OGRC-1 请教几个小小问题

深刻检讨: 我的YP难句看的太粗了!  结果, 碰到不算难的句子,就晕菜了. 谢谢各大侠指点迷津.

问题1: Snyder et al compared the stimulatory effects of a series of caffeine derivatives with their ability to dislodge adenosine from its receptors in the brains of mice.

their represents derivaties? and its means adenosine? right? - i know it's a stupid question.

问题2: the ability of the compounds to compete at the receptors correlates with their ability to stimulate locomotion in the mouse.

此处的compete at 作何解释?

问题3: Therefore, prolonged periods at the elevated conentrations, as might be brought about by a phosphodiesterace inhibtor, could lead to a greater amount of neuron firing and, consequently, to behavioral stimulation.

as might be....黑体字是修饰concentrations? 译文是: 可能被PH抑制物带来的持续升高的含量会导致提高神经兴奋, 从而提高人的兴奋?  

问题4:  which 在sc中不能指代前面整个句子, 但在阅读文章中可以, 对吗?

谢谢了.

没有人回答, 看来这几个问题菜得没有人想回答.

不好意思了......

yes, 但这绝不是stupid question, 你这问题很好

(the ability of the compounds to compete)( at the receptors)( correlates with their ability)( to stimulate locomotion)( in the mouse. )

我想是prolonged periods at the elevated conentrations

能举例吗??因为我没看到这样的例子......

谢谢楼上两位高手赐教.  好感动哦~~~~~~~~~~~~~~~~

问题4是我在新东方听到的, 前面半句非常肯定. which can not modify the whole sentence, but nouns closed to it.

请看此句第二个which...

Snyder et al propose that caffeine, which is struturally similar to adenosine, is able to bind to both types of receptors, which prevents adenosine from attaching there and allows the neurons to fire more readily than they otherwise would.  

第二个which 是modify前面的插入语吧?  

chenchen 说：
WHICH是不能指代整个巨资的
chenchen 说：
指代CAFFEINE
chenchen 说：
CAFFEINE PREVENTS ADENOSINE FROM...
三公子_越剧迷_青衣水袖 说：
是的
三公子_越剧迷_青衣水袖 说：
跳跃修饰好厉害
chenchen 说：
这是跳跃性指代, 这样的文章关键要读懂文章的意思, 不要拘泥与语法
三公子_越剧迷_青衣水袖 说：
这个which还可以直待整个动作
chenchen 说：
这样说的话, 那就是指代前面的整个句子了
chenchen 说：
这个语法现象是有问题的
chenchen 说：
WHICH不能指代句子
三公子_越剧迷_青衣水袖 说：
gmat里面不可以
chenchen 说：
他要有个行为主语, 那个主语不能是句子
chenchen 说：
三兄, 您可考的是GMAT呀
chenchen 说：
偶觉得, GMAT的语法还是很规范的

有点乱，偶不整理了，

顺便想问一句：我没有查到phosphodiesterase一词的含义，是否是XiaoY在其文中提到的ph？

请赐教！

请大家帮帮我：

But Snyder et al point out that the caffeine concentrations needed to inhibit the production
of phosphodiesterase in the brain are much higher than those that produce stimulation.
是否可以翻译成：但是，Snyder等人指出：阻止大脑中phosphodiesterase产生所需的咖啡因浓度要远远高于那些可产生刺激的咖啡因浓度。

这里的those指代的是caffeine吗？