为区分HCl、HClO₄、H₂SO₄、HNO₃四种酸的强度大小,可采用下列()
A.水
B.吡啶
C.冰醋酸
D.乙醚
A.水
B.吡啶
C.冰醋酸
D.乙醚
A.所含的羧基和氨基的极性
B.所含氨基和羧基的数目
C.所含R基团的大小
D.脂肪族氨基酸为极性氨基酸
E.所含的R基团为极性或非极性
梁太子萧统所编的《文赋》是我国第一部按文体聚类区分的文学总集,它的分类是第一次真正"文学"本体意义上的分类。()
A、错误
B、正确
A.n>1
B.0.75<n<1
C.0.2<n≤0.75
D.n≤0.2
将英语短文译为中文
2. Kin Recognition (10分)
Many organisms, from sea squirts to primates, can identify their relatives. Understanding how and why they do so has prompted new thinking about the evolution of social behavior. by David W. Pfennig and Paul W. Sherman Kinship is a basic organizing principle of all societies. Humans possess elaborate means by which to identify relatives, such as using surnames and maintaining detailed genealogies.
Mechanisms for distinguishing kin also occur throughout the plant and animal kingdoms regardless of an organism’s social or mental complexity, in creatures as diverse as wildflowers and wasps. Scientists are beginning to discover that an understanding of the origin and mechanisms of kin recognition offers fresh insights into such diverse topics as how living things choose their mates, how they learn and how their immune system works.
BELDING’S GROUND SQUIRRELS live in groups in which mothers, daughters and sisters cooperate extensively. By using odors, the squirrels can distinguish familiar nestmates, who are close kin, from nonnestmates. They can also discriminate between full sisters and half sisters.
将英语短文译为中文
3 Self-Powered Nanotech (10分)
Nanosize machines need still tinier power plants
By Zhong Lin Wang
The watchmaker in the 1920s who devised the self-winding wristwatch was on to a great idea: mechanically harvesting energy from the wearer’s moving arm and putting it to work rewinding the watch spring.
Today we are beginning to create extremely small energy harvesters that can supply electrical power to the tiny world of nanoscale devices, where things are measured in billionths of a meter. We call these power plants nanogenerators. The ability to make power on a minuscule scale allows us to think of implantable biosensors that can continuously monitor a patient’s blood glucose level, or autonomous strain sensors for structures such as bridges, or environmental sensors for detecting toxins — all running without the need for replacement batteries. Energy sources are desperately needed for nanorobotics, microelectromechanical systems (MEMS), homeland security and even portable personal electronics. It is hard to imagine all the uses such infinitesimal generators may eventually find.
In Brief
★Nanotechnology has huge potential — but those minuscule devices will need a power source that is better than a battery.
★ Waste energy, in the form. of vibrations or even the human pulse, could provide sufficient power to run such tiny gadgets.
★ Arrays of piezoelectric nanowires could capture and transmit that waste energy to nanodevices.
★ Medical devices will likely be a major application. A pacemaker’s battery could be charged so it would not need replacing, or implanted wireless nanosensors could monitor blood glucose for diabetics.
放大器某点为交流地电位,即在放大器工作时,该点电压为零()。
A、正确
B、错误