Enqueue Javascript Correctly for 3.5

Never de-register core-bundled scripts in the WP-Admin. You shouldn’t do it on the front end, either, unless you really, really know what you’re doing. But especially in the WP-Admin, just use the core-bundled scripts.

Also, when you use core-bundled jQuery UI, WordPress already knows that jQuery is a dependency.

Just change the first callback to this:

function my_plugin_load_js() {
    wp_enqueue_script('jquery-ui-core');
}
add_action('admin_enqueue_scripts', 'my_plugin_load_js' );

Note: you should be using a plugin-specific hook here, to enqueue only on your own Plugin’s admin page, rather than enqueueing in the entire WP-Admin.

Also, for jQuery UI Tabs, you’ll need to enqueue the jquery-ui-tabs script. Core registers it with all its needed deps, so you can just enqueue it directly:

function my_plugin_load_js() {
    wp_enqueue_script('jquery-ui-tabs');
}
add_action('admin_enqueue_scripts', 'my_plugin_load_js' );

For the second, just properly wrap the script in no-conflict wrappers:

function mypluginjs() {
    ?>
<script type="text/javascript">
jQuery(document).ready(function($) {
   jQuery( "#tabs" ).tabs();
});
</script>
    <?php
}
add_action( 'admin_print_scripts', 'mypluginjs' );