짐작케 한다.주파수공용통신(TRS)유통업 변혁 이끌 '워키토키 형제'주파수공용통신(Trunk Radio System)은 공중에 떠다니는 전파자원을 이용, 특정집단의 구성원들끼리 의견교환을 가능케 하는 통신서비스다. 비슷한 용도의 사람들끼리 다수의 전파채널을 공동이용하는 것이 효율적이라는 점에 착안한 ...
a cross between a palm and a fern, most cycads are crowned by big leathery leaves emerging from the top of a thick trunk. Scientists once thought that cycads, like pine trees, used only the wind to transfer pollen from their male cones to the eggs in female cones. According to recent work by botanist William Tang, of the University of Miami at Coral Gables, Florida, the cycad Zamia pumila uses ...
from the bark to the center of a living tree without killing it. The pattern can then be matched against that of the trunk of a tree that is known to have been cut down, say, 30 years ago. The pattern of the tree cut down 30 years ago will match the pattern of the contemporary tree up until the last 30 years. If the old tree started growing earlier than the contemporary tree, then there will ...
동아사이언스
디라이브러리
DS스토어
팝콘플래닛
