{ diff(x1, t) = (1*k1/(1 + (x4/k25)^2 + (x6/k26)^2) + 1*k2*k46*x12/(1 + (x4/k25)^2 + (x6/k26)^2) + (-1)*k7*k46*x1 + (-1)*k9*k47*x1)/k48,
  diff(x2, t) = (1*k13*x1 + 1*k14*k46*x1 + (-1)*k18*x2)/k48,
  diff(x3, t) = (1*k8*k46*x12/(1 + (x6/k28)^2 + (x8/k29)^2) + 1*k3/(1 + (x6/k28)^2 + (x8/k29)^2) + 1*k4*x2^2/(k27^2 + x2^2)/(1 + (x6/k28)^2 + (x8/k29)^2) + (-1)*k10*x3)/k48,
  diff(x4, t) = (1*k15*x3 + (-1)*k19*k47*x4 + (-1)*k20*k46*x4)/k48,
  diff(x5, t) = (1*k5/(1 + (x2/k30)^2 + (x6/k31)^2) + (-1)*k11*x5)/k48,
  diff(x6, t) = (1*k16*x5 + (-1)*k21*k47*x6 + (-1)*k22*k46*x6)/k48,
  diff(x7, t) = (1*k46*k6/(1 + (x2/k32)^2 + (x6/k33)^2 + (x8/k34)^2) + (-1)*k12*x7)/k48,
  diff(x8, t) = (1*k17*x7 + (-1)*k23*k47*x8 + (-1)*k24*k46*x8)/k48,
  diff(x9, t) = (1*k35/(1 + (x8/k42)^2) + (-1)*k36*x9)/k48,
  diff(x10, t) = (1*k37*x9 + (-1)*k39*k47*x10 + (-1)*k38*k46*x10)/k48,
  diff(x11, t) = (1*k40 + 1*k41*x10^2/(k43^2 + x10^2))/k48,
  diff(x12, t) = (1*3/10*(1 - x12)*k47 + (-1)*x12*k46)/k48 }