{ diff(x1, t) = ((-1)*k1*k2*x1*x2 + (-1)*k1*k3*x1*x3 + (-1)*k1*k4*x1*x2*x3 + 1*k1*k5*x7 + (-1)*k1*k8*x1 + 1*k1*k11*x4 + 1*k1*k12*x5 + 1*k1*k13*x6)/k1,
  diff(x2, t) = ((-1)*k1*k2*x1*x2 + (-1)*k1*k4*x1*x2*x3 + 1*k1*k6*x8 + (-1)*k1*k9*x2 + 1*k1*k11*x4 + 1*k1*k13*x6)/k1,
  diff(x3, t) = ((-1)*k1*k3*x1*x3 + (-1)*k1*k4*x1*x2*x3 + 1*k1*k7*x9 + (-1)*k1*k10*x3 + 1*k1*k12*x5 + 1*k1*k13*x6)/k1,
  diff(x4, t) = (1*k1*k2*x1*x2 + (-1)*k1*k11*x4 + (-1)*k1*k14*x4)/k1,
  diff(x5, t) = (1*k1*k3*x1*x3 + (-1)*k1*k12*x5 + (-1)*k1*k15*x5)/k1,
  diff(x6, t) = (1*k1*k4*x1*x2*x3 + (-1)*k1*k13*x6 + (-1)*k1*k16*x6)/k1,
  diff(x7, t) = 0/k1,
  diff(x8, t) = 0/k1,
  diff(x9, t) = 0/k1,
  diff(x10, t) = (1*k1*k17*x1 + (-1)*k1*k18*x10)/k1 }