简介：本文所讨论的积图是图的笛卡尔积，图的张量积，图的逻辑积和图的强直积四种积图．证明了：①如果Ｇ１和Ｇ２都是连通图，则积图中笛卡尔积，逻辑积和强直积都是道路正图．②图的张量积是道路正图的是图Ｇ１和Ｇ２是一个连通图，Ｇ１［或Ｇ２］有一个奇圈，且ｍａｘ｛λ１μ１，λｎμｍ｝≥２，其中λ１和λｎ［或μ１和μｍ］分别是图Ｇ１或Ｇ２的最大和最小特征值

简介：AgreatamountoffoodbornepathogenswereGram-positive(G?)bacteria,athreattopublichealth.Inthisstudy,consideringthebindingabilityofnisintowardsG-bacteriaandthestablefluorescentabilityofEGFPprotein,afluorescentnisin–EGFPproteinprobewasconstructedbyageneengineeringmethod.NisinandEGFPwereusedasthereceptorandfluorophore,respectively,todetectG?bacteria.ThenisinandegfpgenewereamplifiedseparatelyaccordingtothesequencepublishedinGenBankusinguniqueprimers.ThetwogeneswereclonedintoapET-28b(?)vectorresultinginapET-28b(?)–nisin–egfpvector.ThevectorwastransferredintoEscherichiacoli(E.coli)BL21(DE3)forexpression.Theexpressedproteinwasextracted,purifiedbyaNi–NTAcolumn,andthentestedbytheSDS-PAGEmethodtoconfirmitsmolecularweight.Listeriamonocytogenes(L.monocytogenes),Staphylococcusaureus(S.aureus),andMicrococcusluteus(M.luteus)wereusedastherepresentationsofG?bacteria.E.coliO157,representingthegram-negative(G-)bacteria,wasusedasanegativecontrol.Thebindingspecificityoftherecombinantproteinwasperformedontwotypesofbacteriaandthendetectedthroughfluorescentmicroscopy.Theresultsindicatedthatthenisin–EGFPprobecoulddetectG?bacteriaat108CFU/mL.