سلام . موفق باشی
<%@ Page Language="C#‎" %>



<!DOCTYPE html>



<html xmlns="http://www.w3.org/1999/xhtml">

<head runat="server">

    <script src="http://code.jquery.com/jquery-1.9.1.js"></script>

</head>

<body>

    <form id="form1" runat="server">

        <div class="sb"><input type="text" /><input type="button" value="button1" /></div>

        <div class="sb"><input type="text" /><input type="button" value="button2" /></div>

        <div class="sb"><input type="text" /><input type="button" value="button3" /></div>

        <div class="sb"><input type="text" /><input type="button" value="button4" /></div>

        <div class="sb"><input type="text" /><input type="button" value="button5" /></div>

        <div class="sb"><input type="text" /><input type="button" value="button6" /></div>

    </form>

    <script>

        $('.sb').each(function () {

            var x = $(this);

            x.find('input[type=text]').keydown(function (event) {

                if (event.which == 13) { x.find('input[type=button]').click(); }

            });

        });

        $('input[type=button]').click(function () { $(this).fadeToggle('slow'); });

    </script>

</body>

</html>