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。

youdao

To control foundation seepage and exit gradient, a plastic concrete cut-off wall, a grout curtain, and a set of downstream pressure relief Wells are incorporated in the design.

为了控制基础渗流和出逸坡降，设计采用了塑性混凝土防渗墙、帷幕灌浆以及在下游增设一套减压井相结合的方案。

youdao

The villages we'd be stopping in would all be 7 to 10 miles apart on a path that follows a steady gradient up a single valley, a positively leisurely prospect compared with the up-and-down slogs from one valley to the next that characterize many Himalayan trails.

WSJ: Trekking the Har Ki Doon Trail in India's Himalayas

Mr. Fischer has painted the surface with a faded pale blue hue, a gradient of color he distilled from a landscape photograph using Photoshop, a computer program he employs in much of his work.

WSJ: Urs Fischer's Beds & Problem Paintings Show in Beverly Hills

The defects which plagued the busway included inadequate gradient in a park and ride site prompting fears of flooding and concerns about gaps between the concrete beams allowing them to expand or contract depending on the weather.

BBC: Guided bus wheel