[ Eq(Derivative(x1, t), (-1)*k1*k2*x1*x2/k1),
  Eq(Derivative(x2, t), (-1)*k1*k2*x1*x2/k1),
  Eq(Derivative(x3, t), (1*k1*k2*x1*x2 + (-1)*k1*k4*x3*x4 + 1*k1*k5*x6)/k1),
  Eq(Derivative(x4, t), ((-1)*k1*k3*x1*x2*x4 + (-1)*k1*k4*x3*x4)/k1),
  Eq(Derivative(x5, t), (1*k1*k3*x1*x2*x4 + 1*k1*k6*x3*x7 + (-1)*k1*k8*x5)/k1),
  Eq(Derivative(x6, t), (1*k1*k4*x3*x4 + (-1)*k1*k5*x6)/k1),
  Eq(Derivative(x7, t), (1*k1*k5*x6 + (-1)*k1*k6*x3*x7 + (-1)*k1*k7*x7)/k1),
  Eq(Derivative(x8, t), 1*k1*k7*x7/k1),
  Eq(Derivative(x9, t), 1*k1*k8*x5/k1) ]