[ Diff(x[1], t) = (1*k[21]*k[1]*piecewise(And(t >= 0, t < 5), 0, piecewise(And(t >= 5, t < 10), 1, 0))/(k[3] + piecewise(And(t >= 0, t < 5), 0, piecewise(And(t >= 5, t < 10), 1, 0))) + (-1)*k[21]*k[4]*x[1])/k[21],
  Diff(x[2], t) = (1*k[21]*k[5]*piecewise(And(t >= 0, t < 5), 1, 0)/(k[7] + piecewise(And(t >= 0, t < 5), 1, 0)) + (-1)*k[21]*k[8]*x[2])/k[21],
  Diff(x[3], t) = (1*k[21]*k[14]*x[1] + 1*k[21]*k[15]*x[2] + (-1)*k[21]*k[16]*x[3])/k[21],
  Diff(x[4], t) = (1*k[21]*k[17]*x[7] + 1*k[21]*k[18]*x[3] + (-1)*k[21]*k[19]*x[4])/k[21],
  Diff(x[5], t) = (1*k[21]*k[11]*x[2]*x[7] + (-1)*k[21]*k[20]*x[5])/k[21],
  Diff(x[7], t) = (1*k[21]*k[10]*(k[13] - x[7] - x[5])*x[1] + 1*k[21]*k[9]*(k[13] - x[7] - x[5])*x[4] + (-1)*k[21]*k[12]*x[7] + (-1)*k[21]*k[11]*x[2]*x[7])/k[21] ]