https://library.ptec.edu.kh/journals daily 0.9 https://library.ptec.edu.kh/journals/journal-of-chemical-education 2026-10-02T03:35:37.228931+00:00 weekly 0.7 https://library.ptec.edu.kh/journals/journal-of-chemical-education/issues 2026-10-02T03:35:37.228931+00:00 weekly 0.5 https://library.ptec.edu.kh/journals/journal-of-chemical-education/issues/vol-91-issue-11 monthly 0.6 https://library.ptec.edu.kh/journals/articles/handmade-conductivity-measurement-device-thin-film-semiconductor-polypyrrole 2026-10-02T03:35:37.228931+00:00 monthly 0.9