[ Eq(Derivative(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),
  Eq(Derivative(x2, t), ((-1)*k14*x2*k32 + 1*k4*x12*k37)/k32),
  Eq(Derivative(x3, t), (1*k14*x2*k32 + (-1)*k11*k33*x3/((k6 + x3)*(1 + x6/k7)) + 1*k20*x12*k37)/k33),
  Eq(Derivative(x4, t), ((-1)*k10*k34*x4/((k6 + x4)*(1 + x6/k7)) + 2*k3*x7*k35 + 1*k3*x8*k35)/k34),
  Eq(Derivative(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),
  Eq(Derivative(x6, t), (1*k35*k38 + (-1)*k35*k39*x6)/k35),
  Eq(Derivative(x7, t), ((-1)*k19*x7*k35 + (-1)*k3*x7*k35 + (-1)*k5*x7*k35 + (-1)*k2*x7*k35 + 1*k35*k8*x8*x9)/k35),
  Eq(Derivative(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),
  Eq(Derivative(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),
  Eq(Derivative(x10, t), (2*k5*x7*k35 + (-1)*k36*k15*x10 + (-1)*k12*k36*x10/((k6 + x10)*(1 + x6/k7)) + 1*k5*x8*k35)/k36),
  Eq(Derivative(x11, t), 0),
  Eq(Derivative(x12, t), (2*k19*x7*k35 + 1*k19*x8*k35 + (-1)*k4*x12*k37 + (-1)*k20*x12*k37)/k37) ]