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欲采用流式细胞术检测分析免疫增殖病小鼠脾脏内免疫细胞表达状况，首先将小鼠处死后获取其脾，然后进一步制备单细胞悬液，采用流式细胞仪分析脾内淋巴细胞表达情况。

流式细胞分析时要求荧光染料需具备的条件中，错误的是 （）

A.有较高的量子产额和消光系数

B.对488nm的激发光波长有较强的吸收

C.容易与被标记的单克隆抗体结合而不影响抗体自身的特异性

D.发射光波长与激发光波长间有较大差距

E.发射光波长与激发光波长接近

答案

参考答案：E

单项选择题

Questions 61-70 are based on the following passage.


While some international couriers are showing signs of exhaustion, EMS (Express Mail Service), the generic name for the courier services of post offices, seems to be finding its stride. Known as Datapost in Britain, as Chronopost in France, and as A1-Barid al-Mumtaz in Saudi Arabia, EMS is now second in the international courier business (jointly with TNT Skypack). Last year it delivered 5.6 million items, weighing less than 20 kilograms each, across borders. That and its annual growth rate of around 5 percent have worried DHL, the market leader, enough for it to counter-attack in the Courts.
On October 26, a Dutch judge ruled against DHL on all three counts filed against the Dutch post office: that the three-initial name was too close to DHL’s; that the orange lines in the EMS logo were too similar to DHL’s dark red ones; and that the claim to the widest route system in the world was unfounded. DHL has threatened the Swiss post office with similar action, but it may reconsider after the Dutch ruling.
EMS has some advantages over the private couriers. One is a dense ready-made network of offices, especially in Europe, the avowed target area of the private couriers. Another advantage is a long tradition of working with customs authorities. In a business where minutes count, it pays to have good friends at customs. That advantage particularly irritates the private couriers because there is no legal way to combat such unquantifiable coziness.
The private courier services are also annoyed because in countries like Switzerland and Italy, where the post office is officially a monopoly, they pay it a fee. In Switzerland DHL says it pays more than SFr lm ($ 708,000) "to the competition" each year. In France the couriers have won a battle for exoneration.
Although governments are under little pressure to keep prices artificially low, EMS is often cheaper than the private couriers, but not always. A recent test in Britain (on a domestic route) showed Datapost about halfway between the least and the most expensive, but gave it full marks for speed and service.
Each national EMS is free to set its rates and follow its own rules on things like bulk discounts. The Universal Postal Union, based in Berne, determines how costs and revenues are split between sending and receiving countries, and standardizes procedures. More than 100 postal administrations have linked into the system—and more are coming, including Russia’s. That makes the feisty EMS particularly happy since its rivals have not been allowed to serve anywhere in Russia.

The recent test in Britain shows that ______.

A. EMS provides better services than the private couriers
B. the private couriers are as cheap as EMS
C. the private couriers are faster than EMS
D. EMS is always cheaper than the private couriers
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选择题

如图所示，向左匀速运动的小车发出频率为f的声波，车左侧A处的静止的人感受到的声波的频率为f1，车右侧B处的静止的人感受到的声波的频率为f2，则

A．f1<f，f2<f

B．f1<f，f2>f

C．f1>f，f2>f

D．f1>f，f2<f
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