subspecialty ['sʌbˌspeʃəlti:]

例句:

• Nobody can be the master of everything, even in a subspecialty of a subdiscipline of a discipline.
  来自SA
• Laparoscopic urology is a subspecialty emerged and popularized worldwide in the last decade.
  摘要泌尿科腹腔镜手术是近十年来崛起且风行全球的一种次专科领域.
  
• Taking on a specialty or a subspecialty can also be a way to reinforce your value to the company.
  来自WSJ