致癌的

mitochondrial dnais the only inheritant substance except for the nuclear dna in a euˉkaryon cell,which is related to the oxidative phosphorylation of a cell.mitochondrial dna is the important target of carcinogens and is vulnerable because of its structure and function.the mutation of mtdna could reduce the nomal respitation and release large quantities of ros,whichincrease the danger of cancer happening.so,mtdna has been thought to be involved in carcinogenesis and recently more and more studies in this aspect have comeout.in this paˉper,we review the researches for relationship among mtdna mutation and tumors in digestion system,woman system,head and neck,urinary systemand blood system.

线粒体dna（mitochondrial dna，mt dna）是真核细胞中唯一存在的独立于核dna之外的遗传物质，与细胞的氧化磷酸化功能密切相关。mtdna自身的结构和功能特点决定了它是致癌物作用的重要靶点，易受致癌因素的损伤而发生突变。mtdna的突变可削弱正常的呼吸功能，释放高水平的活性氧，进而增加肿瘤发生的危险性，所以mtdna被认为与肿瘤发生有密切关系。近年来，这方面的研究越来越多，本文现就mtdna突变与消化系统肿瘤、妇科肿瘤、头颈部肿瘤、泌尿系统肿瘤等实体瘤以及血液系统恶性肿瘤之间的关系作一简单的综述。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。