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We carried out a cyanopolyyne line survey towards a large sample of HMSFRsusing the Shanghai Tian Ma 65m Radio Telescope (TMRT). Our sample consisted of123 targets taken from the TMRT C band line survey. It included three kinds ofsources, namely those with detection of the 6.7 GHz CH3OH maser alone, withdetection of the radio recombination line (RRL) alone, and with detection ofboth (hereafter referred to as Maser-only, RRL-only, and Maser-RRL sources,respectively). We detected HC3N in 38 sources, HC5N in 11 sources, and HC7N inG24.790+0.084, with the highest detection rate being found for Maser-RRLsources and a very low detection rate found for RRL-only sources. Their columndensities were derived using the rotational temperature measured from the NH3lines. And we constructed and fitted the far-infrared (FIR) spectral energydistributions. Based on these, we derive their dust temperatures, H2 columndensities, and abundances of cyanopolyynes relative to H2. The detection rate,the column density, and the relative abundance of HC3N increase from Maser-onlyto Maser-RRL sources and decrease from Maser-RRL to RRL-only sources. Thistrend is consistent with the proposed evolutionary trend of HC3N under theassumption that our Maser-only, Maser-RRL, and RRL-only sources correspond tomassive young stellar objects, ultra-compact HII regions, and normal classicalHII regions, respectively. Furthermore, a statistical analysis of theintegrated line intensity and column density of HC3N and shock-tracingmolecules (SiO, H2CO) enabled us to find positive correlations between them.This suggests that HC3N may be another tracer of shocks, and should thereforebe the subject of further observations and corresponding chemical simulations.Our results indirectly support the idea that the neutral--neutral reactionbetween C2H2 and CN is the dominant formation pathway of HC3N.

Cyanopolyyne line survey towards high-mass star-forming regions with TMRT