聚甲醛

The paper introduced three processes to prepare isochroman from β-phenethyl alcohol and polyformaldehyde:HCl catalysis,AlCl_3 catalysis and toluene-p-sulfonic acid catalysis,and discussed its reaction mechanism,using toluene-p-sulfonic acid catalysis method to prepare isochroman ,the yield is 46%,purity is 96%.

用β-苯乙醇和多聚甲醛为原料，进行了HC l催化法，三氯化铝催化法和对甲苯磺酸催化法的合成路线的实验，并对其反应机理进行了探讨，应用对甲苯磺酸催化法合成异色满的合成路线，得率46%，纯度96%。

A series of SiW_(12)/AC catalysts with different silicotungstic acid loadings supported on acti- vated carbon which was treated with 10% HNO_3 solution were prepared by an impregnation method and the catalytic performance of SiW_(12)/AC for the synthesis of trioxane were investigated.

以10%硝酸溶液处理过的活性炭为载体，采用不同质量分数的硅钨酸SiW_(12溶液为浸渍液，制备了不同负载量的SiW_(12)/AC催化剂，考察了催化剂在合成三聚甲醛中的催化性能，并用XRD、FT-IR、NH_3- TPD、BET、TG-DSC等手段对SiW_(12)/AC催化剂晶粒大小、催化剂表面的酸量及酸强度、比表面积及热稳定性等微观特性进行了表征。

Modified POM ; the three layers composite ; friction and aging resistant property ; supporting material of building in anchor gate

改性聚甲醛；三层复合材料；摩擦与老化特性；闸门滑道支承材料

Japanese Komatsu, Hitachi, Kato, Sumitomo, Carter, the United States and South Korea's Hyundai, Daewoo, Samsung, various kinds of imported excavator seal the fuel tank, the center seal, crankshaft oil seals before and after, and services for major projects in the fuel tank of the domestic plants, for provide users with a variety of piston oil seal (SPGO, SPGW, SPG portfolio, such as seals), piston rod seal (SPNO, IDI, HBY, etc.), a variety of materials to support Central (A phenolic cloth, filled PTFE composites, POM, etc.), V-type combination of seals, all kinds of O-ring, PTFE block films, a variety of automotive oil seals.

提供日本小松、日立、加藤、住友、美国卡特及韩国现代、大宇、三星、各种进口挖掘机油缸密封件、中心油封、曲轴前后油封，并服务于国内各大工程油缸厂，为用户提供各种活塞油封（SPGO、SPGW、SPG等组合密封）、活塞杆密封（SPNO、IDI、HBY等）、各种材料支撑环（酚醛甲布、填充复合聚四氟乙烯、聚甲醛等），V型组合密封圈，各种O型圈、聚四氟乙烯挡片、各种汽车用油封。

Polyacetal ; charging order ; random copolymer ; structure ; dioxolane

聚甲醛；加料方式；无规共聚物；结构；二氧五环

On-hoard determination of picoplankton is preferred, if possible. Otherwise, it is better to use paraformaldehyde or the mixture of paraformaldehyde and glutaraldehyde as fixatives, the samples stored in liquid nitrogen should be analyzed as soon as possible.

如有可能，应该尽量现场测定微微型浮游生物样品，否则建议采用多聚甲醛或其与戊二醛的混合物作为固定剂，将样品保存于液氮中，待返回实验室后尽快进行测定。

Th e tissues were immediately fixed by using one of the following fixatives for 24 hours before conventional tissue processing:(1)2.5%glutaraldehyde and 2%polyf ormaldehyde;(2)2.5%glutaraldehyde and 0.5%cetylpyridinum chloride to fix mainly the glycosaminoglycan;(3)2%OsO4 to fix the phospholipids (PH1);(4)4%OsO4 (PH2) and (5) 3%tannic acid.

取正常大鼠腹膜组织，分别以不同固定液固定：(1)2.5%戊二醛和2%多聚甲醛；(2)2.5%戊二醛和0.5%氯化十六烷基吡啶；(3)2%OsO4(PH1组)；(4)4%OsO4(PH2组)；(5)3%鞣酸。

SF-2 boundary lubricated bearings increase:Acid poly A with formaldehyde, with high wear resistance, bearing surface arrangement of the law must be fitted with a storage pit filled with grease, especially for high load low speed of rotation, rocking motion, and frequently borne, the opening and closing the difficult parts of the formation of lubrication in boundary lubrication conditions, long-term use without refueling and maintenance, where the fuel bearing life can be more extended, currently applicable to metallurgical machinery, mining machinery, hydraulic machinery, automobile parts, construction machinery, agricultural machinery.

SF-2加界润滑轴承：酸多聚甲醛一高耐磨性，轴承表面的法律安排，必须配备与油脂填补了蓄水坑尤其是高负荷低转速旋转，摇摆运动，并经常承担，开幕和闭幕的困难部分在边界润滑条件下，长期不加油和维修，那里的燃料轴承寿命可以更延长，目前适用于冶金机械，矿山机械，液压机械，汽车零部件，工程机械，农业机械使用润滑形成。

From 70's to 80's of the 20th century, the consumption of polyformaldehyde of china wanders up and down in several kilotons for a long time.

20世纪70～80年代，国内聚甲醛消费量长期在数千吨级徘徊。

By machining, To make the measure of area of large-grained spherical copper powder reach 70~80% of the working area of so, achieving the purpose of even alternately distributing of copper powder and POM.

通过机械加工，使大颗粒球形铜粉分布在工作面的面积达到70~80%左右，形成铜粉与改性聚甲醛基本均匀相间分布的状况。

But we don't care about Battlegrounds.

但我们并不在乎沙场中的显露。

Ah! don't mention it, the butcher's shop is a horror.

啊！不用提了。提到肉，真是糟透了。