Let us call a ring R (without identity) to be right symmetric if for any triple a,b,c,∈R?abc = 0 then acb = 0. Such rings are neither symmetric nor reversible (in general) but are semicommutative. With an idempotent ...Let us call a ring R (without identity) to be right symmetric if for any triple a,b,c,∈R?abc = 0 then acb = 0. Such rings are neither symmetric nor reversible (in general) but are semicommutative. With an idempotent they take care of the sheaf representation as obtained by Lambek. Klein 4-rings and their several generalizations and extensions are proved to be members of such class of rings. An extension obtained is a McCoy ring and its power series ring is also proved to be a McCoy ring.展开更多
本文阐述了两例犬血管环异常(vascular ring anomaly,VRA)的CT血管造影(CT angiography,CTA)诊断及手术治疗。通过术前对患犬进行CTA诊断,进行经左侧第4肋间开胸动脉韧带切断的手术治疗,并在术后对病例1进行食道球囊扩张。CTA显示两只...本文阐述了两例犬血管环异常(vascular ring anomaly,VRA)的CT血管造影(CT angiography,CTA)诊断及手术治疗。通过术前对患犬进行CTA诊断,进行经左侧第4肋间开胸动脉韧带切断的手术治疗,并在术后对病例1进行食道球囊扩张。CTA显示两只犬均存在持久性右主动脉弓(persistent right aortic arch,PRAA),并分别伴有右侧颈动脉异位发育和持久性左前腔静脉。手术治疗后,食道狭窄基本得到纠正,返流消失。CTA可对VRA进行更精确地诊断,并有助于制订具体手术方案;犬PRAA的手术治疗效果良好。展开更多
文摘Let us call a ring R (without identity) to be right symmetric if for any triple a,b,c,∈R?abc = 0 then acb = 0. Such rings are neither symmetric nor reversible (in general) but are semicommutative. With an idempotent they take care of the sheaf representation as obtained by Lambek. Klein 4-rings and their several generalizations and extensions are proved to be members of such class of rings. An extension obtained is a McCoy ring and its power series ring is also proved to be a McCoy ring.
文摘本文阐述了两例犬血管环异常(vascular ring anomaly,VRA)的CT血管造影(CT angiography,CTA)诊断及手术治疗。通过术前对患犬进行CTA诊断,进行经左侧第4肋间开胸动脉韧带切断的手术治疗,并在术后对病例1进行食道球囊扩张。CTA显示两只犬均存在持久性右主动脉弓(persistent right aortic arch,PRAA),并分别伴有右侧颈动脉异位发育和持久性左前腔静脉。手术治疗后,食道狭窄基本得到纠正,返流消失。CTA可对VRA进行更精确地诊断,并有助于制订具体手术方案;犬PRAA的手术治疗效果良好。
