Cloning of cDNA for ACC Oxidase from Fruit of Pyrus pyrifolia Nakai and Construction of Its Corresponding Antisense Expression Vector Cloning of cDNA for ACC Oxidase from Fruit of Pyrus pyrifolia Nakai and Construction of Its Corresponding Antisense Expression Vector A New Largest-type Variety of Asian Pear ‘Qingxiang’ A New Largest-type Variety of Asian Pear ‘Qingxiang’ The Changes of Enzymes Activity during the Flower Bud Differentiation of‘Pingguoli’ The Changes of Enzymes Activity during the Flower Bud Differentiation of‘Pingguoli’ Variation of Organic Nutrition on Shoot and Flower Bud of ‘Hosui’Pear (Pyrus pyrifolia Nakai) during Reflorescence Period Cloning and Expression of HHT Gene in ‘Huanghua’ Pear and Its Bud Mutant ‘Lühuanghua’ Pear (Pyrus pyrifolia Nakai) Variation of Endogenous Hormone of Pyrus pyrifolia Nakai in South China during Returning Bloom and Its Relationship with Returning Bloom Cloning and Expression of a Glutathione-S-transferase Gene from Pyrus pyrifolia Nakai cv.Huobali