This paper deals with the synthesis of three new symmetrical bis (macro- cylic) polyamines and their dinuclear copper (......

美国饲料工业协会（American Feed Industry Association）与其合作伙伴家禽学会（Poultry Science Association，PSA）认可了新英格兰大学（Un......

我国安全生产事故频发,职业病危害严重,职业安全卫生形势不容乐观。应借鉴国外工人参与职业安全卫生的立法,完善我国现有的职业安......

<正> Times have changed. May Day in England is not what it used tobe and today many of the ancient customs and tradition......