4HU S P, ZHANG Z, LIU Y G, et al. Pathogenicity and distribution of highly pathogenic Porcine reproductive and respiratory syndrome vi- rus in pigs[J]. Transbound Emerg Dis,2013,60(4) :351 -359.
5SCORNEAUX B, SHRYOCK T R. Intracellular accumulation subcel- lalar distribution and efflux of tilmicosin in swine phagocytes [ J ]. Jvet Pharmacol Ther,1998,21 (4) :257 -268.