Na sua consulta
item
é string, então mude String strquery="select * from Articles where AS_name= "+item;
para
String strquery="select * from Articles where AS_name='" + item + "'";
Ou isto
Cursor cur=null;
cur = db.query("Articles", null, "AS_name" + "=?",
new String[] { item }, null, null, null, null);
ao invés de
Cursor cur=null;
String strquery="select * from Articles where AS_name= "+item;
cur=db.rawQuery(strquery,null);
E mudar
strvalue=cur.getString(0);
para
strvalue=cur.getString(cur.getColumnIndex("Desc_art"));