void Main()
{      
string s="<A title=\"豆油上涨步伐或将放缓\" href=\"zixun/InfoList.asp?id=9164\" target=_blank>豆油上涨步伐或将放缓</A>";
Match m=Regex.Match(s,@"(?is)<a\stitle=""豆油上涨步伐或将放缓""\shref=""([^>].*?)""\s.*?>.*?</a>");
if(m.Success)
{
Console.WriteLine(m.Groups[1].Value);
}
}

//zixun/InfoList.asp?id=9164

------解决方案--------------------
先添加一个webbrowser控件
C# code
 public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            this.webBrowser1.Navigate(textBox1.Text);
        }

        private void button1_Click(object sender, EventArgs e)
        {

            if (webBrowser1.Document != null)
            {
                HtmlElementCollection elems = webBrowser1.Document.GetElementsByTagName("a");
                foreach (HtmlElement elem in elems)
                {
                    String nameStr = elem.GetAttribute("title");
                    if (nameStr == textBox2.Text)
                    {
                        string hrefStr = elem.GetAttribute("href");
                        MessageBox.Show(hrefStr);
                        break;
                    }
                }
            }
            else
                MessageBox.Show("网页加载出错");
        }
    }