Aspirin is synthesized through O - acylating reaction from acid and anhydride acid with anhydrous carbonate as catalyst.以水杨酸和乙酸酐为原料,采用无水碳酸钠作为催化剂经O - 酰化反应合成了阿司匹林.In 2002, we develop Photo - catalyst & electronic Ionizer A...
Braving the biting wind, she went out to beg from door to door.她不顾寒风刺骨, 出去挨门乞讨.Braving snow and frost , the plum trees blossomed defiantly.红梅傲雪凌霜开.Already a few opportunists were braving the snow and collecting cases.已经有...
他只能看见球门柱模糊的轮廓。He could see only the hazy outline of the goalposts.操场的墙上已经标出了球门柱的轮廓.Goalposts were roughly chalked out on the playground wall.球撞到球门柱上斜飞入网.The ball glanced off the goal post into the net....
根和根冠被一鞘 状 结构,即胚根鞘所覆盖.Both root and root cap are covered by a sheath - like structure called the coleorhiza.用来保护发育的胚芽的鞘状的结构.Coleoptile A sheath like structure that protects the developing plumule in grasses.胚根鞘:保护幼根的鞘状结构....