Suspended, atmospheric, solid particle with a radius of less than 0.2 μm. On average, their concentration varies from less than 1000/cm3 over oceans to 150 000/cm3 in urban areas. See aitken nuclei counter; nucleus.
科学参考收录了60776条科技类词条，基本涵盖了常见科技类参考文献及英语词汇的翻译，是科学学习和研究的有利工具。