Asymmetric 1, 3 - dipolar cycloaddition can be strongly catalyzed by chiral oxazaborolidines.手性唑硼烷酮能够催化不对称1, 3偶极加成反应并取得很好的效果.The cycloaddition itself is the slow step.环化作用本身是慢的一步....
His face was ashy grey.他面如土色.His glassy eyes and his ashy face were alight in an instant.他那没光的眼睛和苍白的脸,登时就神采奕奕.Both of the window screens were ashy, you would feel dim when looked out of window.两个窗纱也灰蒙蒙的, 从宿舍向外看朦朦胧胧的感觉....