{ diff(x1, t) = 0,
  diff(x2, t) = 0,
  diff(x3, t) = 0,
  diff(x4, t) = (1*k29*k10 + (-1)*k31*k14*x4 + (-1)*k31*k11*x15*x4/((k23*x15 + x4)*(1 + (x13/k28)^k20)))/k31,
  diff(x5, t) = 0,
  diff(x6, t) = ((-1)*k30*k2*x10*x6 + (-1)*k30*k3*x7*x6 + 1*k31*k16*x24*x12 + (-1)*k30*k12*x6)/k30,
  diff(x7, t) = (1*k30*k2*x10*x6 + (-1)*k30*k3*x7*x6)/k30,
  diff(x8, t) = 0,
  diff(x9, t) = (1*k30*k3*x7*x6 + (-1)*k30*k4*x9*x15)/k30,
  diff(x10, t) = (1*k29*k1/(1 + (x14/k22)^k19) + (-1)*k30*k2*x10*x6)/k30,
  diff(x11, t) = (1*k29*k13 + (-1)*k30*k7*x11*x16)/k30,
  diff(x13, t) = (1*k30*k4*x9*x15 + (-1)*k30*k5*x13*x18 + (-1)*k30*k17*x13)/k30,
  diff(x14, t) = (1*k30*k5*x13*x18 + (-1)*k30*k6*x14)/k30,
  diff(x15, t) = ((-3)*k30*k4*x9*x15 + 2*k30*k7*x11*x16 + 4*k31*k9*x19*x16 + (-1)*k31*k11*x15*x4/((k23*x15 + x4)*(1 + (x13/k28)^k20)))/k30,
  diff(x17, t) = (1*k30*k7*x11*x16 + (-1)*k30*k15*x17 + (-1)*k31*k8*x17*x20)/k30,
  diff(x18, t) = ((-1)*k30*k5*x13*x18 + 1*k30*k15*x17 + (-1)*k30*k18*x18)/k30,
  diff(x19, t) = (1*k31*k8*x17*x20 + (-1)*k31*k9*x19*x16)/k31,
  diff(x21, t) = 0,
  diff(x22, t) = 0,
  diff(x24, t) = ((-1)*k31*k16*x24*x12 + 1*k31*3*k11*x15*x4/((k23*x15 + x4)*(1 + (x13/k28)^k20))*x23/(k21 + x23))/k31,
  diff(x25, t) = 0,
  diff(x26, t) = 0 }