英语高手请进（新概念英语）

it naturally limits /all those（those指的是后面的语句解释的人——把研究结果carrying out出来的人，此处省略了"who are"） engaged in carrying it out /（前面接的是那个limits）from effective contact with（从有效的接触中限制出来） their fellow scientists（后面的语句解释这些科学家，此处省略了"who are"） either in other countries or in universities, or even（甚至是）, often enough（常常，插入的修饰语）, in other departments of the same firm（企业）.

engaged in carrying it out from effective contact with their fellow scientists 是省略who的定语从句

in other countries ， in universities， in other departments of the same firm是their fellow scientists的并列定语成分。

often enough是插入成分。