1. 研究目的与意义、国内外研究现状（文献综述）1.青刀豆也称四季豆，芸豆，玉豆，小刀豆等，一年生缠绕性草本植物，是菜豆中圆荚类型的品种。其是夏秋两季上市的大宗蔬菜，因其色泽嫩绿，肉荚肥厚，味道鲜美，含有丰富的糖类，蛋白质和脂肪，而具有较高的营养价值，故受到广大消费者的喜爱[1]。但是由于青刀豆豆荚组织幼嫩，呼吸强度高，不耐贮存，若不及时食用，会造成萎蔫，褪色，腐烂[1]。目前对鲜青刀豆的研究主要是集中在对其营养成分的分析，关于其嫩度的研究主要是针对罐藏青刀豆[2]及速冻保鲜青刀豆的研究[3]；而尚未有关于新鲜青刀豆嫩度的研究。同时,机器视觉技术的应用越来越广泛,涉及到医学[4]、军事、海洋、地理遥感[5]等领域,在农业方面的研究也逐渐增多。机器视觉不仅局限于可见光区域,还扩展到了紫外、近红外[

1. 研究目的与意义、国内外研究现状（文献综述）1.课题意义灰飞虱[Laodelphax striatellus（Falln）]属半翅目，飞虱科，是一种非常重要的农业害虫。灰飞虱耐寒怕热，最适合的温度是23-25℃，当温度超过30℃时，成虫寿命短，死亡率增加。在南部稻区如广东等地无越冬情况，冬季仍然能够继续危害小麦。其他地区均以3、4龄若虫在麦田、绿肥田等地越冬。刘向东等研究表明江淮稻区冬季低温环境对灰飞虱种群的存活影响很小，3龄若虫在0-4℃低温条件下12小时无冻倒现象，而持续长达20小时冻倒率仅为14.3%，且冻倒者均能在适宜的条件下复苏[1]。为深入揭示自然环境下灰飞虱的种群遗传结构，本课题组前期通过13个微卫星分子标记和2个线粒体分子标记对中国22个地理种群的灰飞虱进行了种群遗传结构研究，结果发现我国灰飞虱在核基因上无显著分化，而在线

1. 研究目的与意义当今社会,课堂学习是学生学习知识的重要方法,而考试则是检验学生学习成果的重要方式。一次传统的考试，需要老师从各大题库和书籍中选取题目，再经过修改拼接算分等一系列步骤才能完成一张完整的考卷。考卷出好后还需要印刷试卷、安排考场、评改试卷、分析试卷等一系列后续工作。一位老师教一门课不可能只有一次，所以下一次再遇到考试时又需要重复的出卷、印卷、改卷，浪费了很多时间和精力，消耗了大量人力物力，随着考试类型的不断增加及考试要求的不断提高，教师的工作量将会越来越大，可以说传统的考试出题方式已经不能很好地满足现代考试的需要，所以拥有一个方便快捷的在线考试系统是十分必要的。老师可以事先在考试系统中录入平时在书中发现的优秀题目，在考试时根据考试的性质、分值由系统随�

1. 研究目的与意义当今社会,课堂学习是学生学习知识的重要方法,而考试则是检验学生学习成果的重要方式。一次传统的考试，需要老师从各大题库和书籍中选取题目，再经过修改拼接算分等一系列步骤才能完成一张完整的考卷。考卷出好后还需要印刷试卷、安排考场、评改试卷、分析试卷等一系列后续工作。一位老师教一门课不可能只有一次，所以下一次再遇到考试时又需要重复的出卷、印卷、改卷，浪费了很多时间和精力，消耗了大量人力物力，随着考试类型的不断增加及考试要求的不断提高，教师的工作量将会越来越大，可以说传统的考试出题方式已经不能很好地满足现代考试的需要，所以拥有一个方便快捷的在线考试系统是十分必要的。老师可以事先在考试系统中录入平时在书中发现的优秀题目，在考试时根据考试的性质、分值由系统随�

1. 研究目的与意义（文献综述） 1.1 The purpose and significance of the electric design 1.1.1 Electric wheel design The early development of electric vehicles is very rapid. The world's first electric car was born in 1834 years, than the first car engine vehicle early more than half a century. Then, the world's first rechargeable battery powered electric cars appeared in France in 1881. The early stage of development of electric vehicles is from 1895 to 1911, during this period, due to internal combustion engine technology is not mature enough, the electric car price has more than internal combustion engine; and the steam car in a water, its mileage is not first rechargeable electric vehicles after the long driving range. Therefore, at the time, popularization and development of electric vehicles is much faster than the internal combustion engines and steam cars, so it occupies 1/3 share of the car market, car in 1900 cases of America's total holdings of electric vehicles

