The movement of a chemical substance through a gradient of concentration or electrical potential in the direction opposite to normal diffusion, requiring the expenditure of energy:活性转移，主动运输：化学物质通过浓缩或电位升降率所进行的移动，与正常的流动方向相反并需消耗能量：active transport across a cell membrane.通过细胞膜的活性转移