$(selector).load(url, data, callback);

$.ajax({
    url: yourUrl,
    type: 'GET',
    success: function(data) {
        $('#yourElement').html(data);
    }
});

$('#yourElement').load(yourUrl, function() {
    // 回调函数
}, function(xhr) {
    xhr.setRequestHeader('X-Requested-With', 'XMLHttpRequest');
});

$.fn.ajaxLoad = function(url, data, callback) {
    return this.each(function() {
        $.ajax({
            url: url,
            data: data,
            beforeSend: function(xhr) {
                xhr.setRequestHeader('X-Requested-With', 'XMLHttpRequest');
            },
            success: function(response) {
                $(this).html(response);
                if (callback) callback.apply(this, arguments);
            }.bind(this)
        });
    });
};

// 使用方式
$('#yourElement').ajaxLoad(yourUrl);

public static bool IsAjaxRequest(this HttpRequestBase request)
{
    if (request == null)
    {
        throw new ArgumentNullException("request");
    }
    
    // 检查标准AJAX头
    if (request.Headers["X-Requested-With"] == "XMLHttpRequest")
    {
        return true;
    }
    
    // 或者检查特定的内容类型
    if (request.ContentType == "application/json")
    {
        return true;
    }
    
    // 或者添加其他你需要的检查条件
    
    return false;
}