doctoral       
adjective [ before noun ] mainly US uk/ˈdɒk.tər.əl/ us/ˈdɑːk.tɚ.əl/
 博士的,博士学位的
relating to a doctorate (= the highest degree from a university)
  a doctoral dissertation 博士学位论文 
 She is a doctoral student in Applied Linguistics. 她是应用语言学的博士生。 
  - More examples
 - He began a doctoral degree in education.
 - I did my doctoral research on religious art.
 - In 1966 he dropped out of a doctoral program at Stanford.
 - She is a doctoral candidate at Yale.