问题 问答题

煤沥青与石油沥青相比,具有哪些特性?

答案

参考答案:(1)塑性差。煤沥青中含有较多的自由碳和固体树脂,易因变形而开裂。
(2)温度感应性大。煤沥青中可溶性树脂含量高,受热软化溶于油分中,使煤沥青由固态或半固态变为粘流态的温度间隔变小,即温度感应性大,夏天易流淌,冬天易脆裂。
(3)大气稳定性差。低温煤沥青中易挥发的油分多,且化学不稳定的不饱和芳香族化合物含量多,故老化过程较快。
(4)与矿物质材料表面的粘结力较强。煤沥青中含有表面活性物质较多,能充分浸润矿物质材料表面,产生较高的粘结强度。
(5)毒性大、防腐能力强。煤沥青中含有酚、蒽等易挥发有刺激味的成分,使用时对人体有害,但用于木材防腐却有较好效果。

多项选择题
单项选择题

Mass production, the defining characteristic of the Second Wave economy, becomes increasingly obsolete as firms install information intensive, often robotized manufacturing systems capable of endless cheap variation, even customization. The revolutionary result is, in effect, the demassification of mass production.

The shift toward smart flex techs promotes diversity and feeds consumer choice to the point that a Wal-Mart store can offer the buyer nearly 110,000 products in various types, sizes, models and colors to choose among. But Wal-Mart is a mass merchandiser. Increasingly, the mass market itself is breaking up into differentiated niches as customer needs diverge and better information makes it possible for businesses to identify and serve micro markets.

Specialty stores, boutiques, superstores, TV home-shopping systems, computer based buying, direct mail and other systems provide a growing diversity of channels through which producers can distribute their wares to customers in an increasingly demassified marketplace. When we wrote Future Shock in the late 1960s, visionary marketers began talking about "market segmentation". Today they no longer focus on " segments" but on " particles "—family units and even single individuals. Meanwhile, advertising is targeted at smaller and smaller market segments reached through increasingly demassified media.

The dramatic breakup of mass audiences is underscored by the crisis of the once great TV networks, ABC, CBS, and NBC, at a time when Tele-Communications, Inc. of Denver, announces a fiber optic network capable of providing viewers with five hundred interactive channels of television. Such systems mean that sellers will be able to target buyers with even greater precision. The simultaneous demassification of production, distribution and communication revolutionizes the economy and shifts it from homogeneity toward extreme heterogeneity.

The author calls those marketers "visionary" mainly because()

A. they began talking about "market segmentation" in 1960s

B. they focus on "market particles"

C. they have a good sense of market prediction

D. they are good at identifying micro markets