Calix[4]arene derivatives have been reported to possess high selectivity for metal ions.In order to analyze the extraction effect of substituents on Hg~(2+)and
Knowledge-based employees are the inexhaustible motive force for the sustainable development of modern enterprises.Being consistent with the psychological expec
In order to achieve high speed of tufting machine,the oval gear is used as the transmission mechanism between the main shaft and the slave shaft. And then,mathe