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   1254篇
  免费   101篇
  国内免费   6篇
耳鼻咽喉   9篇
儿科学   39篇
妇产科学   17篇
基础医学   172篇
口腔科学   56篇
临床医学   163篇
内科学   229篇
皮肤病学   30篇
神经病学   67篇
特种医学   188篇
外科学   129篇
综合类   68篇
一般理论   1篇
预防医学   71篇
眼科学   20篇
药学   58篇
中国医学   1篇
肿瘤学   43篇
  2022年   7篇
  2021年   18篇
  2020年   7篇
  2019年   17篇
  2018年   21篇
  2017年   11篇
  2016年   15篇
  2015年   26篇
  2014年   18篇
  2013年   31篇
  2012年   34篇
  2011年   46篇
  2010年   32篇
  2009年   38篇
  2008年   44篇
  2007年   39篇
  2006年   49篇
  2005年   47篇
  2004年   35篇
  2003年   43篇
  2002年   50篇
  2001年   33篇
  2000年   36篇
  1999年   36篇
  1998年   35篇
  1997年   51篇
  1996年   38篇
  1995年   26篇
  1994年   17篇
  1993年   15篇
  1992年   30篇
  1991年   25篇
  1990年   24篇
  1989年   22篇
  1988年   29篇
  1987年   36篇
  1986年   30篇
  1985年   35篇
  1984年   22篇
  1983年   18篇
  1982年   17篇
  1981年   19篇
  1980年   21篇
  1979年   15篇
  1978年   16篇
  1977年   12篇
  1976年   11篇
  1972年   7篇
  1970年   6篇
  1967年   12篇
排序方式: 共有1361条查询结果,搜索用时 31 毫秒
1.
OBJECTIVE: To examine the influence of in-season injury prevention training on hip and knee kinematics during a landing task. DESIGN: Longitudinal pre-post intervention study. SETTING: Testing sessions were conducted in a biomechanics research laboratory. PARTICIPANTS: Eighteen female soccer players between the ages of 14 and 17 participated in this study. All subjects were healthy with no current complaints of lower extremity injury. INTERVENTIONS: Testing sessions were conducted prior to and following a season of soccer practice combined with injury prevention training. MAIN OUTCOME MEASUREMENTS: During each testing session three-dimensional kinematics were collected while each subject performed a drop landing task. Peak hip and knee joint angles were measured during the early deceleration phase of landing and compared between pre- and post-training using paired t-tests. RESULTS: Following a season of soccer practice combined with injury prevention training, females demonstrated significantly less hip internal rotation (7.1 degrees vs. 1.9 degrees; P = 0.01) and significantly greater hip abduction (-4.9 degrees vs. -7.7 degrees; P = 0.02). No differences in knee valgus or knee flexion angles were found post-season. CONCLUSIONS: Female soccer players exhibited significant changes in hip kinematics during a landing task following in-season injury prevention training. Our results support the premise that a season of soccer practice combined with injury prevention training is effective in altering lower extremity motions that may play a role in predisposing females to ACL injury.  相似文献   
2.
3.
4.
5.
6.
7.
OBJECTIVES: The appearance of Grannum Grade III changes in the placenta at around 34-36 weeks is a predictor of adverse perinatal outcome, which may be reduced by reporting to the clinician. This has led to the suggestion that the placental grade should be noted during any third-trimester scan. There are no published data on the reproducibility of sonographic Grannum grading of the placenta; the objective of this study was to evaluate intra- and interobserver variation. METHODS: Fifty-five placental images from normal and complicated pregnancies of several different gestational ages were collected between April and October 2001. Three fetal medicine consultants and three experienced sonographers graded the images as 0, I, II, III or ungradeable. They then regraded the same images, presented in a different order and with different codes, 4-6 weeks later. Observers were blinded to their previous grading and to each others'. Weighted kappa (kappa), with linear weights, was used to look for strength of agreement. RESULTS: There was good agreement between the two observations of each placental image for five observers (kappa = 0.61 to 0.90), and moderate agreement for one observer (kappa = 0.56). However, the kappa-values for comparisons between the 15 pairs of observers ranged from 0.24 to 0.69 with six values below 0.41, indicating only fair agreement. This was confirmed by the overall kappa-value of 0.24 between all six observers. The agreement between the observers for Grade III placenta was poor, with an overall kappa-value of 0.09. CONCLUSIONS: Although intraobserver agreement was generally good, interobserver agreement was only fair for all grades and poor for Grade III placenta. This may be an indication that Grannum grading is not reproducible or it may reflect a need for training in those performing grading. Such variation may limit the effectiveness of reporting Grannum grades in clinical practice.  相似文献   
8.
Bachelor's and master's degrees in EMS are not yet commonplace, but with each year, they are becoming more important. A degree in EMS can provide not only the essentials of good paramedic skills, but also a knowledge of biology, anatomy and physiology, advanced chemistry and EMS management. Dwight Polk and Stuart Langford discuss the current status of bachelor's and master's degree programs in EMS and talk to people who have gone far in their chosen careers because they have such a degree.  相似文献   
9.
In order to investigate the role of the ferric uptake regulator Fur in the porcine lung pathogen Actinobacillus pleuropneumoniae, we constructed an isogenic in-frame deletion mutant, A. pleuropneumoniae Deltafur. This mutant showed constitutive expression of transferrin-binding proteins, growth deficiencies in vitro, and reduced virulence in an aerosol infection model.  相似文献   
10.
Cholecystokinin-decreased food intake in rhesus monkeys   总被引:1,自引:0,他引:1  
  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