{ diff(x1, t) = (1*k31*k25 + (-1)*k9*k31*x1/((k6 + x1)*(1 + x6/k7)) + (-1)*k13*x1*k31 + 2*k2*x7*k35 + 1*k2*x8*k35)/k31,
  diff(x2, t) = ((-1)*k14*x2*k32 + 1*k4*x12*k37)/k32,
  diff(x3, t) = (1*k14*x2*k32 + (-1)*k11*k33*x3/((k6 + x3)*(1 + x6/k7)) + 1*k20*x12*k37)/k33,
  diff(x4, t) = ((-1)*k10*k34*x4/((k6 + x4)*(1 + x6/k7)) + 2*k3*x7*k35 + 1*k3*x8*k35)/k34,
  diff(x5, t) = (1*k19*x7*k35 + (-1)*k35*k1*x9*x5 + 1*k3*x7*k35 + 1*k5*x7*k35 + 1*k2*x7*k35 + 1*k3*x8*k35 + 1*k19*x8*k35 + 1*k5*x8*k35 + 1*k2*x8*k35)/k35,
  diff(x6, t) = (1*k35*k38 + (-1)*k35*k39*x6)/k35,
  diff(x7, t) = ((-1)*k19*x7*k35 + (-1)*k3*x7*k35 + (-1)*k5*x7*k35 + (-1)*k2*x7*k35 + 1*k35*k8*x8*x9)/k35,
  diff(x8, t) = (1*k35*k1*x9*x5 + (-1)*k35*k8*x8*x9 + (-1)*k3*x8*k35 + (-1)*k19*x8*k35 + (-1)*k5*x8*k35 + (-1)*k2*x8*k35)/k35,
  diff(x9, t) = (1*k9*k31*x1/((k6 + x1)*(1 + x6/k7)) + 1*k11*k33*x3/((k6 + x3)*(1 + x6/k7)) + 1*k10*k34*x4/((k6 + x4)*(1 + x6/k7)) + (-1)*k35*k1*x9*x5 + 1*k12*k36*x10/((k6 + x10)*(1 + x6/k7)) + (-1)*k35*k8*x8*x9)/k35,
  diff(x10, t) = (2*k5*x7*k35 + (-1)*k36*k15*x10 + (-1)*k12*k36*x10/((k6 + x10)*(1 + x6/k7)) + 1*k5*x8*k35)/k36,
  diff(x11, t) = 0,
  diff(x12, t) = (2*k19*x7*k35 + 1*k19*x8*k35 + (-1)*k4*x12*k37 + (-1)*k20*x12*k37)/k37 }