问题 问答题 简答题

生物质的元素分析成分有哪些?生物质的组成成分如何表示?

答案

参考答案:

元素分析成分有碳、氢、氧、氮、硫、磷、钾和灰分等

表示方法有应用基、分析基、干燥基和工业分析法之分。

应用基:按实际进入炉灶的燃料取样分析计算所得到组成成分的质量分数,表示是在该成份符号右上角加“y”,如Cy,由于自由水变化幅度很大,该表示法仅在具体做测试计算时使用,不便作为手册、资料上的数据查用。

分析基:以风干燃料为基准,分析化验计算后所得的各元素组成成分的百分数值,这是一般资料上给出的数据,分析基以成分右上角加“f”表示,如Cf

干燥基:干燥基是以完全干燥的燃料为基准进行测定计算的,它是在元素右上角加“g”表示,如Cg

工业分析法:也称近似分析法,它不是测定各元素含量而是测定燃料的水分(W),灰分(A),挥发分(V),固定碳(C)的含量,以表示燃料的主要燃烧特性指标。

选择题
单项选择题

In one sense, we can trace all the problems of the American city back (91) a single starting point: we Americans don’t like our cities very much.
That is, on the (92) of it, absurd. After all, more than three-fourths of us now live in cities, and more are (93) to them every year. We are told that the problems of our cities are (94) more attention in Washington, and scholarship has discovered a whole new (95) in urban studies.
(96) , it is historically true: in the American psychology, the city has been a basically suspect institution, (97) with the corruption of Europe, totally lacking that sense of spaciousness and innocence of the (98) and the rural landscape.
I don’t pretend to be a scholar on the history of the city in American life. But my thirteen years in public (99) , first as an officer of the U. S. Department of Justice, then as Congressman, and now as Mayor of the biggest city in America have taught me (100) too well the fact that a p antiurban attitude (101) consistently through the mainstream of American thinking. Much of the (102) behind the settlement of America was in reaction (103) the conditions in European industrial centers and much of the theory (104) the basis of freedom in America was linked directly to the availability of land and the perfectibility of man outside the corrupt influences of the city.
What has this to do with the predicament of the modern city I think it has (105) to do with it. For the fact is that the United States (106) the federal government, which has historically established our national priorities, has simply never thought that the American city was "worthy" of (107) —at least not to the (108) of expending any basic resources on it.
Antipathy to the city predates the American experience. When industrialization (109) the European working man into the major cities of the continent, books and pamphlets appeared (110) the city as a source of crime, corruption, filth, disease, vice, licentiousness, subversion, and high prices.

A.with

B.to

C.for

D.as