题目内容

有二个DNA样品，分别来自两种未确认的细菌，两种DNA样品中的腺嘌呤碱基含量分别占它们DNA总碱基的32％和17％。这两个DNA样品的腺嘌呤，鸟嘌呤，胞嘧啶和胸腺嘧啶的相对比例是多少？其中哪一种DNA是取自温泉（64℃）环境下的细菌，哪一种DNA是取自嗜热菌？答案的依据是什么？

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进行某动态压力测量时，所采用的压电式力传感器的灵敏度为90.9nC/MPa，将它与增益为0.005V/nC的电荷放大器相连，而电荷放大器的输出接到一台笔式记录仪上，记录仪的灵敏度为20mm/V。试计算这个测量系统的总灵敏度；当压力变化为3.5MPa时，记录笔在记录纸上的偏移量是多少？

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造林前在选择主要树种的基础上，确定好（）、（）、比例，预防种间不利作用的发生，以确保较长时间地保持有利作用；造林时通过控制造林时间、（）、（）、株行距等措施，调节种间关系；在林分生长过程中平茬、修枝、抚育间伐，或环剥、去顶、断根、化学药剂抑制等。

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患者男，27岁，既往有消化道溃疡病史4年，突发上腹部刀割样疼痛，迅速蔓延至全腹，服抗生素后不能缓解，症状加重，6h后于急诊求治。经腹部X线平片诊断为：急性弥漫性腹膜炎，消化性溃疡穿孔。患者于入院半小时后出现烦躁表现，血压70/40mmHg，发生这种状况的原因是（）。

A. 脱水和电解质紊乱
B. 细菌毒力强
C. 心肺功能障碍
D. 吸收大量毒素和血容量下降
E. 血浆蛋白降低

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Users report that some shortcuts on the Start menu of their Windows 2000 professional computers are hidden. They want to access their shortcuts without having to click a scroll arrow. How must you configure the client computers to always display all Start menu shortcuts？（）

A. In the Folder Options dialog box, clear the Enable Web content check box in My Desktop Properties
B. In the Display Properties dialog box, clear the Transition effects for menus and tooltips check box
C. In the Folder Options dialog box, clear the Hide file extensions for known file types check box
D. In the Taskbar and Start Menu Properties dialog box, clear the Use Personalized Menus check box.

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Users report that some shortcuts on the Start menu of their Windows 2000 professional computers are hidden. They want to access their shortcuts without having to click a scroll arrow. How must you configure the client computers to always display all Start menu shortcuts？ （）

Users report that some shortcuts on the Start menu of their Windows 2000 professional computers are hidden. They want to access their shortcuts without having to click a scroll arrow. How must you configure the client computers to always display all Start menu shortcuts？（）