a = 0.2; b = 0.2; c = 3.5 ; e = 300;
modell = {x'[t] == -y[t] - z[t], y'[t] == 
            x[t] +  a  y[t], z'[t] == b + (x[t] - c) z[t], 
          x[0] == 0, y[0] == 3, 
          z[0] == 0};
loesung = NDSolve[modell, {x, y, z}, {t, 0, e}];
xx[t_] = Evaluate[x[t] /. loesung];
yy[t_] = Evaluate[y[t] /. loesung];
zz[t_] = Evaluate[z[t] /. loesung];
abb = 
        ParametricPlot3D[{xx[t][[1]], yy[t][[1]], zz[
                t][[1]]}, {t, e/2, 
            e}, 
PlotRange -> All, 
          PlotPoints -> 50000, ImageSize -> {400, 300}, 
          AxesLabel -> {"x", "y", "z"}];
abb2 = 
        ParametricPlot[{xx[t][[1]], yy[t][[1]]}, {t, e/2, 
            e}, 
PlotRange -> All, 
          PlotPoints -> 50000, ImageSize -> {400, 300}, 
          AxesLabel -> {"x", "y"}];