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....
And the same evening German motorized elements reached the Serbian frontiers.同日晚间,德国的摩托化部队进抵塞尔维亚边境.Motorized wheelchairs are a rarity here...电动轮椅在这里很罕见。Around 1910 motorized carriages were beginning to replace horse-draw...