[ Diff(x[1], t) = (-k[1])*(k[7] + x[8])*x[1] - k[2]*x[7]*x[1],
  Diff(x[2], t) = k[2]*x[7]*x[1] - k[3]*x[7]^k[6]*x[2],
  Diff(x[3], t) = k[3]*x[7]^k[6]*x[2] - 4*k[4]*x[3],
  Diff(x[4], t) = 4*k[4]*x[3] - 4*k[4]*x[4],
  Diff(x[5], t) = 4*k[4]*x[4] - 4*k[4]*x[5],
  Diff(x[6], t) = 4*k[4]*x[5] - 4*k[4]*x[6],
  Diff(x[7], t) = 4*k[4]*x[6] - k[5]*x[7],
  Diff(x[8], t) = k[5]*x[7],
  Diff(x[9], t) = k[1]*(k[7] + x[8])*x[1] ]