1500字的论文包括哪些

时间：2016-11-08 11:40:19 来源：免费论文网

篇一：1500字论文

Abstract

Genetically modified food is a kind of food that people apply modern molecular biotechnology,transfer some biological gene to other species, transform the genetic material of living things. Through the application of biotechnology, a broad and significant increase of food production can be happily seen at global agricultural production. This essay tells readers the basic knowledge of the GMF and discusses the GMF in a critical attitude.The GMF can help to solve the food shortage problem,and it also can create new varieties.While it brings us a lot of benefits,it also leads to many safety problems. Firstly,The potential for GM foods to cause allergic reactions is the most obvious health concern associated with these products.Secondly,although in developed countries like American the law of the GMF is complicated,the new grain law have same more rigorous rules in China and other developing countries.And the GMF still has some safety problems unseen. we argue that the genetically modified technology can bring more advantage and less disadvantage to us if it is used appropriate and planed.However, it is essential to have a critical attitude toward GMF until it is proved that the GMF is no harm to our body.This essay can help readers to know the GMF critically.

Key Words: transgenic technology ;Genetically modified food ;food shortage;safety

Introduction

In biology class in high school,we first got in touch with transgenic,and we approximately learned the basic transgenic technology.It can reform and make the use of the natural lives on the ingredient of them by taking advantage of the research finds in life sciences,and can greatly follow the will of people.In its purest form,the term "biotechnology" refers to the use of living organisms or their products to modify human health and the human environment.Interestingly, we learned the fluorescent mice.What’s more,I can still clearly remember a fantastic ideas,that if we import the chlorophyll gene into the dairy cattle,we might can make the caw in the sun and can get the milk. Of course,that is a nice dream.Now,let’s scientifically learn the genetically modified food. Biotechnology in one form or another has flourished since prehistoric times. When the first human beings realized that they could plant their own crops and breed their own animals, they learned to use biotechnology. The discovery that fruit juices fermented into wine, or that milk could be converted into cheese or yogurt, or that beer could be made by fermenting solutions of malt and hops began the study of biotechnology. When the first bakers found that they could make a soft, spongy bread rather than a firm, thin cracker, they were acting as fledgling biotechnologists.

The first animal breeders, realizing that different physical traits could be either magnified or lost by mating appropriate pairs of animals, engaged in the manipulations of biotechnology.

The GMF can help to solve the food shortage problem,and it also can create new varieties.While it brings us a lot of benefits,it also leads to many safety problems. The potential for GM foods to cause allergic reactions is the most obvious health concern associated with these products,and the GMF still has some safety problems unseen.It is essential to treat the GMF critically for ordinary people.

Advantages

We all know that the food shortage has been a serious problem around the Middle East and many developing contries.The most important reason why We develop the GM is that it can help to solve the food problem.

The most important contribution of the GMF is that it can help to solve the food shortage problems.Since 1983 when the first time human got transgenic tobacco, potato by using recombinant DNA technology,the plant genetic engineering technology in the world has achieved rapid development of transgenic plants for research and development,which has made a series of remarkable progress and has nurtured a number of crops with disease-resistance,insecticide resistance and even an incredible high-yield.with the help of them,we can feed another more than millions of people,According to statistics,up to now ,no less than 1.6 billion people have benefits from biotechnology.in the area,our mother country China has made tremendous contributions to the world's biotechnology.what must be mentioned is BT cotton and hybrid rice of Yuan Longping.

The nutrition implications are also often cited as an obvious benefit for consumers, since the bioengineering could create plants that could produce more nutritious food. An example of one such product is "Golden Rice." This strain of rice contains beta-carotene, a source of vitamin A and iron. Developing countries that rely on rice as their major food source are often are the same countries to suffer from high rates of childhood blindness and maternal anemia. Iron and vitamin

A have been shown to aid in the prevention and treatment of maternal anemia and blindness, so "Golden Rice" might help to reduce the rates of these problems. Commercialize genetically modified crops dates from the year of 1996,including Soybeans, cotton, cereals and oilseed rape.GM crops now occupy 10% of global arable land. In 2010,81% of worldwide soybean, 64% cotton, 29% and 23% of the grain is genetically modified oilseed rape.Totally,29 countries grow GM products all over the world.the top three country with the largest area of cultivation is United

States, Brazil and Argentina.The problem About the safety of GM products has been controversial.Genetically modified food will bring human and animal allergens and toxins of unknown.

