新手绘图时遇到个不知如何下手的问题，理论上曲线中间还有一小段圈将左右两段勾连在一起，但绘图出来后总是缺这么一小段关键部分断开，求助各位吧友，实在不知道问题出在哪里了不清楚是参数太小了精细度不足还是什么其他原因，以下是代码：
b0 = 0.5;
b1 = 4;
b2 = 0.05;
b3 = 0.003;
x0 = 0.11;
sigma = 0.002;
k = 0.2;
gamma = 0.2;
lambda = 0.3;
alpha = 0.1;
beta[lbk]x_[rbk] := (b0 + b1*x/(b2 + x))*(1 - b3*E^(-(x - x0)^2/sigma));
bb[lbk]x_[rbk] := alpha*k + beta[lbk]x[rbk]*(x + k + gamma);
cc[lbk]x_[rbk] := (x + k + gamma)*k - beta[lbk]x[rbk]*lambda;
i[lbk]x_[rbk] := (-bb[lbk]x[rbk] + Sqrt[lbk]bb[lbk]x[rbk]*bb[lbk]x[rbk] - 4*alpha*cc[lbk]x[rbk][rbk])/(2*alpha);
s[lbk]x_[rbk] := (x + k + gamma + alpha*i[lbk]x[rbk])/beta[lbk]x[rbk];
f[lbk]y_, x_[rbk] := beta[lbk]y[rbk]*s[lbk]x[rbk] - y - k - gamma - alpha*i[lbk]x[rbk];
myplot = ContourPlot[lbk]f[lbk]u, x[rbk], {x, 0.12, 0.16}, {u, 0.1, 0.2}, Contours -> {0}, ContourStyle -> {Red, Thin}, ContourShading -> None[rbk]

好像发出来有点乱码了，重新发一个：
b0 = 0.5;
b1 = 4;
b2 = 0.05;
b3 = 0.003;
x0 = 0.11;
sigma = 0.002;
k = 0.2;
gamma = 0.2;
lambda = 0.3;
alpha = 0.1;
beta[x_] := (b0 + b1*x/(b2 + x))*(1 - b3*E^(-(x - x0)^2/sigma));
bb[x_] := alpha*k + beta[x]*(x + k + gamma);
cc[x_] := (x + k + gamma)*k - beta[x]*lambda;
i[x_] := (-bb[x] + Sqrt[bb[x]*bb[x] - 4*alpha*cc[x]])/(2*alpha);
s[x_] := (x + k + gamma + alpha*i[x])/beta[x];
f[y_, x_] := beta[y]*s[x] - y - k - gamma - alpha*i[x];
myplot = ContourPlot[f[u, x], {x, 0.12, 0.16}, {u, 0.1, 0.2},
Contours -> {0}, ContourStyle -> {Red, Thin}, ContourShading -> None]

要不加一个PlotPoints->150试试？