Submitted on: 27 August 2006.
Revised on: 10 October 2006.
Accepted on: 15 October 2006.
Medisur-Revista de Ciencias Medicas de Cienfuegos
Submitted on: 27 September 2005.
Revised on: 17 October 2005.
Accepted on: 08 November 2005.
Medisur-Revista de Ciencias Medicas de Cienfuegos
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Submitted on: 18 August 2016.
Revised on: 26 August 2016.
Accepted on: 05 September 2016.
Medisur-Revista de Ciencias Medicas de Cienfuegos
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http://reply.papertrans.cn/3/218/21708/21708-36.png