heterocyclic nitrogen compounds

例句：

1. 1. Heterocyclic compounds are widely used in the pharmaceutical industry.
   杂环化合物在制药工业中广泛应用。
2. 2. The structure of a heterocyclic ring is characterized by six-membered rings containing nitrogen or sulfur atoms.
   杂环结构的特点是含有氮或硫原子的六元环。
3. 3. The discovery of new heterocyclic compounds has led to significant advancements in drug development.
   发现新的杂环化合物已导致药物开发的显著进步。