Your interest in prettifying the expression is most likely around the alignment. Regardless, don't use eqnarray
. Rather use the capabilities of amsmath
's align
environment(s):

\documentclass[twocolumn]{article}
\usepackage{lipsum}% http://ctan.org/pkg/lipsum
\usepackage{amsmath}% http://ctan.org/pkg/amsmath
\newcommand{\noeq}{\phantom{=}{}}
\begin{document}
\section{A section}
Here is some text. Your original \verb|eqnarray|:
\begin{eqnarray}
&& B =-0.76562-2.38354S-0.17144R+0.81956\lambda \nonumber \\
&&-0.18059SR+0.14635S\lambda+0.0253R\lambda+0.02885S^2 \nonumber \\
&&+0.00815R^2+0.00332\lambda^2-0.00112SR\lambda+0.01041S^2R\nonumber \\
&&-0.00665S^2\lambda+0.000005SR^2+0.00016S\lambda^2 \nonumber \\
&&-0.000173R^2\lambda+0.00317S^3+0.000006R^3\nonumber \\
&&-0.00017\lambda^3
\end{eqnarray}
Here is an \verb|align| version:
\begin{align}
B &= -0.76562-2.38354S-0.17144R+0.81956\lambda \nonumber \\
&\noeq -0.18059SR+0.14635S\lambda+0.0253R\lambda \nonumber \\
&\noeq +0.02885S^2+0.00815R^2+0.00332\lambda^2 \nonumber \\
&\noeq -0.00112SR\lambda+0.01041S^2R-0.00665S^2\lambda \nonumber \\
&\noeq +0.000005SR^2+0.00016S\lambda^2-0.000173R^2\lambda \nonumber \\
&\noeq +0.00317S^3+0.000006R^3-0.00017\lambda^3
\end{align}
\lipsum[1-3]
\end{document}
As a motivation, see \eqnarray
vs \align
, where you will find additional reference to not using eqnarray
.
alingn
insteadeqnarray
– c.p. Sep 30 '12 at 1:04align
environment instead of aneqnarray
environment. Theeqnarray
environment suffers from several rather severe shortcomings. However, if you absolutely must use the latter environment anyway, at least start off the first line withB&=&-0.76562
instead of&& B =-0.76562
. – Mico Sep 30 '12 at 2:47