NNA=National Newspaper Association 全国报业协会[美]nn.字母nN-acetylhexosamine[化] N-乙酰己糖胺n-hexyl isocyanate异氰酸止己酯n-butyryl chloride[化] 丁酰氯; 正丁酰氯N-bromosuccinimide[化] N-溴代琥珀酰亚胺N/P Ratio in soil土壤氮／磷比Nnt colony algorithm蚁群算法N-phenyl succimide[化] 琥珀酰苯胺N-fertilizer Input氮素投入N-Phenyl benzamide苯甲酰苯胺n - butyl butyrate丁酸丁酯