问题 单项选择题 B1型题

在放射免疫分析中,用于标记抗原的核素是()

A.123

B.124

C.125

D.127

E.131

答案

参考答案:C

解析:凡属于同一种元素的不同核素,在元素周期表中处于同一位置,质子数相同而中子数不同,称为元素的同位素,以上5种碘元素互为同位素。123Ⅰ主要发射γ射线,用于单光子显像;124Ⅰ主要发射β射线,用于正电子显像;125Ⅰ主要发射γ射线,但能量低,半衰期偏长,故用于放射免疫分析;127Ⅰ属于稳定型核素,是食盐中碘的主要形式;131Ⅰ以发射β射线为主,利用其生物学效应高的特点,主要用于治疗。

单项选择题
单项选择题

(D)

Consumers are being confused and misled by the hodge-podge of environmental claims made by household products, according to a "green labeling" study published by Consumers International Friday.

Among the report’s more outrageous findings-a German fertilizer described itself as "earthworm friendly" a brand of flour said it was "non-polluting" and a British toilet paper claimed to be "environmentally friendlier".

The study was written and researched by Britain’s National Consumer Council (NCC) for lobby group Consumer International. It was funded by the German and Dutch governments and the European Commission.

"While many good and useful claims are being made, it is clear there is a long way to go in ensuring shoppers are adequately informed about the environmental impact of products they buy." said Consumers International director Anna Fielder.

The 10-country study surveyed product packaging in Britain, Western Europe, Scandinavia and the United States. It found that products sold in Germany and the United Kingdom made the most environmental claims on average.

The report focused on claims made by specific products, such as detergent insect sprays and by some garden products. It did not test the claims, but compared them to labeling guidelines set by the International Standards Organization (ISO) in September, 1999.

Researchers documented claims of environmental friendliness made by about 2,000 products and found many too vague or too misleading to meet ISO standards.

"Many products had specially-designed labels to make them seem environmentally friendly, but in fact many of these symbols mean nothing." said report researcher Philip Page.

"Laundry detergents made the most number of claims with 158. Household cleaners were second with 145 separate claims, while paints were third on our list with 73. The high numbers show how very confusing it must be for consumers to sort the true from the misleading." he said.

The ISO labeling standards ban vague or misleading claims on product packaging, because terms such as "environmentally friendly" and "non-polluting" can not be verified. "What we are now pushing for is to have multinational corporations meet the standards set by the ISO." said Page.

A study was carried out by Britain’s NCC to().

A. find out how many claims made by products fail to meet environmental standards

B. inform the consumers of the environmental impact of the products they buy

C. examine claims made by products against ISO standards

D. revise the guidelines set by the International Standards Organization