问题 问答题 简答题

什么是标准物质?

答案

参考答案:

用于分析或标准仪器的有定值的化学标准品。

填空题


A
PASSAGE 1:
According to US Trade Representative Robert B. Zoellick, the ambitious US proposal for worldwide zero tariffs is comprehensive, and would benefit both developed and developing nations.
The proposal, said Zoellick, when combined with the far-reaching US agricultural reform proposal submitted to the WTO in July, would eliminate tariffs on the nearly $6 trillion in annual world goods trade, lifting the economic fortunes of workers, families, businesses, and consumers.
"Our proposal would turn every corner store in America into a duty-free shop for working families," said Zoellick. "This historic proposal would benefit the average American family with an extra $1,600 a year, while also removing high foreign tariff barriers on more than $670 billion in US industrial and consumer goods exports. Globally, tariff-free trade could help lift millions of people in developing countries out of poverty."
"President Bush believes that American workers, farmers, ranchers and businesses must have more than just the ability to compete globally, they must also have the opportunity to do so," said US Commerce Secretary Don Evans. "This proposal says that ’no one wins unless we all win’ and ensures a level playing field for America’s goods and ingenuity to compete fairly around the world."
B
PASSAGE 2:
The US proposal envisions a two-step approach to eliminating tariffs on a full-range of consumer and industrial goods ranging from women’s shoes, to tractors, to children’s toys.
First, WTO members would be required to cut and harmonize their tariffs in the five year period from 2005 to 2010. Specifically, WTO members would eliminate all tariffs at or below 5 percent by 2010, cut all other tariffs through a "tariff equalizer" formula to less than 8 percent by 2010, and eliminate tariffs in certain highly traded industry sectors as soon as possible, but not later than 2010.
Next, all WTO members would make equal annual cuts in remaining tariffs between 2010 and 2015. These cuts would result in zero tariffs.
The proposal also calls for a separate program to identify and eliminate non-tariff barriers, which would run on a parallel track with the negotiations on industrial tariffs. The US will put forward an initial list of such barriers in January of 2003.
C
PASSAGE 3:
According to the Office of US Trade Representative (USTR), eliminating US tariffs would significantly benefit US families and consumers through lower import taxes and a more competitive economy. Hidden import taxes cost American consumers $18 billion in 2001, alone. USTR contends that duty-free trade would eliminate these hidden costs and lower prices for consumers. While this proposal would offer substantial benefits to all Americans, it would particularly help low-income families. A recent study by the Progressive Policy Institute found that cutting US import taxes especially benefits single-parent, low-income families, who typically pay a higher proportion of their income on import taxes than other households. A study done by the University of Michigan found that the US economy would expand by $95 billion as a result of tariff-free trade--contributing to job-creation and higher wages. The University of Michigan study also revealed: The elimination of industrial tariffs by other countries could increase US exports by $83 billion annually highly-traded goods exports, such as chemicals, paper, and scientific equipment, which are targeted in the US proposal for total tariff elimination, account for 60 percent of all US exports.
Estimates by the World Bank project that tariff-free global trade would result in a worldwide income gain of $832 billion from trade in all goods including agriculture, of which $539 billion (65 percent) would flow to developing countries. Representing an income increase of about $544 for a family of four, the World Bank estimates that free trade in goods and services could help lift 300 million people out of poverty-- a number greater than the entire population of the United States.
D
PASSAGE 4:
The reduction and elimination of tariffs on consumer and industrial goods is a component of the WTO negotiations launched in Doha, Qatar in 2001 to be completed by January 1, 2005.
Throughout the year, United States leadership has continued to spur momentum on the Doha Development Agenda in the WTO:
·On July 1, the United States announced proposals for liberalizing global trade in services, designed to remove foreign barriers in areas such as financial services, telecommunications, and environmental services.
·On August 9, the United States submitted a proposal to expand transparency and public access to World Trade Organization dispute settlement proceedings. The proposal would open WTO dispute settlement proceedings to the public for the first time and give greater public access to briefs and panel reports.
·On October 17, the United States submitted a paper highlighting the importance of strengthening transparency and due process in the application of trade remedies (antidumping, subsidies, and safeguard actions). It addresses the basic concepts and principles of the trade remedy rules against unfair trade, and the importance of tackling the trade-distorting practices that are frequently the root causes of unfair trade. The US also submitted a paper presenting a number of ideas and recommendations for addressing trade- and market-distorting practices in the steel sector.
·the US will propose tariff-cutting in two phases71. ______
·how a duty-free world would help US consumers 72. ______
·the proposal could averagely save a US family $1,600 a year73. ______
·the US will submit an initial list of non-tariff barriers 74. ______
·the procedure of the tariff-free proposal arranged through the whole year 75. ______
·tariff-free world trade could help lift millions of people out of 76. ______
poverty in the world 77. ______
·the US put forward a paper about reasons of unfair trade78. ______
·the US has called on the WTO to eliminate all tariffs on consumer 79. ______
and industrial goods worldwide80. ______

