The most drastic, and thoroughly illegal, reaction has been the emergence of Sci-Hub, a kind of global photocopier for scientific papers, set up in 2012, which now claims to offer access to every paywalled article published since 2015.
句子主干：The most drastic reaction has been the emergence of Sci-Hub (主系表结构)。
修饰成分：and thoroughly illegal是插入语，thoroughly illega与the most drastic并列，修饰reaction。a kind of global photocopier for scientific papers是Sci-Hub的同位语，对其解释说明。过去分词短语set up in 2012和which从句：which now claims to offer access to every paywalled article published since 2015，都是Sci-Hub的后置定语，对其进行修饰。
翻译：最为猛烈、也是完全违规的抵制是Sci-Hub的出现，Sci-Hub有点类似全球性的科学论文影印机，它创立于2012年，现在声称可以提供2015年以来发表的所有付费论文的访问权。
