These clothes restrict your freedom of movement and stiffen up the whole body.

这些衣服使你的手脚难于自由活动，使整个身体也僵硬起来。

《柯林斯英汉双解大词典》

Straighten up little soldier. Stiffen up that upper lip.

挺直腰杆，咬紧牙关，做个象样的小兵。

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What happens is the fluid that's sprayed into each fibre of the yarn starts to stiffen up and resist that mechanical strain.

渗入纱线纤维的液体黏性开始增大并阻止机械拉力。

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The Sarbanes-Oxley legislation, passed after the collapse of Enron in order to stiffen up corporate governance, has put off foreign companies from listing there.

ECONOMIST: London as a financial centre

The news in the US though, had a slightly more positive tone and this helped the dollar to stiffen up a bit against the common currency.

FORBES: As Consumer Lending in the U.K. Contracts, Pound Slides

In Caymans equipped with the Sport Chrono package, new dynamic transmission mounts stiffen up to minimize shift-shock and to keep the otherwise-bucking powertrain from deranging the car's handling.

WSJ: 2014 Porsche Cayman S Review: 911's Little Brother Grows Up | Rumble Seat by Dan Neil