还有一会儿。

如题。

Lake桑

2018.12.31

每日一词:hark back(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for December 31, 2018 is:

hark back • \HAHRK-BAK\  • verb

1 : to turn back to an earlier topic or circumstance

2 : to go back to something as an origin or source

Examples:

“In Tea With The Dames, [Maggie Smith is] joined by fellow dames Judi Dench, Joan Plowright, and Eileen Atkins; the women hark back on their early roles on stage and screen, talk about their ex-husbands and marriages….” — Hunter Harris, The New York Magazine, 26 Sept. 2018

“To stay connected with senior executives, she made heavy use of WhatsApp’s group-chat function and called her group Table Talk, an effort to hark back to those early days at her kitchen table.” — Sarah Ellison, Vanity Fair, March 2018

Did you know?

Hark, a very old word meaning “to listen,” was used as a cry in hunting. The master of the hunt might cry “Hark! Forward!” or “Hark! Back!” The cries became set phrases, both as nouns and verbs. Thus, a “hark back” was a retracing of a route by dogs and hunters, and to “hark back” was to turn back along the path. From its use in hunting, the verb soon acquired its current figurative meanings. In time, the variants “hearken back” and “harken back” were called, and—like harkhearken and harken can mean “to listen.” Harken, itself, is now used alone to mean “hark back.”


Lake桑

December 31, 2018 at 01:00PM

新版编辑器的测试。Testing the new block editor.

使用电脑来同时观看两个版本的文章。

With the computer, you can read two versions of the passage simultaneously.

新版编辑器的测试。

我说中文。

这是一篇中英文对照的文章。

使用新的区块编辑器,我可以写一篇同时有中英文的文章。

通过使用<div>标签和样式,我们可以分两栏写文章,就像试卷的排版。

这也可以体现中文的短小精悍。

两边不是简单的中英文翻译,你会发现两边的内容有些区别。

但这不包括媒体文件。

Lake桑的存档馆
大概是一样的。

LaTeX 不支持中文,所以没有办法比较。

超链接也会是一样的。

应该是一样的才对。


现在高度是一样的了。

随着内容越来越长,段落也不对齐了。

我不觉得这一是非常件好事。

介词短语的使用会让句子变长。

这样本该不对齐的。

但是新的区块编辑器让它成为可能,你看。

Lake桑

2018.12.31

Testing the new block editor.

I speak English.

This is an article that is written in both Chinese and English.

With the new block editor, I can write an article in both English and Chinese.

By using the tag <div> and its style, we can divide a page into 2 columns, just like the exam papers.

This can also show the verbosity of English.

The contents in 2 columns are not all the same. There are some slight differences between the columns.

Except for the medias.

(Probably.)

LaTeX doesn’t support Chinese, so there isn’t a way to compare.

The hyperlinks should be the same.

Aren’t they?


Now we’re aligned.

The longer content it is, the more unaligned it gets.

I don’t thnik it’s a god tinhg.

By using adverbial phrases, the whole sentence will get longer for sure.

It’s supposed to be unaligned.

But the new block editor makes it possible to do that, see?

L.

2018.12.31

一周年。

一周年了。

野营灯

在黑暗中寻找光明。

WordPress 在一年里,出了一个 Gutenberg 编辑器。

我的 Blog 在一年里,发布了(包括这篇文章以及没发布的)601篇文章。

一年的成长,比你想象的要多。

Lake桑

2018.12.31

又一个周一。

一周又开始了。加油工作!(由 IFTTT 发送)

Lake桑

December 31, 2018 at 07:00AM

每日一词:obdurate(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for December 30, 2018 is:

obdurate • \AHB-duh-rut\  • adjective

1 a : stubbornly persistent in wrongdoing

b : hardened in feelings

2 : resistant to persuasion or softening influences

Examples:

Obdurate lawmakers on both sides of the aisle have made it difficult for the state legislature to get anything done this term.

“The emigrants were strong-willed and obdurate. Their dreams were based as much on imagination as on the writings and maps of land speculators and entrepreneurs.” — Edward Cuddihy, The Buffalo (New York) News, 1 Oct. 2017

Did you know?

When you are confronted with someone obdurate, you may end up feeling dour. During the encounter, you may find that you need to be durable to keep your sanity intact. Maybe you will find such situations less stressful in the future if you can face them knowing that the words obdurate, dour, and durable are etymological kissing cousins. All of those words trace back to the Latin adjective durus, which means “hard.” This adjective can still be found in dura mater, the name for the tough fibrous material that surrounds the brain and spinal cord, which comes from a Medieval Latin phrase meaning, literally, “hard mother.”


