1、本文格式為Word版，下載可任意編輯 研究生復(fù)試專業(yè)英語 The formation of nonlinear optics originated in the early 1960s. From 1970 to 1990, accompanying with the great successes in laser science and technology, many new effects were exploited, including the optical bistability (雙穩(wěn)態(tài)) and soliton （孤子）. Since 1990, the research

2、in nonlinear optical field has been continuously developing both in theoretical and applicable aspects. The developments in the past nearly fifth years have proved that nonlinear optics is a so exciting and fruitful research brand, which provides big progress in study the materials and systems in va

3、rious scientific fields. It can be expected that continuous development of nonlinear optical will bring new achievement and successes for the science and technology. Rainbows can be observed whenever there are water drops in the air and sunlight shining from behind at a low altitude angle. The most

4、spectacular rainbow displays happen when half the sky is still dark with raining clouds and the observer is at a spot with clear sky in the direction of the sun. The result is a luminous rainbow that contrasts with the darkened background. The rainbow effect is also commonly seen near waterfalls or

5、fountains. In addition, the effect can be artificially created by dispersing water droplets into the air during a sunny day. Rarely, a moonbow or nighttime rainbow can be seen on strongly moonlit nights. As human visual perception for colour is poor in low light, moonbows are often perceived to be w

6、hite. Energy is an essential material basis for human survival and development. Over the entire history of mankind, each and every significant step in the progress of human civilization has been accompanied by energy innovations and substitutions. The development and utilization of energy has enormo

7、usly boosted the development of the world economy and human society. Over more than 100 years in the past, developed countries have completed their industrialization, consuming an enormous quantity of natural resources, especially energy resources, in the process. Today, some developing countries ar

8、e ushering in their own era of industrialization, and an increase of energy consumption is inevitable for their economic and social development. China is now the worlds second-largest energy producer and consumer. The sustained growth of energy supply has provided an important support for the countr

9、ys economic growth and social progress, while the rapid expansion of energy consumption has created a vast scope for the global energy market. As an irreplaceable component of the world energy market, China plays an increasingly important role in maintaining global energy security. Guided by the Sci

10、entific Outlook on Development, the Chinese government is accelerating its development of a modern energy industry, taking resource conservation and environmental protection as two basic state policies, giving prominence to building a resource-conserving and environment-friendly society in the cours

11、e of its industrialization and modernization, striving to enhance its capability for sustainable development and making China an innovative country, so as to make greater contributions to the worlds economy and prosperity All elements are composed of scattered units called atoms, which are the small

12、est particles than show the characteristics of the element. Atoms are tiny units of matter composed of positively charged protons, negatively charged elements, and electrically neutral neutrons. Protons (質(zhì)子) and neutrons, which have almost the same mass, are clustered in the nucleus in the middle of the atom. Electrons, which are tiny in comparison to the other units, move around the nucleus at high sp