Highly conserved sequences in the coding regions of the phac genes have been found by gene alignment ofphac genes cloned from 5 known pseudomonas spp . , and these highly conserved sequences can be used as primers for the pcr screening of phacl / phac2 - containing microorganisms . touch - down pcr has been adopted for the cloning of type ii pha synthase genes 根据这些保守区的序列设计出两条用于pcr扩增的通用引物，以细菌的基因组dna为模板，采用特殊的pcr实验方案降落pcr ( touch - downpcr )对型pha合酶基因进行了成功地克隆。
Aiming at the simulation of quasi - brittle fracture of concrete - like materials , the qualitative comparison of the selected models was focused on the follow aspects , i . e . the simulation of the fracture behaviors of crack mode and crack mode by use of the selected models and the simulation of dilatancy properties of the selected models under mixed - mode fracture loading conditions 在对选择的典型黏性界面裂纹进行定性分析比较时着重考虑以下两点：采用选择的模型对型裂纹和型裂纹的断裂行为进行数值计算；对混合型断裂载荷作用下模型的扩容行为特性进行数值分析。
