Many forest tree species have multiple archegonia which, after fertilization produce a number of proembryos.许多林木树种都有颈卵器, 受精以后便产生许多原胚.A similar section through the female plant reveals several bottle - shape archegonia , ...
He achieved notoriety as chief counsel to President Nixon in the Watergate break-in.他因在水门事件中担任尼克松总统的首席法律顾问而声名狼藉。" After Watergate, I sold 400.该事件发生后, 我卖掉了400台.Watergate had begun to turn into a national obsession.水门事件已开始...
本发明提供一种用来将一输入信号降频为一输出信号的混频器.The invention provides a mixer which an input signal into an output signal through frequency reduction.直接降频转换接收器架构能够以较低成本提高无线系统基站接收器的性能.Framework of direct - down conversion receiver can provi...