桦木

Total U.S. hardwood log exports were down 25% through July despite modest year-on-year increases in Yellow Poplar (Tulipwood) and Birch shipments.

在7月，美国硬原口下降了25%，尽管黄杨和口量同比有所上升。

Betulin and betulinic acid, the triterpenes of the lupane family, are considered to be potential agents against tumoral cancer and HIV .

醇、酸是具有羽扇烷结构三萜合物，目前研究发现，它具有较高抗肿瘤、抗HIV病毒活性，它生物也有较高生物活性。