Lake桑

December 30, 2018 at 01:00PM

化学相关:我们周围的空气

目录:化学相关:开坑预告及目录

上一期:化学相关:走进化学实验室

下一期:化学相关:氧气

从宇宙起源开始(下面省略101325个字)我们有了如今的大气层。

省略的字当中,有有机物的化学进化导致地球上的所有生物都共用了一套遗传程序,蓝藻产生的氧气差点把所有生物全部杀死,再到生物进化,出现人类,然后一直到现在。

现在,对于我们来说,人类每时每刻都离不开空气,没有空气就没有了生命,也就没有了生机勃勃的地球。

一、拉瓦锡测定空气成分

首先,我们了解一下伟大的化学之父小作坊主,拉瓦锡(A.-L. Lavoisier,1743-1794)。

TL;DR

安托万-洛朗·德·拉瓦锡(Antoine-Laurent de Lavoisier),法国贵族,著名化学家、生物学家,被广泛认为是人类历史上最伟大的化学家。他使化学从定性转为定量,给出了氧与氢的命名,并且预测了硅的存在。他帮助建立了公制。拉瓦锡提出了“元素”的定义,按照这定义,于1789年发表第一个现代化学元素列表,列出33种元素,其中包括光与热和一些当时被认为是元素的化合物。拉瓦锡的贡献促使18世纪的化学更加物理及数学化。他提出规范的化学命名法,撰写了第一部真正现代化学教科书《化学基本论述》(Traité Élémentaire de Chimie)。他倡导并改进定量分析方法并用其验证了质量守恒定律。他创立氧化说以解释燃烧等实验现象,指出动物的呼吸实质上是缓慢氧化。这些划时代贡献使得他成为历史上最伟大的化学家。

他用定量的方法研究了空气的成分。具体的方法是,在一个曲颈甑里加入少量的汞,将其放在火炉上加热。有一个汞槽,里面放着一个玻璃钟罩,曲颈甑的另一头伸在玻璃钟罩内部。

这一次加热连续了12天。他发现,有一部分银白色的液态汞变成了红色的粉末,同时玻璃钟罩里空气的体积差不多减少了五分之一。他研究了剩余五分之四体积的气体发现,这一部分气体既不能供给呼吸,也不能支持燃烧。他认为这些气体全部都是氮气。在命名这一部分气体的时候,他使用了拉丁文,其中的词根包含“不能维持生命”的意思。

他把汞表面生成的红色粉末又收集起来,放在另一个小小的容器里,再次加强热得到了汞(化学符号 \rm Hg)和氧气(\rm O_2)。其中氧气的体积恰好等于玻璃钟罩里所减少的体积。他把得到了氧气加入了玻璃钟罩,所得的气体与空气的性质一模一样。

通过这些实验,拉瓦锡得出了空气由氧气和氮气(\rm N_2)组成,其中氧气约占空气体积的五分之一的结论。

化学符号?

化学符号,就是化学式,是用元素符号与数字的组合来表示物质组成的式子。每一种纯净物只有一个化学式。但一个化学式可能不只代表一种物质。比如说下面这个例子。化学式\rm C_2H_6O,它的意义有

这样,有相同分子式而有不同的原子排列的化合物又称为同分异构体。

二、学生测定空气成分

但是汞具有毒性。汞的蒸气也具有毒性。我们现在仿照历史上这个著名的实验测定,空气中氧气的含量时,使用的药品是红磷。它燃烧产物的毒性要弱上许多,因为用量上也少了很多。

步骤

在集气瓶内加入少量的水,并将水面上放的空间分为五等份,用弹簧夹夹紧胶皮管。点燃燃烧匙内的红磷后,立即伸入瓶中,并把塞子塞紧。观察红磷燃烧的现象。待红磷熄灭冷却以后打开弹簧夹,观察实验现象和水面的变化情况。

还记得上一次的内容吗?在这之前我们需要检查装置的气密性。首先将导管放入水中,然后再手握集气瓶观察是否有气泡冒出。

现象

点燃,我们可以看到红磷发出黄色的火焰,放热,并且生成大量的白烟。由于生成的白烟有毒,我们在瓶中加入的水就是为了吸收它。冷却后,打开弹簧夹水,将会沿导管回流到集气瓶中,并且这一部分的体积约占原瓶内空气体积的五分之一。

