{ diff(x1, t) = (1*k41*k1*x3/(k2 + x3)*k3/(k3 + x1)*k4/(k4 + x2) + (-1)*k41*k5*x1*x5 + 1*k41*k6*x2 + (-1)*k41*k7*x1)/k41,
  diff(x2, t) = (1*k41*k5*x1*x5 + (-1)*k41*k6*x2 + (-1)*k41*k29*x2*x9 + 1*k41*k30*x7 + (-1)*k41*k32*x2)/k41,
  diff(x3, t) = (1*k41*(k8 + k9*(k10^2 + x3^2)/(k11^2 + x3^2)*k12/(k12 + x1)*k13/(k13 + x2)) + (-1)*k41*k14*x3)/k41,
  diff(x4, t) = (1*k41*(k15*x6 + k16*x3*k17/(k17 + x1)*k18/(k18 + x2)) + 1*k41*k22*x5 + (-1)*k41*k19*x4*x5/(k20 + x5) + (-1)*k41*k21*x4)/k41,
  diff(x5, t) = ((-1)*k41*k22*x5 + 1*k41*k19*x4*x5/(k20 + x5) + (-1)*k41*k23*x5)/k41,
  diff(x6, t) = (1*k41*(k24 + k25*x3*k26/(k26 + x1)*k27/(k27 + x2)) + (-1)*k41*k28*x6)/k41,
  diff(x7, t) = (1*k41*k29*x2*x9 + (-1)*k41*k30*x7 + (-1)*k41*k31*x7)/k41,
  diff(x8, t) = (1*k41*k33*x3*k34/(k34 + x1)*k35/(k35 + x2) + (-1)*k41*k36*x8*x9/(k37 + x9) + 1*k41*k38*x9 + (-1)*k41*k39*x8)/k41,
  diff(x9, t) = (1*k41*k36*x8*x9/(k37 + x9) + (-1)*k41*k38*x9 + (-1)*k41*k40*x9)/k41 }