方法: 用溴代及胺化反应合成了四甲基吡嗪衍生物.METHODS: The target compound was prepared by the bromination and amination reaction.用溴—甲醇溶解Al_2O_3, 其回收率在91%以上.If Al 2 O 3 is dissolved by Br 2 - CH 3 OH, its Recovery rate is above 91 %.用溴比用氯时产出率...
Marks in the roadway seem to indicate that he skidded taking a sharp turn.从车道上的痕迹来看，他似乎在急转弯时打滑了。His drive hit a tree and caromed off into a roadway.他击出的球撞到一棵树上而反弹到路上.The destructive reasons and countermeasures of bolting...
他们最终的目标是为匈牙利建立起市场经济体制。Their ultimate aim was a market economy for Hungary.他在神学和政治事务上都是最终的仲裁人。He was the ultimate arbiter on both theological and political matters.等到最终的数字统计出来后，几乎可以肯定销售额下降了。When the final numbers are tall...