jgg     2013 33 (4):  44-47    ISSN: 0412-1961  CN: 21-1139/TG ANALYSIS OF LONG-TERM ABSOLUTE GRAVITY CHANGE  AT JIXIAN DATUM 1）61365 Troops of PLA, Tianjin 300140 2）Institute of Surveying and Mapping, Information Engineering University, Zhengzhou 450052 3）Institute of Geodesy and Geophysics, CAS, Wuhan 430077 Received: 2013-01-09  Revised: null  Online: 2013-08-16 Supporting info