add_link_to_google_scholar_in_google_header.user.js

// ==UserScript==
// @name        add link to google scholar in google header
// @namespace   http://profile.livedoor.com/ronekko/
// @description add link to google scholar in google header
// @include     https://www.google.co.jp/search?*
// @version     1
// ==/UserScript==
function get_url_vars()
{
  var vars = {}, params;
  var temp_params = window.location.search.substring(1).split('&');
  for(var i = 0; i <temp_params.length; i++) {
    params = temp_params[i].split('=');
    vars[params[0]] = params[1];
  }
  return vars;
}

var query_str = get_url_vars()['q'];
var link_str = 'http://scholar.google.co.jp/scholar?hl=ja&q=' + query_str

var span = document.createElement('span');
span.textContent = 'Scholer';
span.className = 'gbts';

var a = document.createElement('a');
a.href = link_str;
a.className = 'gbzt';
a.appendChild(span);

var header = document.querySelector('#hdtb-msb');
header.appendChild(a);