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   1709篇
  免费   209篇
  国内免费   21篇
耳鼻咽喉   10篇
儿科学   59篇
妇产科学   27篇
基础医学   95篇
口腔科学   73篇
临床医学   272篇
内科学   443篇
皮肤病学   38篇
神经病学   60篇
特种医学   295篇
外科学   124篇
综合类   18篇
预防医学   291篇
眼科学   11篇
药学   33篇
肿瘤学   90篇
  2024年   4篇
  2023年   53篇
  2022年   16篇
  2021年   18篇
  2020年   42篇
  2019年   19篇
  2018年   55篇
  2017年   33篇
  2016年   47篇
  2015年   56篇
  2014年   98篇
  2013年   119篇
  2012年   34篇
  2011年   51篇
  2010年   64篇
  2009年   82篇
  2008年   48篇
  2007年   73篇
  2006年   51篇
  2005年   36篇
  2004年   40篇
  2003年   17篇
  2002年   14篇
  2001年   27篇
  2000年   23篇
  1999年   30篇
  1998年   66篇
  1997年   89篇
  1996年   79篇
  1995年   57篇
  1994年   62篇
  1993年   52篇
  1992年   16篇
  1991年   13篇
  1990年   31篇
  1989年   42篇
  1988年   31篇
  1987年   34篇
  1986年   33篇
  1985年   33篇
  1984年   13篇
  1983年   13篇
  1982年   24篇
  1981年   30篇
  1980年   17篇
  1979年   7篇
  1978年   5篇
  1977年   15篇
  1976年   14篇
  1975年   10篇
排序方式: 共有1939条查询结果,搜索用时 15 毫秒
31.
In a simulated field trial Bacillus thuringiensis var israelensis (BTI) pellet formulation exhibited an enhanced efficacy with increasing dose. A dosage of 1.0 and 1.5 ppm was most effective under simulated field conditions. In field trials persistence of BTI pellet (1.0 ppm) was observed for 35 days in moderately polluted water collection as compared to 21 days in highly polluted water bodies.KEY WORDS: Bacillus thuringiensis, Malaria, Mosquito control  相似文献   
32.
33.
Objective  To develop and implement Project LEAD (leadership, education, and advocacy development), a science course for breast cancer activists.
Population  Students were breast cancer activists and other consumers, mainly affiliated with advocacy organizations in the United States of America.
Setting  Project LEAD is offered by the National Breast Cancer Coalition; the course takes place over 5 days and is offered 4 times a year, in various cities in the United States of America.
Results  The Project LEAD curriculum has developed over 5 years to include lectures, problem-based study groups, case studies, interactive critical appraisal sessions, a seminar by an 'expert' scientist, role play, and homework components. A core faculty has been valuable for evaluating and revising the course and has proved necessary to provide consistent high quality teaching. Course evaluations indicated that students gained critical appraisal skills, enhanced their knowledge and developed confidence in selected areas of basic science and epidemiology.
Conclusions  Project LEAD comprises a unique curriculum for training breast cancer activists in science and critical appraisal. Course evaluations indicate that students gain confidence and skills from the course.  相似文献   
34.
Pathological gambling (PG) is a signi.cant public health concern associated with high rates of psychiatric comorbidity and mortality. Although research into the biology of PG is still in an early stage, recent advances in our understanding of motivation, reward, and addiction have provided substantial insight into the possible pathophysiology of this disorder. In addition, over the past 5 years, extraordinary progress has been made in the area of clinical research examining treatments for PG. Although PG is a disabling disorder that continues to represent a clinical challenge for the healthcare professional, our current knowledge of pharmacotherapy and psychosocial interventions offers potentially effective treatment options.  相似文献   
35.
Introduction Postoperative paraplegia remains a dreaded complication of repair of traumatic rupture of the aortic isthmus. Claims have been made that left atrial-femoral bypass provides better spinal cord protection. To test the hypothesis that left atrial-femoral bypass is better than femoral vein-to-femoral artery bypass in regard to postoperative paraplegia, we concurrently compared the two techniques. Methods We compared the occurrence of paraplegia in 18 patients whose ruptures were repaired utilizing left atrial-femoral bypass with 10,000 units of systemic heparin (group A) and 72 patients with femoral-femoral bypass with heparin 300 units/kg and an oxygenator (group B) operated on between January 1995 and July 2004. Results The mortality rate was 5.6% (5/90), with no statistical difference between the two groups. Postoperative paraplegia was present in three (16.7%) group A patients and five group B (6.9%) patients. However, the specific etiology of the neurologic defect was not clear, as one patient’s paraplegia was transient following a period of cardiac arrest, and four others had had neurologic injuries prior to the aortic repair. Median aortic cross-clamp times were shorter in group A (34 minutes vs. 49 minutes). No patient required reexploration for bleeding, and no patient developed a graft infection. Conclusions Paraplegia rates were higher in the left atrial-femoral group, but the difference was not statistically significant. This occurred despite the decreased cross-clamp times in this group. In patients undergoing repair of traumatic rupture of the aortic isthmus, left atrial-femoral bypass does not provide better spinal cord protection than femoral-femoral bypass.  相似文献   
36.
37.
38.
SUMMARY The efficacy and safety of the methylprednisolone prodrugs methylprednisolone suleptanate and methylprednisolone sodium succinate were evaluated in a multicentre, randomised, double-blind, double-dummy parallel study of 88 patients hospitalised with acute asthma. Each study drug was administered as a bolus intravenous injection of 40mg methylprednisolone equivalents every 6 hours for 48 hours. Methylprednisolone 32mg was administered orally 6 hours after the last dose. Pulmonary function, medical events, and clinical laboratory values were assessed at predefined intervals before and during the 72-hour study. The primary response measure of pulmonary function was per cent predicted forced expiratory volume in one second (FEV1) at 48 hours. Secondary response measures were peak expiratory flow rate (PEFR) and FEV1/forced vital capacity (FVC) ratio. Although both drugs demonstrated within-group mean changes from baseline (starting at 6 hours) that were statistically significant for each response, there were no statistically significant differences between the two groups. The mean percent predicted FEV1 at 48 hours and mean per cent change from baseline were 64% and 13% (p<0.0001) for the methylprednisolone suleptanate group and 67% and 17% (p<0.0001) for the methylprednisolone sodium succinate group, respectively. The mean PEFR and FEV1/FVC ratio at 48 hours were 5.77 l/s and 73% for the methylprednisolone suleptanate group and 5.78 l/s and 76% for the methylprednisolone sodium succinate group, respectively. There were no clinically or statistically significant between-group differences in any of the safety parameters. In this study, methylprednisolone suleptanate and methylprednisolone sodium succinate have been shown to be therapeutically equivalent in the treatment of patients hospitalized with acute asthma.  相似文献   
39.
The use of the newly dead to teach procedures is widely practiced in training institutions. This model allows a realistic opportunity both to become more familiar with lifesaving maneuvers before they are actually necessary and to maintain proficiency. Whether to notify the next of kin first has been an issue of ethical debate. Some argue a "don't ask, don't tell" policy is justified, while others mandate open consent by family members prior to the practice. Several medical studies have found that patients and families are likely to consent to the procedures but prefer to be asked permission first. Multiple legal cases have addressed the issue of usage of cadavers postmortem without expressed permission. Earlier cases emphasized the concept of "pseudo-property" rights and declared that the next of kin do not have constitutional ownership of the deceased person's body. More recent legal cases are declaring that families do, in fact, possess these rights. In this day and age of increasing recognition of personal autonomy, it is probably prudent to approach the next of kin for permission before performing procedures on the newly deceased.  相似文献   
40.
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