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   2412781篇
  免费   197983篇
  国内免费   4329篇
耳鼻咽喉   34631篇
儿科学   73867篇
妇产科学   63631篇
基础医学   339766篇
口腔科学   68223篇
临床医学   220091篇
内科学   475505篇
皮肤病学   48508篇
神经病学   204081篇
特种医学   97440篇
外国民族医学   886篇
外科学   366462篇
综合类   56742篇
现状与发展   1篇
一般理论   1029篇
预防医学   194834篇
眼科学   56355篇
药学   180200篇
  5篇
中国医学   4406篇
肿瘤学   128430篇
  2018年   25088篇
  2017年   19428篇
  2016年   21269篇
  2015年   24072篇
  2014年   34708篇
  2013年   52586篇
  2012年   71298篇
  2011年   74915篇
  2010年   43942篇
  2009年   42165篇
  2008年   71039篇
  2007年   75622篇
  2006年   76475篇
  2005年   74435篇
  2004年   71608篇
  2003年   69168篇
  2002年   68278篇
  2001年   112932篇
  2000年   117000篇
  1999年   98838篇
  1998年   28290篇
  1997年   25872篇
  1996年   25779篇
  1995年   24987篇
  1994年   23482篇
  1993年   21845篇
  1992年   79661篇
  1991年   76633篇
  1990年   73829篇
  1989年   71072篇
  1988年   66074篇
  1987年   64997篇
  1986年   61536篇
  1985年   58637篇
  1984年   44448篇
  1983年   37817篇
  1982年   23047篇
  1981年   20484篇
  1979年   41398篇
  1978年   29113篇
  1977年   24452篇
  1976年   22937篇
  1975年   24067篇
  1974年   29747篇
  1973年   28142篇
  1972年   26335篇
  1971年   24236篇
  1970年   22841篇
  1969年   21178篇
  1968年   19248篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
71.
The aim of the present study was to explore differences in the clinical expression, clinical diagnoses and management of airway diseases in a primary-care setting. Patients aged >or=35 yrs who had ever smoked were enrolled when they presented for any reason to one of eight rural primary-care practices. Respiratory symptom questionnaires and spirometry were administered. In total, 1,034 patients had acceptable and reproducible spirometry, of whom 550 (53%) were males and 484 (47%) were females. Males smoked more than females (41.2 versus 29.2 pack-yrs) respectively, and were more likely to have a pre-bronchodilator forced expiratory volume in one second/forced vital capacity <0.70 at 22.4 versus 11.8%, respectively. However, more females than males reported breathlessness (51.0 versus 42.8%, respectively), a prior diagnosis compatible with airflow obstruction and taking respiratory medications (23.4 versus 14.9%, respectively). In conclusion, the current results suggest that females are more likely than males to report breathlessness and be prescribed respiratory medications independent of differences in the severity of airflow obstruction.  相似文献   
72.
73.
High levels of tumor necrosis factor-alpha (TNF-alpha), a pro-inflammatory cytokine, are present in the wound fluid of chronic nonhealing wounds. This leads to increased inflammation, cytokine expression, and ultimately results in impaired wound healing and tissue destruction. Etanercept is a recombinant fusion protein that consists of the soluble TNF receptor (p75) linked to the Fc portion of human IgG1. It is an effective inhibitor of TNF-alpha and has been shown to provide rapid and sustained improvement in rheumatoid arthritis by acting as a soluble receptor binding TNF-alpha and preventing its proinflammatory activities. Therefore, the aim of this study was to determine whether Etanercept could inhibit TNF-alpha activity in chronic wound fluid. Wound fluid was collected from the venous leg ulcers of 16 different patients. The effect of Etanercept on TNF-alpha activity was evaluated using both a TNF-alpha bioassay and an enzyme-linked immunoassay. Etanercept was found to reduce the cytotoxic effect of chronic wound fluid on L929 fibroblasts by approximately 30% and neutralized TNF-alpha binding in the enzyme-linked immunoassay by up to 80%. Direct application of Etanercept to chronic wounds may therefore reduce the inflammatory activity of TNF-alpha, which could reduce the chronicity of venous leg ulcers and thus aid in the healing of these wounds.  相似文献   
74.
75.
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   
76.
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   
77.
78.
79.
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   
80.
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   
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