{ diff(x1, t) = 0,
  diff(x2, t) = (1*k31*(k1 + k2*k3) + (-1)*k32*k4*x2^2/(k5^2 + x2^2) + 1*k33*k6*x3^4*x4^2*x2^k7/((k8^4 + x3^4)*(k9^2 + x4^2)*(k10^k7 + x2^k7)) + 1*k33*k11*x4 + (-1)*k32*k12*x2)/k32,
  diff(x3, t) = (1*k32*k3*k13 + (-1)*k32*k14*x3^k30*x2^k15/((k16^k30 + x3^k30)*(k17^k15 + x2^k15)) + (-1)*k32*k18*x3)/k32,
  diff(x4, t) = (1*k32*k4*x2^2/(k5^2 + x2^2) + (-1)*k33*k6*x3^4*x4^2*x2^k7/((k8^4 + x3^4)*(k9^2 + x4^2)*(k10^k7 + x2^k7)) + (-1)*k33*k11*x4)/k33,
  diff(x5, t) = (1*k32*k19*(1 + k20*x2^4/(k21^4 + x2^4))*(1 - x5)/(k22/(1 + x2^4/k23^4) + 1 - x5) + (-1)*k32*k24*(1 + k25*k26/(k27 + k26))*x5/(k28/(1 + k26/k29) + x5))/k32 }