单项选择题

山兰凤蝶是澳大利亚的一种常见蝶,其雄性翅膀的颜色为异常亮丽的蓝色,但周边镶嵌有黑色,其黑色部分越黑,蓝色部分就越艳丽,在求偶竞争中也就越有优势。专家们以前认为,这是由于其中的黑色素吸收了大部分入射光所致。但现在发现,这种蝴蝶不只是通过化学方式,更是通过物理方式,即一种特别的光学手段来使其黑色部分显得更黑,[ ]它包含黑色素的微细鳞片结构能“捕捉”住光,[ ]创造出一种比黑色还黑的“超黑”。
许多动物的鲜艳色彩或伪装效果都不是仅用色素就能获得的,还需要利用物理方法。例如,雄性孔雀的尾羽翠绿绚丽,这是因为其中发生了“建设性光学干涉效应”所致,它们的羽毛中具有独特结构的微小蛋白质能够以特别的方式对光进行反射,不需要的波长都被消除掉了。
受此启发,英国埃克塞特大学的生物学家皮特·武库希奇及其同事对山兰凤蝶进行了研究,目的是探索它的机体结构物能否把彩色消除掉而制造出深黑色,这与孔雀制造出绚烂色彩是同样的机理,但导致的结果正相反。
研究者发现,山兰凤蝶翅膀中的微细鳞片结构是排列成许多直径不超过1微米的小凹坑.犹如蜂巢。这种结构能够最大限度地利用介质光折射率的不同而“捕捉”光。
光通过两种不同折射率的介质时,会发生折射和虚化现象,其中一些光会被“捕捉”在密度较大的介质中。水对空气的光折射率之比为1.3:1,而山兰凤蝶机体组织对空气的光折射率之比为1.6:1,这就使其中的色素能最大限度地吸收光。
研究者对这一推断做了一次测试。他们把山兰风蝶的翅膀浸到三溴甲烷溶液中,该种溶液的光折射率与山兰凤蝶翅膀机体组织的光折射率大致相同,结果其翅膀中的黑色部分真不那么黑了;在空气中,其吸收光的比率超过了90%,但在三溴甲烷溶液中,这一数字只有50%多一点。
英国国家物理实验室的化学工程师理查德·布朗在2002年曾用一种凹状镍磷合金膜衣料制造出与山兰凤蝶相似的“超黑”。他认为“超黑”将成为今后的流行色,其最大的用途将是在光学设备上;同时,那些对黑颜色不满意的艺术家们也会对此感兴趣。

下列对于山兰凤蝶的色素能够吸收光的机理的解说,错误的一项是( )。

A.当光通过空气投射到山兰风蝶的机体时,山兰凤蝶的机体结构物就会把其中的彩色消除掉而强化黑色,从而制造出“超黑”

B.山兰凤蝶翅膀中的微细鳞片,排列成许多直径不超过1微米的小凹坑,这种蜂巢状的结构能够在特定条件下最大限度地“捕捉”光

C.光通过两种不同的介质时,会发生折射和虚化现象,有些光就会被“捕捉”在密度较大的介质中

D.山兰凤蝶机体组织和空气是两种不同折射率的介质,其光折射率之比为1.6:1,这就使密度较大的山兰凤蝶机体组织的色素能最大限度地吸收光