将脚本编写为

<script type="text/javascript">
    function Validate(event) {
        var regex = new RegExp("^[0-9-!@#$%*?]");
        var key = String.fromCharCode(event.charCode ? event.which : event.charCode);
        if (!regex.test(key)) {
            event.preventDefault();
            return false;
        }
    }       
</script>

并像

<asp:TextBox ID="txtcheck" onkeypress="return Validate(event);" runat="server" />