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   1165篇
  免费   69篇
  国内免费   9篇
耳鼻咽喉   9篇
儿科学   42篇
妇产科学   17篇
基础医学   142篇
口腔科学   29篇
临床医学   111篇
内科学   275篇
皮肤病学   16篇
神经病学   137篇
特种医学   16篇
外科学   169篇
综合类   1篇
预防医学   74篇
眼科学   5篇
药学   76篇
中国医学   2篇
肿瘤学   122篇
  2023年   5篇
  2022年   9篇
  2021年   27篇
  2020年   17篇
  2019年   24篇
  2018年   20篇
  2017年   26篇
  2016年   16篇
  2015年   23篇
  2014年   37篇
  2013年   59篇
  2012年   88篇
  2011年   88篇
  2010年   38篇
  2009年   44篇
  2008年   76篇
  2007年   75篇
  2006年   88篇
  2005年   68篇
  2004年   81篇
  2003年   60篇
  2002年   70篇
  2001年   15篇
  2000年   11篇
  1999年   12篇
  1998年   12篇
  1997年   8篇
  1996年   9篇
  1995年   12篇
  1994年   7篇
  1993年   6篇
  1992年   15篇
  1991年   12篇
  1990年   11篇
  1989年   6篇
  1988年   9篇
  1987年   8篇
  1986年   3篇
  1985年   6篇
  1984年   6篇
  1983年   8篇
  1982年   3篇
  1981年   3篇
  1978年   3篇
  1976年   2篇
  1969年   3篇
  1968年   2篇
  1966年   1篇
  1939年   1篇
  1937年   2篇
排序方式: 共有1243条查询结果,搜索用时 62 毫秒
101.
AIMS AND BACKGROUND: The objectives of the present study were to validate the social stratification variables adopted by the European Prospective Investigation into Cancer and Nutrition (EPIC) by comparing them with data from another independent source and to evaluate the geographic and social distribution of eating habits in the Italian EPIC population. METHODS: The validation of the socioeconomic data collected by the EPIC study was performed with the Turin Longitudinal Study as gold standard and using Cohen's kappa statistics to evaluate the concordance between the studies. We then analyzed food groups based on the consumption of meat and fats, carbohydrates, sweets and alcohol, and on an index of the Mediterranean diet. The standardized scores for each food group were subdivided into quartiles, which were used to compare persons in the extreme quartiles. Analysis of the differences in eating habits by center and by educational level was conducted separately for men and women, calculating the prevalence rate ratios and controlling for age, area of birth and body mass index. RESULTS: Concordance between the two data sources was high for educational level and low for the social-class index based on occupation. Most of the eating habits considered to be potentially harmful (high consumption of meat or fats and alcohol and low consumption of olive oil and fish) were more frequent in Northern than in Southern Italy. These habits were inversely correlated with educational level, especially in the South. CONCLUSIONS: A significant improvement in health could be obtained in the Italian population if culturally and socioeconomically disadvantaged individuals were to abandon their diet rich in meat and fats, as done by more advantaged persons. In the absence of preventive interventions specifically addressed to disadvantaged groups, it is likely that social inequalities in mortality and morbidity will increase.  相似文献   
102.
103.
Previous studies have shown an increased number of inflammatory cells and, in particular, of CD8+ T lymphocytes, in central airways, peripheral airways, lung parenchyma and pulmonary arteries of smokers with COPD. In this study we investigated whether this inflammatory process is restricted to the lung tissue or whether a similar process is also present in the lymph nodes of these subjects. We examined paratracheal lymph nodes obtained from 6 smokers with COPD (FEV1/VC < 88% predicted and FEV1/FVC < 70% both before and after 200 microg of inhaled salbutamol) and 6 smokers without COPD (FEV1/VC > 88% predicted and FEV1/FVC > 70%) undergoing lung resection for localised pulmonary lesions. By immunohistochemistry we quantified CD4+ and CD8+ T-lymphocytes in the lymph nodes. Smokers with COPD had a decreased ratio CD4/CD8 compared to smokers without COPD. When all subjects were considered together, the ratio CD4/CD8 showed a positive correlation with the values of FEV1/VC and a negative correlation with cigarette consumption. In conclusion, smokers with COPD have an increased proportion of CD8+ cells in the lymph nodes, indicating that a T-lymphocyte pattern similar to that present in the lung tissue is also present in the lymph nodes of these subjects. This finding suggests that, in COPD, the polarisation of the immune response may occur in the regional lymph nodes, possibly as a consequence of the presentation of an endogenous antigen that remains unknown.  相似文献   
104.
105.
106.
107.
We gave a single fraction of 750 cGy preoperatively (within 16 h of surgery) to 143 patients prior to total hip arthroplasty. The patients were evaluated for heterotopic ossification at 1, 3 and 6 months. The preoperative radiation did not affect the surgical procedure. After a median follow-up of 12 (6-24) months we encountered six patients with heterotopic ossifications of Brooker grade I-II. Potential late risks from ionising radiation should be considered when treating younger patients.  相似文献   
108.
Severe ventricular dysfunction and concomitant infection are considered absolute contraindications for major thoracic operations and immunosuppressive therapy, respectively. However, cardiac transplantation represents the first-choice treatment in advanced heart failure. We report the case of a patient with dilated cardiomyopathy and severe left ventricular dysfunction (ejection fraction = 25%), initially not considered as a potential heart transplant candidate due to the presence of a lung abscess. The patient subsequently underwent atypical pulmonary resection with intraoperative and perioperative intraaortic balloon counter-pulsation for circulatory support and was then listed for cardiac transplant. Pitfalls and intra/postoperative strategy, all of which are potentially important aspects in minimizing operative risk, are discussed.  相似文献   
109.
The MICs and minimum bactericidal concentrations (MBCs) for the biocides benzalkonium chloride and chlorhexidine were determined against 1,602 clinical isolates of Staphylococcus aureus. Both compounds showed unimodal MIC and MBC distributions (2 and 4 or 8 mg/liter, respectively) with no apparent subpopulation with reduced susceptibility. To investigate further, all isolates were screened for qac genes, and 39 of these also had the promoter region of the NorA multidrug-resistant (MDR) efflux pump sequenced. The presence of qacA, qacB, qacC, and qacG genes increased the mode MIC, but not MBC, to benzalkonium chloride, while only qacA and qacB increased the chlorhexidine mode MIC. Isolates with a wild-type norA promoter or mutations in the norA promoter had similar biocide MIC distributions; notably, not all clinical isolates with norA mutations were resistant to fluoroquinolones. In vitro efflux mutants could be readily selected with ethidium bromide and acriflavine. Multiple passages were necessary to select mutants with biocides, but these mutants showed phenotypes comparable to those of mutants selected by dyes. All mutants showed changes in the promoter region of norA, but these were distinct from this region of the clinical isolates. Still, none of the in vitro mutants displayed fitness defects in a killing assay in Galleria mellonella larvae. In conclusion, our data provide an in-depth comparative overview on efflux in S. aureus mutants and clinical isolates, showing also that plasmid-encoded efflux pumps did not affect bactericidal activity of biocides. In addition, current in vitro tests appear not to be suitable for predicting levels of resistance that are clinically relevant.  相似文献   
110.
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