而且所有声频均有指向性,声频愈高, 指向性愈强.The higher the acoustic frequency is, the stronger its directivity is.它表现在空间生产力发展的继承性 、 指向性 、 加速性和国际性四个方面.The inheritance that its performance grows in dimensional productivity, directivity, accel...
狄氏剂与艾氏剂有关,对蚯蚓的毒性是相似的.Dieldrin is related to aldrin, and its toxicity to earthworms is similar.艾氏剂和氯丹都是重要的杀虫剂.Both Aldrin and Chlordane are valuable insecticides....