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名词解释题
干细胞(stem)
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对于STEM教育,以下选项中不正确的理解是()。
A、STEM教育强调全社会共同参与教育创新实践B、STEM教育强调跨学科C、STEM教育面向所有学生并培养综合素质D、STEM教育注重传统知识的灌输
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提出造血干细胞(hematopoietic stem cell，HSC)概念的依据是A、造血干细胞是由胚胎干细胞发育而来B、维持体内恒定的血细胞数量C、1961年Till等在小鼠体内发现了造血干细胞D、1979年，体外培养人造血祖细胞成功E、采用天然的细胞标志纯化造血干细胞和发展体外造血干细胞培养技术
考题
A frame with two，or sometimes four，arms through which are threaded the guidelines and which is used to keep the drill stem and bit in line with the center opening in the temporary guide base is the ______.A.drill stem guideB.guide frameC.drill string frameD.casing guide
考题
共用题干
Stem Cell Therapy May Help Repair the HeartAccording to scientists in the USA,stem cell therapy may one day be able to repair the hearts of people with heart failure.Researchers at Pittsburgh University School of Medicine examined 20 patients who had severe heart failure and were going to have surgery.They injected stem cells into the parts of their hearts that were damaged.They then compared their hearts with those of people who had undergone surgery without having the stem cells injected into them(they had also suffered from severe heart failure).The patients who had had the stem cells injected had hearts that were able to pump（用泵抽运） more blood than the others.According to Professor Robert Kormos,one of the researchers,these results could revolutionize heart treatment.Although previous studies had indicated that there might be a benefit,this is the first study that has actually proved that stem cell therapy can help thefailing heart work better．All the patients in this study had hearts that could not pump blood properly.The scientists measured their ejection fraction（射血分数）.This is a measure of heart performance;you measure how much blood is being pumped out by the left ventricle（心室）.Healthy people's ejection fraction is about 55%.These patients had ejection fraction ofunder 35%. They all had by-pass surgery（搭桥手术）performed on them. Some of the patients had stem cells taken from their hip bones and injected into 25-30 sites in the damaged heart muscle.Six months later their ejection fraction rate was 46.1%while those who just had surgery but no stem cell injections averaged 37. 2%.No side effects were reported.Heart failure is a common problem all over the world.In the UK alone about 650, 000 people suffer from heart failure every year. As the number of people suffering from heart failure increases in the world in general these findings are particularly significant.Current treatments relieve the symptoms.This new stem cell therapy actually repairs the damaged muscle in the heart and has the potential of curing the disease. The 20 patients had stem cell injections instead of surgery.A:Right B:Wrong C:Not mentioned
考题
有时风大流急，船舶靠码头时必须掉头顶流。（）A、A ship has to turn to stem the tide because the wind is strong when she is getting alongside a wharf.B、Sometimes the wind is strong and the current is rough, so a ship has to turn to stem the tide when she is getting alongside a wharf.C、The wind is big, a ship must get alongside a wharf so she has to turn to stem the tide.D、A ship has to turn to stem the tide so she can get alongside a wharf.
考题
同源重组（homologous recombination）与胚胎干细胞（embryonic stem cell）结合起来，创造了基因打靶技术（gene targeting），并得到基因敲除模型，获得了（）年的诺贝尔奖A、2006B、2007C、2008D、2009
考题
单选题A frame with two，or sometimes four，arms through which are threaded the guidelines and which is used to keep the drill stem and bit in line with the center opening in the temporary guide base is the（）.A
drill stem guideB
guide frameC
drill string frameD
casing guide
考题
单选题A built-up exhaust valve is one in which （）.A
the stem and heads are made of different materialB
low-alloy steel is used throughoutC
a replaceable valve disk is welded to the headD
the self-centering action comes from motion of the valve stem in the guide
考题
单选题How should the lifeboat sea painter be rigged?（）A
Spliced into the ring on the stem postB
Secured to the inboard side of a forward thwart and led inboard of the fallsC
Secured by a toggle to the stem post and led outboard of the fallsD
Secured by a toggle around the outboard side of a forward thwart
考题
单选题同源重组（homologous recombination）与胚胎干细胞（embryonic stem cell）结合起来，创造了基因打靶技术（gene targeting），并得到基因敲除模型，获得了（）年的诺贝尔奖A
2006B
2007C
2008D
2009
考题
单选题有时风大流急，船舶靠码头时必须掉头顶流。（）A
A ship has to turn to stem the tide because the wind is strong when she is getting alongside a wharf.B
Sometimes the wind is strong and the current is rough, so a ship has to turn to stem the tide when she is getting alongside a wharf.C
The wind is big, a ship must get alongside a wharf so she has to turn to stem the tide.D
A ship has to turn to stem the tide so she can get alongside a wharf.
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