Main Concerns

Through the application of biotechnology, a broad and significant increase of food production can be happily seen at global agricultural production. But when we enjoy the enormous benefits of the GM food,a new but alarming problem also came that if these food is safe enough for people?

The potential for GM foods to cause allergic reactions is the most obvious health concern associated with these products. Specific proteins in milk, eggs, wheat, fish, tree nuts, peanuts, soybeans, and shellfish cause over 90% of food allergies. If a protein from one of these food types were to be incorporated into a food that normally would not have this protein, people who are allergic to these proteins could unknowingly consume such a food and suffer allergic reactions. A new report (see article) shows that 25 countries now grow GM crops, with the total area under cultivation now larger than Peru. Three-quarters of the farmland used to grow soya is now sown with a genetically modified variant, and the figures for cotton are not that far behind, thanks to its success in India. China recently gave the safety go-ahead to its first GM rice variety and a new GM maize that should make better pig feed. More and more plants are having their genomes sequenced: a full sequence for maize was published late last year, the soya genome in January. Techniques for altering genomes are moving ahead almost as fast as the genomes themselves are stacking up, and new crops with more than one added trait are coming to market.

It is said that in American, GM food is up to 4000 kinds,and it has been a normal goods in their daily life. However,in China and other developing countries, the new grain law have less rigorous rules.For example,the genetically modified seeds' scientific research,experiments,productions,sales,imports and exports should be followed to the country's laws,and every individual person and unit are not allowed to imply genetically modified technology at principle grain cultivars without authorization.That leads to many safety problems. Such stories of success will strike fear into some hearts, and not only in GM-averse Europe; a GM backlash is under way in India, focused on insect-resistant aubergines. Some of these fears are understandable, but lacking supporting evidence they have never been compelling. On safety, the fear which cuts closest to home, the record continues to look good. Governments need to keep testing and monitoring, but that may be becoming easier. More precise modifications, and better technologies for monitoring stray DNA both within plants and in the environment around them, mean that it is getting easier to be sure that nothing untoward is going on.

Then there is the worry that GM crops are a way for big companies to take over the livelihoods of small farmers and, in the end, a chunk of nature itself. Seen in this light the fact that 90% of the farmers growing GM crops are comparatively poor and in developing countries is sinister, not salutary; given Monsanto’s dominance in America’s soyabean market, it seems to

suggest incipient world domination. It is certainly true that big firms make a lot of money selling GM seeds: the GM seed market was worth $10.5 billion in 2009, and the crops that grew from that seed were worth over $130 billion. But multinationals are not the only game in town. The governments of China (which has increased agricultural research across the board), India and Brazil are also developing new GM crops. In 2009 a GM version of an Indian cotton variety, developed in the public sector, came to market, and a variety engineered by a private Indian firm has been approved for commercialisation. Charities, such as the Bill and Melinda Gates Foundation, are also funding efforts in various countries to make crops more hardy or nutritious. GM seeds that come from government research bodies, or from local firms, may not arouse quite so much opposition as those from large foreign companies, especially when they provide characteristics that make crops better, not just easier to farm.

There is another worry about GM technology, though, that should be taken seriously. It is that its success and appeal to technophiles may, in the minds of those who pay for agricultural research, crowd out other approaches to improving farming. Because it depends on intellectual property that can be protected, GM is ripe for private investment. There is a lot of other agricultural research that is less amenable to corporate ownership but still needs doing. From soil management to weather forecasts to the preservation, study and use of agricultural biodiversity, there are many ways to improve the agricultural systems on which the world’s food supply depends, and make them more resilient as well as more profitable. A farm is not a just a clever crop: it is an ecosystem managed with intelligence. GM crops have a great role to play in that development, but they are only a part of the whole.

