{ diff(x1, t) = ((-1)*k1*k12*x1*k35 + 1*k1*k22*x3)/k1,
  diff(x2, t) = (1*k1*k12*x1*k35 + (-1)*k1*k19*x2)/k1,
  diff(x3, t) = (1*k1*k19*x2 + (-1)*k1*k22*x3)/k1,
  diff(x4, t) = 0,
  diff(x5, t) = 0,
  diff(x6, t) = (1*k2*k14*x10 + (-1)*k2*k21*x6)/k2,
  diff(x7, t) = (1*k2*k18*x12 + (-1)*k2*k29*x7*x26)/k2,
  diff(x8, t) = (1*k2*k11*x9*k36 + (-1)*k2*k24*x8*x16)/k2,
  diff(x9, t) = ((-1)*k2*k11*x9*k36 + 1*k2*k24*x8*x16)/k2,
  diff(x10, t) = (1*k2*k6*x14*x13 + 1*k2*k13*x11*x13 + (-1)*k2*k14*x10)/k2,
  diff(x11, t) = (1*k7*x14*x2 + (-1)*k2*k13*x11*x13 + (-1)*k2*k15*x11)/k2,
  diff(x12, t) = ((-1)*k2*k18*x12 + 1*k2*k29*x7*x26)/k2,
  diff(x13, t) = (1*k2*k4*x22*x8 + (-1)*k2*k5*x13)/k2,
  diff(x14, t) = ((-1)*k2*k6*x14*x13 + (-1)*k7*x14*x2 + 1*k2*k15*x11 + 1*k2*k21*x6)/k2,
  diff(x15, t) = (1*k2*k8*x20*x11 + (-1)*k2*k9*x15*x12 + 1*k2*k16*x21 + (-1)*k2*k17*x15 + (-1)*k2*k30*x15*x25)/k2,
  diff(x16, t) = (1*k2*k3*x23 + (-1)*k2*k10*x16*x15 + (-1)*k2*k20*x16*x21)/k2,
  diff(x17, t) = ((-1)*k2*k23*x17*x21 + (-1)*k2*k25*x17*x15 + 1*k2*k26*x19 + 1*k2*k27*x18 + (-1)*k2*k28*x17*x8)/k2,
  diff(x18, t) = ((-1)*k2*k27*x18 + 1*k2*k28*x17*x8)/k2,
  diff(x19, t) = (1*k2*k23*x17*x21 + 1*k2*k25*x17*x15 + (-1)*k2*k26*x19)/k2,
  diff(x20, t) = ((-1)*k2*k8*x20*x11 + 1*k2*k17*x15)/k2,
  diff(x21, t) = (1*k2*k9*x15*x12 + (-1)*k2*k16*x21 + 1*k2*k30*x15*x25)/k2,
  diff(x22, t) = ((-1)*k2*k4*x22*x8 + 1*k2*k5*x13)/k2,
  diff(x23, t) = ((-1)*k2*k3*x23 + 1*k2*k10*x16*x15 + 1*k2*k20*x16*x21)/k2,
  diff(x24, t) = (1*k2*k31*x25 + (-1)*k32*x24*x2)/k2,
  diff(x25, t) = ((-1)*k2*k31*x25 + 1*k32*x24*x2)/k2,
  diff(x26, t) = (1*k33*x27*x2 + (-1)*k2*k34*x26)/k2,
  diff(x27, t) = ((-1)*k33*x27*x2 + 1*k2*k34*x26)/k2,
  diff(x28, t) = 0 }