Polycyclic aromatic hydrocarbons (PAHs), which is a kind of hazardous substance for its'nondegradable, carcinogenicity, accumulation and nonvolatility characteristics, has external effect on the environment.
多环芳烃（PAHs）是一类具有难降解性、致癌性、环境累积性及非挥发性的有害化学物质。
Land can be polluted by many materials. There are two major types of pollutants: degradable and nondegradable.
有许多物质都能对陆地产生污染。主要的污染物分为两类：可降解的和不可降解的。
Comparison of biocompatibility between degradable and nondegradable drug eluting stents
可降解与非可降解药物洗脱支架生物相容性的差异比较
A Study on Nondegradable Protein Dietary Use in the Rumen of Milk Cattle
奶牛瘤胃非降解蛋白日粮应用研究