{ diff(x1, t) = (1*k36*x1*k1*1/(1 + (k30*x1 + k31*x3)^2)*x6 + (-1)*k36*k4*x1 + (-1)*k36*k2*x1 + (-1)*k36*k9*x6*x1)/k36,
  diff(x2, t) = (1*k36*k2*k3*x1 + (-1)*k36*k5*x2)/k36,
  diff(x3, t) = (1*k36*k9*x6*x1 + 1*k36*k11*1/(1 + (k32*x1 + k33*x3)^2)*x6*x3 + (-1)*k36*k34*x3 + (-1)*k36*k29*x3)/k36,
  diff(x4, t) = (1*k36*k29*k28*x3 + (-1)*k36*k35*x4)/k36,
  diff(x5, t) = (1*k36*k4*x1 + 1*k36*k5*x2 + 1*k36*k34*x3 + 1*k36*k35*x4 + (-1)*k36*k19*x5*x6)/k36,
  diff(x6, t) = (1*k36*k18*x5 + (-1)*k36*k8*x6 + 1*k36*k10)/k36 }