{ diff(x1, t) = (-1)*(k2*x2*x1 - k3*x3)*k1/k1,
  diff(x2, t) = (-1)*(k2*x2*x1 - k3*x3)*k1/k1,
  diff(x3, t) = (1*(k2*x2*x1 - k3*x3)*k1 + (-2)*(k4*x3*x3 - k5*x4)*k1)/k1,
  diff(x4, t) = (1*(k4*x3*x3 - k5*x4)*k1 + (-1)*(k6*x4 - k7*x5)*k1 + 1*k8*x5/(k9 + x5)*k1)/k1,
  diff(x5, t) = (1*(k6*x4 - k7*x5)*k1 + (-1)*k8*x5/(k9 + x5)*k1 + (-1)*(k10*x5*x6 - k11*x7)*k1 + 1*(k14*x8 - k15*x5*x9)*k1 + (-1)*(k18*x5*x10 - k19*x11)*k1 + 1*(k22*x13 - k23*x5*x14)*k1 + (-1)*(k26*x5*x15 - k27*x16)*k1 + 1*(k30*x17 - k31*x18*x5)*k1 + 1*(k36*x19 - k37*x5*x20)*k1 + 1*(k40*x21 - k41*x22*x5)*k1)/k1,
  diff(x6, t) = ((-1)*(k10*x5*x6 - k11*x7)*k1 + 1*k16*x9/(k17 + x9)*k1)/k1,
  diff(x7, t) = (1*(k10*x5*x6 - k11*x7)*k1 + (-1)*(k12*x7 - k13*x8)*k1)/k1,
  diff(x8, t) = (1*(k12*x7 - k13*x8)*k1 + (-1)*(k14*x8 - k15*x5*x9)*k1)/k1,
  diff(x9, t) = (1*(k14*x8 - k15*x5*x9)*k1 + (-1)*k16*x9/(k17 + x9)*k1 + (-1)*(k50*x9 - k51*x23)*k1)/k1,
  diff(x10, t) = ((-1)*(k18*x5*x10 - k19*x11)*k1 + 1*(k24*x14 - k25*x10*x12)*k1 + (-1)*(k34*x17*x10 - k35*x19)*k1 + (-1)*(k42*x18*x10 - k43*x20)*k1)/k1,
  diff(x11, t) = (1*(k18*x5*x10 - k19*x11)*k1 + (-1)*(k20*x11*x12 - k21*x13)*k1)/k1,
  diff(x12, t) = ((-1)*(k20*x11*x12 - k21*x13)*k1 + 1*(k24*x14 - k25*x10*x12)*k1 + (-1)*(k38*x19*x12 - k39*x21)*k1 + (-1)*(k44*x20*x12 - k45*x22)*k1)/k1,
  diff(x13, t) = (1*(k20*x11*x12 - k21*x13)*k1 + (-1)*(k22*x13 - k23*x5*x14)*k1)/k1,
  diff(x14, t) = (1*(k22*x13 - k23*x5*x14)*k1 + (-1)*(k24*x14 - k25*x10*x12)*k1 + 1*(k46*x22 - k47*x18*x14)*k1 + (-1)*(k48*x17*x14 - k49*x21)*k1)/k1,
  diff(x15, t) = ((-1)*(k26*x5*x15 - k27*x16)*k1 + 1*k32*x18/(k33 + x18)*k1)/k1,
  diff(x16, t) = (1*(k26*x5*x15 - k27*x16)*k1 + (-1)*(k28*x16 - k29*x17)*k1)/k1,
  diff(x17, t) = (1*(k28*x16 - k29*x17)*k1 + (-1)*(k30*x17 - k31*x18*x5)*k1 + (-1)*(k34*x17*x10 - k35*x19)*k1 + (-1)*(k48*x17*x14 - k49*x21)*k1)/k1,
  diff(x18, t) = (1*(k30*x17 - k31*x18*x5)*k1 + (-1)*k32*x18/(k33 + x18)*k1 + (-1)*(k42*x18*x10 - k43*x20)*k1 + 1*(k46*x22 - k47*x18*x14)*k1)/k1,
  diff(x19, t) = (1*(k34*x17*x10 - k35*x19)*k1 + (-1)*(k36*x19 - k37*x5*x20)*k1 + (-1)*(k38*x19*x12 - k39*x21)*k1)/k1,
  diff(x20, t) = (1*(k36*x19 - k37*x5*x20)*k1 + 1*(k42*x18*x10 - k43*x20)*k1 + (-1)*(k44*x20*x12 - k45*x22)*k1)/k1,
  diff(x21, t) = (1*(k38*x19*x12 - k39*x21)*k1 + (-1)*(k40*x21 - k41*x22*x5)*k1 + 1*(k48*x17*x14 - k49*x21)*k1)/k1,
  diff(x22, t) = (1*(k40*x21 - k41*x22*x5)*k1 + 1*(k44*x20*x12 - k45*x22)*k1 + (-1)*(k46*x22 - k47*x18*x14)*k1)/k1,
  diff(x23, t) = 1*(k50*x9 - k51*x23)*k1/k1 }