题干

某人手指不慎划破出血,血液中与止血和避免发炎有关的是(  )

A:血小板、血浆

B:血小板、白细胞

C:红细胞、血浆

D:白细胞、血浆

上一题 下一题 0.0难度 选择题 更新时间:2018-06-19 12:03:32

答案(点此获取答案解析)

B

同类题2

某校化学兴趣小组同学在实验室整理药品时,发现氢氧化钠溶液的试剂瓶未塞瓶塞,且试剂瓶口周围有一些白色固体,他们怀疑氢氧化钠已经变质,于是进行了如下实验探究.

【提出问题】氢氧化钠溶液是否变质?

【查阅资料】氯化钠溶液、氯化钡溶液呈中性.

【实验探究】小王、小李两同学分别设计了不同方案并加以实验.


实验步骤

实验现象

结论

小王

用pH试纸测溶液的pH

溶液的pH>7

说明氢氧化钠溶液没有变质

小李

取少量溶液于试管中,加入适量氯化钡溶液

A

说明氢氧化钠溶液已经变质

(1)小李同学认为小王同学的结论不科学,其理由是____.

(2)小李同学的实验中观察到实验现象A为____.该反应的化学方程式为____ .

(3)小张同学认为该氢氧化钠溶液只是部分变质.为确定小张同学的猜想,应该对小李同学的实验进行如下改进:向试管中加入____的氯化钡溶液,再向试管中滴加酚酞试液,通过观察溶液颜色变化来检验该溶液是否含有氢氧化钠.

(4)小王同学在测定溶液pH实验中,由于紧张先将pH试纸润湿后再去测氢氧化钠溶液的pH,你认为他测出该溶液的pH会____(填“偏大”、“偏小”或“不变”).

【反思】

(5)该氢氧化钠溶液变质的原因是____ (用化学方程式表示).

【拓展应用】

(6)要证明氢氧化钠溶液是否变质,你认为还可使用与小李实验所加试剂不同类别的试剂是____ (填一种试剂即可,用化学式填写).

(7)若要除去上述变质的氢氧化钠溶液中的杂质应加入适量的____(填化学式)溶液而除去.

同类题4

阅读理解

    The Israeli farmers who pioneered the revolutionary technology known as drip irrigation weren't trying to solve one of the world's most urgent problems.They were just trying to survive.They lived in the desert,and they didn't have enough water to grow their crops.

    In its simplest form, it was little more than a pipe with holes in it. But behind each hole was a hi-tech dripper that let out just the right amount of water. Snaked along a row of crops so that the holes were positioned directly above the roots, the pipe could direct each precious drop of water directly to the plants, getting a bigger harvest while using a very small amount of the water.

    Over time, the farmers improved upon the technology, perfecting the drippers that regulated the flow of water, and connecting the pipelines to computers that could determine exactly how much water each plant needed and when.

    If the global population kept growing, the rest of the world would increasingly resemble their little community in the desert. So they began selling their irrigation systems in other parts of the world,eventually expanding to more than 110 countries. Netafirm, the company says it's lifting people out of poverty and conserving water at a time when the importance of doing so has never been clearer.

    The mass adoption of drip irrigation won't save the world by itself. To avoid the coming catastrophe, nearly everybody will, in some way, have to do more with less, perhaps through accepting and using other new technologies. Otherwise, it's going to get ugly.