Costa Rica becomes a signatory to the Buenos Aires copyright treaty.1916年,哥斯达黎加成为布宜诺斯艾利斯版权条约的签字国之一....banana plantations in Costa Rica.哥斯达黎加的香蕉种植园Here, a female floats through a cloud forest in Costa Rica.这里, 一雌性漂浮物通过云雾林...
脸盆架上方用钉子挂着一面镜子。A mirror hung on a nail above the washstand.卫生间里装了两个抽水马桶、两个淋浴器、和两个洗脸盆。The bathroom is furnished with 2 toilets, 2 showers, and 2 sinks.脸盆边上有个小豁口。The washbasin had a small chip....
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...