演示：http://inksci.com/web/baidu_search.demo.html

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />

  <section class="box-login v5-input-txt" id="box-login"> 
   <!-- visible-xs --> 
   <form name="f1" target="_blank" action="https://m.baidu.com/s" autocomplete="off" class="visible-xs"> 
    <br /> 
    <br /> 
    <ul> 
     <li class="form-group"><input class="form-control" id="id_account_l" maxlength="50" name="word" placeholder="请输入搜索内容" type="text" /></li> 
     <!--
                                    <li class="form-group"><input class="form-control" id="id_password_l" name="password_l" placeholder="请输入密码" type="password"></li>
                                    --> 
    </ul> 
    <input name="si" type="hidden" value="inksci.com" /> 
    <!--
                            <p class="good-tips marginB10"><a id="btnForgetpsw" class="fr">忘记密码？</a>还没有账号？<a href="javascript:;" target="_blank" id="btnRegister">立即注册</a></p>
                            --> 
    <br /> 
    <div class="login-box marginB10"> 
     <button id="login_btn" type="submit" class="btn btn-micv5 btn-block globalLogin">站内搜索</button> 
     <div id="login-form-tips" class="tips-error bg-danger" style="display: none;">
       错误提示 
     </div> 
    </div> 
    <!--
                            <div class="threeLogin"><span>其他方式登录</span><a class="nqq" href="javascript:;"></a><a class="nwx" href="javascript:;"></a></div>
                            --> 
   </form> 
   <!-- visible-xs --> 
   <form name="f1" onsubmit="return g(this)" target="_blank" autocomplete="off" class="hidden-xs"> 
    <br /> 
    <br /> 
    <ul> 
     <li class="form-group"><input class="form-control" id="id_account_l" maxlength="50" name="word" placeholder="请输入搜索内容" type="text" /></li> 
     <!--
                                    <li class="form-group"><input class="form-control" id="id_password_l" name="password_l" placeholder="请输入密码" type="password"></li>
                                    --> 
    </ul> 
    <input name="tn" type="hidden" value="SE_zzsearchcode_shhzc78w" /> 
    <input name="cl" type="hidden" value="3" /> 
    <input name="ct" type="hidden" /> 
    <input name="si" type="hidden" value="inksci.com" /> 
    <!--
                            <p class="good-tips marginB10"><a id="btnForgetpsw" class="fr">忘记密码？</a>还没有账号？<a href="javascript:;" target="_blank" id="btnRegister">立即注册</a></p>
                            --> 
    <br /> 
    <div class="login-box marginB10"> 
     <button id="login_btn" type="submit" class="btn btn-micv5 btn-block globalLogin">站内搜索</button> 
     <div id="login-form-tips" class="tips-error bg-danger" style="display: none;">
      错误提示
     </div> 
    </div> 
    <script src="http://s1.bdstatic.com/r/www/cache/global/js/BaiduHttps_20150714_zhanzhang.js"></script> 
    <script>
    function checkHttps () {
        BaiduHttps.useHttps();
    };
    function g(formname) {
        var data = BaiduHttps.useHttps();
        var url = '';
        url = data.s == 0 ? "http://baidu.com/baidu" : 'https://baidu.com/baidu' + '?ssl_s=1&ssl_c' + data.ssl_code;

        formname.ct.value = "2097152";

        formname.action = url;
        return true;
    };
</script> 
    <!--
                            <div class="threeLogin"><span>其他方式登录</span><a class="nqq" href="javascript:;"></a><a class="nwx" href="javascript:;"></a></div>
                            --> 
   </form> 
  </section>