{ diff(x1, t) = (1*k29*k1/k18 + (-1)*k29*k2*x1 + (-1)*k29*k3*k18*x1*x3 + (-1)*k29*k4*x1*x2)/k29,
  diff(x2, t) = (1*k29*k5*x2 + (-1)*k29*k6*x2 + (-1)*k29*k8*k18*x1*x2 + (-1)*k29*k7*x2 + (-1)*k29*k9*x3*x2 + (-1)*k29*k10*x2^2/(k11/k18 + x2))/k29,
  diff(x3, t) = ((-1)*k29*k17*x3*x2 + (-1)*k29*k14*x3 + 1*k29*k12*x3*(1 - x3/(k13/k18)) + (-1)*k29*k16*k18*x1*x3 + (-1)*k29*k15*x3 + 1*k29*k10*x2^2/(k11/k18 + x2))/k29 }