Expire after a specified time.

在指定的时间后过期。

youdao

Take effect at a specified time.

在指定的时间生效。

youdao

Recur at a specified time interval.

按指定时间间隔重复发生。

youdao

But it's only an effective vaccine in the context where you have people who can go to the doctor's office, or to an urgent care, some kind of medical facility, three times, reliably, at a specified period of time.

但为了保证接种效果,人们必须亲自去诊疗室,或者在急诊室里,使用一些医学设施辅助接种,还需要接种三次,它只在一段时间内有效

耶鲁公开课 - 生物医学工程探索课程节选

Value-at-risk is an analysis of the potential loss in its trading positions during a specified time frame.

FORBES: Goldman's Speed Bumps

Potential Winner will be contacted via email and asked to provide their full name, age and mailing address within a specified time period.

ENGADGET: blogger-avatar

Google's Joe Britt showed an alarm clock that can be set, using a mobile application, to turn on lights and music in the bedroom at a specified time.

CNN: Motorola deal boosts Google's move into home automation