{ diff(x1, t) = (1*k24*k5 + (-1)*k24*x1*(k2 + k1) + 1*k24*x6/k14)/k24,
  diff(x2, t) = ((-1)*k24*x2*(k3 + k1) + 1*k24*x7/k8)/k24,
  diff(x3, t) = ((-1)*k24*x3*(k4 + k1) + (-1)*k24*k13*x2*x3/(k12 + x3) + 1*k24*k9*x2*x4/(k15 + x4))/k24,
  diff(x4, t) = ((-1)*k24*k9*x2*x4/(k15 + x4) + (-1)*k24*x4*(k16 + k1) + (-1)*k24*k21*x5*x4/(k10 + x4) + 1*k24*k18*x5*k25/(k22 + k25))/k24,
  diff(x5, t) = ((-1)*k24*x5*(k17 + k1) + 1*k24*x8/(k8 + k20))/k24,
  diff(x6, t) = ((-1)*k24*x6/k14 + 1*k24*k7*(k23*exp(k1*k14*(-2))*x3^2 + 1)/(k6 + k23*exp((-2)*k1*k14)*x3^2))/k24,
  diff(x7, t) = ((-1)*k24*x7/k8 + 1*k24*k11*x1*exp(-k1*k8))/k24,
  diff(x8, t) = ((-1)*k24*x8/(k8 + k20) + 1*k24*k19*x1*exp((-1)*k1*(k8 + k20)))/k24,
  diff(x9, t) = 0 }