\begin{table}%t4
\caption{\label{steady_state1}Fractional abundances and abundance ratios from the standard gas-phase model$^a$.}
%\centering
\par
\begin{tabular}{lllllccc}
\hline
\hline\noalign{\smallskip}
 $T = 10$~K  & HNCO/H$_{2}$     & HOCN/H$_2$    & HCNO/H$_2$     & HONC/H$_{2}$      & HNCO/HOCN & HNCO/HCNO  & HCNO/HOCN    \\ 
   &                 $\times 10^{13}$ & $\times 10^{13}$  & $\times 10^{13}$&   $\times 10^{13}$                               &     &    & \\
 \hline\noalign{\smallskip}
 $n$(H$_2$)~cm$^{-3}$ &   &     &      &   &   \\
$1 \times 10^3$     & 3.3 & 0.67 & 5.1 & 1.5  &    5.0    &    0.6     & 7.7  \\
                   & 4.7 & 1.0 & 7.1 & 2.0 &     4.7   &   0.7      &  7.1  \\
$3 \times  10^3$   & 9000 & 720 & 2000 & 380  &    13    &    4.6      & 2.7 \\
                    &  20~000 & 1400 & 4900 & 1100 &   14     &   4.1     & 3.5 \\
$1 \times  10^4$     & 19~000  & 1300 & 2100& 170  &   14      &    8.9     &  1.6  \\ 
                   & 47~000 &  2300 &  4500 & 400 &  20      &    11       &  1.9 \\
$3 \times  10^4$   & 18~000  & 1200 & 1300 & 41  &   15      &   13     &  1.1  \\ 
                    &  55~000 & 1900& 2500 & 90 &   30    &    22         &   1.{\bf3} \\
$1  \times 10^5$     & 9200 & 670 & 680 & 6.8  &   14    &   14     &  1.0  \\  
                   & 41~000 & 980 & 1000 & 11 &  42     &      39     &    1.1 \\
$3 \times  10^5$   & 3400 & 300 & 380 & 1.3  &   11    &    9.0    &  1.3 \\ 
                    & 20~000 & 420 &  440 & 1.5  &   47   &   45 &  1.1\\
$5 \times  10^5$   & 2000 & 190 & 290 & 0.6  &   10      &    6.7    &  1.5  \\ 
                    & 13~000 & 290 & 340 & 0.8 &   45     &  38  &  1.2 \\
10$^6$     & 900 & 100 & 200 & 0.2  &    8.7      &    4.5     &  1.9  \\  
                   & 7100 & 160 & 180 & 0.2 &    46    &  39 &  1.2 \\
\hline
 $T = 50$~K  & HNCO/H$_2$     & HOCN/H$_2$     & HCNO/H$_2$     & HONC/H$_2$      & HNCO/HOCN & HNCO/HCNO  & HCNO/HOCN    \\ 
    &                 $\times 10^{13}$ & $\times 10^{13}$  & $\times 10^{13}$&   $\times 10^{13}$                               &     &    & \\ 
 \hline\noalign{\smallskip}
$n$(H$_2$)~cm$^{-3}$ &   &     &   &   &   &   \\
$1 \times 10^3$     & 16~000  & 240 & 5200 & 2100  &   66      &    3.1     &   22   \\  
                      & 24~000 &  330 & 8500 & 4000  &  74      &     2.8    &   26   \\
$1 \times 10^4$     & 32~000  & 650 & 2400 & 220  &   49      &   13     &    3.8 \\ 
                      &  110~000 & 1700 & 3300 & 240 &  63      &   33       &   1.9 \\
$1\times  10^5$     & 9600 & 240 & 380 & 4.1  &  40      &   25       &   1.6 \\  
                     &  49~000 & 670 & 180 & 1.4  &  73        &  280      &  0.3 \\
$1\times  10^6$     & 1000 & 17 & 36 & 0.04  &   59      &   28     &    2.1    \\  
                       &  6700 & 22 & 7.0 & 0.005 &  300   &  960       &  0.3 \\
 \hline
\end{tabular}
\tablefoot{For each density and temperature, the first line refers to steady state whereas the second line 
refers to early time. Early-time results computed at maximum of HNCO abundance.
\tablefoottext{a}{With the rate coefficients for CH$_{2}$ + NO measured by \citet{fikri01}, in which HCNO is the major product.}}
\end{table}