{ diff(x1, t) = 0/k16,
  diff(x2, t) = ((-1)*k1*x1^3*k14^2*x18/((x18 + k14)*(x1^2*k14^2 + k13*x18^2 + 2*k13*k14*x18 + k13*k14^2))*x2*k16 + 1*k2*x7*k16)/k16,
  diff(x3, t) = (-1)*k3*x3*x7*k16/k16,
  diff(x4, t) = (-1)*k11*x4*(x10 + x11)*k16/k16,
  diff(x5, t) = (-1)*k12*x5*(x10 + x11)*k16/k16,
  diff(x6, t) = (-1)*k12*x6*x11*k16/k16,
  diff(x7, t) = (1*k1*x1^3*k14^2*x18/((x18 + k14)*(x1^2*k14^2 + k13*x18^2 + 2*k13*k14*x18 + k13*k14^2))*x2*k16 + (-1)*k2*x7*k16 + (-1)*k3*x3*x7*k16 + 1*k4*x10*k16 + 1*k5*x10*(x8 + x9)*k16 + 1*k6*x10*x10*k16 + 1*k7*x9*k16 + 1*k8*x9*(x8 + x9)*k16 + 1*k9*x9*x10*k16)/k16,
  diff(x8, t) = (1*k3*x3*x7*k16 + (-1)*k4*x8*k16 + (-1)*k5*x8*(x8 + x9)*k16 + (-1)*k6*x8*x10*k16 + (-1)*k7*x8*k16 + (-1)*k8*x8*(x8 + x9)*k16 + (-1)*k9*x8*x10*k16)/k16,
  diff(x9, t) = (1*k4*x8*k16 + 1*k5*x8*(x8 + x9)*k16 + 1*k6*x8*x10*k16 + (-1)*k7*x9*k16 + (-1)*k8*x9*(x8 + x9)*k16 + (-1)*k9*x9*x10*k16)/k16,
  diff(x10, t) = ((-1)*k4*x10*k16 + (-1)*k5*x10*(x8 + x9)*k16 + (-1)*k6*x10*x10*k16 + 1*k7*x8*k16 + 1*k8*x8*(x8 + x9)*k16 + 1*k9*x8*x10*k16)/k16,
  diff(x11, t) = (1*k4*x10*k16 + 1*k5*x10*(x8 + x9)*k16 + 1*k6*x10*x10*k16 + 1*k7*x9*k16 + 1*k8*x9*(x8 + x9)*k16 + 1*k9*x9*x10*k16 + (-1)*k10*x11*k16)/k16,
  diff(x12, t) = 1*k10*x11*k16/k16,
  diff(x13, t) = 1*k11*x4*(x10 + x11)*k16/k16,
  diff(x14, t) = 1*k12*x5*(x10 + x11)*k16/k16,
  diff(x15, t) = 1*k12*x5*(x10 + x11)*k16/k16,
  diff(x16, t) = 1*k12*x6*x11*k16/k16,
  diff(x17, t) = 1*k12*x6*x11*k16/k16,
  diff(x18, t) = 0/k16 }