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求专业英语高人指点
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More in detail the aryl amine compound employed in the novel composition of the present invention is selected by the group consisting of aminophenol, N-alkyl aminophenol, wherein the alkyl contains from 1 to about 4 carbon atoms, toluene diamine, phenylene diamine and any of the above amine compounds substituted with a sulfate group. Examples of suitable aryl amine compounds include: o-phenylene diamine m-aminophenol p-phenylene diamine p-aminophenol 2,3-toluene diamine p-aminophenol sulfate 2,6-toluene diamine p-(N-methylamino)phenol sulfate 2,4-toluene diamine o-(N-butylamino)phenol The quinone compounds suitable as a stabilizing agent in the composition of the present invention is selected from the group consisting of quinone, naphthoquinone and anthraquinone and their hydroxyl forms, for example, pyrocatechol or hydroquinone. Preferred compounds are the hydroxyl forms of the quinones, for example, hydroquinone. In the novel composition of the present invention, the catalytic proportion of the mixture of an aryl amine compound and a quinone compound contains a ratio by weight of the aryl amine compound to the quinone compound of from about 10:1 to about 300:1 and preferably from about 15:1 to about 200:1. The catalytic proportion is added to provide a weight ratio of hydrazine to the quinone compound from about 2000:1 to about 10,000:1, and preferably from about 2200:1 to about 8000:1. While the exact mechanism through which the removal of oxygen by hydrazine is accelerated by the mixture of aryl amine compound and quinone compound is not clearly understood, it is believed that the mixture truly acts as a catalyst. A catalytic proportion is the amount of the mixture of aryl amine compound and quinone compound capable of accelerating the removal of oxygen. In the novel composition of this invention, a catalytic proportion of the mixture is generally equivalent to a weight ratio of hydrazine to the mixture of from about 40:1 to about 1500:1 and preferably from about 50:1 to about 150:1 but greater ratios of the hydrazine to the mixture may be employed, if desired. |
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【答案】应助回帖
爱与雨下: ？ 2012-12-10 21:13:44
| In 1988,Kirby and Sirovich applied principle component analysis, a standard linear algebra technique, to the face recognition problem. This was considered somewhat of a milestone as it showed that less than one hundred values were required to accurately code a suitably aligned and normalized face image.2 |
2楼2012-12-09 22:07:11
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3楼2012-12-10 20:32:27
