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   2479461篇
  免费   197057篇
  国内免费   5335篇
耳鼻咽喉   36356篇
儿科学   80610篇
妇产科学   64810篇
基础医学   351190篇
口腔科学   65157篇
临床医学   234684篇
内科学   496813篇
皮肤病学   58394篇
神经病学   197819篇
特种医学   93454篇
外国民族医学   489篇
外科学   388479篇
综合类   47802篇
现状与发展   84篇
一般理论   855篇
预防医学   188682篇
眼科学   57361篇
药学   176205篇
  11篇
中国医学   4616篇
肿瘤学   137982篇
  2021年   21705篇
  2019年   21456篇
  2018年   33346篇
  2017年   26558篇
  2016年   29690篇
  2015年   32653篇
  2014年   49127篇
  2013年   67178篇
  2012年   79611篇
  2011年   84423篇
  2010年   55926篇
  2009年   56537篇
  2008年   79722篇
  2007年   83198篇
  2006年   85974篇
  2005年   81157篇
  2004年   77106篇
  2003年   73518篇
  2002年   71233篇
  2001年   111922篇
  2000年   113999篇
  1999年   96174篇
  1998年   29979篇
  1997年   26474篇
  1996年   26738篇
  1995年   25331篇
  1994年   22434篇
  1993年   20968篇
  1992年   73113篇
  1991年   71253篇
  1990年   69270篇
  1989年   66613篇
  1988年   61132篇
  1987年   59855篇
  1986年   55964篇
  1985年   53608篇
  1984年   39768篇
  1983年   33822篇
  1982年   20279篇
  1979年   36112篇
  1978年   25923篇
  1977年   21546篇
  1976年   20531篇
  1975年   22049篇
  1974年   26333篇
  1973年   25001篇
  1972年   23462篇
  1971年   22189篇
  1970年   20451篇
  1969年   19373篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
SETTING: Homes in Delhi, India. OBJECTIVE: To study the reach of mass media campaigns and their impact on awareness about tuberculosis (TB) control among homemakers/housewives. DESIGN: A community-based cross-sectional survey among homemakers residing in Delhi for more than 6 months. RESULTS: Of a total of 920 women interviewed, about 74.2% had seen specific TB-related health messages in one or more of the mass media. The maximum number of subjects could recall having seen billboards or television campaigns. The percentage of respondents who had correct information about various aspects of the disease was higher among those who had seen TB campaigns on any of the mass media. The effectiveness of radio and newsprint in communicating TB messages was found to be more limited than that of television and billboards. CONCLUSION: The mass media can be effective in getting messages about TB across to the community of women who are homemakers, especially in developing countries. In view of our findings, it may be recommended that television and billboards be used as tools for reaching out to them with specific campaigns regarding TB control, and that the use of these media should be strengthened further.  相似文献   
993.
BACKGROUND: Asthma is a chronic inflammatory disorder of the airways. The persistence of airway inflammation depends on a decrease in apoptosis of T lymphocytes and eosinophils and survival of these activated cells. T lymphocytes expressing gamma delta receptors can be identified in human lungs and play an important role in immune defence against pathogens and in the regulation of chronic inflammation. Aging is associated with evidence of some immune dysregulation. OBJECTIVE: The aim of this study was to analyze the apoptosis receptors of T lymphocytes in long-lasting asthma, to establish their correlation with activation markers such as CD25+ and human leukocyte antigen (HLA)-DR+, and to analyze the gama delta T cell expression in this disease. METHODS: A group of 64 individuals (group A) who had had asthma for more than 30 years (mean age [+/-SD] 72 +/- 5 years) and 61 healthy individuals acting as controls--group B with 41 individuals (mean age 79 +/- 7 years) and group C with 20 individuals (mean age 38 +/- 12 years) were included in the study. All subjects underwent clinical evaluation and spirometric testing. Peripheral blood cells were stained with monoclonal antibodies anti-CD3, anti-CD4, anti-CD8, anti-CD25, anti-TCR gamma delta, anti-HLA-DR and anti-CD95. Statistical comparisons were performed between the asthmatics and the elderly control group and between the elderly control group and the adult control group. RESULTS: The average percentage of predicted forced expiratory volume in the first second was 73.6 gamma delta 25.3. The mean values of T cell receptors for asthma group A vs elderly control group B vs adult control group C respectively, were the following: CD3, 74.9+/-7 vs. 74.8 +/- 8.8 (P=ns) vs. 76.7 +/- 4.2 (P=ns); CD4, 48.8 +/- 8.7 vs. 43.5 +/- 10.2 (P=ns) vs. 44.8 +/- 3.8 (P=ns); CD8, 23.3 +/- 7.9 vs. 25.7 +/- 10.2 (P=ns) vs. 25.6 +/- 4.5 (P=ns); CD25, 14.3 +/- 5.9 vs. 22.4 +/- 7.8 (P = .0001) vs. 5.5 +/- 2.4 (P = .0001); TCR gamma delta, 2.8 +/- 2.1 vs. 4.1 +/- 3.3 (P < .05) vs. 4.6 +/- 2.1 (P=ns); HLA-DR, 18.4 +/- 9.2 vs. 17.8 +/- 5.9 (P=ns) vs. 15.4 +/- 5.1 (P=ns) and CD95, 49.3 +/- 13.7 vs. 52.6 +/- 12.1 (P=ns) vs. 13.8 +/- 10.8 (P = .0001). CONCLUSIONS: The immunological and inflammatory changes related to ageing may cause an increase in CD95 and CD25 T cell expression. In asthma, blood cells may express increased activation and apoptosis markers but in elderly patients taking steroids, these receptors remain within normal ranges. The number of gamma delta T cells may be lower in long-lasting asthma, and have a limited modulatory effect on allergic inflammatory reactions. The evaluation of patients with long-lasting asthma should take into account the immunological and inflammatory changes present in the elderly in order to avoid results being misinterpreted.  相似文献   
994.
Many types of seafood require cooking before ingestion and it has been demonstrated that this cooking process may affect the antigenicity and allergenicity of the food. We describe a case of anaphylaxis caused by selective sensitization to razor shell, a mollusc. In vivo and in vitro studies confirmed sensitization to boiled razor shell. Analysis of the nature of the allergen yielded results that were consistent with the findings of other authors and suggested that allergens involved in seafood allergy are commonly high molecular weight proteins that, in most cases, are heat stable.  相似文献   
995.
996.
997.
Migräne     
Migraine is a prevalent disease that affects women more frequently than men. A particular trigger for migraine is the perimenstrual period. Acute migraine attacks during menstruation are treated similarly to nonmenstrual attacks, e.g., with analgesics or triptans. In women with pure menstrual migraine, short-term prophylaxis can be performed with nonsteroidal anti-inflammatory drugs (NSAIDs), estrogens, or low-dose triptans. During pregnancy migraine improves. After menopause frequency and severity of migraine attacks improve.  相似文献   
998.
999.
1000.
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