private void Form1_Load(object sender, EventArgs e)
        {
            this.MouseWheel += new MouseEventHandler(Form1_MouseWheel);
        }

        void Form1_MouseWheel(object sender, MouseEventArgs e)
        {           
            if (e.Delta > 0)
            {
                this.Text = "正在向上滚动滑轮";
            }
            else
            {
                this.Text = "正在向下滚动滑轮";             
            }
        }