【单选题】已知A与B两物质的相对比移值为1.5。当B物质在某薄层板上展开后,斑点距原点8 cm,此时原点至溶剂前沿距离为16 cm时,问A若在此板上同时展开,A物质的展距应为多少?A物质的Rf值应为多少
【单选题】设x,y∈R且 x≥1 x-2y+3≥0 y≥x ,则z=x+2y的最小值等于( )
【简答题】设x,y∈R且x+y=5,则3 x +3 y 的最小值是______.
【简答题】We are glad to welcome our Chinese friends to this special Business Training program. Here, you will have a variety of activities and a chance to exchange ideas with each other. We hope that all of yo...
【单选题】设x,y∈R且 ,则z=x+2y的最小值等于 [ ]
【单选题】患者,男性,45岁。搬抬重物后出现腰痛伴右下肢放射痛3天来院就诊,诊断为腰椎间盘突出症。检查时发现患者小腿外侧及 趾的针刺觉减退。 腰椎间盘突出症多发于
【简答题】设x,y∈R,且x+y=4,则5 x +5 y 的最小值是______.
【判断题】Here, the group of the series of instructions is called program.
【单选题】Mr. Baker, a dozen students want to see you. () they wait here or outside?
【简答题】已知 A 与 B 两物质的相对比移值为 1.5 。当 B 物质在某薄层板上展开拮,斑点距原点 9cm ,此时原点至溶剂前沿距离为 18.0cm 时,问 A 若在此板上同时展开, A 物质的展距应为多少? A 物质的 R f 值应为多少。