难句解析：①No clear-cut distinction can be drawn between professionals and amateurs in science: exceptions can be found to any rule. Nevertheless, the word "amateur" does carry a connotation that the person concerned is not fully integrated into the scientific community and, in particular, may not fully share its values.▲先看前面的句子的主干是No... distinction can be drawn between...，冒号后面的内容是进一步说明前面的观点。在第二个句子中，一上来就有一个转折词nevertheless，表示语意的转折，其主句是the word "amateur" does carry a connotation，后面有一个同位语从句，里面有两个并列谓语。△注意nevertheless表示转折，其后的信息与其前面的信息意思相反，前面讲二者没有很明显的区别，后面便说业余和专业就是不一样。其次要看清the word "amateur" DOES carry a connotation而非DOES NOT。②The trend was naturally most obvious in those areas of science based especially on a mathematical or laboratory training, and can be illustrated in terms of the development of geology in the United Kingdom.▲两个分句有同一个主语，即the trend，两个谓语为was obvious和can be illustrated。前一个分句中based especially on a mathematical or laboratory training修饰areas of science。△注意be illustrated的用法，这里是“举例说明，例证说明”的意思；另外in terms of是“就某事来说，以某事为例”的意思。③A comparison of British geological publications over the last century and a half reveals not simply an increasing emphasis on the primacy of research, but also a changing definition of what constitutes an acceptable research paper.▲本句的主语是a comparison of British geological publications over the last century and a half（中心词为a comparison），谓语是reveals，宾语主体结构是not simply... but also...所连接的两个并列宾语，注意宾语emphasis和definition前都有分词来修饰。△an increasing emphasis on the primacy of research译为“对科研的重要性的强调不断攀升”，a changing definition of what constitutes an acceptable research paper译为“一篇过得去的科研论文创作标准也有所变化”，其中what指代the elements that。④The overall result has been to make entrance to professional geological journals harder for amateurs, a result that has been reinforced by the widespread introduction of refereeing, first by national journals in the nineteenth century and then by several local geological journals in the twentieth century.▲全句的主干结构是The... result has been to do sth.。注意逗号后面只是一个名词性的短语，其核心词是a result，可以被看成是前面句子主语的同位语，在其内部主要是一个长的定语从句，而定语从句中又有两个并列的状语first by..., and then by...。△entrance入口，此处指发表文章，进入专业圈子。reinforce增强，也就是使难度更高。本句的理解重点在于理顺句子结构，要看到在第一个逗号之后没有动词了，可以一层一层地把这个名词短语分解开。⑤A rather similar process of differentiation has led to professional geologists coming together nationally within one or two specific societies, whereas the amateurs have tended either to remain in local societies or to come together nationally in a different way.▲这是一个并列关系的并列句，两个分句由whereas（而）连接，说明了两种情况，前面是在说professional，而后面说amateurs。△coming together nationally within one or two specific societies理解为“组成一到两个全国性的专科学术社团”。 内容来自:可可英语 http://www.kekenet.com/kaoyan/201405/299823.shtml