核电子学（nuclear electronics）

A.核辐射探测器

B.前置放大器的第一级放大器件

C.前置放大器的所有放大器件

A.原子核物理学

B.核化学、核电子学

C.辐射剂量学、核辐射探测技术

D.放射生物学、放射卫生学、放射生态学

E.辐射评价学

核转移技术(nuclear transferring technique)

the Sun; in fact, at the Sun's very center. It is here that is to be found the source of the energy that the Sun constantly pours out into space as light and heat. This energy is liberated at the center of the Sun as billions upon billions of nuclei of hydrogen atoms collide with each other and fuse together to form. nuclei of helium, and, in doing so, release some of the energy that is stored in the nuclei of atoms. The output of light and heat of the Sun requires that some 600 million tons of hydrogen be converts into helium in the Sun every second. This the Sun has been doing thousands of millions of years.

The nuclear energy is released at the Sun's center as high-energy gamma radiation, a form. of electro magnetic radiation like light as radio waves, only of every much shorter wavelength. This gamma radiation is absorbed by atoms inside the Sun, to be reemitted at slightly longer wavelengths. This radiation, in its turn, is absorbed and reemitted. As the energy filters through the layers of the solar interior, it passes through the x-ray part of the spectrum, eventually becoming light. At this stage, it has reached what we call the solar surface, and can escape into space, without being absorbed further by solar atoms. A very small fraction of the Sun's light and heat is emitted in such directions that, after passing unhindered through interplanetary space, it hits the Earth.

What does the passage mainly discuss？

A．The production of solar light and heat.

B．The physical and chemical nature of life.

C．The conversion of hydrogen to helium.

D．Radiation in the x-ray part of the spectrum.

核不均一性RNA(heterogeneous nuclear RNA，hnRNA)

核被膜(nuclear envelope)