Conclusion

Ordinary people should believe that the genetically modified technology can bring more advantage and less disadvantage to us if it is used appropriate and planed.However,we should have a critical attitude toward it until it is proved that the GMF is no harm to our body.

Reference

[1] December 2005 - Safety of artificial sweetener called into question by MP (Guardian, UK)

[2]Fred Gould:Can Agricultural Biotechnology be Green?

[3]Norman Borlaug:Biotechnology and the Green Revolution

[4] JEFFERY SMITH:65 Health Risks of GM Foods

[5] Conner AJ, Glare TR, Nap JP (January 2003). The release of genetically modified crops into the environment.

[6] Dorsch, J.A; Candas, M; Griko, N.B; Maaty, W.S.A; Midboe, E.G; Vadlamudi, R.K; Bulla Jr, L.A (2002). Cry1A toxins of Bacillus thuringiensis bind specifically to a region adjacent to the membrane-proximal extracellular domain of BT-R1 in Manduca sexta

[7] Nathanael Johnson for Grist. Jul 8, 2013 The genetically modified food debate: Where do we begin?

[8] Hunt, Lesley (2004). "Factors determining the public understanding of GM technologies"

[9] Marlene-Aviva Grunpeter (August 5, 2013). "GMOs, A Global Debate: Israel a Center for Study, Kosher Concerns". Epoch Times. "

[10] Deloitte 2010 Food Survey Genetically Modified Foods retrieved 10 October 2012

[11] "Genetically modified (GM) foods". Food Standards Australia and New Zealand. 4 October 2012. Retrieved 5 November 2012

[12] Philip Case for Farmer's Weekly. October 25, 2013 Scientific consensus on GM crops safety 'overwhelming'

[13] Take the Flour Back Press Release, 27/05/12 European activists link up to draw the line against GM

[14] Amy Harmon, July 27, 2013 A Race to Save the Orange by Altering Its DNA

[15] U.S. Department of Energy Genome Programs (2008). "Genetically Modified Foods and Organisms". Archived from the original on May 5, 2013. Retrieved August 28, 2013.

[16] "Greenpeace activists in costly GM protest". Sydney Morning Herald. 2012-08-02. Retrieved 2013-11-08.

篇二：优秀论文1500字摘要

手机后壳注塑模具设计

材料科学与工程系

指导教师

一、内容简介

本文主要设计手机后壳注塑模具，并选取了标准模架，进一步设计型腔、型芯、浇注系统、脱模系统等，最终确定了一整套的手机后壳注塑模具。

关键词：手机后壳，注塑模具，ABS，模具设计

二、塑料模具的发展现状

塑料模具技术是一门涉及面广、技术综合性强的精密基础工艺装备技术，包括：各类模具设计、制造、保管、修理、调试、标准化、专业化生产。中国塑料模具工业从起步发展到现在，已经有半个多世纪的时间了，模具水平有了较大提高。在大型模具方面，已能生产48英寸大屏幕彩电塑壳注射模具、以及汽车保险杠以及6.5 kg大容量洗衣机全套塑料模具等塑料模具；精密塑料模具方面，已经能生产出相机塑料件模具、多型腔小模数齿轮模具、塑封模具、厚度仅为0.08 mm的航空杯模具和难度很高的塑料门窗挤出模等等。但目前我国模具标准化程度和国外先进工业国家相比，仍有很大差距。

三、塑件的成型材料选择及模具结构形式的初步拟定

本设计采用ABS（丙烯腈—丁二烯—苯乙烯）作为最终手机后壳原材料。采用一模两腔单分型面的模具结构。分型面位置在截面积最大处，边缘浇口两点均匀进浇。型腔排列方式如下：

图1 型腔布置

四、成型设备的选用和浇注系统的设计

该设计采用的注塑机设备型号是XS—ZY—125。其主要技术规格见下表：

斜导抽芯的注射模。

根据所选择的注塑机的型号可知：注射机喷嘴圆弧半径=12mm；喷嘴孔直径=4mm。所以，主流道小端直径d为4mm；深度取3mm；锥角取3°；主流道前端球面半径R为14mm。分流道采用圆形截面，平衡式布置。

