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   5531篇
  免费   327篇
  国内免费   10篇
耳鼻咽喉   19篇
儿科学   173篇
妇产科学   169篇
基础医学   888篇
口腔科学   80篇
临床医学   455篇
内科学   1003篇
皮肤病学   175篇
神经病学   575篇
特种医学   181篇
外科学   492篇
综合类   58篇
预防医学   483篇
眼科学   303篇
药学   447篇
中国医学   10篇
肿瘤学   357篇
  2023年   26篇
  2022年   51篇
  2021年   93篇
  2020年   55篇
  2019年   81篇
  2018年   112篇
  2017年   69篇
  2016年   122篇
  2015年   137篇
  2014年   166篇
  2013年   212篇
  2012年   344篇
  2011年   432篇
  2010年   211篇
  2009年   205篇
  2008年   355篇
  2007年   331篇
  2006年   358篇
  2005年   351篇
  2004年   309篇
  2003年   284篇
  2002年   306篇
  2001年   69篇
  2000年   55篇
  1999年   87篇
  1998年   97篇
  1997年   85篇
  1996年   62篇
  1995年   57篇
  1994年   51篇
  1993年   45篇
  1992年   44篇
  1991年   29篇
  1990年   25篇
  1989年   17篇
  1988年   43篇
  1987年   30篇
  1986年   31篇
  1985年   32篇
  1984年   22篇
  1983年   22篇
  1982年   22篇
  1981年   21篇
  1980年   21篇
  1979年   17篇
  1978年   18篇
  1977年   16篇
  1976年   14篇
  1975年   15篇
  1974年   15篇
排序方式: 共有5868条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Alzheimer's disease (AD) patients often present with concurrent major depression (MD). To investigate the reasons for this comorbidity, e.g. MD being a risk factor for AD, or both diagnoses having a common neurobiology, the temporal relationship between the first onset of AD and of MD during lifetime was investigated-57 out of 146 AD patients had a lifetime diagnosis of MD. The correlation between the ages at onset of MD and dementia was calculated. The incidence of MD in AD patients in several 5-year-intervals before and after the onset of AD was compared with the average incidence of MD in the present AD sample and with the expected incidence of MD in the general population. No significant correlation between the onset of AD and of MD could be found after controlling for age, gender and the Mini-Mental-State. However, the incidence of MD 5 years before and after the onset of AD significantly exceeded the expected incidences-MD is only partially related to AD. However, the increased incidence of MD within 5 years before and after the onset of dementia may indicate that a common neurobiological process causes cognitive decline and depression in a subsample of AD patients.  相似文献   
5.
BACKGROUND: The long-term observation of vegetarians in affluent countries can provide insight into the relative effects of a vegetarian diet and lifestyle factors on mortality. METHODS: A cohort study of vegetarians and health-conscious persons in Germany was followed-up prospectively for 21 years, including 1,225 vegetarians and 679 health-conscious nonvegetarians. Standardized mortality ratios compared with the German general population were calculated for all causes and specific causes. Within the cohort, Poisson regression modeling was used to investigate the joint effects of several risk factors on overall and cause-specific mortality. RESULTS: Standardized mortality ratios for all-cause mortality was significantly below 100: 59 [95% confidence interval (95% CI), 54-64], predominantly due to a deficit of deaths from circulatory diseases. Within the cohort, vegetarian compared with nonvegetarian diet had no effect on overall mortality [rate ratio (RR), 1.10; 95% CI, 0.89-1.36], whereas moderate and high physical activity significantly reduced risk of death (RR, 0.62, 0.64), adjusted for age, sex, smoking, alcohol intake, body mass index, and educational level. Vegetarian diet was however associated with a reduced RR of 0.70 (95% CI, 0.41-1.18) for ischemic heart disease, which could partly be related to avoidance of meat. CONCLUSIONS: Both vegetarians and nonvegetarian health-conscious persons in this study have reduced mortality compared with the general population. Within the study, low prevalence of smoking and moderate or high level of physical activity but not strictly vegetarian diet was associated with reduced overall mortality. The nonsignificant reduction in mortality from ischemic heart diseases in vegetarians compared with health-conscious persons could be explained in part by avoidance of meat intake.  相似文献   
6.
7.
8.
Muscle biopsies from the apex of both sides of the curve of 31 patients with idiopathic scoliosis showed abnormalities in fiber-type distribution in 68 per cent and in fiber size in 55 per cent. There was no preference for either side. Type 1 fiber predominance was as common as type 1 fiber deficiency. Atrophy occurred in 33 per cent and affected mainly type 1 fibers: atrophy of type 2 fibers was rare. Hypertrophy was limited to type 2 fibers, and occurred in 26 per cent. The strength factor for type 1 fibers exceeded that for type 2. Type 2A fibers were no larger than 2B fibers: there was a large type 2A predominance, more so on the convex side. Most of the muscle changes appear to be secondary and compensatory: none suggests a pathogenesis for the curve.  相似文献   
9.
10.
This paper presents a statistical model constructed using logisticregression to identify those at high-risk of repeating parasuicide. Thesubjects in the study are Cork city residents who exhibited parasuicidalbehaviour between 1 January and 30 June 1995. Repetition of the behaviourwithin six months of the index episode distinguishes repeaters fromnon-repeaters. The model was designed so that it could be used bynon-clinicians and hence does not require information relating topsychiatric diagnosis or use of psychiatric services. The proportion ofsubjects correctly classified remained stable across a range of cut-pointprobabilities (mean = 86%, range: 83.9–87.5%). Using acut-point of 0.2, 96% of repeaters and 81% of non-repeaters were correctly classified. Using 0.45 led to the correct identification of81% of repeaters and 90% of non-repeaters. If these highlevels of sensitivity and specificity are maintained in validation tests onfuture cohorts in Cork city then the model could form the basis of anintervention programme designed to prevent the repetition of parasuicide.  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