【简答题】在数据通信系统中,常用数据传输方式有哪几种?简述它们的基本原理。
【简答题】温度对表面活性剂的临界胶束浓度有何影响?
【单选题】在病例对照研究中,由于研究者事先知道研究对象的分组情况,而对病例组的询问仔细认真,对对照组的询问则不太认真。研究者认为对照组不需要像病例组那样花费精力认真调查,由此产生的偏倚是( )
【简答题】完形填空。 Mr Smith lived in a village. He had 1 farms and about twenty people worked for him. He often told them 2 hard and be honest. One day he went to a farm and worked with the workers there. Soon aft...
【简答题】根据短文内容及首字母提示补全单词。 Another weekend is coming. My classmates are talking about how to s 1 the weekend. Some of them are going to have a sound s 2 and get up late. Some are going to watch TV, o 3 are ...
【简答题】在病例对照研究中,由于调查者事先知道谁是病例谁是对照,于是对病例组的询问十分认真细致,而对照组则不大认真,由此而来的偏倚是
【单选题】在病例对照研究中,由于研究者事先知道研究对象的分组情况,而对病例组的询问仔细认真,对对照组的询问则不太认真。研究者认为对照组不需要像病例组那样花费精力认真调查,由此产生的偏倚是( )