题目内容

放射性碘标记下列哪种描述错误

A. 常用的标记方法有亲电取代标记与联接标记
B. 固相氧化法标记率高，但对蛋白质生物活性有损伤
C. 氯胺T法：用氯胺T作氧化剂，用偏重亚硫酸钠终止反应
D. 乳过氧化物酶法：用乳过氧化物酶与微量氧化剂(H2O2)底物进行氧化，反应温和，对蛋白质生物活性损伤小
E. 联接标记先用123I/131I标记一前体，再将标记的前体与待标记的蛋白质等分子联接

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为什么链条的链节数Lp通常取偶数

The American economic system is organized around a basically private-enterprise, market-oriented economy in which consumers largely determine what shall be produced by spending their money in the market place for those goods and services that they want most. Private businessmen, striving to make profits, produce these goods and services in competition with other businessmen; and the profit motive, operating under competitive pressures, largely determines how these goods and services are produced. Thus, in the American economic system it is the demand of individual consumers, coupled with the desire of business men to maximize profits and the desire of individuals to maximize their incomes, that together determine what shall be produced and how resources are used to produce it. An important factor in a maket-oriented economy is the mechanism by which consumer demands can be expressed and responded to by producers. In the American economy, this mechanism is provided by a price system, a process in which prices rise and fall in response to relative demands of consumers and supplies offered by seller-producers. If the product is in short supply relative to the demand, the price will be bid up and some consumers wil be eliminated from the market. If, on other hand, producing more of a commodity results in reducing its cost, this will tend to increase the supply offered by sellers. Price is the regulating mechanism in the American economic system. The important actor in a private-enterprise economy is that individuals are allowed to own poductive resources (private property), and they are permitted to hire labor, gain control over natural resources, and produce goods and services for sale at a profit. In the American economy, the concept of private property embraces not only the ownership of productive resources but also certain rights, including the right to determine the price of a product or to make a free contract with another private individual. What are the private businessmen striving to do

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B. To advertise their products.
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