We should consider the students' request

题型:选择题

问题:

We should consider the students' request _____ the school library provide more books on popular science. [ ]

A. that

B. when

C. which

D. where

考点:同位语从句
题型:选择题

关于N-乙酰-β-D-氨基葡萄糖苷酶 (NAG)错误的是

A.NAG不通过肾小球滤过,因而尿中排出量不受血中其来源的影响

B.其为溶酶体酶的一种

C.分子量为140kD,在肾皮质含量最高

D.在肾单位远曲小管细胞内含量最丰富

E.其活性对肾小管活动性损伤有灵敏反应

题型:选择题

在荧光定量分析法中,下列哪种不是影响荧光强度的因素()

A.溶剂的性质

B.荧光物质的浓度

C.溶液的pH值

D.温度

E.荧光物质的摩尔吸光系数

题型:选择题

A bite of a cookie containing peanuts could cause the airway to constrict fatally. Sharing a toy with another child who had earlier eaten a peanut butter and jelly sandwich could raise a case of hives. A peanut butter cup dropped in a Halloween bag could contaminate the rest of the treats, posing an unknown risk.

These are the scenarios that "make your bone marrow turn cold" according to L. Val Giddings, vice president for food and agriculture of the Biotechnology Industry Organization. Besides representing the policy interests of food biotech companies in Washington, D. C., Giddings is the father of a four-year-old boy with a severe peanut allergy. Peanuts are only one of the most allergenic foods; estimates of the number of people who experience a reaction to the beans hover around 2 percent of the population.

Giddings says that peanuts are only one of several foods that biotechnologists are altering genetically in an attempt to eliminate the proteins that do great harm to some people’s immune systems. Although soy allergies do not usually cause life-threatening reactions, the scientists are also targeting soybeans, which can be found in two thirds of all manufactured food, making the supermarket a minefield for people allergic to soy. Biotechnologists are focusing on wheat, too, and might soon expand their research to the rest of the "big eight" allergy-inducing foods: tree nuts, milk, eggs, shellfish and fish.

Last September, for example, Anthony J. Kinney, a crop genetics researcher at DuPont Experimental Station in Wilmington, Del., and his colleagues reported using a technique called RNA interference (RNAi) to silence the genes that encode p34, a protein responsible for causing 65 percent of all soybean allergies. RNAi exploits the mechanism that cells use to protect themselves against foreign genetic material; it causes a cell to destroy RNA transcribed from a given gene, effectively turning off the gene.

Whether the public will accept food genetically modified to be low-allergen is still unknown. Courtney Chabot Dreyer, a spokesperson for Pioneer Hi-Bred International, a subsidiary of DuPont, says that the company will conduct studies to determine whether a promising market exists for low allergen soy before developing the seeds for sale to farmers. She estimates that Pioneer Hi-Bred is seven years away from commercializing the altered soybeans.

Doug Gurian-Sherman, scientific director of the biotechnology project at the Center for Science in the Public Interest—a group that has advocated enhanced Food and Drug Administration oversight for genetically modified foods—comments that his organization would not oppose low-allergen foods if they prove to be safe. But he wonders about "identity preservation" a term used in the food industry to describe the deliberate separation of genetically engineered and no nengineered products. A batch of nonengineered peanuts or soybeans might contaminate machinery reserved for low-allergen versions, he suggests, reducing the benefit of the gene-altered food. Such issues of identity preservation could make low-allergen genetically modified foods too costly to produce, Chabot Dreyer admits. But, she says, "it’s still too early to see if that’s true. \

What is the author’s attitude towards genetically modified foods()

A. Supportive

B. Unbiased

C. Partial

D. Skeptical

题型:选择题

WWW是以超文本标注语言为基础,能够提供面向Internet服务的信息浏览系统。WWW系统的结构采用了 【10】 模式。

题型:选择题

探水接近老空,预计有沼气和其它有害气体涌出时,必须有瓦斯检查员。

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