[ Eq(Derivative(x1, t), ((-1)*k12*k1*x1*x2 + 1*k12*k2*x3 + 1*k12*k5*x4)/k12),
  Eq(Derivative(x2, t), ((-1)*k12*k1*x1*x2 + 1*k12*k2*x3 + 1*k12*k11*x11)/k12),
  Eq(Derivative(x3, t), (1*k12*k1*x1*x2 + (-1)*k12*k2*x3 + (-1)*k12*k3*x3*x9 + 1*k12*k4*x4)/k12),
  Eq(Derivative(x4, t), (1*k12*k3*x3*x9 + (-1)*k12*k4*x4 + (-1)*k12*k5*x4)/k12),
  Eq(Derivative(x5, t), (1*k12*k5*x4 + (-1)*k12*k6*x5*x7 + 1*k12*k7*x8)/k12),
  Eq(Derivative(x6, t), (1*k12*k5*x4 + (-1)*k12*k9*x6*x10 + 1*k12*k10*x11)/k12),
  Eq(Derivative(x7, t), ((-1)*k12*k6*x5*x7 + 1*k12*k7*x8 + 1*k12*k8*x8)/k12),
  Eq(Derivative(x8, t), (1*k12*k6*x5*x7 + (-1)*k12*k7*x8 + (-1)*k12*k8*x8)/k12),
  Eq(Derivative(x9, t), ((-1)*k12*k3*x3*x9 + 1*k12*k4*x4 + 1*k12*k8*x8)/k12),
  Eq(Derivative(x10, t), ((-1)*k12*k9*x6*x10 + 1*k12*k10*x11 + 1*k12*k11*x11)/k12),
  Eq(Derivative(x11, t), (1*k12*k9*x6*x10 + (-1)*k12*k10*x11 + (-1)*k12*k11*x11)/k12) ]