如果代码缩进正确，语法错误更容易发现。

if citation_array.blank?
  flash.now[:error] = "There was a problem saving the publications selected!"
  @user = current_user
  render  'pubmed_search'
else
  citation_array.each do |user_publication|
    begin
      publication = Publication.new
      render_publication(user_publication)
      publication.citation = user_publication
      publication.user_id  = current_user.id
      publication.title = @title
      publication.authors = @authors
      publication.journal = @journal
      publication.year = @year
      publication.volume = @volume
      publication.pages  = @pages
      if publication.save
        next
      end
    rescue
      next
    end
  end
  @user = current_user
  redirect_to current_user
  return false
end

语法似乎是正确的。不过，更简单的方法是运行代码。
但是代码中的一些东西是不必要的。在稍微清理代码之后，它看起来像这样，具有相同的功能。

@user = current_user
if citation_array.blank?
  flash.now[:error] = 'There was a problem saving the publications selected!'
  render 'pubmed_search'
else
  citation_array.each do |user_publication|
    begin
      render_publication(user_publication)
      Publication.create!( # create! here so that if something does go wrong, then you're not just ignoring it, but you can log it in your rescue block.
        citation: user_publication,
        user_id: current_user.id,
        title: @title,
        authors: @authors,
        journal: @journal,
        year: @year,
        volume: @volume,
        pages: @pages
        # This hash should be extracted to a method.
      )
    rescue
      # Just doing nothing here is valid syntax, but you should at least log your error.
    end
  end
  redirect_to current_user
  false # This can most likely be omitted as well since not many places care about the return value of a controller action.
end

begin-rescue的语法
begin your code... rescue => e Rails.logger.debug 'Exception is #{e}' end