无体系的

The third is the establishment of marker-free and skelecton-free transformation vector systems, which are efficient and simple.

第三是着力发展无因、无载体骨架的简单高效转化体系。

Metal hydroxides like aluminium trihydroxide (ATH) or magnesium dihydroxide (MDH) are commonly used halogen-free flame retardants in polyolefins.

金属氧化物如氢氧化铝（ATH）或氢氧化（MDH）是常用的无卤阻燃体系。