Li xiaoyan.Gravel-sand mulch for soil and water conservation in the semiarid loess region of northwest China[J].Catena,2003,2:105-127.是什么意思_Li xiaoyan.Gravel-sand mulch for soil and water conservation in the semiarid loess region of northwest China[J].Catena,2003,2:105-127.在线翻译_英语_读音_用法_例句