实验设计（二）

4　实验设计的类型根据实验设计的目的和实验设计原则 ,研究者可选择适宜的设计类型。目前用于实验研究的设计模式有多种 ,在此仅介绍几种常用类型。4.1　完全随机化设计 ( completely randomdesign)完全随机化设计又称单因素设计 ,在实际工作中应用较多。在这种设计中 ,研究因素只有一个 ,但具有几个水平 (处理 )。它是将研究对象随机地分配到各个处理组 (水平组 )中进行实验观察 ,或者分别从不同总体中随机抽样进行对比观察。可以作两样本的比较 ,也可作多样本的比较 ,各个样本含量可以相等 ,也可不等。分组时可用抽签法 ,也可用随机数字…

Semiquantitative Detection of iNOS Gene Expression in Brain from Limb Ischemia-Reperfused Rats

Objective To detect the expression of iNOS gene in brain tissues from limb ischemia\|reperfused SD rats.Method SD rats were randomly divided into three groups:limb ischemia\|reperfusion group(I\|R), simple ischemia group(I) and normal control group(N).The expression of iNOS mRNA in brain was semiquantitatively detected by using of RT\|PCR.The distribution and the expression of iNOS and peroxynitrite protein in brain were measured by immunohistochemistry.Results iNOS mRNA was not detected in brain from control rats,while it was detected in both I and I\|R groups.After I\|R, the expression of iNOS mRNA gradually increased at 2h and peaked at 6h( P <0.01 vs I group),then decreased,but there was also a little expression at 24h.The morphologic results showed that there were more iNOS positive cells and more dispersal NT positive neurons in I\|R group than I group.Conclusion The expression of iNOS mRNA in brain significantly increased after limb ischemia\|reperfusion in a time\|dependent manner.