近20年来黄河流域植被覆盖变化分析
杨胜天,刘昌明,孙睿
The Vegetation Cover over Last 20 Years in Yellow River Basin
YANG Shengtian, LIU Changming, SUN Rui
地理学报 . 2002, (6): 679 -684 .  DOI: 10.11821/xb200206007