\documentclass[12pt]{jarticle}\pagestyle{empty}
\def\theequation{}\begin{document}
\def\vect#1{\mbox{\boldmath$#1$}}
\def\Mtt#1#2#3#4{\left(\begin{array}{rr}#1&#2 \\ #3&#4\end{array}\right)}
\def\Vt#1#2{\left(\begin{array}{r}#1 \\ #2\end{array}\right)}
\def\Mss#1#2#3#4#5#6#7#8#9{\left(\begin{array}{rrr}#1&#2&#3 \\ #4&#5&#6 \\ #7&#8&#9\end{array}\right)}
\def\Vs#1#2#3{\left(\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right)}
\def\Mqqa#1#2#3#4#5#6#7#8{\left(\begin{array}{rrrr}#1&#2&#3&#4 \\ #5&#6&#7&#8 \\}
\def\Mqqb#1#2#3#4#5#6#7#8{#1&#2&#3&#4 \\ #5&#6&#7&#8\end{array}\right)}
\def\Vq#1#2#3#4{\left(\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right)}
\def\sth{\sin\theta}\def\cth{\cos\theta}\def\Sth{S\theta}\def\Cth{C\theta}
\def\sph{\sin\phi}\def\cph{\cos\phi}\def\Sph{S\phi}\def\Cph{C\phi}
\def\sal{\sin\alpha}\def\cal{\cos\alpha}\def\Sal{S\alpha}\def\Cal{C\alpha}
\def\sps{\sin\psi}\def\cps{\cos\psi}\def\Sps{S\psi}\def\Cps{C\psi}
%
\begin{eqnarray}
%
\mathrm{Cv,sk}\ =N_{sk}R\left\{D_1(\frac{\theta_1}{T})-(\frac{\theta_2}{\theta_1})\left[D_1(\frac{\theta_2}{T})-D_2(\frac{\theta_2}{T})\right]-(\frac{\theta_3^2}{\theta_1\theta_2})\left[D_2(\frac{\theta_3}{T})-D_3(\frac{\theta_3}{T})\right]\right\}%
\nonumber\end{eqnarray}
\end{document}