{ diff(x1, t) = ((-1)*k2*x16*x1*k19 + (-1)*k6*x1*k19 + 1*k7*x2*k19)/k19,
  diff(x2, t) = (1*k6*x1*k19 + (-1)*k7*x2*k19)/k19,
  diff(x3, t) = (1*k2*x16*x1*k19 + (-1)*k3*x3*x7*k19)/k19,
  diff(x4, t) = (1*k3*x3*x7*k19 + (-1)*k4*x4*k19)/k19,
  diff(x5, t) = (1*k4*x4*k19 + (-1)*k5*x5*k19)/k19,
  diff(x6, t) = ((-1)*k8*x3*x6/(1 + k14*x14)*k19 + (-1)*k8*x4*x6/(1 + k14*x14)*k19 + 1*k9*x7*x8*k19)/k19,
  diff(x7, t) = (1*k8*x3*x6/(1 + k14*x14)*k19 + 1*k8*x4*x6/(1 + k14*x14)*k19 + (-1)*k9*x7*x8*k19)/k19,
  diff(x8, t) = 0/k19,
  diff(x9, t) = ((-1)*k10*x9*x7*k19 + 1*k11*x10*x8*k19)/k19,
  diff(x10, t) = (1*k10*x9*x7*k19 + (-1)*k11*x10*x8*k19)/k19,
  diff(x11, t) = 1*x10*k12*k19/k19,
  diff(x12, t) = (-1)*k13*x16*x12*k19/k19,
  diff(x13, t) = 1*k13*x16*x12*k19/k19,
  diff(x14, t) = (1*x11*k15/(k16 + x11)*k19 + (-1)*k17*x14*k19)/k19,
  diff(x15, t) = 1*x10*k18*k19/k19 }