[分享]阅读机经相关英文背景材料---持续更新（至机经39飞蛾拟声）

buda

Price skimming

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Price Skimming

Price skimming is a pricing strategy in which a marketer sets a relatively high price for a product or service at first, then lowers the price over time. It is a temporal version of price discrimination/yield management. It allows the firm to recover its sunk costs quickly before competition steps in and lowers the market price.

Price skimming is sometimes referred to as riding down the demand curve.The objective of a price skimming strategy is to capture the consumer surplus If this is done successfully, then theoretically no customer will pay less for the product than the maximum they are willing to pay. In practice it is impossible for a firm to capture all of this surplus.

[edit]
            Limitations of Price Skimming

There are several potential problems with this strategy.

• It is effective only when the firm is facing an inelastic demand curve. If the long run demand schedule is elastic (as in the diagram to the left), market equilibrium will be achieved by quantity changes rather than price changes. Penetration pricing is a more suitable strategy in this case. Price changes by any one firm will be matched by other firms resulting in a rapid growth in industry volume. Dominant market share will typically be obtained by a low cost producer that pursues a penetration strategy.
• A price skimmer must be careful with the law. Price discrimination is illegal in many jurisdictions, but yield management is not. Price skimming can be considered either a form of price discrimination or a form of yield management. Price discrimination uses market characteristics (such as price elasticity) to adjust prices, whereas yield management uses product characteristics. Marketers see this legal distinction as quaint since in almost all cases market characteristics correlate highly with product characteristics. If using a skimming strategy, a marketer must speak and think in terms of product characteristics in order to stay on the right side of the law.
• The inventory turn rate can be very low for skimmed products. This could cause problems for the manufacturer's distribution chain. It may be necessary to give retailers higher margins to convince them to enthusiastically handle the product.
• Skimming encourages the entry of competitors. When other firms see the high margins available in the industry, they will quickly enter.
• Skimming results in a slow rate of stuff diffusion and adaptation. This results in a high level of untapped demand. This gives competitors time to either imitate the product or leap frog it with a new innovation. If competitors do this, the window of opportunity will have been lost.
• The manufacturer could develop negative publicity if they lower the price too fast and without significant product changes. Some early purchasers will feel they have been ripped-off. They will feel it would have been better to wait and purchase the product at a much lower price. This negative sentiment will be transferred to the brand and the company as a whole.
• High margins may make the firm inefficient. There will be no incentive to keep costs under control. Inefficient practices will become established making it difficult to compete on value or price

小月sky

不好意思，弱问。。。请问这些到底是什么啊？是机经吗？我好茫然啊。。。

buda

哦，只是我搜集到的一些机经提到的关键词的背景材料，便于理解文章中的一些说法。

比如说泰勒制，我们只知道中文，或者中文的一些概念性的东西，寻找到英文的背景材料可以加深印象，也对一些相关词汇敏感了。不至于考场上紧张。

仅仅是个人看法，看不看还是根据个人情况吧，毕竟这些材料都挺长的。

bgv793

肯定是要感謝樓主的.

jarlin

确实都挺长的....等有空了再看 哈哈 谢谢LZ

大宝贝007

谢谢lz

buda

感觉妇女与工业化进程的这个材料不是特别贴切，比较难找。但是讲述了英国妇女的一些状况，中国的没有。机经已经比较详细了。

大家不用仔细研究偶的相关材料，偶只是贴上来，大家扫过一眼，混个眼熟就OK。考场上可千万别想着，否则偶就耽误大家了。

buda

De-icing is the process of removing ice from a surface.

Anti-icing is the process of preventing ice from forming on a surface.

Freezing-point depression describes the phenomenon that the freezing point of a liquid (a solvent) is depressed when another compound is added, meaning that a solution has a lower freezing point than a pure solvent. This happens whenever a solute is added to a pure solvent, such as water. The phenomenon may be observed in sea water, which due to its salt content remains liquid at temperatures below 0°C, the freezing point of pure water.

De-icing can be accomplished by mechanical methods (scraping), through the application of heat, by use of chemicals designed to lower the freezing point of water (various salts or alcohols), or a combination of these different techniques.

Roads

De-icing of roads has traditionally been done with salt, spread by snowplows or other dump trucks designed to spread it, along with sand and gravel, on slick roads. Sodium chloride (rock salt) is normally used, as it is inexpensive and readily available in large quantities. However, since salt water still freezes at -18°C or 0°F, it is of no help when the temperature falls below this point. It also has a strong tendency to cause corrosion, rusting the steel used in most vehicles and the rebar used in concrete bridges. More recent snowmelters use other salts, such as calcium chloride and magnesium chloride, which not only depress the freezing point of water to a much lower temperature, but also produce an exothermic reaction. They are somewhat safer for concrete
        sidewalks, but excess should still be removed.

