependence of individual species on particular habitats and other conditions that are available only in PAs. These findings highlight the importance of current PAs for facilitating range expansions and show that a small subset of the landscape receives a high proportion of colonizations by range-expanding species.  相似文献   
77.
78.

Background

Cardiovascular disease and mental health both hold enormous public health importance, both ranking highly in results of the recent Global Burden of Disease Study 2010 (GBD 2010). For the first time, the GBD 2010 has systematically and quantitatively assessed major depression as an independent risk factor for the development of ischemic heart disease (IHD) using comparative risk assessment methodology.

Methods

A pooled relative risk (RR) was calculated from studies identified through a systematic review with strict inclusion criteria designed to provide evidence of independent risk factor status. Accepted case definitions of depression include diagnosis by a clinician or by non-clinician raters adhering to Diagnostic and Statistical Manual of Mental Disorders (DSM) or International Classification of Diseases (ICD) classifications. We therefore refer to the exposure in this paper as major depression as opposed to the DSM-IV category of major depressive disorder (MDD). The population attributable fraction (PAF) was calculated using the pooled RR estimate. Attributable burden was calculated by multiplying the PAF by the underlying burden of IHD estimated as part of GBD 2010.

Results

The pooled relative risk of developing IHD in those with major depression was 1.56 (95% CI 1.30 to 1.87). Globally there were almost 4 million estimated IHD disability-adjusted life years (DALYs), which can be attributed to major depression in 2010; 3.5 million years of life lost and 250,000 years of life lived with a disability. These findings highlight a previously underestimated mortality component of the burden of major depression. As a proportion of overall IHD burden, 2.95% (95% CI 1.48 to 4.46%) of IHD DALYs were estimated to be attributable to MDD in 2010. Eastern Europe and North Africa/Middle East demonstrate the highest proportion with Asia Pacific, high income representing the lowest.

Conclusions

The present work comprises the most robust systematic review of its kind to date. The key finding that major depression may be responsible for approximately 3% of global IHD DALYs warrants assessment for depression in patients at high risk of developing IHD or at risk of a repeat IHD event.
  相似文献   
79.
80.
Objective To systematically review the literature of factors affecting adherence to Antiretroviral treatment (ART) in Asian developing countries. Methods Database searches in Medline/Ovid, Cochrane library, CINAHL, Scopus and PsychINFO for studies published between 1996 and December 2010. The reference lists of included papers were also checked, with citation searching on key papers. Results A total of 437 studies were identified, and 18 articles met the inclusion criteria and were extracted and critically appraised, representing in 12 quantitative, four qualitative and two mixed‐method studies. Twenty‐two individual themes, including financial difficulties, side effects, access, stigma and discrimination, simply forgetting and being too busy, impeded adherence to ART, and 11 themes, including family support, self‐efficacy and desire to live longer, facilitated adherence. Conclusion Adherence to ART varies between individuals and over time. We need to redress impeding factors while promoting factors that reinforce adherence through financial support, better accessible points for medicine refills, consulting doctors for help with side effects, social support and trusting relationships with care providers.  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