[ Eq(Derivative(x1, t), (-1)*k12*(k1*x1*x7 - k2*x6)/k12),
  Eq(Derivative(x2, t), 0/k12),
  Eq(Derivative(x3, t), ((-1)*k12*(k4*x8*x3 - k5*x9) + 1*k12*k10*x4)/k12),
  Eq(Derivative(x4, t), ((-1)*k12*k10*x4 + 1*k12*k6*x9)/k12),
  Eq(Derivative(x5, t), (1*k12*k7*x4 + (-1)*k12*k8*x8*x5)/k12),
  Eq(Derivative(x6, t), (1*k12*(k1*x1*x7 - k2*x6) + (-1)*k12*(k3*x6 - k9*x8))/k12),
  Eq(Derivative(x7, t), (-1)*k12*(k1*x1*x7 - k2*x6)/k12),
  Eq(Derivative(x8, t), (1*k12*(k3*x6 - k9*x8) + (-1)*k12*(k4*x8*x3 - k5*x9) + (-1)*k12*k8*x8*x5 + 1*k12*k6*x9)/k12),
  Eq(Derivative(x9, t), (1*k12*(k4*x8*x3 - k5*x9) + (-1)*k12*k6*x9)/k12),
  Eq(Derivative(x10, t), 1*k12*k8*x8*x5/k12) ]