This sets up a chemical concentration gradient that tells stem cells how and where to develop.

形成化学浓度梯度，告诉干细胞如何以及向哪儿发育。

youdao

(chemotactic movement) a TXIS in response to a chemical concentration gradient.

趋化现象：一种对化学浓度梯度的趋化反应。

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For reactive sputtering, the gradient films with varying ratio of chemical component can be prepared by changing gas flow rate continuously.

对于反应溅射，可通过连续改变反应气体流量制得化学成分比连续变化的梯度薄膜。

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My proposal with this fellowship will use the novel method of applying an electric field gradient instead of chemical substitution to induce charge carriers in large gap insulators, and thereby create new superconductors.

UNESCO: 2013 UK and Ireland Fellows