为解决在三维空间状态下零件无法自动标注尺寸的问题,提出一种采用基于模型的定义(Model Based Definition,MBD)技术的零件三维尺寸自动标注方法。首先根据工艺和拓扑相关的表面(Technologically and Topologically Related Surfaces,TT...为解决在三维空间状态下零件无法自动标注尺寸的问题,提出一种采用基于模型的定义(Model Based Definition,MBD)技术的零件三维尺寸自动标注方法。首先根据工艺和拓扑相关的表面(Technologically and Topologically Related Surfaces,TTRS)理论的功能表面分类和边界表示(Boundary Representation,B-Rep)方法,提取出零件的所有拓扑表面,并消除重复多余的表面;然后将提取出的零件表面进行分类,并提取出对应的几何元素;根据其需要标注的定形和定位尺寸制定规则,进而去除冗余元素,构建标注元素集合;最后对CATIA进行二次开发实现零件尺寸的自动标注功能,完成尺寸信息模型的构建。展开更多
【目的】为了研究噬菌体整合酶基因在猪链球菌2型(Streptococcus suis type 2,SS2)中的分布情况。【方法】根据噬菌体整合酶基因设计引物,建立了PCR方法,并对扩增产物进行测序。【结果】结果显示,25株SS2致病菌株均扩增出目的片段,非毒...【目的】为了研究噬菌体整合酶基因在猪链球菌2型(Streptococcus suis type 2,SS2)中的分布情况。【方法】根据噬菌体整合酶基因设计引物,建立了PCR方法,并对扩增产物进行测序。【结果】结果显示,25株SS2致病菌株均扩增出目的片段,非毒力株T15、5株其它血清型猪链球菌及兰氏C群猪源链球菌未扩增出目的片段。经丝裂霉素C诱导后,SS2致病菌株出现完全的细胞溶解,而非毒力株T15未出现溶解。SS2致病株HA9801和ZY05719诱导均产生溶原性噬菌体,分别命名为SS2-HA和SS2-ZY,电镜观察,二者均头部呈正六边形,无尾部,其核酸类型为dsDNA,可鉴定为复层噬菌体科(Tectiviridae)的成员。噬菌体SS2-HA和SS2-ZY整合酶基因序列与已报道的SS2噬菌体整合酶基因序列高度同源,显示SS2噬菌体整合酶具有较高的特异性。【结论】从SS2致病株中检出溶原性噬菌体和噬菌体整合酶基因,且噬菌体整合酶基因与SS2溶菌酶释放蛋白(mrp)等7种毒力相关基因有相关性,表明SS2的溶原性噬菌体可能与其致病性有关。展开更多
Based on the reported Big liver and spleen disease virus （BLSV） gene sequence, a pair of primers was designed and a 375bp product was amplified from the total RNA extracted from homogenates of BLSV-infected livers. ...Based on the reported Big liver and spleen disease virus （BLSV） gene sequence, a pair of primers was designed and a 375bp product was amplified from the total RNA extracted from homogenates of BLSV-infected livers. Twenty liver samples were randomly collected from two commercial broiler breeder flocks in Nanjing.One of ten liver samples was positive reaction in RT-PCR in one flock but not in another. The RT-PCR detection for cDNA from BLSV was specific with the sensitivity of 4.16×10-3μg/μL. Phylogentic tree analysis suggested that the 338bp sequence of the isolated strain （BLSV-NJ2002） shared 97.3% and 83.6% nt hemologue indentities with that of Australia strain and avian HEV respectively.展开更多
文摘为解决在三维空间状态下零件无法自动标注尺寸的问题,提出一种采用基于模型的定义(Model Based Definition,MBD)技术的零件三维尺寸自动标注方法。首先根据工艺和拓扑相关的表面(Technologically and Topologically Related Surfaces,TTRS)理论的功能表面分类和边界表示(Boundary Representation,B-Rep)方法,提取出零件的所有拓扑表面,并消除重复多余的表面;然后将提取出的零件表面进行分类,并提取出对应的几何元素;根据其需要标注的定形和定位尺寸制定规则,进而去除冗余元素,构建标注元素集合;最后对CATIA进行二次开发实现零件尺寸的自动标注功能,完成尺寸信息模型的构建。
文摘【目的】为了研究噬菌体整合酶基因在猪链球菌2型(Streptococcus suis type 2,SS2)中的分布情况。【方法】根据噬菌体整合酶基因设计引物,建立了PCR方法,并对扩增产物进行测序。【结果】结果显示,25株SS2致病菌株均扩增出目的片段,非毒力株T15、5株其它血清型猪链球菌及兰氏C群猪源链球菌未扩增出目的片段。经丝裂霉素C诱导后,SS2致病菌株出现完全的细胞溶解,而非毒力株T15未出现溶解。SS2致病株HA9801和ZY05719诱导均产生溶原性噬菌体,分别命名为SS2-HA和SS2-ZY,电镜观察,二者均头部呈正六边形,无尾部,其核酸类型为dsDNA,可鉴定为复层噬菌体科(Tectiviridae)的成员。噬菌体SS2-HA和SS2-ZY整合酶基因序列与已报道的SS2噬菌体整合酶基因序列高度同源,显示SS2噬菌体整合酶具有较高的特异性。【结论】从SS2致病株中检出溶原性噬菌体和噬菌体整合酶基因,且噬菌体整合酶基因与SS2溶菌酶释放蛋白(mrp)等7种毒力相关基因有相关性,表明SS2的溶原性噬菌体可能与其致病性有关。
文摘Based on the reported Big liver and spleen disease virus （BLSV） gene sequence, a pair of primers was designed and a 375bp product was amplified from the total RNA extracted from homogenates of BLSV-infected livers. Twenty liver samples were randomly collected from two commercial broiler breeder flocks in Nanjing.One of ten liver samples was positive reaction in RT-PCR in one flock but not in another. The RT-PCR detection for cDNA from BLSV was specific with the sensitivity of 4.16×10-3μg/μL. Phylogentic tree analysis suggested that the 338bp sequence of the isolated strain （BLSV-NJ2002） shared 97.3% and 83.6% nt hemologue indentities with that of Australia strain and avian HEV respectively.