图2 主流道结构

五、成型零部件的设计

构成模具型腔的零件统称为成型零件，它主要包括凹模、凸模、型芯和镶块等。本设计模具属于中小型模具，所以采用了组合式凹、凸模结构。下面我就说一下本设计中成型零部件尺寸的计算公式。

1.定模型腔尺寸计算：（1）径向尺寸计算：

(Lm)0（2）高度尺寸计算： ??z?[(1?)L5?x?]0??z

??z??z(H)?[(1?S)H?x?]m0s0

2.动模型芯尺寸计算：（1）型芯类径向尺寸计算：

0(lm)0?[(1?S)l?x?]??zs??z

（2）型腔类径向尺寸计算：

??z??z(lm)0?[(1?S)ls?x?]0

（3）型芯高度尺寸计算： 0(hm)0?[(1?S)h?x?]??zs??z

六、合模导向和脱模机构的设计

模具闭合时为保证型腔形状和尺寸的准确性，应按一定的方向和位置合模，所以必须设有导向定位机构。本次设计中采用的是导柱导向。为了确保在推出过程和复位过程中的稳定性，需在推板上增加推板导柱和推板导套。

图3 动、定模导柱导向机构

本次设计的手机后壳的脱模装置如图4所示：

图4 脱模装置

对于手机后盖这个塑件，由于内部中空圆柱体包紧力大，脱模阻力较大，所以在手机后盖内部中空圆柱体部位设置推杆，如图5所示，共设置了12根推杆。

图5 推杆的分布

七、结论

通过这次毕业设计，我对一整套的模具设计有了更清楚而直观的认识。知道了注塑模的工作原理，能计算出模具中型腔、型芯等主要零件的尺寸，并能确定出精度。现在自己具备了一定的经验知识，能够合理的解决模具设计中常出现的问题，能够正确地选取注塑机、确定模架的结构、确定型腔数等等。

我的主要成果如下：

图6 模具二维装配图

1—锁模脚螺钉；2—定模底板；3—凸模；4—定位圈；5—浇口套；6—固定螺钉；7—凹模；8—冷却水道；9—导套；10—导柱；11—定模板；12—动模板；13—动模垫块；14—推杆固定板；15—推板；16—支架；17—动模底板；18—锁模脚螺钉；19—推板螺钉；20—推杆；21—拉料杆；22—推板导套；23—推板导柱；24—复位杆；25—档钉；26—锁公模螺钉

八、主要参考文献

1 李雪梅等.精密注塑用模具设计问题的探讨[J].机床与液压，2006，(4)：217-218. 2 张友根.加快我国注塑设备自主创新科学发展和完善推进调整产品结构的研究[J].塑料工业，2010.38(5)：1-6.

3 葛朋.精密注塑成型技术浅谈[J].2008，(4)：40-41.

4 刘方辉等. CAD / CAE / CAM 技术在现代塑料模设计制造中的应用[J].模具工业， 2010.36(1)：1-6.

5 张克惠.塑料材料学[M].西安：西北工业大学出版社，2006：29-40.

6 黄虹.塑料成型加工与模具[M].北京：化学工业出版社，2003：81.

7 许发樾.实用模具设计与制造手册[M].北京：机械工业出版社，2000：10-13.

篇三：1500 字论文

作业题目

研究生姓名：蒋秋桂

所在专业：教育硕士

递交课程老师姓名: 王卫东

课程名称：教育理念与教育发展

学号：2111318020 研究生所在学院：外国语学院评分（百分制）：评分教师签名：

1教育质量的内涵是什么？影响学校教育质量的因素有哪些？如何通过改良这些因素来提升学校的教育质量？请您根据自己学校的实际情况，并结合自己的工作心得，谈谈对上述问题的看法。