1. 研究目的与意义（文献综述） Vehicle transmission is used to coordinate the engine speed and the actual speed of the wheel. It can change the engine output speed and torque to adapt to different working conditions in the process of driving, and make the engine work in the best state. Therefore, the transmission is an important device of automobile. The performance of the transmission will affect the comfort, fuel economy and power performance of the whole vehicle. [1-3] With the development of automobile industry, transmission in China is in a period of high-speed development, and has occupied a dominant position in the field of mechanical transmission. But in the field of automatic transmission with higher level of design, manufacture and technology, our country is still in a backward period. At present, the proportion of automatic transmission used in high-end vehicles is as high as 90% in the world. The proportion of automatic transmission used in middle-grade and midd

全文总字数：7531字1. 研究目的与意义（文献综述） Vehicle transmission is used to coordinate the engine speed and the actual speed of the wheel. It can change the engine output speed and torque to adapt to different working conditions in the process of driving, and make the engine work in the best state. Therefore, the transmission is an important device of automobile. The performance of the transmission will affect the comfort, fuel economy and power performance of the whole vehicle. [1-3] With the development of automobile industry, transmission in China is in a period of high-speed development, and has occupied a dominant position in the field of mechanical transmission. But in the field of automatic transmission with higher level of design, manufacture and technology, our country is still in a backward period. At present, the proportion of automatic transmission used in high-end vehicles is as high as 90% in the world. The proportion of automatic transmission used

1. 研究目的与意义（文献综述包含参考文献）1. Introduction1.1 Research backgroundNowadays, with the prevalence of English, reading in English has become one of the necessary abilities of students. Therefore, reading comprehension has become an indispensable part in various English tests. There are many factors correlated with reading comprehension, such as strategy knowledge, reading speed, and vocabulary (Muijselaar Ye, 2005), background knowledge (Chou, 2011), syntactic awareness or metacognitive awareness (Nergis, 2013) and so on. Since it is impossible to study all the factors once, it is reasonable to choose two factors to make a comparison on their predictive effects on reading comprehension.Among these factors, having a pervasive and copious vocabulary is the prerequisite of language acquisition, no matter what language is (Folse, 2004). The knowledge of word meanings and the ability to access the knowledge efficiently are recognized as an essential factor in r

1. 研究目的与意义（文献综述） The theory ofIconicity, as a feverish topic in the academic circle nowadays, is beingexplored heatedly in cognitive linguistics. Iconicity can be revealed at alllevels of language. So it is of great significance for the analysis of literarywork and the study of translation. What’s more, it can be very instructive tothe teaching of English. In fact, iconicitydeveloped very slowly. It hasn’t made much progress until R. Jakobson (1965)challenged arbitrariness in the essay Questfor the language of essence for the first time. Throughout history,arbitrariness has been considered as one of the most distinguished features oflanguage. Saussure (1857-1913) is a famous linguistic who established amilestone in the exploration of iconicity of language. He put forward thistheory, asserted that there was no interrelationship between the signifier and signifiedor such relation cannot be testified. That’s to say, they are casual andconventional. However,

1. 研究目的与意义（文献综述包含参考文献）Validierungsanalyse der TestDaF Prfung und die Anregungen fr chinesische Deutschlerner德福试题效度研究及对中国德语学习者的启示EinleitungAufgrund der sich in den letzten Jahrzehnten verbessernden diplomatischen Beziehung zwischen China und Deutschland nimmt in China das Interesse am Studium in Deutschland und an der deutschen Sprache immer weiter zu. Um den direkten Zugang zu deutschen Hochschulen zu erhalten, mssen alle auslndische Hochschulbewerber ein internationales Deutschsprachzeugnis erwerben. Die Sprachprfung Deutsch als Fremdsprache, nmlich der TestDaF, gilt heute als die einzige Sprachprfung, dessen Nachweis von allen deutschen Hochschulen anerkannt wird. Wie valid ist denn diese Sprachprfung? Die Antwort darauf rckt zunehmend ins Blickfeld. In dieser Arbeit werden mithilfe der auf Bachmans und Palmers kommunikativer Sprachtest-Theorie beruhenden Validierungsanalyse insgesamt 7 TestDaF Musterprfung