These alloys are very suitable for casting because Si increases the fluidity of the melt and reduces the melting temperature. Si also has a low density of 2.34 kg/dm3, which provides the alloy with the advantage of reducing weight. This is why this alloy group is used for automotive and ...
(3) 信息开放获取运动的缘起及发展 信息开放获取 (Information Open Access) 源于1946年联合国第一次大会对“信息自由” (The Freedom of Information) 思想的阐述, 大会第59 (1) 号决议宣告:“信息自由是一项基本人权, 也是联合国追求的所有自由的基石。”在1948年联合国通过的《世界人权宣言》的第19条款中就规...