protected void Buscar()
 {
     try
     {
         MateriaLogic malogic = new MateriaLogic();
         this.gridview.DataSource = malogic.GetByMateria(this.txtbuscar.Text);
         this.gridview.DataBind();
     }
     catch (Exception ex)
     {
         msgError.Text = ex.Message;
     }
 }