以下是一个使用Ruby实现的Amazon销售合作伙伴API签名请求的示例代码：

require 'uri'
require 'net/http'
require 'openssl'
require 'base64'

def generate_signature(request_url, http_method, secret_key, access_key, timestamp)
  # 构建要签名的字符串
  string_to_sign = "#{http_method}\n#{URI.parse(request_url).host}\n#{URI.parse(request_url).path}\n#{URI.parse(request_url).query}\n#{timestamp}"
  
  # 使用HMAC-SHA256算法计算签名
  signature = OpenSSL::HMAC.digest('sha256', secret_key, string_to_sign)
  
  # 对签名进行Base64编码
  encoded_signature = Base64.strict_encode64(signature)
  
  # 返回编码后的签名
  return encoded_signature
end

def send_api_request(request_url, http_method, access_key, secret_key)
  # 获取当前时间戳
  timestamp = Time.now.utc.strftime('%Y-%m-%dT%H:%M:%SZ')
  
  # 生成签名
  signature = generate_signature(request_url, http_method, secret_key, access_key, timestamp)
  
  # 构建HTTP请求
  uri = URI.parse(request_url)
  http = Net::HTTP.new(uri.host, uri.port)
  http.use_ssl = true if uri.scheme == 'https'
  
  if http_method == 'GET'
    request = Net::HTTP::Get.new(uri.request_uri)
  elsif http_method == 'POST'
    request = Net::HTTP::Post.new(uri.request_uri)
  else
    # 其他HTTP方法的处理...
  end
  
  # 设置必要的请求头
  request['Authorization'] = "AWS #{access_key}:#{signature}"
  request['Content-Type'] = 'application/json'
  request['Host'] = uri.host
  request['x-amz-date'] = timestamp
  
  # 发送请求并返回响应
  response = http.request(request)
  return response
end

# 示例用法
request_url = 'https://api.example.com/products'
http_method = 'GET'
access_key = 'your-access-key'
secret_key = 'your-secret-key'

response = send_api_request(request_url, http_method, access_key, secret_key)
puts response.body

请注意，这只是一个示例代码，需要根据实际情况进行适当的修改和调整，比如根据实际的API请求URL、HTTP方法和请求头等进行设置。另外，在实际使用中，建议将access key和secret key存储在安全的地方，并使用环境变量或其他安全的方式进行读取。