Response of Nitraria tangutorum and Artemisia sphaerocephala seedling membrane permeability and membrane protection system to different duration times of wind-sand flow

• SHI Xinping, 
• MA Yanjun, 
• MA Rui, 
• WEI Linyuan, 
• YANG Yongyi, 
• ZHANG Yinghua, 
• TANG Weidong