closed extension

In this paper, we investigate extension closure of the full subcategory IkT (R) of mod-R consisting of T-k-torsionfree modules by the grade condition and strong grade condition of modules, and obtain a sufficent condition and an equivalence characterization for IkT (R) to be extension closed.

本文研究了由T-k-挠自由模所构成的mod-R的完全子模范畴IkT(R)的扩张闭。

The follow-up of patients with mitral stenosis after closed mitral commisurotomy for ten years;

二尖瓣狭窄306例闭式扩张术后10年随访报告