{ diff(x1, t) = (1*k14*k1*x1 + (-1)*k14*k1*k2*x1*x1 + (-1)*k14*k4*x2*x1/(k5 + x1))/k14,
  diff(x2, t) = ((-1)*k14*k8*x2 + 1*k14*k3*x1 + 1*k14*k9*x2*x3/(k10 + x3) + 1*k14*k6)/k14,
  diff(x3, t) = (1*k14*k7 + (-1)*k14*k13*x3 + 1*k14*k11*x2*x1/(k12 + x1))/k14 }