答：认为素质教育不仅是知识、技能水平的提高，还应该包括人格、心理健康方面的教育。第一，素质教育是面向全体学生的教育。《教育法》规定公民“依法享有平等的受教育的机会”。受教育机会平等是国家法律规定的一项基本教育方针。对政府和教育行政部门来说，应当为所有适龄儿童少年提供平等的教育；对学校和教师而言，要努力使每个班和每个学生都得到全面而健康的发展。基础教育特别是义务教育的根本宗旨，是为提高全民族的素质打下扎实基础，为全体适龄儿童少年今后的学习和参与社会生活打下良好基础。实施素质教育要求面向全体儿童少年，促进每个学生的发展，与这一根本宗旨是一致的。第二，素质教育是促进学生全面发展的教育。全面发展，这是党的教育方针的核心部分。它提出了教育所要培养的人的合理素质结构，包括生理的、心理的、思想的、文化的素质。教育是要教给学生文化知识，作为检验学习成果的重要方法之一，考试是重要的，也是必要的。“应试教育”的问题在于，它主要是为应付考试而教和应付考试而学，忽视学生的全面发展；在教育实践上，忽视德育、体育、美育和学生身心健康，造成学生的片面发展。有的人书念得很好，考分很高，但是没有正确的人生观、世界观、价值观，道德修养很差，缺乏与人交往、团结合作的能力，这不能认为是好人才。有的人只有书本知识，没有创造性，不会解决实际问题，“高分低能”，也不能认为是好人才。道德修养好和本事大的人，身体不好也派不了大用场。当然，在学校不好好学习，文化知识差，更不能担起社会主义现代化建设的重任。我们决不能重犯“文革”中不学好知识，甚至提倡交白卷那种极其荒谬的错误。有一点我想再次说明

的是，全面发展不等于平均的全面发展，而是和谐的全面发展。实施素质教育就是要培养学生品德高尚、身心健康、知识丰富、学有专长、思路宽广、实践能力强，使学生学会做人、学会学习、学会劳动、学会创造、学会生活、学会健体、学会审美，成长为有理想、有道德、有文化、有纪律的社会主义事业的建设者和接班人。第三，素质教育是促进学生个性健康发展的教育。人的个性是千差万别的，社会也需要各种各样的人才。实施素质教育的重要目的之一，也是为了使有不同天赋和爱好的孩子，在受教育的过程中，除了统一的基础课程外，通过各种教育方式给予他们能发挥天赋和爱好的空间和时间。培养人不能如同用一个统一的模子，把不同形态的材料都压成一模一样的东西一样。联合国儿童发展基金会在《教育质量定义》中提出，影响教育质量的因素有五个：学习者、教育坏境、教育内容、教育过程和教育成果。在中国素质教育推行的大环境中，各个不同的学校对教育的发展有着不同的影响因素。比如就国家盛行把初高中学划分为省重点和普通的高中,而当地的教育局根据学生的学习成绩来把学生分学校，这一做法很明显的会对有些学校有好处，从而提高他们有些重点中学的质量，相反一些不好的学校招的学生在一开始就有了明显的区别。对于这点来说不同的人应该有不同的想法，有人认为按成绩分学校是件很公平的事，因为学习成绩的高低直接可以看出该学生的努力程度，而被反配到普通的学生只能说读书还不够努力。但是有些人认为这样分学校对有些学生是不负责任的行为，因为成绩只能说明一时，而不能作为学生学习的选择地。

对于教育环境来说，不同的学校也有不同的环境。比如一些重点中学的教学设施在不知不觉中会比其他的学校好一点。就如学校的图书馆，一般的中学的图书馆规格有限并且一般图书馆只能作为一种装饰而已，但是在重点中学学生和老师能用到的资源远远的超过了普通的中学。这一因素的出现是因为上一个因为的产生而造成的。它不仅造成学校的环境不同同时在教育者的层次上也出现了不同。正如一句古话说过良禽择木而栖。老师也不例外。一般的好老师希望自己能到一所好一点的学校教书，所以接直接导致了一些普通学校的教学质量没有什么可以保证的。久而久之这种病态分布成了一种常态，一种恶性循环。

对于出现这些问题，我国的教育学者也在纷纷讨论如何来解决这些重大的问题。教育是国之根本。要想把我国建设成为富强的国家，我们必须要把这些根本问题解决好才能发展好我们的国家。

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