有一种新合成的化学物质,拟应用于化妆品中,先需对其进行安全性评价。提示:在该化学物安

题型:单项选择题 共用题干题

问题:

有一种新合成的化学物质,拟应用于化妆品中,先需对其进行安全性评价。提示:在该化学物安全性评价的基础上,结合其危险度评价的资料来制定其安全限值(卫生标准)。

如果用BMD来替代NOAEI。或LOAEL计算该物质的参考剂量,优点如下,除外()

A.BMD是依据剂量-反应关系曲线的所有数据计算获得的,而不是依据一个点值,在可靠性与准确性上都大大提高了

B.用BMD计算是把试验组数、每组实验动物数以及终点指标观察值的离散度等均考虑在内了

C.不存在从实验动物资料外推到人的不确定性

D.未直接观察到NOAEL的试验结果,仍可通过计算求出BMD

E.既可以通过计数资料,也可通过计量资料获得

考点:放射卫生(医学高级)放射毒理学放射毒理学题库
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假定当汽油的互补品汽车价格上升 10 %时,汽油的需求变动量为 20 单位:当汽油的替代品车用天然气价格下降 10 %时,汽油的需求变动量为 30 单位。如果其他条件不变,当汽车价格上升 10 %、车用天然气价格下降 10 %同时出现时,那么,汽油的需求数量

A.增加 50 单位

B.增加 10 单位

C.减少 50 单位

D.减少 10 单位

题型:单项选择题 共用题干题

仿照示例,分别从褒扬和批评的角度写一个句子。

蜡烛 褒扬:每燃烧一段,都贡献一份光和热。批评:过分地炫耀,终究会被泪水淹没。

①腊梅 褒扬:____________________________。批评:____________________________。

②彩虹 褒扬:____________________________。批评:____________________________。

题型:单项选择题 共用题干题

根据红细胞形态可将贫血分为____________、_____________、______________、______________四类。

题型:单项选择题 共用题干题

强迫风冷条件下,变压器容量可提高()。

A、50%~60%

B、60%~70%

C、30%~50%

D、40%~50%

题型:单项选择题 共用题干题

For many people today, reading is no longer relaxation. To keep up their work they must read letters, reports, trade publications, interoffice communications, not to mention newspapers and magazines: a never ending flood of words. In (1) a job or advancing in one, the ability to read and comprehend (2) can mean the difference between success and failure. Yet the unfortunate fact is that most of us are (3) readers. Most of us develop poor reading (4) at an early age, and never get over them. The main deficiency (5) in the actual stuff of language itself—words. Taken individually, words have (6) meaning until they are strung together into phrases, sentences and paragraphs. (7) , however, the untrained reader does not read groups of words. He laboriously reads one word at a time, often regressing to (8) words or passages. Regression, the tendency to look back over (9) you have just read, is a common bad habit in reading. Another habit which (10) down the speed of reading is vocalization—sounding each word either orally or mentally as (11) reads.

To overcome these bad habits, some reading clinics use a device called an (12) , which moves a bar(or curtain) down the page at a predetermined speed. The bar is set at a slightly faster rate (13) the reader finds comfortable, in order to "stretch" him. The accelerator forces the reader to read fast, (14) word by word reading, regression and subvocalization practically impossible. At first (15) is sacrificed for speed. But when you learn to read ideas and concepts, you will not only read faster, (16) your comprehension will improve. Many people have found (17) reading skill drastically improved after some training. (18) Charlie Au, a business manager, for instance. His reading rate was a reasonably good 172 words a minute(19) the training; now it is an excellent 1,378 words a minute. He is delighted that how he can (20) a lot more reading material in a short period of time.

第(9)空应选择()

A.what

B.which

C.that

D.if

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