\frac{dx_{1}}{dt} = \left(1 \cdot k_{1} \cdot k_{2} \cdot x_{1} / \left(k_{2} \cdot x_{1} + \left(k_{3} + k_{4} \cdot x_{1}\right) \cdot x_{2}\right) + -1 \cdot k_{5} \cdot x_{1}\right) / k_{19}\\
\frac{dx_{2}}{dt} = \left(1 \cdot k_{6} \cdot x_{1} + -1 \cdot k_{7} \cdot x_{2} \cdot x_{5} + -1 \cdot k_{8} \cdot x_{2}\right) / k_{19}\\
\frac{dx_{3}}{dt} = \left(1 \cdot k_{7} \cdot x_{2} \cdot x_{5} + -1 \cdot k_{9} \cdot x_{3}\right) / k_{19}\\
\frac{dx_{4}}{dt} = \left(1 \cdot k_{10} \cdot x_{1} + 1 \cdot k_{11} \cdot x_{6} + -1 \cdot k_{12} \cdot x_{4} \cdot x_{5} + 1 \cdot k_{13} \cdot x_{5} + -1 \cdot k_{14} \cdot x_{4}\right) / k_{19}\\
\frac{dx_{5}}{dt} = \left(1 \cdot k_{12} \cdot x_{4} \cdot x_{5} + -1 \cdot k_{13} \cdot x_{5} + -1 \cdot k_{15} \cdot x_{5}\right) / k_{19}\\
\frac{dx_{6}}{dt} = \left(1 \cdot k_{16} \cdot x_{1} + 1 \cdot \operatorname{piecewise}(\frac{11}{250}, t \le 60, 0) + -1 \cdot k_{18} \cdot x_{6}\right) / k_{19}