[ Eq(Derivative(x1, t), 0/k13),
  Eq(Derivative(x2, t), ((-1)*k1*x1**3*k11**2*x18/((x18 + k11)*(x1**2*k11**2 + k10*x18**2 + 2*k10*k11*x18 + k10*k11**2))*x2*k13 + 1*k2*x7*k13)/k13),
  Eq(Derivative(x3, t), (-1)*k3*x3*x7*k13/k13),
  Eq(Derivative(x4, t), (-1)*k8*x4*(x10 + x11)*k13/k13),
  Eq(Derivative(x5, t), (-1)*k9*x5*(x10 + x11)*k13/k13),
  Eq(Derivative(x6, t), (-1)*k9*x6*x11*k13/k13),
  Eq(Derivative(x7, t), (1*k1*x1**3*k11**2*x18/((x18 + k11)*(x1**2*k11**2 + k10*x18**2 + 2*k10*k11*x18 + k10*k11**2))*x2*k13 + (-1)*k2*x7*k13 + (-1)*k3*x3*x7*k13 + 1*k4*x10*k13 + 1*k5*x9*(x8 + x9)*k13 + 1*k6*x9*x10*k13)/k13),
  Eq(Derivative(x8, t), (1*k3*x3*x7*k13 + (-1)*k4*x8*k13 + (-1)*k5*x8*(x8 + x9)*k13 + (-1)*k6*x8*x10*k13)/k13),
  Eq(Derivative(x9, t), (1*k4*x8*k13 + (-1)*k5*x9*(x8 + x9)*k13 + (-1)*k6*x9*x10*k13)/k13),
  Eq(Derivative(x10, t), ((-1)*k4*x10*k13 + 1*k5*x8*(x8 + x9)*k13 + 1*k6*x8*x10*k13)/k13),
  Eq(Derivative(x11, t), (1*k4*x10*k13 + 1*k5*x9*(x8 + x9)*k13 + 1*k6*x9*x10*k13 + (-1)*k7*x11*k13)/k13),
  Eq(Derivative(x12, t), 1*k7*x11*k13/k13),
  Eq(Derivative(x13, t), 1*k8*x4*(x10 + x11)*k13/k13),
  Eq(Derivative(x14, t), 1*k9*x5*(x10 + x11)*k13/k13),
  Eq(Derivative(x15, t), 1*k9*x5*(x10 + x11)*k13/k13),
  Eq(Derivative(x16, t), 1*k9*x6*x11*k13/k13),
  Eq(Derivative(x17, t), 1*k9*x6*x11*k13/k13),
  Eq(Derivative(x18, t), 0/k13) ]