习书写画鉴古观今 平沙落雁逸士心怀（上）——访故宫博物院著名的书画鉴赏家杨臣彬先生

In the formulation of gypsum-bonded casting investments, small amounts of certain modifiers are sometimes added to increase the investment's thermal expansion. In the present investigation, a systematic study has been made of the effects on thermal expansion of adding boric acid and sodium chloride ... View More