分为四个不同的类群: 苏铁类 、 银杏类 、 松柏类、买麻藤类植物以及一些化石类群.There are four widely different living groups: the cycads , ginkgo, conifers , gnetophytes, and several fossil groups....
Hydrotalcite - rare earth - Zinc complex heating stabilizer was prepared, its'stability was compared.研究了水滑石 - 稀土 - 锌复合热稳定剂的制备, 并比较了其热稳定效果.This thesis selects hydrotalcite as selective IR absorption material by its c...
穹丘的 横断面 为圆形或卵圆形.The domes are circular or ovoid in cross - section .桥面横断面可能由于过量的升力而发生扭转.The cross section of a bridge deck may twist as a result of excessive life.如将显微镜载物台旋转,便能从纤维横断面中看到第三层胞壁.A third layer transverse cell...