Active transport The use of energy to move a solute across a membrane against a concentration gradient, a potential gradient, or both (electrochemical potential) . Uphill transport.

主动吸收：亦称代谢吸收。指细胞直接利用能量做功，逆着电化学势梯度吸收离子的过程。

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Water potential reflects energy level of soil water and the gradient of water potential is an impotent factor describing direction and velocity of water flow.

水势反映土壤水的能态，而水势梯度则是决定水流方向和速度的重要因素。

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High energy heavy ions generate potential tracks on the face of insulated material, and a porous surface with gradient refractive index can be formed by etching the ion tracks.

高能重离子在绝缘材料表面产生的潜径迹经过蚀刻后形成一定形貌的核径迹孔，而密集的径迹孔表面相当于渐变折射率层。

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