我在 Beamer 课堂上做演讲，我希望我的一个方程式能够产生这样的效果：每个项的注释慢慢出现，如下图所示。但是，我不知道该怎么做。我该如何创建这样的效果？
\documentclass[12pt,compress,mathserif,serif,t]{beamer}%
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{hyperref}
\usepackage{graphicx}
\usepackage{caption}
\usepackage{subfig}
\usepackage{color,xcolor}
\usepackage{ragged2e}
\usepackage[T1]{fontenc}
\usepackage[brazil]{babel}
\usepackage{fouriernc}
\usepackage{indentfirst}
\usepackage{dsfont}
\usepackage{tikz}
\begin{document}
\begin{frame}
\frametitle{Chern-Simons baby Skyrme model}\framesubtitle{The model and its equations of motion}
\only<1>{The baby Skyrme model%
\begin{equation}
\mathcal{L}=\dfrac{\nu^{2}}{2}\partial_{\mu}\boldsymbol{\phi}\cdot
\partial^{\mu}\boldsymbol{\phi}-\dfrac{\lambda^{2}}{4}\left( \partial_{\mu
}\boldsymbol{\phi}\times\partial_{\nu}\boldsymbol{\phi}\right) \cdot\left(
\partial^{\mu}\boldsymbol{\phi}\times\partial^{\nu}\boldsymbol{\phi}\right)
-V\left( \boldsymbol{\hat{n}}\cdot\boldsymbol{\phi}\right) \label{S1A0}%
\end{equation}
is (1+2)-dimensional a non-linear theory that provides
\alert{topological solitons}.}
\only<2>{The baby Skyrme model%
\begin{equation}
\mathcal{L}=\underbrace{\dfrac{\nu^{2}}{2}\partial_{\mu}\boldsymbol{\phi}%
\cdot\partial^{\mu}\boldsymbol{\phi}}_{\text{sigma}}-\underbrace{\dfrac
{\lambda^{2}}{4}\left( \partial_{\mu}\boldsymbol{\phi}\times\partial_{\nu
}\boldsymbol{\phi}\right) \cdot\left( \partial^{\mu}\boldsymbol{\phi}%
\times\partial^{\nu}\boldsymbol{\phi}\right) }_{\text{Skyrme}}%
-\underbrace{V\left( \boldsymbol{\hat{n}}\cdot\boldsymbol{\phi}\right)
}_{\text{potencial}}%
\end{equation}
is (1+2)-dimensional a non-linear theory that provides
\alert{topological solitons}.}
\only<3>{The baby Skyrme model%
\begin{equation}
\mathcal{L}=\overbrace{\underbrace{\dfrac{\nu^{2}}{2}\partial_{\mu
}\boldsymbol{\phi}\cdot\partial^{\mu}\boldsymbol{\phi}}_{\text{sigma}%
}-\underbrace{\dfrac{\lambda^{2}}{4}\left( \partial_{\mu}\boldsymbol{\phi
}\times\partial_{\nu}\boldsymbol{\phi}\right) \cdot\left( \partial^{\mu
}\boldsymbol{\phi}\times\partial^{\nu}\boldsymbol{\phi}\right) }%
_{\text{Skyrme}}}^{U\left( 1\right) \text{ and }SO\left( 3\right) \text{
invariant}}-\underbrace{\overbrace{V\left( \boldsymbol{\hat{n}}%
\cdot\boldsymbol{\phi}\right) }^{\substack{U\left( 1\right) \text{
invariant}\\S0\left( 3\right) \text{ partially breaking}}}}%
_{\text{potencial}}%
\end{equation}
is (1+2)-dimensional a non-linear theory that provides
\alert{topological solitons}.}\pause
\end{frame}
\end{document}
更新：
我尝试了以下解决方案，但是仍有需要改进的地方：
\begin{frame}
\frametitle{Chern-Simons baby Skyrme model}
\framesubtitle{The model and its equations of motion}
\tikzstyle{na} = [baseline=+.5ex]
The baby Skyrme model
\begin{equation}
\mathcal{L}=\only<1>{\dfrac{\nu^{2}}{2}\partial_{\mu}\boldsymbol{\phi}\cdot
\partial^{\mu}\boldsymbol{\phi}-\dfrac{\lambda^{2}}{4}\left( \partial_{\mu
}\boldsymbol{\phi}\times\partial_{\nu}\boldsymbol{\phi}\right) \cdot\left(
\partial^{\mu}\boldsymbol{\phi}\times\partial^{\nu}\boldsymbol{\phi}\right)-V\left( \boldsymbol{\hat{n}}\cdot\boldsymbol{\phi}\right)}%
\only<2>{\tikz[baseline]{\node(t1){$\underbrace{\dfrac{\nu^{2}}{2}\partial_{\mu}\boldsymbol{\phi}\cdot
\partial^{\mu}\boldsymbol{\phi}}$}}-\tikz[baseline]{\node(t2){$\underbrace{\dfrac{\lambda^{2}}{4}\left( \partial_{\mu
}\boldsymbol{\phi}\times\partial_{\nu}\boldsymbol{\phi}\right) \cdot\left(
\partial^{\mu}\boldsymbol{\phi}\times\partial^{\nu}\boldsymbol{\phi}\right)}$}}-\tikz[baseline]{\node(t3){$\underbrace{V\left( \boldsymbol{\hat{n}}\cdot\boldsymbol{\phi}\right)}$}}}%
\only<3>{\tikz[baseline]{\node(t4){$\overbrace{\tikz[baseline]{\node(t1){$\underbrace{\dfrac{\nu^{2}}{2}\partial_{\mu}\boldsymbol{\phi}\cdot
\partial^{\mu}\boldsymbol{\phi}}$}}-\tikz[baseline]{\node(t2){$\underbrace{\dfrac{\lambda^{2}}{4}\left( \partial_{\mu
}\boldsymbol{\phi}\times\partial_{\nu}\boldsymbol{\phi}\right) \cdot\left(
\partial^{\mu}\boldsymbol{\phi}\times\partial^{\nu}\boldsymbol{\phi}\right)}$}}}$}}-\tikz[baseline]{\node(t5){$\overbrace{\tikz[baseline]{\node(t3){$\underbrace{V\left( \boldsymbol{\hat{n}}\cdot\boldsymbol{\phi}\right)}$}}}$}}}%
\end{equation}
\begin{tikzpicture}[remember picture,overlay]{
\draw[] (t5) node[anchor=south,text = black]{$\substack{ U\left( 1\right)\text{
invariant}\\S0\left( 3\right) \text{ partially breaking}}$};
\draw[] (t4) node[anchor=south ,text = black]{$U\left(1\right)$ and $SO\left(3\right)$ invariant};
\draw[] (t3) node[anchor=north,text = black]{potential};
\draw[] (t2) node[anchor=north,text = black]{Skyrme};
\draw[] (t1) node[anchor=north,text = black]{sigma model};}
\end{tikzpicture}