public function index($id)
 {
     //$articles=DB::table('blog_articles')->where('blog_id','=',$id)->paginate(15);
     if (Auth::user()->tag == 'teacher') {
         $user = User::find($id);
         $blog = $user->blog;
         if (empty($blog)) {
             # code...
             $blog = new Blog();
             $blog->name = $user->name;
             $blog->user_id = $user->id;
             $blog->save();
         }
         $articles = $blog->articles()->get();
         $user = User::find($id);
         $data = array('articles' => $articles, 'user' => $user, 'blog' => $blog);
         //return $data;
         return view('blog.admin.index')->with('data', $data);
     } else {
         return '该博客暂时不对实验室外部人员开放';
     }
 }