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   6828篇
  免费   430篇
  国内免费   11篇
耳鼻咽喉   45篇
儿科学   262篇
妇产科学   136篇
基础医学   739篇
口腔科学   106篇
临床医学   1473篇
内科学   1160篇
皮肤病学   65篇
神经病学   513篇
特种医学   123篇
外科学   601篇
综合类   80篇
一般理论   9篇
预防医学   874篇
眼科学   82篇
药学   356篇
中国医学   1篇
肿瘤学   644篇
  2024年   3篇
  2023年   33篇
  2022年   52篇
  2021年   120篇
  2020年   79篇
  2019年   93篇
  2018年   145篇
  2017年   107篇
  2016年   123篇
  2015年   135篇
  2014年   228篇
  2013年   328篇
  2012年   495篇
  2011年   578篇
  2010年   302篇
  2009年   268篇
  2008年   490篇
  2007年   563篇
  2006年   525篇
  2005年   544篇
  2004年   499篇
  2003年   459篇
  2002年   462篇
  2001年   44篇
  2000年   27篇
  1999年   63篇
  1998年   58篇
  1997年   55篇
  1996年   50篇
  1995年   42篇
  1994年   45篇
  1993年   29篇
  1992年   32篇
  1991年   26篇
  1990年   17篇
  1989年   12篇
  1988年   9篇
  1987年   12篇
  1986年   8篇
  1985年   11篇
  1984年   21篇
  1983年   11篇
  1982年   18篇
  1981年   11篇
  1980年   19篇
  1979年   4篇
  1978年   4篇
  1977年   2篇
  1976年   2篇
  1975年   3篇
排序方式: 共有7269条查询结果,搜索用时 15 毫秒
1.
2.
3.
We report a case of successful transvenous, catheter-based, cavotricuspid isthmus ablation for treatment of atrial flutter using microwave energy. Microwave energy was delivered at 900–930 MHz using 21 W of power. Bidirectional cavotricuspid isthmus conduction block was achieved by microwave ablation without any patient discomfort or complication during the procedure. Our initial experience suggests that transcatheter microwave ablation is feasible for the cure of typical atrial flutter.  相似文献   
4.
BACKGROUND: Despite increasing numbers of morbidly obese patients admitted to acute care facilities for surgery or treatment of nonsurgical conditions, there is little evidence of the problems nurses face in providing care to these patients. Anecdotal evidence suggests that the care of these patients is more demanding than the care of nonobese patients. The objective of this study was to describe nurses' perceptions of the challenges that they face when caring for morbidly obese patients. METHODS: Focus groups of nurses from a tertiary care facility were convened. A trained facilitator posed questions to the group concerning various aspects of care for morbidly obese patients. Comments of respondents were categorized using NVIVO software. RESULTS: Nurses reported concerns about the increased staffing needs required for care of these patients and the particular challenges of the physical care. Concerns also included the availability, placement, and use of specialized equipment. Room size and the absence of some equipment were also problematic. Finally, nurses perceived safety issues, both for themselves and their patients. CONCLUSIONS: Morbidly obese patients in the acute care setting require specialized nursing care in terms of techniques, levels of staffing required, and the use of specialized equipment.  相似文献   
5.
BACKGROUND: The impact of infection with Burkholderia gladioli in cystic fibrosis, other chronic airway diseases and immunosuppressed patients is unknown. METHODS: A six-year retrospective review of all patients with B. gladioli infection was performed in a tertiary referral center with cystic fibrosis and lung transplantation programs. In addition, a targeted survey of all 251 lung transplant recipients was performed. Available B. gladioli isolates were analyzed via pulsed field gel electrophoresis. RESULTS: Thirty-five patients were culture positive for B. gladioli, including 33 CF patients. No bacteremia was identified. Isolates were available in 18 patients and all were genetically distinct. Two-thirds of these isolates were susceptible to usual anti-pseudomonal antibiotics. After acquisition, only 40% of CF patients were chronically infected (> or =2 positive cultures separated by at least 6 months). Chronic infection was associated with resistance to > or =2 antibiotic groups on initial culture and failure of eradication after antibiotic therapy. The impact of acquisition of B. gladioli infection in chronic infection was variable. Three CF patients with chronic infection underwent lung transplantation. One post-transplant patient developed a B. gladioli mediastinal abscess, which was treated successfully. CONCLUSIONS: The majority of patients' culture positive for B. gladioli at our center have CF. B. gladioli infection is often transient and is compatible with satisfactory post-lung transplantation outcomes.  相似文献   
6.
7.
8.
9.
10.
A population-based study on 1008 postmenopausal women identified that the 24% of women achieving high levels of PA and CI had 3.4-4.4% higher femoral bone strength in axial compression and 1.7-5.2% in bending than those achieving low levels, indicating that lifestyle factors influence bone strength in the proximal femur. INTRODUCTION: Extensive research has shown that increased physical activity (PA) and calcium intake (CI) decrease the rate of bone loss; however, there is little research on how these lifestyle variables affect bone geometry. This study was designed to investigate the effects of modifiable lifestyle variables, habitual PA and dietary CI, on femoral geometry in older women. MATERIALS AND METHODS: Femoral geometry, habitual PA, and dietary CI were measured in a population-based sample of 1008 women (median age+/-interquartile range, 75+/-4years) enrolled in a randomized controlled trial (RCT) of calcium supplementation. Baseline PA and CI were assessed by validated questionnaires, and 1-year DXA scans (Hologic 4500A) were analyzed using the hip structural analysis technique. Section modulus (Z), an index of bending strength, cross-sectional area (CSA), an index of axial compression strength, subperiosteal width (SPW), and centroid position, the position of the center of mass, were measured at the femoral neck (NN), intertrochanter (IT), and femoral shaft (FS) sites. These data were divided into tertiles of PA and CI, and the results were compared using analysis of covariance (ANCOVA), with corrections for age, height, weight, and treatment (calcium/placebo). RESULTS AND CONCLUSIONS: PA showed a significant dose-response effect on CSA all hip sites (p<0.03) and Z at the narrow neck and intertrochanter sites (p<0.02). For CI, there was a dose-response effect for centroid position at the intertrochanter (p=0.03). These effects were additive, such that the women (n=240) with PA in excess of 65.5 kcal/day and CI in excess of 1039 mg/day had significantly greater CSA (NN, 4.4%; IT, 4.3%; FS, 3.4%) and Z (NN, 3.9%; IT, 5.2%). These data show a favorable association between PA and aspects of bone structural geometry consistent with better bone strength. Association between CI and bone structure was only evident in 1 of 15 variables tested. However, there was evidence that there may be additive effects, whereby women with high levels of PA and CI in excess of 1039 mg/day had significantly greater CSA (NN, 0.4%; FS, 2.1%) and Z (IT, 3.0%) than women with high PA but low CI. These data show that current public health guidelines for PA and dietary CI are not inappropriate where bone structure is the health component of interest.  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