排卵期出血（） A.基础体温单相 B.基础体温双相，体温上升日有少量 * * 出血 C.基

发布时间：2017-08-04 06:55 │ 来源：www.tikuol.com

题型：单项选择题 B型题

问题：

排卵期出血（）

A.基础体温单相

B.基础体温双相，体温上升日有少量 * * 出血

C.基础体温双相，升温相时间9天

D.基础体温双相，升温相下降缓慢

E.基础体温双相，升温相时间13天

考点：妇产科护理主管护师月经失调患者的护理月经失调患者的护理题库

题型：单项选择题 B型题

向Cr₂（SO₄）₃的水溶液中加入NaOH溶液，当pH=4.6时，开始出现Cr（OH）₃沉淀，随着pH的升高，沉淀增多；但当pH＞13时，沉淀消失，出现亮绿色的亚铬酸根离子（CrO₂^2-）．其平衡关系如下：

Cr³⁺（紫色）+3OH^-⇌Cr（OH）₃（灰绿色）⇌CrO₂^2-（亮绿色）+H⁺+H₂O

向0.05mo1•L^-1 Cr₂（SO₄）₃溶液50mL中，加入1.0mol•L^-1NaOH溶液50mL，充分反应后，溶液中可观察到的现象是（　　）

A．溶液为紫色

B．溶液中有灰绿色沉淀

C．溶液为亮绿色

D．无法判断

查看答案

题型：单项选择题 B型题

镜泊湖是什么成因的湖泊（）。

A.冰川湖

B.构造湖

C.火口湖

D.堰塞湖

查看答案

题型：单项选择题 B型题

常言道：“父母恩难报，难报父母恩。”看了下边漫画《给父母磕一个头》，思考以下问题：

（1）“给父母磕一个头”，这一报恩的做法你赞同吗？并简要说明理由。

________________________________________________________________________________________________________________________________________________________________________________________

（2）作为八年级的学生，你觉得现在感谢父母应该怎么做？

________________________________________________________________________________________________________________________________________________________________________________________

（3）你知道母亲节是哪一天吗？请写出来。在这一天，你准备为你的母亲做些什么？

________________________________________________________________________________________________________________________________________________________________________________________

查看答案

题型：单项选择题 B型题

某学校食堂为了确保师生健康并预防“禽流感”，坚持把师生用过的餐具进行高温蒸煮消毒．在餐具放进冷水直至加热到水沸腾的过程中，关于餐具的下列相关物理量肯定没有变化的是（　　）

A．温度

B．质量

C．体积

D．密度

查看答案

题型：单项选择题 B型题

Scientists studying the activity of the living brain with widely used new imaging techniques have been missing some of the earliest steps in brain activity because those changes are subtle and are masked by reactions that happen seconds later, Israeli scientists say.
The imaging techniques — positron emission tomography scanning and magnetic resonance imaging, known as PET and functional M. R. I. scans — are used prominently in studies of brain activity. The most active brain areas appear to light up on the scans as specific tasks are performed. The two techniques do not measure nerve-cell activity directly; they measure the extra flow of blood that surges to the most active brain areas.
Researchers at the Weizmann Institute of Science in Rehovot, Israel, have monitored these changes in blood flow in anesthetized cats by removing parts of the skull and observing how the nerve cells in activated regions fuel their activities by rapidly removing oxygen from nearby red blood cells.
This rapid uptake of oxygen, made evident by visible changes in the color of the red cells, proves that early oxygen transfer gives these neurons the energy to do their work, the researchers said.
They also found that subtle changes in blood flow began significantly earlier than was detected by PET and functional M. R. I. scans, which lack sufficient resolution and do not form their images quickly enough to follow such rapid changes. Dr. Amiram Grinvald published the findings in the Journal Science.
"The initial event is very localized and will be missed if you don’t look for it soon enough and use the highest possible resolution," Dr. Grinvald said. "Now people are beginning to use our results with other imaging methods."
Working on the exposed brain lets researchers follow electrical activity and the accompanying blood flow in greater detail than is possible by using indirect imaging methods that track neural activity through the skull. However, opportunities for open-skull studies of humans are limited to some kinds of neurosurgery, and researchers must mostly rely on PET and functional M. R. I. images for studies linking behavior with specific brain activity.
By directly observing exposed cat brains and in similar work with a few human cases, Dr. Grinvald and his associates have been able to observe the first evidence of electrical activity and other changes in brain cells after a light has been seen or a limb moved.
The newest research showed that it took three seconds or more after an event for the flow of blood to increase to an area of the brain dealing with a stimulus. That is the blood-flow increase usually pictured in brain-function studies with PET or functional M. R. I techniques, the Israeli researchers said. However, the initial reaction observed in the Weizmann research by directly imaging the exposed brain — the direct transfer of oxygen from blood cells to neurons — occurred in the first-tenth of a second and was lost to conventional imaging, they said.
The later increase in blood flow to the area, Dr. Grinvald said, was obviously an attempt by the body to supply more oxygen for brain activity. But the increase in blood was so abundant that it covered an area much larger than the region directly involved in the activity being studied, masking some of the subtle changes, he said.
The body’s reaction, the researchers said in the paper, was like "watering the entire garden for the sake of one thirsty flower."
Dr. Kamil Ugurbil, said that the Israeli research provided clues that allowed the use of functional M. R. I. scans to picture earlier events in the activity of brain cells.
"Dr. Grinvald’s observations are very important, and they have significant implications for functional imaging with high resolution," Dr. Ugurbil said in an interview. "We have actually been able to look at the early changes with magnetic resonance imaging, but you need to use higher magnetic fields to see them clearly because they are small effects."
By timing their images more carefully and by using per magnetic fields than normal, he said, researchers have used Dr. Grinvald’s findings to study early neuronal responses to stimuli at smaller, more specific sites in the brain.

According to the passage, why couldn’t PET and functional M. R. I. scans detect subtle changes in blood flow earlier

A．Because there is early oxygen transfer.

B．Because they do not form their images quickly enough to follow such rapid changes.

C．Because researchers control the changes in blood flow.

D．Because early oxygen transfer gives the flow blood energy.

查看答案

更多题库