Analysis and consideration on Ginkgo Folium event HPLC determination of proanthocyanidins in Ginkgo Folium preparation Insight into recently issued community herbal monograph on Ginkgo biloba L., folium and its impact on registration strategy of Ginkgo Folium productsin EU Best harvesting time of Ginkgo Folium from Guilin Optimization of bi-layer osmotic pump controlled release tablets of total flavonoids from Ginkgo Folium by central composite design-response surface methodology