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   71114
   The observation of high z quasars are essential for the study of
   evolution of AGNs and its connection to cosmic X-ray backgroud. So far,
   seven high z (z>3) quasars were observed with ASCA. The correlation
   between z-value and spectral index showed the trend of spectral
   hardening with incresing z-value. The flux of radio loud quasars was
   higher than that of radio quiet quasars in average. The X-ray spectra
   were flatter than those in optical and UV bands. These properties
   suggests blazar type activity and structure. By this reason, we propose
   organized observation of X-rays and space VLBI to study connection of
   X-ray emission to sub-mas radio morphology.
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