氟化作用

With the coordinated interacton of the abrasive particles in dentifrice, can it abrade or corrode dental restorations made from titanium and change their luster and color so as to influence their appearance and long-term use.

含氟牙膏中一般含有氟化钠或单氟磷酸钠，pH值低于7，在摩擦剂的协同作用下是否对口腔中钛制修复体有磨损和腐蚀作用，使其发生失泽和变色，以致影响它的美观和长期使用？

Tieguanyin fluoride in about 40% to 80% dissolved in water, with the teeth vulnerable combination of calcium, in the teeth formed on the surface layer of calcium fluoride, played the role of anti-acid anti-caries.

铁观音中的氟化物约有40%～80%溶解于开水，极易与牙齿中的钙质相结合，在牙齿表面形成一层氟化钙，起到防酸抗龋的作用。

The calixarenes used as PTC in the fluorination of tetrachlorophthahaloyl chloride to obtain dimethyl tetrafluoroterephthalate were studied in this paper.

研究了杯芳烃在四氯对苯二甲酰氯氟化制备四氟对苯二甲酸二甲酯反应中的相转移催化作用，发现以杯芳烃作相转移催化剂使产品收率得到了明显提高。

Large single crystals were also obtained by using pyrocatechol as additive. It was shown by 〓Si-NMR and IR that Sipyrocatechol complex was formed in the reaction system.

在F〓体系中，F〓对铝源和硅源起络合和矿化作用，形成可溶性氟硅酸盐AlF〓〓、SiF〓〓络合物，然后缓慢水解成含氧氟硅酸盐络合物，它们再发生定向缩聚，提供了分子筛晶体生长所需的可溶性结构单元。

In the occurrence of arcs discharges, spark discharges and corona discharges, sulfur hexafluoride (SF6) would be decomposed to complicated byproducts such as carbon dioxide (CO2), carbon tetrafluoride (CF4), etc.

六氟化硫（SF6）气体在电弧、电火花和电晕放电的作用下会发生分解，产生二氧化碳（CO2）、四氟化碳（CF4）等分解产物。

Tetrachloroterephthalic acid was prepared by chlorinating terephthalic acid, oleumsolvent and iodine catalyst. Tetrachloroterephthalic acid was acylated by sulphurous oxychloride in the presence of DMF to form tetrachloroterephthaloyl chloride. The acyl chloride product was fluorinated by potassium fluoride and esterified by methanol to synthesize dimethyl tetrafluoroterephthalate. The ester was reduced with potassium borohydride and lithium chloride to give tetrafluoroterephthalyl alcohol. The above product was bromated in the hydrobromic acid to obtain 4-bromomethyl-2,3,5,6-tetrafluoro-benzene methanol. 4-Methyl-2,3,5,-6-tetrafluorobenzene ethanol was obtained by reducing the bromide with magnesium. In the exist of DCC and DMAP, tefluthrin was got by the condensation reaction between 4-methyl-2,3,5,6-tetrafluoro-benzene methanol and-(1RS,3RS)- 3-(2- chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethyl cycolpropanecar-boxylate acid.

对苯二甲酸与氯气在碘存在下以发烟硫酸为溶剂进行氯化制备四氯对苯二甲酸；再以DMF为催化剂与二氯亚砜反应生成四氯对苯二甲酰氯；以氟化钾为氟化剂，环丁砜为溶剂置换氟化，再与甲醇酯化得到四氟对苯二甲酸甲酯；以KBH4-LiCl为还原剂二甲醚为溶剂反应制得四氟对苯二甲基苄醇；以氯苯为溶剂在溴化氢溶液中溴化得到溴化产物；在乙醇溶液中经镁粉还原得到4-甲基-2，3，5，6-四氟苄醇；甲基苄醇与功夫酸在催化剂二环己基碳二亚胺和4-二甲氨基吡啶作用下缩合得到七氟菊酯，总收率达43.6%。

Results Fluoridated milk had significant effects of remineralization,anti-deminer alization and anti-caries.

结果 氟化牛奶有明显的再矿化、抗酸脱矿及抗龋作用，而氟水有一定的抗酸脱矿及抗龋作用，无再矿化作用。

Methods A set of demineralized bovine teeth specimens we re measured for microhardness to assess the degree of remineralization,and other two sets of bovine teeth specimens were examined with polarizing microscope to assess the anti-demineralization and anti-caries effect.

利用显微硬度计测定氟化牛奶和氟水对早期人工龋的再矿化作用。利用偏光显微镜观察氟化牛奶和氟水的抗酸脱矿作用及抗龋作用。

CPP-ACP has the ability of promoting remineralization of enamel artificial white spot lesions which can be enhanced by fluorid.The remineralization ability depends on the concentration of calcium phosphate stabilized by CPP-ACP.

CPP-ACP溶液可于体外使脱矿牙釉质发生再矿化，且矿化作用可被氟加强；再矿化作用与CPP稳定的钙磷浓度呈剂量-效应关系。

The application results from fluorination showed microwave heating could accelerate chemical reactions markedly. The reaction time could be shortened 50% at least than that of conventional heating. The relationship between fluorinating agents\' structure and their activity was studied systematically. In addition, an anhydrous KF with higher activity was prepared by using expansion effect of microwave heating. As we known, solvents were very important to reaction. The comprehensive study showed some less polar aromatic solvents could be used as dipolar solvents. In addition, they had better effect than dipolar solvents in some occasions, such as fluorination of chlorobenzaldehydes and chlorinated diphenyl ketones etc. The primary applications of ionic liquids were also studied which indicated reactions with ionic liquids as solvents were more efficient and simple.

研究表明，微波是一种节能高效的加热方式，在微波作用下的卤素交换氟化反应具有反应速度快、转化率高、选择性好的优点，其反应时间可较常规加热缩短50%以上；同时也系统地研究了氟化剂种类及制备方式对其反应活性的影响，并利用微波加热的膨化作用制备出了一种活性较高的KF，其活性与喷雾干燥KF相差不大；溶剂对反应具有重要的作用，在此系统地研究了强极性非质子溶剂和中等极性非质子溶剂的应用情况，发现一些中等极性的非质子溶剂如硝基芳烃和氯代芳烃类溶剂在氯代苯甲醛类化合物的氟化反应中具有比强极性非质子溶剂更好的使用效果。

It has been put forward that there exists single Ball point and double Ball points on the symmetrical connecting-rod curves of equilateral mechanisms.

从鲍尔点的形成原理出发，分析对称连杆曲线上鲍尔点的产生条件，提出等边机构的对称连杆曲线上有单鲍尔点和双鲍尔点。

The factory affiliated to the Group primarily manufactures multiple-purpose pincers, baking kits, knives, scissors, kitchenware, gardening tools and beauty care kits as well as other hardware tools, the annual production value of which reaches US$ 30 million dollars.

集团所属工厂主要生产多用钳、烤具、刀具、剪刀、厨具、花园工具、美容套等五金产品，年生产总值3000万美元，产品价廉物美、选料上乘、质量保证，深受国内外客户的青睐