{ diff(x1, t) = (1*k1*k4*x1^2*(x2 - x1)/(k5^2 + x1^2) + 1*k1*k6*(x2 - x1) + (-1)*k2*k7*x1 + 1*k1*x3*(k8*x1^2/(k9^2 + x1^2) + k10) + (-1)*k3*k11*x1^8/(k12^8 + x1^8) + 1*k1*k13*x4 + (-1)*k1*k14*x1*x5)/k1,
  diff(x2, t) = (-1/4*k1*k4*x1^2*(x2 - x1)/(k5^2 + x1^2) + -1/4*k1*k6*(x2 - x1) + 1/4*k2*k7*x1)/k2,
  diff(x3, t) = (-1/4*k1*x3*(k8*x1^2/(k9^2 + x1^2) + k10) + 1/4*k3*k11*x1^8/(k12^8 + x1^8))/k3,
  diff(x4, t) = ((-1)*k1*k13*x4 + 1*k1*k14*x1*x5)/k1,
  diff(x5, t) = (1*k1*k13*x4 + (-1)*k1*k14*x1*x5)/k1 }