replace-punctuation.el

(defun my-replace-punctuation-to-scientific ()
  (interactive)
  (my-replace-punctuation 'scientific))

(defun my-replace-punctuation-to-normal ()
  (interactive)
  (my-replace-punctuation 'normal))

(defun my-replace-punctuation (to)
  (let ((pos (point))
        (source (cond ((eq to 'normal) "\\(，\\)\\|\\(．\\)")
                      ((eq to 'scientific) "\\(、\\)\\|\\(。\\)"))))
    (if (not source)
        (error "Target punctuation is wrong")
      (goto-char (point-min))
      (while (re-search-forward source nil :noerror)
        (let ((w (match-string-no-properties 0)))
          (cond ((equal w "，") (replace-match "、"))
                ((equal w "．") (replace-match "。"))
                ((equal w "、") (replace-match "，"))
                ((equal w "。") (replace-match "．")))))
      (goto-char pos))))