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   849篇
  免费   46篇
  国内免费   18篇
耳鼻咽喉   11篇
儿科学   62篇
妇产科学   11篇
基础医学   75篇
口腔科学   29篇
临床医学   75篇
内科学   190篇
皮肤病学   6篇
神经病学   30篇
特种医学   144篇
外科学   140篇
综合类   12篇
预防医学   24篇
眼科学   8篇
药学   46篇
中国医学   4篇
肿瘤学   46篇
  2022年   4篇
  2021年   11篇
  2020年   8篇
  2019年   14篇
  2018年   16篇
  2017年   10篇
  2016年   14篇
  2015年   12篇
  2014年   22篇
  2013年   27篇
  2012年   22篇
  2011年   36篇
  2010年   27篇
  2009年   32篇
  2008年   19篇
  2007年   27篇
  2006年   28篇
  2005年   23篇
  2004年   10篇
  2003年   15篇
  2002年   16篇
  2001年   17篇
  2000年   15篇
  1999年   20篇
  1998年   37篇
  1997年   21篇
  1996年   28篇
  1995年   20篇
  1994年   24篇
  1993年   17篇
  1992年   13篇
  1991年   20篇
  1990年   14篇
  1989年   33篇
  1988年   51篇
  1987年   31篇
  1986年   23篇
  1985年   22篇
  1984年   21篇
  1983年   9篇
  1982年   14篇
  1981年   6篇
  1980年   11篇
  1979年   4篇
  1978年   5篇
  1977年   9篇
  1976年   7篇
  1973年   4篇
  1971年   5篇
  1966年   5篇
排序方式: 共有913条查询结果,搜索用时 15 毫秒
1.

Introduction

In the United States there has been a large increase in participation in lacrosse for both males and females. The purpose of this study was to analyze the number of head injuries, injury rates (calculated using the reported number of participants) and types of head injuries that are seen in emergency departments in the United States.

Methods

We compared injuries between male and female lacrosse participants. This was a retrospective study using a publicly available database produced by the US Consumer Product Safety Commission and information about lacrosse participation from US Lacrosse.

Results

A linear regression was performed and showed a positive correlation between number of head injuries to males and time from 2002 to 2010 (R2?=?0.823; p?=?0.001). While the number of injuries to the head in female lacrosse participants was not significant. There was a negative correlation between the number of head injuries to males from 2010 to 2016 (R2?=?0.800; p?=?0.007), but again, there was no significance for female injury count (R2?=?0.417; p?=?0.117). Other significant differences between head injuries in males and females included the mechanism of injury and the type of injury recorded.

Conclusion

The most recent data from 2010 to 2016, suggest that both males and females have had a decrease in injury rate. However the total number of female head injuries is not significantly decreasing and as the sport continues to grow there will likely be more total head injuries and visits to the emergency department.  相似文献   
2.
3.
The aim of this study was to compare the effects of a physical exercise test and of voluntary hyperventilation between controls and children with absence epilepsy. Eighteen children (6 controls and 12 epileptics) were studied during rest (R), a maximal physical exercise test (15 min; PE), recovery (REC) and voluntary hyperventilation (3 min; VHPV). EEG and ECG were recorded during the experiment; respiratory parameters were measured to quantify PE; plasma levels of pH, lactate, pyruvate, glucose and antiepileptic drugs were determined. A decrease in the number of absences was observed during PE whereas an increase was observed during VHPV. We found significant positive correlations between the number of children with absences, the total number of absences for each state, frequency of absences per minute and the corresponding mean plasma pH, which demonstrate that the lower the pH is, the fewer absences occur. On the other hand, there was no relationship between the number of absences and the values of other parameters. Relations between variations of the plasma value of the pH, and thus the probable cerebral value of pH, and neuronal excitability are discussed. Our results indicate that children who suffer absence epilepsy should not be discouraged from sport practice.  相似文献   
4.
Chitambar  CR; Zivkovic  Z 《Blood》1989,74(2):602-608
Information regarding transferrin (Tf) receptor degradation is largely incomplete. HL60 cells were shown to release to their growth medium a Tf-binding protein which could be immunoprecipitated by anti-Tf receptor monoclonal antibodies (MoAbs) B3/25 and OKT9. Soluble Tf receptor was detected in the medium within one hour of replating of cells, and its release was inhibited at 4 degrees C. The affinity of Tf for the soluble receptor released by cells (kd = 2.3 x 10(-10) mol/L) was slightly lower than its affinity for the detergent-solubilized cellular receptor (kd = 1.2 x 10(-10) mol/L). 125I-Tf internalized and released by cells subsequently bound to Tf receptor released by the same cells, and soluble Tf receptor in the conditioned medium (CM) inhibited 125I-Tf binding to intact cells. The soluble Tf receptor isolated from the CM was smaller (78,000 daltons) than the cell surface receptor (94,000 daltons) when analyzed by gel electrophoresis under reducing conditions. Isolated cell membranes readily released soluble receptor; however, this release could be blocked by protease inhibitors. The soluble Tf receptor may represent the extracytoplasmic domain of the cellular Tf receptor released from the surface of HL60 cells through proteolytic cleavage by a membrane-based protease.  相似文献   
5.
EEG findings in hypomelanosis of Ito.   总被引:1,自引:0,他引:1  
The EEG findings in 15 children with Hypomelanosis of Ito have been reviewed and related to the clinical and CT scan data. Although no consistent electroclinical associations were found in the group as a whole, there was some association between the presence of abnormal rhythmic EEG activity and the radiological appearances of neuronal migration defects. In addition, the possibility is raised that there may be a distinctive sub-group of children with Ito's syndrome who present with an early onset of intractable seizures and who have a neuronal migration defect.  相似文献   
6.
7.
Prior studies have shown that pneumothorax is one of the more difficult entities to diagnose with digitized radiography. This study was designed to test whether increasing resolution from 1.25 to 2.5 line pairs per millimeter (lp/mm) and image processing (edge enhancement from unsharp masking) would increase accuracy and confidence in the diagnosis of pneumothorax, as well as normal cases and other forms of lung disease. Conventional radiographs were digitized with use of a laser reader and then reformatted as film hard copy. Eleven observers read 35 cases reformatted in three different ways (1.25 lp/mm, 2.5 lp/mm, 1.25 lp/mm unsharp mask). The images with finer resolution (2.5 lp/mm) and unsharp mask images were superior to those with coarser resolution (1.25 lp/mm) for the diagnosis of pneumothorax. There was no difference in diagnostic accuracy for normal patients. For abnormalities other than pneumothorax, the unsharp mask images were significantly worse. Confidence in the diagnosis of pneumothorax and other abnormalities was highest with the finest resolution (2.5 lp/mm).  相似文献   
8.
9.
10.
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