var how_many_ads=5; var now=new Date(); var sec=now.getSeconds(); var ad=sec % how_many_ads; ad +=1; 
if (ad==1) { code='<a href="http://www.hidrogenio.net" target="_top"><img border=0 src="http://www.hidrogenio.net/imagens/banner/b5.gif" width="445" height="60"></a>';}
if (ad==2) { code='<a href="http://www.hidrogenio.net" target="_top"><img border=0 src="http://www.hidrogenio.net/imagens/banner/b5.gif" width="445" height="60"></a>';}
if (ad==3) { code='<a href="http://www.hidrogenio.net" target="_top"><img border=0 src="http://www.hidrogenio.net/imagens/banner/b2.gif" width="445" height="60"></a>';}
if (ad==4) { code='<a href="http://www.dionefonseca.com/index.php?url=jari" target="_top"><img border=0 src="http://www.dionefonseca.com/imagens/banner_jari.jpg" width="445" height="60"></a>';}
if (ad==5) { code='<a href="http://www.dionefonseca.com/index.php?url=contato" target="_top"><img border=0 src="http://www.dionefonseca.com/imagens/banner_anuncieaqui.gif" width="445" height="60"></a>';}
document.write(code);