The timed release pellets consist of 5 laminar layers from the center to the outside :the core, the drug layer, the swelling agent layer , the block layer and the controlled layer .
该脉冲微丸由5层结构组成，从内而外分别是丸芯、药物层、溶胀层、阻滞层和水不溶性控释层。
2
Like in an infinite flow, we find that laminar boundary layer, transition region and turbulent boundary layer also exist along a flat plate in open channel flow boundary layers.
The characteristic parameters of fluid during the transition in boundary layer are obviously different from that of the laminar flow or the turbulent flow.