{ diff(x1, t) = (1*k51*(k1*(1 + k36*(k33*t^k34/(k35^k34 + t^k34)/k44)^k38)/(1 + (k33*t^k34/(k35^k34 + t^k34)/k44)^k38) + k2*x6)*(1 + 1/10/(3/10)*(k33*t^k34/(k35^k34 + t^k34)/k45)^k41)/(1 + (k33*t^k34/(k35^k34 + t^k34)/k45)^k41) + (-1)*k51*x1*log(2)/k3)/k51,
  diff(x2, t) = 1*k51*1000000000/602300000000000000000000*k49*201/10*3600*x2/(k5 + x2)/k51,
  diff(x3, t) = (1*k51*k10*k6/(1 + k9*x4/k43)*(x2 + x8)/(k7 + x2 + x8)*x12/(2*(k11 + x12)) + (-1)*k51*x3*log(2)/k12)/k51,
  diff(x4, t) = (1*k51*(k13*(1 + k36*(k33*t^k34/(k35^k34 + t^k34)/k44)^k38)/(1 + (k33*t^k34/(k35^k34 + t^k34)/k44)^k38) + k14*x3)*(1 + 1/10/(3/10)*(k33*t^k34/(k35^k34 + t^k34)/k45)^k41)/(1 + (k33*t^k34/(k35^k34 + t^k34)/k45)^k41) + (-1)*k51*x4*log(2)/k15)/k51,
  diff(x5, t) = (1*k51*(k16*x3 + 3600*89/1000000000000*x6)*(1 + 1/10/(3/10)*(k33*t^k34/(k35^k34 + t^k34)/k45)^k41)/(1 + (k33*t^k34/(k35^k34 + t^k34)/k45)^k41) + (-1)*k51*x5*log(2)/k18)/k51,
  diff(x6, t) = 1*k51*k19*x5*(1 + k36*(k33*t^k34/(k35^k34 + t^k34)/k44)^k38)/(1 + (k33*t^k34/(k35^k34 + t^k34)/k44)^k38)/k51,
  diff(x7, t) = (1*k51*k20*x6*(1 + 1/10/(3/10)*(k33*t^k34/(k35^k34 + t^k34)/k45)^k41)/(1 + (k33*t^k34/(k35^k34 + t^k34)/k45)^k41) + (-1)*k51*x7*log(2)/k21)/k51,
  diff(x8, t) = 1*k51*1000000000/602300000000000000000000*k49*201/10*3600*x7/(k5 + x7)/k51,
  diff(x9, t) = (1*k51*(1 + 1/10/(3/10)*(k33*t^k34/(k35^k34 + t^k34)/k45)^k41)/(1 + (k33*t^k34/(k35^k34 + t^k34)/k45)^k41)*(k22*(1 + k36*(k33*t^k34/(k35^k34 + t^k34)/k44)^k38)/(1 + (k33*t^k34/(k35^k34 + t^k34)/k44)^k38) + k23*x10/(k24 + x10)) + (-1)*k51*x9*log(2)/k25)/k51,
  diff(x10, t) = 1*k51*1000000000/602300000000000000000000*k49*46*3600*x9/(k27 + x9)/k51,
  diff(x11, t) = (1*k51*(k28*(1 + k36*(k33*t^k34/(k35^k34 + t^k34)/k44)^k38)/(1 + (k33*t^k34/(k35^k34 + t^k34)/k44)^k38) + 3600*1/200000*x3)*(1 + 1/10/(3/10)*(k33*t^k34/(k35^k34 + t^k34)/k45)^k41)/(1 + (k33*t^k34/(k35^k34 + t^k34)/k45)^k41) + (-1)*k51*x11*log(2)/k30)/k51,
  diff(x12, t) = (1*k51*k31*x11 + (-1)*k51*x12*log(2)/k32)/k51 }