System.Runtime.InteropServices.Marshal.ReleaseComObject(sheets);
        System.Runtime.InteropServices.Marshal.ReleaseComObject(worksheet);
        System.Runtime.InteropServices.Marshal.ReleaseComObject(excelApp);
        System.Runtime.InteropServices.Marshal.ReleaseComObject(range);

        excelApp = null;
        wbclass = null;
        sheets = null;
        worksheet = null;
        range = null;
        GC.Collect();
        GC.WaitForPendingFinalizers();

//調用底層函數獲取進程標示
    [DllImport("User32.dll")]
    public static extern int GetWindowThreadProcessId(IntPtr hWnd, out int ProcessId);
    private static void KillExcel(Microsoft.Office.Interop.Excel.Application theApp)
    {
        int id = 0;
        IntPtr intptr = new IntPtr(theApp.Hwnd);
        System.Diagnostics.Process p = null;
        try
        {
            GetWindowThreadProcessId(intptr, out id);
            p = System.Diagnostics.Process.GetProcessById(id);
            if (p != null)
            {
                p.Kill();
                p.Dispose();
            }
        }
        catch (Exception ex)
        {

        }
    }