She found out about the volcanic activity that has shaped the surface of Mars.

VOA: special.2010.07.28

In this case, a receptor tyrosine kinase is a receptor molecule that binds a ligand at its surface outside the cell and initiates this enzyme activity - this kinase activity - and causes phosphorylation of another molecule.

在这个例子中,酪氨酸激酶受体可以,在细胞表面区域与配体结合,从而激发出,激酶的活性,使其能够磷酸化另一类分子

耶鲁公开课 - 生物医学工程探索课程节选

Scientists measure solar activity by counting dark areas on the sun's surface.

VOA: special.2009.09.29