乙烯一种无色易燃气体，C2H4，可从天然气和石油中获得，用作许多有机化合物的来源，用于焊接和切割金属，柑桔属水果的着色，以及用作麻醉剂。
C2H4, derived from natural gas and petroleum and used as a source of many organic compounds, in welding and cutting metals, to color citrus fruits, and as an anesthetic.
方法对栀子属三种植物的根和茎药材来源性状、显微进行了较详细的比较鉴别。
OBJECTIVE To study the comparative identification of Gardenia roots and stems derived from three different species on morphology for developing and utilizing these new medical resources.
当前国际税收管辖权原则主要有属地主义原则和属人主义原则两种，由此产生了国家税收的收入来源地管辖权、居民管辖权和公民管辖权等。
There are now two principles in the international tax jurisdiction, which forms the jurisdiction of income resource of the state taxation, resident jurisdiction and citizen jurisdiction.
应用推荐