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   960篇
  免费   59篇
  国内免费   3篇
耳鼻咽喉   5篇
儿科学   28篇
妇产科学   22篇
基础医学   108篇
口腔科学   14篇
临床医学   167篇
内科学   231篇
皮肤病学   3篇
神经病学   70篇
特种医学   10篇
外科学   110篇
综合类   8篇
一般理论   2篇
预防医学   73篇
眼科学   29篇
药学   90篇
中国医学   7篇
肿瘤学   45篇
  2023年   10篇
  2022年   9篇
  2021年   55篇
  2020年   32篇
  2019年   35篇
  2018年   33篇
  2017年   23篇
  2016年   33篇
  2015年   39篇
  2014年   34篇
  2013年   55篇
  2012年   81篇
  2011年   84篇
  2010年   37篇
  2009年   39篇
  2008年   71篇
  2007年   73篇
  2006年   49篇
  2005年   50篇
  2004年   31篇
  2003年   26篇
  2002年   34篇
  2001年   14篇
  2000年   8篇
  1999年   3篇
  1998年   9篇
  1997年   9篇
  1996年   3篇
  1995年   3篇
  1994年   5篇
  1993年   4篇
  1992年   6篇
  1991年   4篇
  1990年   3篇
  1988年   2篇
  1987年   1篇
  1986年   2篇
  1984年   1篇
  1982年   7篇
  1981年   2篇
  1980年   1篇
  1975年   2篇
排序方式: 共有1022条查询结果,搜索用时 15 毫秒
1.
Background Despite improving surgical techniques, treatment of heart valve disease in children remains controversial. Somatic growth and adequate anticoagulation are of concern when children undergo valve replacement. We conducted this study to evaluate the performance of valves in this age group. Methods 42 children under the age of 13 years who underwent valve replacement were included in this study. Totally, 50 valves were implanted in 42 patients: 48 were mechanical prostheses, two were bioprosthetic both in pulmonary position. 37 (74%) valves were implanted in mitral position, 10 (20%) in aortic position, 1 (2%) in tricuspid position and 2 (4%) in pulmonary position. Preoperatively, 14 (33,3%) patients were in New York Heart Association (NYHA) class IV, while 27 (64.2%) were in NYHA class III. Results There were 2 (4.7%) hospital deaths and 2 (4.7%) late deaths while 2 (4.7%) patients were lost to follow up. The mean follow up period was 9.4 yrs. 35 (83.3%) patients are in NYHA Class I and free of all medications except warfarin. 3 (7.1%) patients have undergone 5 successful pregnancies. The median INR was 2.23. Major thrombo-embolic episode occurred in 1 (2.3%) patient. Conclusions In view of the problems of sizing, anticoagulation and need for re-operation at an early age, there is a reluctance to replace valves in children. This study shows that despite these problems, valve replacement can be undertaken safely and successfully in children, when repair has failed or not technically feasible.  相似文献   
2.
3.

Background  

West Nile virus (WNv) has recently emerged as a health threat to the North American population. After the initial disease outbreak in New York City in 1999, WNv has spread widely and quickly across North America to every contiguous American state and Canadian province, with the exceptions of British Columbia (BC), Prince Edward Island and Newfoundland. In this study we develop models of mosquito population dynamics for Culex tarsalis and C. pipiens, and create a spatial risk assessment of WNv prior to its arrival in BC by creating a raster-based mosquito abundance model using basic geographic and temperature data. Among the parameters included in the model are spatial factors determined from the locations of BC Centre for Disease Control mosquito traps (e.g., distance of the trap from the closest wetland or lake), while other parameters were obtained from the literature. Factors not considered in the current assessment but which could influence the results are also discussed.  相似文献   
4.
5.
The glucose deprivation-induced release of [3H]D-aspartate was studied in bovine and human retinas in a superfusion apparatus. [3H]D-aspartate release was significantly increased upon omitting glucose in the superfusion buffer. This effect was dependent on external Ca2+ because L- and N-type Ca2+-channel blockers, such as diltiazem (1 microM), nitrendipine (1 microM), and omega-conotoxin (100 nM), significantly reduced the effect of glucose-deprivation induced release of [3H]D-aspartate. Furthermore, while glutamate receptor agonists (L-glutamate, N-methyl-D-aspartate, but not kainate) potentiated the effects of glucose deprivation, antagonists (MK-801, MCPG, ifenprodil, and L-AP3) at these receptors blocked the glucose deprivation-induced release process. Taken together, these studies have demonstrated that under conditions of glucose deprivation, as may happen during ischemic events in vivo, the retinal glutamatergic nerve endings and/or glial cells promote the efflux of [3H]D-aspartate into the extracellular environment. This process appears to be receptor-mediated and dependent on extracellular Ca2+ and is similar to previous reports pertaining to brain tissues.  相似文献   
6.
7.
Objectives: The primary objective of this study was to compare faculty assessment and third year students' self-assessment of performance in clinical case discussions. The secondary objective was to evaluate if student characteristics influence self-assessments.

Methods: This retrospective analysis compared faculty and student self-assessment scores for two clinical case discussions using Spearman’s correlation and Wilcoxon’s signed ranks test. Chi-squared test was used to compare frequency of faculty and student self-assessments indicating the highest possible rating for the pooled score and for each individual component. The pooled score included three individual components: level of engagement, quality of contribution, and professionalism.

Results: Pooled faculty and student self-assessments correlated for both the first (r?=?0.41, p?r?=?0.35; p?p?=?0.25) and second (58.6% vs. 47.4%, p?=?0.05) clinical case discussions. Student characteristics (age, gender, and grade point average at graduation) did not influence self-assessments.

Conclusions: Students’ self-assessment correlated with faculty assessment of performance during clinical case discussions. Increased use of self-assessments for professional development in pharmacy and other healthcare professional curricula should be considered.  相似文献   
8.
Article Title: Transesophageal Echocardiographic Assessment of Pulmonary Veins and Left Atrium in Patients Undergoing Atrial Fibrillation Ablation (Echocardiography 2011;28:774)  相似文献   
9.
Objective. To evaluate the impact of incorporating student-directed (SD) vs instructor-directed (ID) active learning on student performance in a pharmacotherapy capstone course.Design. This 9-credit course was redesigned from exclusively ID case discussions to a format in which half were SD and half were ID. Student performance on evaluation questions derived from SD sessions was compared with that from ID sessions.Assessment. Overall, students (n=299) performed better on ID-session questions than on SD-session questions (78.7% vs 75.3%, correctly answered, respectively; p<0.001). For written evaluations, students performed better on ID-session questions than on SD-session questions (79.8% vs 73.9%, respectively; p<0.001). For verbal evaluations, students performed better on SD-session questions than on ID-session questions (79.5% vs 74.5%, respectively; p<0.001). After the course revision, student confidence regarding their ability to think critically, solve problems, make decisions, and pursue lifelong learning was high, and student and faculty feedback was positive.Conclusion. Student performance in a pharmacotherapy capstone course remained acceptable when a combination of SD and ID active learning was used, but the addition of SD learning did not translate to better performance on course evaluations.  相似文献   
10.
Methylmalonic acidemia (MMA) is most common inherited type of organic acidemia. It has diverse presentation in older infants without any initial apparent symptoms. MMA sometimes present with sudden metabolic decompensation, which may mimics common emergencies like septic shock and diabetic ketoacidosis (DKA) without early recognition can be fatal. In born error of metabolism especially organic acidemia should be suspected in any infant presented with severe high anion gap metabolic acidosis. We report two cases of MMA in infants presented acutely mimicking DKA and septic shock.  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