Oil painting on canvas Russian school late 19th century with portrait of a man Riabouchkine

Painting, oil on canvas mounted on panel with portrait of a man. Russian school late 19th century. Cyrillic marking on the back: riabouchkine for andreï riabouchkine 1861-1904. I note the presence of small frictions. Max dimensions with frame: 43.2 x 35.7 cm. Dimensions seen only: 27.5 x 20.2 cm.