查询词典 ketene

The sizing performance of alkyl ketene dimmer in bamboo pulp was studied in this paper.

本文研究了AKD对竹浆的施胶性能。

We have had the extensive studies on theα-acetyl-α-carbamoyl ketene--acetals and its further applications, for example, their adols condensations with aldehydes giveα-alkenoyl-α-carbamoyl ketene--acetals which can be utilized as the 1,5-bielectronic five-carbon components to react with various binucleophlilic species in a [5+1] annulation.

我们小组在以前的工作中对α-乙酰基-α-胺甲酰基二硫缩烯酮在合成中的应用进行了深入的研究，如与醛缩合生成α-烯酰基-α-胺甲酰基二硫缩烯酮，将其作为1，5-双亲电五碳合成子的[5+1]成环策略等。

In this thesis, a convenient and efficient synthesis of highly functionalizeddihydropyrido[2,3-d]pyrimidines via a double [5 + 1] annulation strategy startingfrom easily available α-alkenoyl-α-carbamoyl ketene--acetals 1 and cheapreagents (NH4OAc, DMF, and POCl3) has been developed.

本论文探索了一种简便有效的合成高度官能化的二氢吡啶并[2，3-d]嘧啶的方法，此方法由易得的α-乙酰基-α-氨基乙酰基二硫缩烯酮1和便宜的试剂(醋酸铵，二甲基甲酰胺和三氯氧磷)通过两步[5 + 1]加成而实现。

A large molecular sizing agent modified AKD was prepared through the reaction between alkyl ketene dimmer and polyamide then cationization by epichlorohydrin. The large molecular sizing agent has high positive charge and emulsifiability.

摘 要：将聚酰胺多胺与AKD反应，并用环氧氯丙烷将其阳离子化，制备出一种具有高阳电荷的改性AKD大分子，并在中、碱性条件下用该改性AKD对漂白硫酸盐阔叶木浆进行施胶。

In this reaction, the first example of 1,3-addition to ketene was observed.

研究中，我们首次观察到了对烯酮的1，3-加成反应。

It is important theoretically and practically that the ketene photodissociationas a model system for unimolecular dissociation.

乙烯酮分子的光解反应作为研究单分子解离的模型系统具有重要的理论和实际意义。

Therefore, studies on the synthesis and the applications ofα-alkenoyl ketene dithioacetals should be a valuable research project.

因此，α-烯酰基二硫缩烯酮的合成及其在合成中的应用研究是一重要的研究课题。

However, in the case of TsN〓 withsilyl ketene acetals, an unexpected alkoxy migration occurred.

而且在研究对甲苯磺酰叠氮和silyl ketene acetals的对比反应中，我们还发现了烷氧基迁移的现象。

Among the variousα-oxo ketene dithioacetals,α-alkenoyl ketene dithioacetals are easier to prepare and bear much more functionalities.

在众多的α-羰基二硫缩烯酮类化合物中，α-烯酰基二硫缩烯酮具有易于制备，官能团多等特点。

A novel zwitterion derived from the addition of thiazole carbene to ketene was discovered and captured by an activated alkyne. In this process, we developed a facile and efficient three-component tandem reaction involving thiazole or benzothiazole carbene, disubstituted ketene and activated alkyne.

我们发现了一种新的噻唑卡宾和烯酮形成的两性离子的存在，并用活泼炔成功捕捉，从而发展了一个新的噻唑卡宾或苯并噻唑卡宾、二取代烯酮和活泼炔的三组分串联反应。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。