function getra(){

var_name = $("input[name='isspecialcnt']:checked").val();
//alert(var_name);
if(var_name=='1'){
$("#isspecialcntyes").show();
$("#isspecialcntno").hide();
}
if(var_name=='0'){
$("#isspecialcntyes").hide();
(www.1sucai.cn) $("#isspecialcntno").show();
}
}

<form name="form1" method="post" action="">
<p>
<label>
<input type="radio" name="radiogroup1" value="单选" id="radiogroup1_0">
单选</label>
<br>
<label>
<input type="radio" name="radiogroup1" value="单选" id="radiogroup1_1">
单选</label>
<br>
<label>
<input type="radio" name="radiogroup1" value="单选" id="radiogroup1_2">
单选</label>
<br>
<label>
<input type="radio" name="radiogroup1" value="单选" id="radiogroup1_3">
单选</label>
<br>
<label>
<input type="radio" name="radiogroup1" value="单选" id="radiogroup1_4">
单选</label>
<br>
<label>
<input type="radio" name="radiogroup1" value="单选" id="radiogroup1_5">
单选</label>
<br>
</p>
</form>