{ diff(x1, t) = 0,
  diff(x2, t) = 0,
  diff(x3, t) = 0,
  diff(x4, t) = 0,
  diff(x5, t) = 0,
  diff(x6, t) = 0,
  diff(x7, t) = 0,
  diff(x8, t) = 0,
  diff(x9, t) = 0,
  diff(x10, t) = 0,
  diff(x11, t) = (1*(k1 + k2*k57 + k3*x11*x12 + k4*x11*x12*x13)/(1 + k5*k57 + k6*x11 + k7*x11*x12 + k8*x11*x12*x13 + k9*x15*x11 + k10*x16) + (-1)*k11*x11)/k47,
  diff(x12, t) = (1*(k12 + k13*x11*x12 + k14*x11*x12*x13)/(1 + k15*x11 + k16*x11*x12 + k17*x11*x12*x13) + (-1)*k19*x12)/k47,
  diff(x13, t) = (1*(k2*x17 + k3*x17*x13)/(1 + k6*x17 + k7*x17*x13 + k8*x17*x14) + (-1)*k46*x13)/k47,
  diff(x14, t) = (1*(k13*x17 + k14*x14)/(1 + k16*x17 + k17*x14 + k18*x13) + (-1)*k45*x14)/k47,
  diff(x15, t) = (1*(k28 + k29*x15)/(1 + k30*x15 + k31*x15*x11) + (-1)*k32*x15)/k47,
  diff(x16, t) = (1*(k33 + k34*x15 + k35*x14)/(1 + k36*x15 + k37*x14) + (-1)*k38*x16)/k47,
  diff(x17, t) = 0/k47,
  diff(x18, t) = 0/k47 }