... PO 4 - 活度常数(activity constant)： HA+B A - +HB + K 0 = a A - a HB + /( a HA a A - ) 浓度常数(concentration constant)： K c = [A-] [HB+] / [HA] [B]= K 0 /（r HB + r A - ） 混合常数(mix constant)：K mix 有浓度，有活度 3.1.3 溶液中其它相关...
So this is where the concentration of B is roughly constant over time.
那么这是B的浓度，粗略地随时间变化保持常量。
2
In response to the appearance of such variants in the cell population the concentration of the toxic chemical in the growth medium is increased, thus keeping the selection pressure constant.
为应对细胞污染中出现的变异，有毒物质的浓度是逐步增加的，以此保证筛选力度的稳定。
3
Now, scientists report that they've created a contact lens that can deliver a high concentration of antibiotic at a constant rate for more than 30 days.