free sheet,wood-free paper

Total coloring of C_4-free plane graphs with Δ(G)= 9;

Δ(G)=9且不含4-圈的平面图的全色数

This study is aimed on a new Be-free Nickle-Ceramic alloy.

本文通过优化镍基合金的元素组份,研制新型不含铍的镍基烤瓷合金,以期改变现有烤瓷合金铍元素对人体组织细胞有毒性反应的现况。