{ diff(x1, t) = (-1)*k1*k2*x1/k1,
  diff(x2, t) = 1*k1*k2*x1/k1,
  diff(x3, t) = (1*k1*k3 + 1*k1*k4*x4 + (-1)*k1*k5*x3)/k1,
  diff(x4, t) = (1*k1*k7*x5*x2 + (-1)*k1*k9*x4)/k1,
  diff(x5, t) = (1*k1*k6*x3 + (-1)*k1*k7*x5*x2 + (-1)*k1*k8*x5)/k1,
  diff(x6, t) = (-1)*k1*k10*x6/k1,
  diff(x7, t) = 1*k1*k10*x6/k1,
  diff(x8, t) = ((-1)*k1*k11*x8*x9 + (-1)*k1*k12*x8 + 1*k1*k19*x7*x4)/k1,
  diff(x9, t) = (1*k1*k17*x10 + (-1)*k1*k18*x9)/k1,
  diff(x10, t) = (1*k1*k13 + 1*k1*k14*x7 + (-1)*k1*k15*x10*x4 + (-1)*k1*k16*x10)/k1 }