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   2597729篇
  免费   200081篇
  国内免费   4545篇
耳鼻咽喉   36063篇
儿科学   80605篇
妇产科学   67080篇
基础医学   357711篇
口腔科学   70378篇
临床医学   233629篇
内科学   508503篇
皮肤病学   49545篇
神经病学   222052篇
特种医学   106330篇
外国民族医学   889篇
外科学   396932篇
综合类   59273篇
现状与发展   1篇
一般理论   1084篇
预防医学   212355篇
眼科学   59437篇
药学   190386篇
  4篇
中国医学   5071篇
肿瘤学   145027篇
  2018年   45138篇
  2017年   35252篇
  2016年   38981篇
  2015年   25636篇
  2014年   36517篇
  2013年   54834篇
  2012年   80008篇
  2011年   96097篇
  2010年   61924篇
  2009年   53807篇
  2008年   90556篇
  2007年   97080篇
  2006年   79574篇
  2005年   78754篇
  2004年   77093篇
  2003年   75148篇
  2002年   72489篇
  2001年   113288篇
  2000年   117265篇
  1999年   99105篇
  1998年   28876篇
  1997年   26332篇
  1996年   26038篇
  1995年   25190篇
  1994年   23642篇
  1993年   22023篇
  1992年   79704篇
  1991年   76741篇
  1990年   73893篇
  1989年   71093篇
  1988年   66083篇
  1987年   65037篇
  1986年   61519篇
  1985年   58622篇
  1984年   44461篇
  1983年   37869篇
  1982年   23161篇
  1981年   20553篇
  1980年   19246篇
  1979年   41363篇
  1978年   29087篇
  1977年   24430篇
  1976年   22900篇
  1975年   24023篇
  1974年   29707篇
  1973年   28090篇
  1972年   26260篇
  1971年   24175篇
  1970年   22784篇
  1969年   21128篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
For many parents stopping life-sustaining medical treatment on their dying infant is psychologically impossible. Dostoevsky's insights into human behavior, particularly the fact that individuals do not want the anxiety and guilt associated with responsibility for making difficult decisions, might change the way physicians approach parents for permission to withdraw life-prolonging medical interventions on dying infants.  相似文献   
83.
The authors discuss techniques for Monte Carlo (MC) cohort simulations that reduce the number of simulation replications required to achieve a given degree of precision for various output measures. Known as variance reduction techniques, they are often used in industrial engineering and operations research models, but they are seldom used in medical models. However, most MC cohort simulations are well suited to the implementation of these techniques. The authors discuss the cost of implementation versus the benefit of reduced replications.  相似文献   
84.
85.
86.
Consecutive patients (n = 215) who were referred to optometric (55%) or multidisciplinary (45%) low-vision services and above 50 years of age were recruited from four hospitals in the Netherlands. They completed two vision-related quality of life questionnaires, the Vision Quality of Life Core Measure (VCM1) and the Low Vision Quality of Life Questionnaire (LVQOL), before their first visit with low-vision services and 1 year later. At follow-up, patients referred to multidisciplinary low-vision services had lower scores on the mobility subscale of the LVQOL than patients referred to optometric low-vision services [5.3 points; 95% confidence interval (CI): 0.2-10.5]. Paired sample t-tests for the two groups of patients taken together show improvement for the VCM1 (3.1 points; 95% CI: 0.6-5.6) and deterioration for the basic aspects of vision (3.5 points; 95% CI: 1.1-5.9) and the mobility (6.6 points; 95% CI: 3.7-9.5) subscales of the LVQOL. In conclusion, people referred to optometric services showed less deterioration in mobility than those referred to multidisciplinary services. No differences were observed for any of the other subscales of the LVQOL and the VCM1. Future research in this field should include randomized controlled designs comparing low-vision services with no treatment or placebo.  相似文献   
87.
This prospective clinic-based study evaluated the pretreatment periodontal status of the orthodontic patients seen at the University College Hospital, Ibadan, Nigeria, and assessed the relationship between dental aesthetic index (DAI) scores and periodontal status according to community periodontal index of treatment needs (CPITN) scores. One hundred forty five patients-70 (48.3%) males and 75 (51.7%) females from 6 to 45 years (mean 15.8 +/- 7.5)-were seen. World Health Organization (WHO) guidelines were followed in the examination and reporting of the periodontal status, and DAI scores were assessed based on WHO guidelines. The chi-square test was used to determine the association between the DAI and the CPITN scores. Most patients were in the 6-15 (55.9%) or 16-25 (35.9%) age groups. Based on the WHO preferred cumulative calculations of treatment need (TN), 35.2% of the patients had TN 0, 64.9% had TN 1, 24.9% had TN 2, and only 0.7% had TN 3. The relationship between DAI scores and periodontal treatment needs was not statistically significant (P >.05). Although many patients were yet to attain the WHO goal of no more than 1 sextant affected by bleeding or calculus at the age of 15, over one third had satisfactory periodontal health.  相似文献   
88.
Summary: The mosaic (Atp7a mo-ms ) is an X-linked, lethal mutation in mice. In mosaic mutant males, many clinical features characteristic of defective copper metabolism have been observed and they die at the age of 15 days, exhibiting strongsimilarities to the brindled and macular mutants. About 4% of the mutant males live to sexual maturity and some of them are fertile. In this paper, alterationsin the structure of the kidney from adult mutants are described. Owing to an inherited defect of efflux, copper is accumulated in the kidney of the mutants up to a toxic level and this leads to severe damage of the renal cortex. Pathological changes in the kidney mostly affected the structure of the renal corpuscle and renaltubules.  相似文献   
89.
90.
OBJECTIVE: To determine whether under-reporting of rheumatic fever occurs at hospital, municipal, provincial and national levels of the South African health system. BACKGROUND: Information on the incidence of rheumatic fever (RF) and the prevalence of rheumatic heart disease (RHD) is required for the prevention of valvular heart disease in developing countries. In South Africa, RF was made a notifiable condition in 1989. It has recently been suggested that the reporting of RF cases may be incomplete, possibly because of underreporting by health care professionals and deficient administration of the disease notification system in South Africa. METHOD AND RESULTS: We assessed whether underreporting of RF cases occurs by comparing the numbers of RF cases reported per year at hospital, municipal, provincial and national levels from 1990 to 2004. There was a fall in the number of RF cases reported per year at national and provincial level over the 15 years of observation. A detailed analysis of the number of RF cases reported at hospital, municipal and provincial level for a 5-year period showed that more cases were diagnosed in one hospital (serving a smaller population) than were captured at municipal and provincial level (serving a larger population), suggesting underreporting by health care professionals. There were discrepancies in the number of cases reported at municipal, provincial and national level, suggesting poor administration of the notification system. CONCLUSION: There appears to be underreporting of RF cases by health care professionals, and poor administration of the RF notification system. Health care professionals need to be educated about the statutory requirement to notify all RF cases in South Africa. An effective national disease notification system is required.  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