明代正統, 景泰, 天順御窯瓷器 : 景德鎮御窯遺址出土與故宮博物院藏傳世瓷器對比 = Imperial porcelains from the reigns of Zhengtong, Jingtai and Tianshun in the Ming dynasty : a comparison of porcelains from the imperial kiln site at Jingdezhen and the imperial collection of the Palace Museum