More recently, organic compounds have been developed that reduce the environmental issues connected with salts and have longer residual effects when spread on roadways, usually in conjunction with salt brines or solids. These compounds are generated as byproducts of agricultural operations such as sugar beet refining or the distillation process that produces ethanol.^[3]

Since the 1990s, use of liquid chemical melters has been increasing, being sprayed on roads by nozzles instead of a spinning spreader. Liquid melters are more effective at preventing the ice from bonding to the surface than melting through existing ice.

In Nagano, Japan, relatively inexpensive hot water bubbles up through holes in the pavement to melt snow, though this solution is only practical within a city or town. Some individual buildings may melt snow and ice with electric
        heating elements buried in the pavement, or even on a roof to prevent ice dams under the shingles, or to keep massive chunks of snow and dangerous icicles from collapsing on anyone below. Small areas of pavement can be kept ice-free by circulating heated liquids in embedded piping systems.

The phenomenon of freezing point depression is used in technical applications to avoid freezing. In the case of water, ethylene glycol or other forms of antifreeze is added to cooling water in internal combustion engines, making the water stay a liquid at temperatures below its normal freezing point.

FDP

The use of freezing-point depression through "freeze avoidance" has also evolved in some animals that live in very cold environments. This happens through permanently high concentration of physiologically rather inert substances such as sorbitol or glycerol to increase the molality of fluids in cells and tissues, and thus decrease the freezing point. Examples include some species of arctic-living fish, such as rainbow smelt, which need to be able to survive in freezing temperatures for a long time. In other animals, such as the peeper frog (Pseudacris crucifer), the molality is increased temporarily as a reaction to cold temperatures. In the case of the peeper frog, this happens by massive breakdown of glycogen in the frog's liver and subsequent release of massive amounts of glucose.^[4]

Together with formula above, freezing-point depression can be used to measure the degree of dissociation or the molar mass of the solute. This kind of measurement is called cryoscopy (Greek "chillawatchsts") and relies on exact measurement of the freezing point. The degree of dissociation is measured by determining the van 't Hoff factor i by first determining m_B and then comparing it to m_solute. In this case, the molar mass of the solute must be known. The molar mass of a solute is determined by comparing m_B with the amount of solute dissolved. In this case, i must be known, and the procedure is primarily useful for organic compounds using a nonpolar solvent. Cryoscopy is no longer as common a measurement method as it once was. As an example, it was still taught as a useful analytic procedure in Cohen's Practical Organic Chemistry of 1910,^[5] in which the molar mass of napthalene is determined in a so-called Beckmann freezing apparatus.

In principle, the boiling point elevation and the freezing point depression could be used interchangeably for this purpose. However, the cryoscopic constant is larger than the ebullioscopic constant and the freezing point is often easier to measure with precision, which means measurements using the freezing point depression are more precise.

buda

In the broadest sense, an immune system is any method an organism
has protect itself from succeeding to another organism's efforts to undermine
its health and integrity.  In this sense, yes, plants have immune systems. 
Plants do NOT have "active" immune systems, like humans, including
macrophages, lymls, antibodies, complements, interferon, etc., which help us
ward off infection.  Rather, plants have "passive" mechanisms of protection. 
For instance, the waxy secretion of some plants (cuticle) functions to help
hold in moisture and keep out microorganisms.  Plants can also secrete
irritating juices that prevent insects and animals from eating it.  The thick
bark of woody plants is another example of a defensive adaptation, that
protects the more delicate tissues inside.  The chemical secretions of some
plants are downright poisonous to many organisms, which greatly enhance the
chances of survival for the plant.  Fruits of plants contain large amounts of
vitamin C and bioflavonoids, compounds which have been shown in the lab to be
anti-bacterial and antiviral.  So in these ways, plants can improve their
chances of survival.  Hundreds of viruses and bacteria attack plants each
year, and the cost to agriculture is enormous.  I would venture to guess that
once an organism establishes an infection in a plant, the plant will not be
able to "fight" it.  However, exposure to the sun's UV light may help control
an infection, possibly even defeat it, but the plant does not have any
inherent "active" way to fight the infection.

jesuisdesole

太牛啦太牛啦，这样下去的话ＣＤ可以出自己的科学月刊啦～～