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   1638500篇
  免费   104155篇
  国内免费   2231篇
耳鼻咽喉   23237篇
儿科学   53897篇
妇产科学   43252篇
基础医学   243872篇
口腔科学   45883篇
临床医学   142679篇
内科学   304046篇
皮肤病学   38452篇
神经病学   123937篇
特种医学   64768篇
外国民族医学   286篇
外科学   249034篇
综合类   30033篇
现状与发展   1篇
一般理论   407篇
预防医学   114818篇
眼科学   38763篇
药学   129398篇
  7篇
中国医学   3853篇
肿瘤学   94263篇
  2018年   17620篇
  2017年   13722篇
  2016年   15952篇
  2015年   17902篇
  2014年   23296篇
  2013年   34528篇
  2012年   47947篇
  2011年   50717篇
  2010年   29790篇
  2009年   27361篇
  2008年   47778篇
  2007年   51536篇
  2006年   52264篇
  2005年   50505篇
  2004年   48684篇
  2003年   46858篇
  2002年   45596篇
  2001年   82587篇
  2000年   84670篇
  1999年   70429篇
  1998年   18053篇
  1997年   15834篇
  1996年   15808篇
  1995年   14693篇
  1994年   13430篇
  1993年   12793篇
  1992年   52047篇
  1991年   51022篇
  1990年   50636篇
  1989年   48624篇
  1988年   44086篇
  1987年   43165篇
  1986年   40647篇
  1985年   38442篇
  1984年   28154篇
  1983年   23780篇
  1982年   13265篇
  1979年   26040篇
  1978年   18068篇
  1977年   15819篇
  1976年   14296篇
  1975年   16423篇
  1974年   19214篇
  1973年   18322篇
  1972年   17700篇
  1971年   16776篇
  1970年   15440篇
  1969年   14846篇
  1968年   13546篇
  1967年   12234篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
Low molecular weight heparins are widely used in the prophylaxis and treatment of thrombotic disorders. The effect of low molecular weight heparins on coagulation was examined ultrastructurally in an animal model. A test and a control group was formed, each consisting of five rabbits. Nadroparine (225 Institute of Chaoy Unit/kg twice daily) was applied to the test group for 10 days. The control group received 1 ml saline solution subcutaneously. Blood and vascular tissue samples collected at the end of the 10th day were evaluated under a JEM 100 B electron microscope. Platelet degranulation and agglutination was observed in the control group. Fibrin materials were detected in the cytoplasms and surroundings of degranulated platelets. Erythrocyte accumulation was remarkable on the vascular endothelium with intact coagulation periods. In the test group, outer membranes of platelets, hyalomere, and granular structures in the granulomeres were detected to be nearly intact. There were rare erythrocytes in the large vascular lumens. The aggregation phase had occurred but no agglutination was detected. Nadroparine seems to preserve consistency of lipoprotein membranes of platelets and granular structures containing enzymes, which contribute to the coagulation mechanisms.  相似文献   
43.
Pulmonary hamartomas are usually an incidental finding and range in size from 1 cm to 8 cm in diameter in various series. We report a case of a massive pulmonary hamartoma (size 25.5 × 17.5 × 6.5 cm and weighing 1134 g) in a 61 year old male who presented with a short history of breathlessness. The tumour was arising from the medial border of the right lung and occupying most of the right chest extending in to the anterior mediastinum. The tumour was compressing the right lung and there was no evidence of infiltration into the surrounding structures. It was successfully treated by surgical resection and final histology was pulmonary hamartoma with predominantly adipose and leiomyomatous differentiation.  相似文献   
44.
45.
Although studies have documented underuse of controller medications and overuse of short-acting inhaled ss(2)-agonist among children with persistent asthma in disadvantaged communities, the persistence of oral ss(2)-agonist use in pediatric practice has not been studied since inhaled short-acting ss(2)-agonists became widespread. We describe medications used to treat asthma among children 3 to 5 years of age at 10 Head Start and other subsidized preschool centers in East and Central Harlem, New York City. We interviewed 149 parents/guardians of children who were identified as having probable asthma based on physician's diagnosis, persistent symptoms, hospitalization, and medication use. We classified 86 of the 149 children (58%) as having current persistent asthma. Only 15 of them (17%) were reported to have used controller medications at least 5 days/week in the last 4 weeks-only 2 of whom used inhaled corticosteroids. By contrast, 53 children (62%) used oral ss(2)-agonist in the last 4 weeks, often (72%) in conjunction with nebulized or inhaled short-acting ss(2)-agonist. Use of oral ss(2)-agonist was associated with more severe symptoms. This study documents the continued widespread use of oral ss(2)-agonist for treatment of children in a low-income community with high prevalence of asthma.  相似文献   
46.
47.
48.
目的:描述胚胎种植前遗传诊断在1例携带Ⅰ型白细胞黏附缺陷病(LAD-1)携带者并完成健康妊娠夫妇中的应用。设计:病例报道。机构:大学医院生殖中心。患者:1例男女双方都是LAD-1携带者的夫妇,女方CD18基因的外显子4携带有G400A置换,男方的外显子5携带有C562T置换。干预:标准体外受精(IVF)后第3天行卵裂期活检和分裂球遗传分析以检测2处突变以及21号染色体标记物。主要观察指标:1个未罹患LAD-1婴儿的出生。结果:得到15个卵母细胞,其中10个受精。8个胚胎适宜胚胎活组织检查。  相似文献   
49.
Using the SF-12 to measure physical and mental functioning, the authors examine the intra-individual changes in health-related quality of life (HRQOL) 6 months post-discharge for depressed older adults. In addition, they examine three sets of predictors that might influence these changes. The sample of depressed older adults was recruited from an inpatient geropsychiatry unit. Although their physical and mental health scores on the SF-12 were lower than comparable norms, the sample showed an average increase in their mental functioning but a decrease in the physical functioning over the 6 months. Negative life-events were significant predictors of people who reported no change in their mental health functioning and decreases in their physical health functioning. Interestingly, those who experienced positive life events were more likely to report declines and younger participants were more likely to report no change in their physical functioning. The findings indicate that the effects of depression on HRQOL can have enduring effects on a sample of previously hospitalized older adults. The significance of life event changes might signify the importance of taking into account non-traditional areas of medical interventions. Further, the findings indicate the usefulness of the SF-12 quantifying HRQOL outcomes.  相似文献   
50.
Abstrakt 1. Ein nicht ausgefülltes und nicht unterschriebenes Aufkl?rungsformular in der Krankenakte bildet ein Indiz nicht für, sondern gegen die Durchführung eines Aufkl?rungsgespr?chs. 2. Wenn vor dem ?rztlichen Eingriff überhaupt keine Aufkl?rung erfolgt, genügt für den Beginn der Verj?hrung eines auf eine Aufkl?rungspflichtverletzung gestützten Anspruchs die Kenntnis vom Eintritt schwerwiegender Komplikationen. Nicht erforderlich ist das Wissen, dass sich ein typisches Risiko des Eingriffs verwirklicht hat.  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