url_str="http://eit.ebscohost.com/Services/SearchService.asmx/Search?prof=webdes.eit.bbates&pwd=ebsco&query=(TX+(test))+AND+FT+Y&db=a9h&sort=date"

search_txt = 'hello'
url_str.sub!(/\+\((.*)\)\)/, "+(#{search_txt}))")

, "db"=>"a9h", "page_start"=>"11"