Chemical constituents in flowers of Polygonum cuspidatum Study on HPLC-DAD-ELSD fingerprint of Polygoni Cuspidati Rhizoma et Radix Anti-complementary anthraquinones from Polygonum cuspidatum and their action targets Construction of RNA interference vector of Polygonum cuspidatum chalcone synthase gene and its genetic transformation Studies on water-soluble constituents in rhizome of Polygonum cuspidatum Effects of processing on piceid and emodin in Polygonum cuspidatum Evaluation of consistency and difference of Polygoni Cuspidati Rhizoma et Radix pieces using total statistical moment method combined with cluster analysis and principal component analysis