问题 多选题

由电场强度的定义E=

F
q
可知(  )

A.这个定义只适于点电荷电场

B.式中的F是放入电场中的电荷所受的电场力,q是该电荷所带的电荷量

C.式中的F是放入电场中的电荷所受的电场力,q是产生电场的电荷的电荷量

D.由库仑定律F=

KQ1Q2
r2推导出的:
KQ2
r2
是点电荷Q2产生的电场在Q1所在处的场强大小

答案

A、电场强度E的定义式E=

F
q
适用于任何电场.故A错误.

B、电场强度E的定义式E=

F
q
中,F是放入电场中的试探电荷所受的电场力,q是试探电荷的电量,不是产生电场的电荷的电量.故B正确,C错误.

D、由库仑定律F=

KQ1Q2
r2
推导出的:
KQ2
r2
是点电荷Q2产生的电场在Q1所在处的场强大小,故D正确.

故选BD.

论述题

(26分)

材料一 温 * * * * 在哥本哈根气候大会发表了题为《凝聚共识加强合作推进应对气候变化历史进程》的重要讲话,全面阐述中国政府应对气候变化问题的立场和主张。温 * * 指出中国高度重视气候变化问题,从中国人民和人类长远发展的根本利益出发,为应对气候变化做出了不懈努力和积极贡献。中国政府坚持“共同但有区别的责任”原则是国际合作应对气候变化的核心和基石。发达国家必须率先大幅量化减排并向发展中国家提供资金和技术支持。发展中国家应根据本国国情,在发达国家资金和技术转让支持下,尽可能减缓温室气体排放。中国政府确定减少温室气体排放的目标是中国根据国情采取的自主行动,是对中国人民和全人类负责的,不附加任何条件,不与任何国家的减排目标挂钩。我们将进一步完善国内统计、监测、考核办法,改进减排信息的披露方式,增加透明度,积极开展国际交流、对话与合作。

(1)结合材料一,运用当代国际社会的相关知识,说明中国政府应对气候变化问题的立场和主张的理论依据。(11分)

材料二 中国当前的玉米种植面积和产量仅次于美国。近年来,随着科技的发展,中国的玉米深加工产业发展很快。成为玉米需求新的增长点。

表一  中国玉米产需表                  单位:10000吨

年度产量年度总需求需 求 结 构
饲料消费食用消费工业加工其他
20011060011813838077111801482
20021113612410832773713801966
20031213013789902082814502500
20041140013077915679215401589
20051216013181936082017301271
2006130001340010000600
(2)根据表一中玉米产量与需求变化情况,分析玉米价格变化的趋势,并指出这种趋势对玉米生产可能产生的影响。(15分)

单项选择题

Animal studies are under way, human trial protocols are taking shape and drug makers are on alert. All the international health community needs now is a human vaccine for the bird flu pandemic sweeping a cluster of Asian countries.

The race for a vaccine began after the first human case emerged in Hong Kong in 1997. Backed by the World Health Organization (WHO), three research teams in the US and UK are trying to create a seed virus for a new vaccine. Their task is formidable, but researchers remain optimistic." There are obstacles, but most of the obstacles have been treated sensibly," says Richard Webby, a virologist at St. Jude Children’s Research Hospital in Memphis, Tennessee.

The biggest challenge is likely to be the rapidly mutating virus. Candidate vaccines produced last year against the H5N1 virus are ineffective against this year’s strain. Scientists will have to constantly monitor the changes and try to tailor the vaccine as the virus mutates. They can’t wait to see which one comes next.

The urgency stems from fears that I-ISN1 will combine with a human flu virus, creating a pathogen(病原体) that could be transmitted from person to person. But if people have no immunity to the virus, the strain may not mutate as rapidly in people as it does in birds.

To quickly generate the vaccine, researchers are using reverse genetics, which allows them to skip the long process of searching through reassorted viruses for the correct genetic combination. Instead, scientists clone sequences for hemagglutinin(红血球凝聚素) and neuraminidase(神经氨酸苷酶), the two key proteins in the virus. The sequences are then combined with human influenza genes to create a customized reference strain.

Because products developed with reverse genetics have never been tested in humans, the candidate vaccines will first have to clear regulatory review. In anticipation, the US Food and Drug Administration (FDA) and the European Agency for the Evaluation of Medicinal Products (EMEA) are both preparing pandemic response plans. The EMEA has produced a fist-track licensing program, an industry task force and detailed guidance for potential applicants.

In Europe, a reassortant influenza virus -- but not the inactivated vaccine -- produced by reverse genetics would be considered a genetically modified organism, and manufacturers would need approval from their national or local safety authorities. The WHO has prepared a preliminary biosafety risk assessment of pilot-lot vaccine, which could help speed up the review.

A preliminary version of their protocol calls for several hundred subjects, beginning with a group of young adults and gradually expanding to include those most susceptible to the flu -- children and the elderly." If we had product," says Lambert," it would probably be a couple of months at the earliest before we have early data in healthy adults.

The vaccine generated by reverse genetics is required to review in that ()

A. it has p side effect to the elderly

B. it may turn ineffective in a short period

C. it is useless in preventing the virus

D. it hasn’t been tested in humans