Array ( [0] => Array ( [title] => L18A [link] => https://www.youtube.com/embed/Semomq7B7WU ) [1] => Array ( [title] => L18B [link] => https://www.youtube.com/embed/We-03fuoiSk ) ) 國立清華大學開放式課程OpenCourseWare(NTHU, OCW) - 第18講 kinematic theory +structure factor