Your question us not very clear. But if yo want call your Javascript function. That can be done by registering your method as.
- If you are using AJAX on your page
ScriptManager.RegisterStartupScript(Page, typeof(System.Web.UI.Page),
"botaoCarregarNotas", @"<script type='text/javascript'>botaoCarregarNotas();</script>", false);
- If not using AJAX
Page.ClientScript.RegisterStartupScript(typeof(System.Web.UI.Page),
"botaoCarregarNotas", @"<script type='text/javascript'>botaoCarregarNotas();</script>");