In order to search for intensity fluctuations on the HCN(1--0) and HCO$^+$(1--0) line profiles which could arise due to possible small-scale inhomogeneous structure long-time observations of the S140 and S199 high-mass star-forming cores were carried out. The data were processed by the Fourier filtering method. Line temperature fluctuations that exceed noise level were detected. Assuming the cores consist of a large number of randomly moving small thermal fragments a total number of fragments is $sim 4cdot 10^6$ for the region with linear size $sim 0.1$~pc in S140 and $sim 10^6$ for the region with linear size $sim 0.3$~pc in S199. Physical parameters of fragments in S140 were obtained from detailed modeling of the HCN emission in a framework of the clumpy cloud model.
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