Intragastric floating system, an optimal controlled drug delivery vehicle, is currently utilized in the prolongation of the gastric residence time to extend significantly the period of time over which drug is released and increase the drug absorption and bioavailability.

We calculate the residence time and environmental capacity of Cd element in the soil-water-paddy-atmosphere system.

The infiltration of carbon fiber preforms was studied by microwave pyrolysis chemical vapor infiltration technique,CH_4 as the carbon source gas,and N_2 as diluent gas,at 1100℃and methane partial pressure of 10kPa with residence time of 0.

7%,and infiltrated by the novel ICVI at ambient pressure and 1100℃,residence time of 0.

It can play a synthetic role including phy- sically,chemically and biologically in delaying the retention time of water intothe pre-dam,reducing the flow speed and homogenizing flow field, purifying thewater and damming the silt and nutrient salt in pre-dam for the purpose ofreducing the content of nutrient salt and inhibiting the ove.

The effect of retention time on rotifer distribution was also analyzed in three reservoirs: Feilaixia Reservoir, Liuxihe Reservoir and Xinfengjiang Reservoir with different retention time from 2001 to 2003.