Determination of Content of Nodakenin in Notopterygium incisum Ting from Different Source by HPLC Absorption and transportation characteristic of dihydrofurocoumarins from Rhizome et Radix Notopterygii in a model of Caco-2 cell monolayers Determination of Nodakenin in Peucedanum Determination of Nodakenin in the Rhizome or Root of Notopterygium incisum Ting by TLC-scanning