近视,是眼睛看不清远物、却看清近物的症状。在屈光静止的前提下,远处的物体不能在视网膜汇聚,而在视网膜之前形成焦点,因而造成视觉变形,导致远方的物体模糊不清。近视分屈光和轴性两类。其中屈光近视最为严重。屈光近视可达到600度以上,即高度近视。
疾病:相当数量的患者曾患过麻疹、百日咳等传染病,这些患者大多出现眼球膨大,而眼球处于膨大状态时,眼球的屈光度下降,视力减弱。
噪音:有关专家的研究表明,当音响强度在90分贝以上时,眼底视网膜中视杆细胞区别光亮度的敏感性开始下降,识别弱光反应的时间延长,超过45分贝时,40%的人瞳孔散大,达到115分贝时,眼睛对光亮度的适应性下降20%,同时伴有色觉能力削弱。
矿物元素不足:医学研究表明,钙、铬等矿物元素是保证青少年视力正常的一个重要条件,钙元素在维持眼晶体正常压力,铬元素在保持眼睛屈光度等方面都有不可替代的作用。特别要提醒注意的是,加工过细的米、面,会丧失80%的铬元素,故意吃一些粗粮有益于视力健康。
吃甜食太多:甜食为酸性食物,一方面大量消耗体内的钙元素,另一方面升高血糖,改变晶体渗透压,是导致近视眼形成的又一祸根,监督孩子少吃为妙。
5被动吸烟:德国专家发现,烟草中含有一种毒性较强的氰化物,它在人体内积存到一定程度,可造成中毒性弱视。而青少年的眼球正处于发育期,对烟草中的有害物更为敏感。
6睡眠不足:10—13岁是近视眼形成的高峰期。此年龄段的孩子若睡眠不足,交感与副交感神经功能失去平衡,造成眼睫状肌的调节功能紊乱,故保证每晚睡足9—11小时,有保护视力的作用。
(一)图像在教学中的最大优势——形象性
图像具有非凡的表现力。课堂教学中有许多内容,用文字去表述会比较抽象,而用图像去表现时却十分形象。图像具有信息量大、现场感强、直观感强、容易记忆、便于再现等特点,能充分地激活课堂的教学气氛,给教学注入新的活力。它可以多方面、多角度,以不同的形式描述某一事物,提供直观的教学素材,克服文字与口头表达形象性弱的缺点,有助于学生观察能力、自学思维能力的培养。
(二)符合初中学生的认知心理
图像输入具有直观性、新颖性、多样性和趣味性,形象生动的图像,既能提高学习效率,又能集中学生注意力,提高教学效果。图像的`运用能最大限度地调动不同感官在学习中的作用,使学生确立鲜明的、完整的表象,把注意力集中到学习的对象上,从而产生强烈的学习***和运用语言来表达的***。这种强烈的求知欲正是学生学习知识技能必须具备的内驱动力。初中学生年龄小,心理不够成熟,认知较直观,注意力不容易长时间集中,形象思维比较突出,对感性的事物较容易理解,对理性的知识则不易理解,课堂教学活动只有形式多样化,才能吸引学生注意力,激发兴趣。在教学中通过生动的语言、实物、动作、图像等创设一定的、真实的、有趣的情景,进行丰富多彩的课堂组织活动,可以激发学生的学习兴趣,充分发挥学生的主观能动性,让学生在模仿中熟悉和感知语言知识。
总之,运用图像进行英语教学,突破了传统教学的局限,提供了丰富的声像并茂的语言内容,最接近语言实际的自然语境,能使学生在真切的语境中学习到活的语言,实现语言习得的目标。
我最喜欢的小动物有很多,燕子、小狗、小兔子、小松鼠……这其中,要数我最喜欢的那就是小猫了,说起小猫来,我家也有一只,那么我就来讲讲我和小猫的故事吧。
那只小猫的毛软软的,滑滑的,头上还有好看的花纹,所以,我给它取名为花花花花的胡子很长,有一次我拿爸爸的刮胡刀去给花花刮胡子。妈妈说:花花的胡子不能刮,因为在很暗的地方,她能微微的抽动胡须,才能量出来道路的宽度。哇,原来它的胡子还有这么大的作用啊!我说。
花花非常爱干净,它拉便便也要去上厕所,一个便盆里放了很多煤渣,它每次拉完便便的时候都要用煤渣把便便埋起来。
花花是我的好朋友,每次我有零食都给它分一点,我穿袜子它就在我的脚上蹭来蹭去,我和它一起晒太阳,跟它一起说悄悄话。
这就是我最喜欢的小动物——花花。
There are a lot of my favorite small animals, swallows, puppies, rabbits, squirrels... Of which, the number I like most is the cat, talking about the kitten and my family, so I'll tell about the story of my cat and my cat.
