A heme (HEM) is a multi-atom, non-proteinaceous organic structure capable of positioning an iron (FE) ion in its center.

亚铁血红素 (HEM) 是一个多原子、非蛋白质的有机结构，能够将一个铁 (FE) 离子置于其中心。

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The metal ion may be the catalytic center of the cofactor, or it may serve to bind the enzyme and substrate together to hold the enzyme in a catalytically active conformation.

金属离子可以是辅助因素的催化中心，也可以帮助形成酶活性所必须的构象。

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The negative ion element will become the gas source center and form an ejection in the process of evaporation of coating material, so decrease the damage threshold of the coatings.

并且提出负离子元素在膜料蒸发过程中形成气源中心，产生喷溅，从而使薄膜的损伤阈值降低。

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So, for example, if I have a sodium ion over here, and I have a chloride ion over here, where the distance from center to center r I'm denoting as r, this is nucleus to nucleus separation.

所以，比如这有一个钠离子，和一个氯离子，它们中心与中心间的距离,我把它设为，这是原子核和原子和的间距。

麻省理工公开课 - 固态化学导论课程节选

These components are combined with electrical parts that are also "made by Volkswagen, " such as the lithium-ion battery in the center tunnel and the 54-hp front and 114-hp rear electric motors.

ENGADGET: VW unveils CrossBlue plug-in SUV with iPad mini headrests and 85MPGe efficiency (eyes-on)

Another example: A123 Systems, a Massachusetts company that produces lithium-ion batteries, has created a large design and manufacturing center in Michigan to be near their automotive customers for electric and hybrid vehicles.

FORBES: Alternative Energy: Creating Non-Exportable Jobs

The CrossBlue's lithium-ion battery has an energy capacity of 9.8 kWh and is housed in the center tunnel.

ENGADGET: VW unveils CrossBlue plug-in SUV with iPad mini headrests and 85MPGe efficiency (eyes-on)