Note 10 - Share-based Compensation (Tables)
 6 Months Ended
Jun. 30, 2017
Notes Tables  
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]
 
    
Six months ended June 30,
  
     
2016
      
2017
  
     
(Unaudited)
      
(Unaudited)
  
                 
Research and development    
-
      
6,930
  
General and administrative    
-
      
1,826
  
                 
Total    
-
      
8,756