链传动的优点是什么?
参考答案:
链传动的优点:能保持准确的平均传动比。磨损小,传动效率高。因有链条作为中间传动件,故可用在两轴中心距较大的地方。作用在轴和轴承上的力小。
环磷酰胺属于哪一类抗肿瘤药
A.烷化剂B.抗肿瘤抗生素C.抗代谢抗肿瘤药D.抗肿瘤生物碱E.抗肿瘤金属配合物
SET stands for Secure Electronic Transaction. It is a system that will allow you to make purchase on the Internet with your credit card, without having to worry whether your credit card information and/or your personal data will be compromised.