[ Eq(Derivative(x1, t), ((-1)*k23*k1*x1 + 1*k23*k2*x6**(3/2))/k23),
  Eq(Derivative(x2, t), (1*k23*k3*x2 + (-1)*k23*k3*x2**2/((k4*x1 + k5)/(x1 + k6)))/k23),
  Eq(Derivative(x3, t), (1*k23*k9*x3 + (-1)*k23*k9*x3**2/(k11 + k10*x4/(1 + x4/k12)))/k23),
  Eq(Derivative(x4, t), (1*k23*k7*x1 + (-1)*k23*k8*x4)/k23),
  Eq(Derivative(x5, t), (1*k23*k13*x1/(k14 + x1) + (-1)*k23*k15*x5)/k23),
  Eq(Derivative(x6, t), ((-1)*k23*k20*x5*x2*x6 + (-1)*k23*k21*x5*x3*x6 + 1*k23*k18 + 1*k23*x6**((-1)/2)*x6**(3/2)*10**(-6))/k23) ]