which mean "help me." Frederick Stanley Mockford created the mayday call signal in the nineteen twenties.

VOA: special.2010.04.18

The signal comes in the form of molecules which we're going to call throughout the lecture here 'ligands'.

信号通常以分子的形式来传递,在这门课里我们把这种分子叫做配体

耶鲁公开课 - 生物医学工程探索课程节选