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   1620篇
  免费   130篇
  国内免费   2篇
耳鼻咽喉   21篇
儿科学   46篇
妇产科学   38篇
基础医学   243篇
口腔科学   28篇
临床医学   201篇
内科学   269篇
皮肤病学   41篇
神经病学   158篇
特种医学   58篇
外科学   156篇
综合类   6篇
一般理论   2篇
预防医学   241篇
眼科学   15篇
药学   119篇
中国医学   1篇
肿瘤学   109篇
  2023年   13篇
  2022年   19篇
  2021年   42篇
  2020年   25篇
  2019年   33篇
  2018年   34篇
  2017年   32篇
  2016年   46篇
  2015年   42篇
  2014年   65篇
  2013年   70篇
  2012年   115篇
  2011年   103篇
  2010年   68篇
  2009年   52篇
  2008年   86篇
  2007年   77篇
  2006年   95篇
  2005年   82篇
  2004年   75篇
  2003年   77篇
  2002年   60篇
  2001年   55篇
  2000年   44篇
  1999年   45篇
  1998年   12篇
  1997年   7篇
  1996年   11篇
  1995年   6篇
  1994年   12篇
  1992年   15篇
  1991年   19篇
  1990年   12篇
  1989年   10篇
  1988年   12篇
  1987年   14篇
  1986年   21篇
  1985年   12篇
  1984年   9篇
  1983年   8篇
  1979年   6篇
  1978年   6篇
  1977年   10篇
  1976年   9篇
  1975年   8篇
  1974年   6篇
  1973年   7篇
  1972年   7篇
  1971年   9篇
  1968年   6篇
排序方式: 共有1752条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
BACKGROUND: Microbial intestinal colonization in early in life is regarded to play a major role for the maturation of the immune system. Application of non-pathogenic probiotic bacteria during early infancy might protect from allergic disorders but underlying mechanisms have not been analysed so far. OBJECTIVE: The aim of the current study was to investigate the immune effects of oral application of probiotic bacteria on allergen-induced sensitization and development of airway inflammation and airway hyper-reactivity, cardinal features of bronchial asthma. METHODS: Newborn Balb/c mice received orally 10(9) CFU every second day either Lactobacillus rhamnosus GG or Bifidobacterium lactis (Bb-12) starting from birth for consecutive 8 weeks, during systemic sensitization (six intraperitoneal injections, days 29-40) and airway challenge (days 54-56) with ovalbumin. RESULTS: The administration of either Bb-12 or LGG suppressed all aspects of the asthmatic phenotype: airway reactivity, antigen-specific immunoglobulin E production and pulmonary eosinophilia (mean: 137 vs. 17 and 13 cellsx10(3)/mL, respectively). Antigen-specific recall proliferation by spleen cells and T-helper type 2 cytokine production (IL-4, IL-5 and IL-10) by mesenteric lymph node cells also showed significant reduction, while TGF production remained unchanged. Oral LGG administration particularly suppressed allergen-induced proliferative responses and was associated with an increase in numbers of TGF-beta-secreting CD4+/CD3+ T cells in mesenteric lymph nodes (6.5, 16.7%) as well as nearly 2-fold up-regulation of Foxp3-expressing cells in peribronchial lymph nodes. CONCLUSIONS: Neonatal application of probiotic bacteria inhibits subsequent allergic sensitization and airway disease in a murine model of asthma by induction of T regulatory cells associated with increased TGF-beta production.  相似文献   
5.
6.
7.
Fifty six children with a birth weight of less than 1500 g and gestational age less than 34 weeks were studied at a mean age of 7.7 years. All had required mechanical ventilation, 36 suffered from hyaline membrane disease, 17 from atelectasis and three from pneumonia. Of these patients 37 developed broncho-pulmonary dysplasia (BPD). The study included skin prick test, measurement of ciliary beat frequency, chest X-ray, whole-body plethysmography and histamine challenge. Eight patients suffered from recurrent pulmonary infections up to the age of 4 years. Eleven children had a positive skin prick test. Three suffered from allergic asthma and six from hay-fever. The family history of atopy in these premature infants was no different from that of the general population. Ciliary beat frequency was normal in all cases (frequency: 11.8 +/- 1.8 Hz). In 34 patients X-rays showed minimal changes (peribronchial thickening n = 6, mild emphysema n = 28). Pulmonary function was normal except for an increase of thoracic gas volume which was correlated to grade of BPD according to Northway. There was a significant correlation between oxygen-score and radiological stage of BPD (r = 0.7). Histamine challenge showed hyperresponsiveness in 53% of the children. Eight patients showed a threshold similar of mild asthma (less than 1000 micrograms histamine per ml). The degree of airway hyperreactivity was correlated to the grade of BPD (r = 0.7; p less than 0.01) and the oxygen-score (r = -0.63; p less than 0.05). The oxygen-score may be considered a predictor of hyperresponsiveness and pulmonary outcome in later childhood.  相似文献   
8.
The health status of many people in developing countries is often dismal compared with the norms in industrialized countries. Increasingly, medical practitioners in the United States and other industrialized countries have become interested in global health issues, an interest that often takes the form of short-term international medical trips. We discuss several ethical issues associated with participation in such trips and use our experiences in developing the Children's Health International Medical Project of Seattle (CHIMPS) to outline and illustrate a set of 7 guiding principles for making these trips. CHIMPS is a resident-run, faculty-supported international medical program founded in 2002 by pediatric residents at the University of Washington in Seattle. Members of CHIMPS work with a rural community in El Salvador to support ongoing public health interventions there and provide sustainable medical care in collaboration with the community and a local nongovernmental organization. The 7 principles developed as a result of this work-mission, collaboration, education, service, teamwork, sustainability, and evaluation-can be used as a model for health practitioners as they develop or select international medical trips. The importance of partnering with the community and working within the existing medical and public health infrastructure is emphasized. Many of the challenges of doing international medical work can be overcome when efforts are guided by a few specific principles, such as those we have outlined.  相似文献   
9.
A real-time, genus-specific 5' nuclease PCR assay for amplification of a 322-bp fragment of the per gene was developed for rapid (<2 h) identification of Brucella spp. from agar plates. The assay, including an internal amplification control (116 bp), identified Brucella strains (n = 23) and did not detect non-Brucella strains (n = 174), indicating its usefulness, particularly for laboratories with stringent quality assurance programs.  相似文献   
10.
We proposed that double exposure to stressors at work and from family are associated with increased coronary risk in women and that the same exposures are accompanied by depressive feelings. The study group comprised 292 women coronary patients (30-65 years) and 292 age-matched healthy controls. Work-stress, marital-stress, and depressive symptoms were assessed by standardized questionnaires and evaluated in both case-control and 5-year follow-up analyses. We found that double exposure to stress from work and family was accompanied by the highest risk and the worst prognosis in women's coronary disease. In women patients depressive feelings were frequent, and they were more closely related to family than to work stress. In healthy women, both stressors, but in particular their combination, lead to depressive symptoms.  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