请教一个定语从句问题！

which US leadership has been founded的先行词是research
介词on 是介词提前
结果，几乎没有公司支持这项长期研究，美国的领导关系是基于这样研究建立的。

因此,现在几乎没有公司支持美国政府已经建立的长期研究项目.

是介词提前,

be founded on/upon sth
a) to be the main idea, belief etc that something else develops from

b) to be the solid layer of cement, stones etc that a building is built on
The castle is founded on solid rock.
technical to melt metal and pour it into a mould (=a hollow shape) , to make things such as tools and parts for machines

先行词是research,on是短语on the research中的被提前了，意思是结果很少有几家公司支持这一长期研究项目，而美国的领导关系也正是基于这项研究建立起来的。

是这样的。从句是which US leadership has been founded on，然后介词提前。

因为是“建立于某点”，所以用found on.

整个句子可以分裂成这样：US leadership has been founded on the kind of long-term research. Few companies are now supporting the kind of long-term research.

解释出来就是，“所以，一些公司现在很支持这类长期研究（项目），[是哪写长期研究呢]，就是US leadership has been founded on[美国经济的领头作用所建立于的，或者翻译为，使美国经济（一直）处于主导地位