综述了芳香族置换氟化的反应机理与最新研究状况,并展望了其未来发展前景。
The reaction mechanism and the latest research status of displacement fluorination of aromatics are summarized, and the development trends are forecasted also.
关注的氟化聚合物在它们的重复单元中具有芳基并且具有至少约25 %的有效的可被氟化的芳环位置。
Fluorinated polymers of interest have aromatic groups in their repeat units and at least about 25 % of available aromatic ring positions fluorinated.
在这个阶段,牙齿可以借助唾液中的氟化物和矿物质修复脆弱的部位。
At this stage, the tooth can repair the weakened area with the help of fluoride and minerals in saliva.
一升茶树含有高达9毫克的氟化物,过量会导致氟骨症,降低骨骼质量,导致疼痛和韧带僵硬。
A litre of teacan contain up to 9mg of fluoride, which in excess can cause skeletal fluorosis, reducing bone quality and causing pain and stiffening of the ligaments.
因此,非法进口氯氟化碳的黑市已经扩大。
Consequently, a black market in imported illicit CFC's has grown.
选牙膏的时候要确保它含有氟化物。
When you're choosing a kind of toothpaste, make sure it has fluoride.
在氟化钾催化下,芳香醛与氰乙酸乙酯发生克脑文格尔缩合反应,得到高产率的缩合产物。
The knoevenagel condensation of aromatic aldehydes with ethyl cyanoacetate proceeds smoothly in the presence of potassium fluoride giving products in high yield.
我们分别采用离子色谱法和氟离子选择电极法对茶叶中氟化物的含量进行测定。
We tested the quantity of fluoride in tea leaves by separately using fluorinion selective electrode and the ion chromatographys.
伊斯法罕的铀转化设施,是生产六氟化铀(UF 6,一种铀化合物转化为气体,进入离心机进行浓缩)的装置,在地表以上易于攻击。
The Isfahan conversion plant, which produces uranium hexafluoride (UF6, the uranium compound that is passed as a gas into the centrifuges to be enriched), is above ground and vulnerable to attack.
也许这样一来,就能够发现过量的氯氟化碳(如果外星人也使用头发定型剂的话)。
Or maybe finding excessive chlorofluorocarbons (if the aliens all use hairspray).
《饮用水中的氟化物》是世卫组织系列专著之一,这些专著论述对饮用水中的其他化学品的管理,比如砷或微囊藻毒素。
Fluoride in Drinking-water is one out of a series of WHO monographs, which address the management of other chemicals in drinking-water, such as arsenic or cyanotoxins.
而且在这些当中有些你或许认识,是二氯二氟化碳,它也是众所周知的氟利昂。
And, this one here, some of you might recognize, is dichlorodifluoromethane. It's also known as a CFC.
普莱瑟说我们现在应当密切关注大气中的三氟化氮含量。
Prather says we should now be following nitrogen trifluoride concentrations in the atmosphere closely.
德国的科学家利用X射线光电光谱得到了牙齿在氟化物处理后的表面细节图像。
Scientists in Germany used X-ray photoelectron spectroscopy to get a detailed image of the surface of a treated tooth.
尽管有如此的潜在后果,三氟化氮的使用并没有被控制,电子公司也没有被要求记录其使用量或逸出量。
Despite its potential consequences, the gas is not regulated and electronics companies are not required to keep a record of how much they use or emit.
这么说是因为一项新研究表明氟化物形成的保护膜比专家们料想的还有薄。
Because a new study shows that fluoride forms a thinner protective shield than experts thought it did.
少用非褶皱材料,五分钟的熨烫会让你免于长时间暴露在PFC(全氟化碳)之中。
Cut down on the wrinkle-free materials. Five minutes of ironing will spare you from a lifetime of PFC exposure.
根据韦斯博士尚未发表的数据,六氟化硫目前的排放量是框架公约下所报告的排放量的四倍。
According to Dr Weiss's as-yet-unpublished figures, about four times as much of it is being emitted as is reported under the framework convention.
你是否知道茶中量有少量的氟化物和某些抗生素,可以预防牙龈疾病和牙斑的形成。
Did you know that teas contain some a small amount of fluoride and some certain antibiotic that can help prevent gum diseases and the formation of plaque?
一些公司选择了接受三氟化氮的替代品来解决这个问题。
Some companies are solving the problem by adopting alternatives to nitrogen trifluoride.
他发现2006年中有大约563公吨的三氟化氮被排放。
He found that about 563 metric tons of nitrogen trifluoride was emitted in 2006.
为了预防龋坏的发生,你可以做两件事情——用氟化物和封闭剂增强牙齿保护,减少口腔内细菌。
To prevent your teeth from decaying, you can do two things - strengthen your teeth's defenses with fluoride and sealants, and reduce the number of bacteria in your mouth.
这样能使能量消耗比使用三氟化氮时更少,而且没有促进全球变暖的危险,皮尔格林说。
That takes less energy than splitting nitrogen fluoride and there is no global warming risk, Pilgrim says.
加入萤石粉(即氟化钙)可以使熔融态的金属更具有流动性,并在钛冷却过程中将钛与空气隔绝。
Adding ground fluorite powder makes the molten metals more fluid and protects the titanium from air as it cools.
美国牙医协会(ada)建议给不具备最佳饮用含氟水的社区中的儿童补充氟化物。
The American Dental Association (ADA) recommends fluoride supplements for children who live in communities that don't have optimally fluoridated drinking water.
美国牙医协会(ada)建议给不具备最佳饮用含氟水的社区中的儿童补充氟化物。
The American Dental Association (ADA) recommends fluoride supplements for children who live in communities that don't have optimally fluoridated drinking water.
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