  Observations of large supernova remnants (SNRs) at high frequencies are rare,
but provide valuable information about their physical properties. The total
intensity and polarization properties of 16 large SNRs in the Galactic plane
were investigated based on observations of the Urumqi $\lambda$6\ cm
polarization survey of the Galactic plane with an angular resolution of
9$\farcm$5. We extracted total intensity and linear polarization maps of large
SNRs from the Urumqi $\lambda$6\ cm survey, obtained their integrated flux
densities, and derived the radio spectra in context with previously published
flux densities at various frequencies. In particular, Effelsberg $\lambda$11\
cm and $\lambda$21\ cm survey data were used for calculating integrated flux
densities. The $\lambda$6\ cm polarization data also delineate the magnetic
field structures of the SNRs. We present the first total intensity maps at
$\lambda$6\ cm for SNRs G106.3+2.7, G114.3+0.3, G116.5+1.1, G166.0+4.3 (VRO
42.05.01), G205.5+0.5 (Monoceros Nebula) and G206.9+2.3 (PKS 0646+06) and the
first polarization measurements at $\lambda$6\ cm for SNRs G82.2+5.3 (W63),
G106.3+2.7, G114.3+0.3, G116.5+1.1, G166.0+4.3 (VRO 42.05.01), G205.5+0.5
(Monoceros Nebula) and G206.9+2.3 (PKS 0646+06). Most of the newly derived
integrated radio spectra are consistent with previous results. The new flux
densities obtained from the Urumqi $\lambda$6\ cm, Effelsberg $\lambda$11\ cm
and $\lambda$21\ cm surveys are crucial to determine the spectra of SNR
G65.1+0.6, G69.0+2.7 (CTB 80), G93.7-0.2 and G114.3+0.3. We find that
G192.8$-$1.1 (PKS 0607+17) consists of background sources, \ion{H}{II} regions
and the extended diffuse emission of thermal nature, and conclude that
G192.8$-$1.1 is not a SNR.
