For women, the biological clock governs the time for having children.

对于女性，生物钟控制着孕育子女的时间。

《柯林斯英汉双解大词典》

The biological clock is a fact of life, but there's nothing magical about age 35.

生物钟是一个不争的事实，35岁并没什么特殊的。

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"We know that the biological clock regulates mood in humans," said study researcher McMahon.

“我们已经知道生物钟控制着人类的情绪，”研究人员麦克马洪说道。

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Traveling across the world and turning your biological clock essentially upside down can definitely cause problems with sleep, both while you are away and when you return.

CNN: Can melatonin prevent jet lag?

Darren Spedale, 38, the website's founder, says he started the company in 2012 after realizing his own biological clock was ticking but he didn't have someone with whom to raise a child.

WSJ: Tech's Over-Sharing Economy

Darren Spedale, 38, the website's founder, says he started the company this year after realizing his own biological clock was ticking but he didn't have someone with whom to raise a child.

WSJ: Tech's Over-Sharing Economy