The cat's fur is soft, slippery, and beautiful pattern on the head, so I gave it a name flower flower beard, once I took the razor to shave flower dad. Mother said: the flower mustache can not be shaved, because in a very dark place, she can gently tap the beard, to measure the width of the road. Wow, it turns out that its beard has such a big effect! I said.
Huahua is very clean. It URLs and URLs and goes to the toilet. There are lots of cinders in a bedpan. Every time it pulls out, it uses coal cinder to bury the toilet.
Huahua is a good friend of mine. Every time I have snacks, I want to share it with you. When I wear socks, it will rub on my feet. I will share the sun with them and talk quietly with them.
This is my favorite little animal - flower flower.
Do you know what kind of animal I like most? It’s monkey. Monkey is a kind of lovely animal. Many people like monkeys very much. Generally, monkey has small body covered with fur. Some kinds of monkeys have two big eyes and ears and a long tail. I can see them on TV or the zoo. Every time I go to the zoo, I will go to see them. Monkeys often stay in trees and jump between them. They are so lively and favorable. When they are happy, they will act for visitors. It’s very funny.
近视眼的机理
当人眼球在调节松弛状态下,来自5米以外的平行光线经眼的屈光系统屈折后,不能聚焦在视网膜上者称非正视眼,又称屈光不正。屈光不正分为近视、远视和散光三大类。所谓近视眼是眼在调节松弛状态下,平行光线经眼的屈光系统屈折后形成的焦点在视网膜之前,在视网膜上形成一个弥散光环,所以看远处目标模糊不清。从近视眼视网膜发出的光线为集合光线,其焦点位于眼球和无限远之间,称为近视眼的远点。如被看目标恰好位于近视眼的远点上,则可在视网膜上形成焦点,所以近视眼看近距离目标清晰。
近视眼的病因
近视眼按程度分为轻度(-3.0D以下,中度(-3.0D--6.0D,高度(-6.0D以上,近视眼的病因目前尚不完全了解,可能与下列因素有关。
1.遗传因素:据调查近视有一定遗传倾向,一般认为高度近视属常染色体隐性遗传,中低度近视属多基因遗传。
2.发育因素:婴幼儿时期眼球较小,常为生理性远视,随着年龄的增长,眼轴逐渐加长而趋向正视,如发育过度则形成近视。
3.外因:青少年学生与近距离工作者中近视眼较多,这表明,近视眼的发生和发展与近距离工作有密切关系,尤其是照明不足,阅读距离过近,阅读时间过久,字体不清或过小,以及姿势不良等都与近视的发生有关。?
4、轴性近视:是指眼轴较长而眼的屈光力正常,这是最常见的一种近视。常见为发育和遗传有关,不良的卫生习惯加速发展,如阅读时灯光照明不合理,坐姿不端正,距书本及工作目标太近,以及过度用眼等。
5、屈光性近视:是指眼轴正常但眼的屈光力增强。常见有:
A.角膜膨隆,圈袍角膜。
B.晶状体异常,球悬晶体,晶体位置倾斜。
C.睫状肌痉挛,引起晶体过度调节。
I get early last Sunday.I take a bus to the zoo with my parents.We see many kinds of animals there,like elephants,pandas,lions,tigers … Some of them are very cute,but some are ugly.Some are scary,but some are friendly.My favorite animal is the panda.It is very cute and shy.My father takes a photo for me with the panda.I am tired when I get home,but I have a good time in the zoo.
I got up early last Sunday.I took a bus to the zoo with my parents.We saw many kinds of animals there,like elephants,pandas,lions,tigers … Some of them were very cute,but some were ugly.Some were scary,but some were friendly.My favorite animal is the panda.It is very cute and shy.My father took a photo for me with the panda.I was tired when I got home,but I had a good time in the zoo.
Visiting the Zoo
Yesterday was Sunday and it was a fine day.My parents and I visited the zoo.We went by bus.We started out at 8:00 in the morning and got there at 8:30.There were many people in the zoo.Some were watching the animals,some were playing games and others were resting under the trees.We went to watch the birds first.Then we came to see the monkeys.They were very lovely.We also saw the tigers and the lions.We saw many animals in the zoo.We felt very happy.
I have a cat .Its name is Mimi. It's very lovey.My family all like it.
It always plays with me every day .It has black and white fur.As long as we say'Mimi',It right away runs to you.
It's very good!so My family all like it!
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