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   4434篇
  免费   190篇
  国内免费   55篇
耳鼻咽喉   12篇
儿科学   42篇
妇产科学   50篇
基础医学   435篇
口腔科学   24篇
临床医学   398篇
内科学   1928篇
皮肤病学   25篇
神经病学   222篇
特种医学   157篇
外科学   584篇
综合类   109篇
预防医学   279篇
眼科学   32篇
药学   125篇
  5篇
中国医学   18篇
肿瘤学   234篇
  2024年   5篇
  2023年   515篇
  2022年   586篇
  2021年   582篇
  2020年   531篇
  2019年   192篇
  2018年   145篇
  2017年   187篇
  2016年   171篇
  2015年   199篇
  2014年   419篇
  2013年   228篇
  2012年   153篇
  2011年   47篇
  2010年   129篇
  2009年   128篇
  2008年   34篇
  2007年   46篇
  2006年   48篇
  2005年   31篇
  2004年   18篇
  2003年   20篇
  2002年   27篇
  2001年   21篇
  2000年   16篇
  1999年   28篇
  1998年   24篇
  1997年   23篇
  1996年   38篇
  1995年   23篇
  1994年   21篇
  1993年   15篇
  1992年   6篇
  1991年   4篇
  1990年   5篇
  1989年   6篇
  1988年   5篇
  1986年   1篇
  1984年   1篇
  1980年   1篇
排序方式: 共有4679条查询结果,搜索用时 15 毫秒
21.
22.
23.
BackgroundThe severity score of Ebstein anomaly (EA) that corresponds to clinical status is still under research, with the Celermajer index (Cel-ind) being one of those. The agreement between echocardiographic and cardiac magnetic resonance (CMR) assessment of Cel-ind is not known. We determined the agreement between echocardiography- and CMR-derived Cel-ind and its relationship with heart failure markers.MethodsA total of 37 unoperated adults with EA (mean age, 43.0 ± 14.4 years) underwent echocardiography, CMR, and cardiopulmonary tests. For the Cel-ind, end-diastolic areas in echocardiography or end-diastolic volumes in CMR were used according to the following formula: Cel-ind = (right atrium + atrialized right ventricle)/(functional right ventricle + left atrium + left ventricle). On the basis of this assumption, patients were classified as follows: grade 1 = Cel-ind < 0.5, grade 2 = 0.5 to 0.99, grade 3 = 1.0 to 1.49, grade 4 > 1.5. The agreement between echocardiographic and CMR was determined with the intraclass correlation coefficient or Cohen’s kappa (<0.2 poor agreement; 0.2-0.4 fair agreement; 0.4-0.6 moderate agreement; 0.6-0.8 good agreement; 0.8-1.0 very good agreement).ResultsThe median echoCel-ind was 0.9 (range, 0.4-2.3), and the median cmrCel-ind was 0.7 (range, 0.3-5.3). Grade 1 or 2 was found in 19 patients (51.3%) by echocardiography and in 27 patients (72.9%) by CMR. The agreement between imaging methods was only fair (kappa = 0.39, P = 0.002) for the 4-grade classification and moderate (intra-class correlation coefficient = 0.43; 95% confidence interval, 0.13-0.66) for Cel-ind calculation. Significant correlations between Cel-ind in CMR and cardiopulmonary parameters were found (for peak oxygen uptake: R = −0.35, P = 0.034; for the ventilation/carbon dioxide slope: R = 0.46, P = 0.005). Neither of them correlated with echocardiographic severity score.ConclusionsThe agreement between echocardiographic and CMR assessment of the Cel-ind is at most moderate; echocardiography usually overestimates, but rarely underestimates, EA severity. Cel-ind by CMR seems to be more valuable, because it is associated with heart failure markers.  相似文献   
24.
25.
Henningfield brilliantly dissected the deadly comprehensive tactics of the tobacco industry but Food and Drug Administration and WHO strategies against the tobacco epidemic must be questioned. The Food and Drug Administration has the authority to regulate tobacco production (2009 Tobacco Control Act) but fails to ban menthol and reduce cigarettes nicotine content. As little has changed, the Healthy People 2010 objective of reducing the prevalence of cigarette smoking among adults to 12% by 2010 in the US will be attained by 2030. The monitoring of the WHO Framework Convention on Tobacco Control (WHO FCTC) is passive, even when governments repeatedly violate the Article 5.3 of the Convention, which specifically requires protecting public policy from tobacco industry interference. Since 2004, the year after the adoption of the Convention, the prevalence of daily smoking has leveled off and the 2012 annualized rate of change in prevalence of daily smoking was almost null. This contrasts with a 2% annual decrease in the prevalence of daily smoking from 1980 to 2004. The tobacco endgame needs acts, not bureaucracies. Two counties have been moving forward, Brazil has banned menthol and Australia has implemented plain packaging.  相似文献   
26.
27.
28.
《Vaccine》2020,38(32):4940-4943
To determine the duration of immunity provided by the Hepatitis A vaccination (HepA), we evaluated a cohort of participants in Alaska 20 years after being immunized as infants. At recruitment, participants received two doses of inactivated HepA vaccine on one of three schedules. We conducted hepatitis A antibody (anti-HAV) testing for participants at the 20-year time-point. Seventy-five of the original 183 participants (41%) were available for follow-up. The overall anti-HAV geometric mean concentration was 29.9 mIU/mL (95% CI 22.4 mIU/mL, 39.7 mIU/mL) and 50 participants (68%) remained seropositive (titer ≥ 20 mIU/mL). Using a fractional polynomial model, the predicted percent seropositive at 25 years was 55.3%, 49.8% at 30 years and 45.7% at 35 years, suggesting that the percent sero-positive could drop below 50% earlier than previously expected. Further research is necessary to understand if protection continues after seropositivity diminishes or if a HepA booster dose may become necessary.  相似文献   
29.
30.
IntroductionGrowing geriatric mental health needs of urban population in India pose several programmatic challenges. This study aimed to assess anxiety, depression and cognitive disorders among urban elderly, and explore availability of social support mechanisms and of a responsive health system to implement the national mental health programme.Methods244 respondents were randomly selected from Berhampur city. We administered a semi-structured interview schedule to assess substance abuse, chronic morbidity, anxiety, depression and cognitive abilities. Further, in-depth interviews were conducted with 25 key informants including district officials, psychiatrists, and programme managers. We used R software and ‘thematic framework’ approach, respectively, for quantitative and qualitative data analysis. Ethical standards were complied with.ResultsAbout half of the respondents were economically dependent; 57.3% had moderate to severe anxiety; 46.7% had moderate to severe depression; while about 25% had severe cognitive impairments. We found association of chewing tobacco (1.34(0.28–2.40)) and depression (0.52(0.37–0.68)) with anxiety; negative perception about elderly-friendly society (1.64(0.75–2.53)) and physical inactivity (2.88(1.60–4.16)) with depression; and age (-0.11(-0.20 – -0.02)) and physical inactivity (-3.44(-5.13 – -1.74)) with cognitive disorders. Qualitative analysis revealed lack of awareness, social stigma, poor availability of trained human resources, and poor political commitment as important systemic barriers to early detection and treatment of mental ailments among the elderly.ConclusionEstablishing tobacco cessation centres, sensitizing community about mental health needs of elderly, incentivizing physical activity of elderly, integrating mental health with primary care, multi-skilling providers and developing a cadre of community counsellors need urgent attention of policy makers and programme implementers.  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