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脱灰过程中易出现的问题及注意事项主要有哪些？

答案

参考答案：

易出现问题：极易产生硫化氢气体。

注意事项：

（1）脱灰碱前要充分水洗，尽可能将皮内外特别是皮胶原纤维空隙中的石灰颗粒或自由碱洗去；

（2）水洗要求水量足，闷洗与流洗相结合，水洗液的pH稳定在9~9.5时作为水洗结束时的终点，水洗升温，水温不超过45℃；

（3）脱灰时严格控制脱灰液的pH，脱灰时pH不能低于4，否则易产生表面酸肿；

（4）、需要脱灰的裸皮应尽快进行，以防止灰皮放置过久空气中二氧化碳与皮中的石灰起反应，生成不溶性碳酸钙存在于皮内而影响成革品质；

（5）、脱灰液比不宜大，一般起始液比控制在0.5~1.0（尽可能偏低），以保证脱灰剂的脱灰浓度，缩短生产周期；一般氯化铵脱灰水量少些，硫酸铵脱灰水量大些

（4）、脱灰温度一般控制在25~35℃，但用氯化铵脱灰，水洗程度一般要高些，温度低些，避免氯化钙对胶原的过度胶解；

（5）、脱灰中可加入亚硫酸钠，双氧水等，避免硫化氢的产生；

（6）、可采取分次脱灰，脱灰快，效果好。

选择题

寿光市被誉为“中国蔬菜之乡”，年产优质无公害蔬菜40亿公斤左右，40亿公斤用科学记数法可表示为（　　）

A．40×108公斤

B．4.0×109公斤

C．4.0×108公斤

D．40×109公斤
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填空题

Part 2


Questions 9-18


·Read the following article and answer questions 9-18 on the next page.

Shopping Pattern


1. Napoleon once described Britain as "a nation of shopkeepers", but since the 1960s the traditional corner shop has been slowly disappearing. The neighbourhood comer shop used to sell everything a housewife needed and the shopkeeper was an important person in the local community. The shop itself was a focus of community life, a place to chat as well as shop, in the days when Britons knew their local baker, local grocer and local butcher personally. So what happened to the comer shop
2. Shopping patterns changed dramatically in the 1970s and 1980s and the customers changed too. Shops began to get bigger and the owners opened more branches in different towns, each branch selling the same goods and offering cheaper prices than the local comer shop. The smaller shops closed as these large "chains" of shops took over. Customers liked the chains as they were self-service, offered a wider range of goods and introduced credit cards for customers. People in Britain now like shopping at a "name" they know, because they can be sure of the quality.
3. The very large retailers have such an enormous number of stores that they are called multiple retailers. During the "economic boom" of the 1980s the multiples developed superstores, offering an even wider choice of goods at even cheaper prices, on the edge of towns where giant shopping complexes often grew up around them.
4. Now that most Britons are car-owners they are prepared to travel further to shop, and like the choice offered by big stores. Most people are now paid monthly and prefer to buy in bulk once a month. The self-service and late-night shopping at superstores is convenient for the many women who work during the week. The corner shop is now empty during the day and people tend to use their local shops only in emergencies, if they have "forgotten" to buy something.
5. Corner shops are no longer profitable in the face of competition from the "giants". Britain could now be described as a nation of multiple retailers. Who could hope to survive and compete against their enormous choice and cheap prices Supporters of the corner shop say they prefer to pay higher prices because they get a friendlier and more personal service. Others shop there because they have no choice—the elderly or disabled, people without cars and young mothers with small children for whom a trip to a superstore would take a lot of planning and effort—but they are in the minority. Unfortunately for small shopkeepers, the majority of customers prefer speed and choice to the personal service of their local shops.

Questions 9-13


·For questions 9-13, choose from the list A-G which best summarizes each part of the article.
·For each numberedparagraph (1-5), mark one letter (A-G) on the Answer Sheet.
·Do not mark any letter twice.
  • A. Possibilities of traveling far to shop
  • B. Emergence of multiple retailers
  • C. Disappearing of corner shops
  • D. Economic boom
  • E. Anew shopping pattern
  • F. Discovery of shopping centers
  • G. Roles of corner shops


Paragraph 3 ______
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