private void lecturasToolStripMenuItem_Click_1(object sender, EventArgs e)
 {
     lecturas = new Lecturas();
     lecturas.MdiParent = this;
     lecturas.Show();
 }
 private void lecturasToolStripMenuItem_Click(object sender, EventArgs e)
 {
     //if (lecturas == null)
     //{
         lecturas = new Lecturas();
     //}
     lecturas.MdiParent = this;
     lecturas.Show();
 }