在这一反应中,红磷(\rm P)与空气中的氧气反应,生成一种叫做五氧化二磷(\rm P_2O_5)的新物质,这一反应可以用符号表达式表示如下。

\rm P+O_2 \overset{Fire}{\longrightarrow} P_2O_5

若要使用文字来表达的话,只需要将对应的化学符号以及条件(箭头上方的Fire,中文一般写作点燃)换为你的语言中对应的文字就好了。

集气瓶内水平面上升了约五分之一,说明空气中的氧气被消耗了,并且消耗的体积约占空气体积的五分之一。

结论

于是,我们可以得出氧气约占空气体积的五分之一。

红磷熄灭时,我们可以推测,此时瓶内氧气几乎被消耗完毕。

剩下的主要是氮气。我们可以推测,它难溶于水,并且不可燃,不助燃。

分析

这个实验的原理就是利用红磷燃烧消耗氧气,使得瓶内的气压变小形成内外的气压差。

当回到集气瓶里的水小于原瓶内空气体积到五分之一时,我们需要分析发生了什么。

可能是氧气并没有被消耗完。那么我们就有理由怀疑,瓶中红磷的量是不足的。

同样你也可能没有检查装置的气密性。那么装置漏气也是有可能的。

如果你没有等它冷却就打开了弹簧夹开始读数,那么也是会导致体积小于五分之一的。

那么大于五分之一又会是什么情况?

点燃红磷时,伸进瓶内的速度,即塞瓶塞的速度如果过慢,那么,由热胀冷缩可得气体受热时会膨胀逸出。弹簧夹没有夹紧也会导致这个情况。

改进

我们将红磷换成白磷。已知白磷燃烧时需要的空气的浓度较低,也就是说可以进一步消耗氧气,它的着火点也比较低,方便引燃。在原装置的橡皮塞上再加一个孔连接一个导管至一个气球,用来缓解气压。气球先变大后变小。这个装置有以下的优点。

  • 污染小
  • 误差小

我们也可以使用手握装置,也就是传感器来测定气压的变化和氧气含量的变化。


在19世纪末以前,人们和拉瓦锡一样认为空气中仅含有氧气和氮气。后来,人们陆续发现了一系列的稀有气体,即氦,氖,氩,氪,氙,氡(\rm He,Ne,Ar,Kr,Xe,Rn)。这时,人们才意识到空气中除了有氧气和氮气外,还有许多其他的成分。目前人们已经可以用实验的方法精确地测定空气中的成分。

三、物质的分类

通过实验测定空气中的成分按照体积来计算,大约是:

氮气78%,氧气21%,稀有气体0.94%,二氧化碳0.03%,其他气体与杂质0.03%。

饼干会变软,就是因为空气当中含有水蒸气。而食品变质,就是因为氧气。氧气供呼吸,并且助燃。氮气可以用来制硝酸,也可以做冶炼金属,灯泡,食品的保护气,并且液氮可以用来制冷或冷冻麻醉。

稀有气体因为其化学性质稳定,可以用来做保护气。他们也可以做不同颜色的电光源,比如说是试电笔的氖管,或者是人造小太阳中的氙气。

像空气这样由两种或两种以上的物质混合而成的物质叫做混合物。组成混合物的各种成分,保持他们各自的性质。

而像氮气呀,氧气,二氧化碳等分别只由一种物质构成的物质都叫做纯净物。只有纯净可以使用化学符号来表示,比如上面的氮气在括号内已经给出了它的化学符号。氧气呀,二氧化碳(\rm CO_2)等等,也可以用化学符号来表示。上面实验中的红磷和生成的五氧化二磷也都是纯净物。

四、保护空气

空气中存在着因为人类的工业生产产生的污染物。比如说一些有害气体,例如,二氧化硫(\rm SO_2),氮氧化合物({\mathrm{NO}}_x),一氧化碳(\rm CO),臭氧(\rm O_3),等等。同时也包含一些可吸入的颗粒物,更大一点的也叫粉尘。

可吸入颗粒物,粒径在10微米(\rm 10\,\mu m)以下的,记作PM10,即漂尘。同理,粒径在2.5微米(\rm 2.5\,\mathrm{\mu} m)以下的,记作PM2.5

人类排放的二氧化碳过多也会导致温室效应的加剧。但二氧化碳本身并不算污染物,因为二氧化碳提供的温室效应,将地球地表的温度提升到了人类适宜居住的温度。当然,像甲烷(\rm CH_4),氟氯代烷(是一类化合物,即氟利昂的总称,以二氟二氯甲烷为例:\rm CF_2Cl_2)等等也算作温室气体。

通过植树造林,处理工厂排放的废气,加强大气质量监测等方式,可以帮助人类改善地球的空气质量。
下一期讲氧气,记得来看哦。

Lake桑

2018.12.30

化学相关:走进化学实验室

化学仪器
化学仪器的图示

目录:化学相关:开坑预告及目录

上一期:化学相关:从认识开始

下一期:化学相关:我们周围的空气

化学,也是一门以实验为基础的科学。说完这么多理论上的东西,我们得讲讲实验。实验也得讲究,不可以随随便便地,毫无章法地就去实验。

举个例子,当你在闻气体时,你一定要做到“扇闻”。即

……用手轻轻地在瓶口扇动,使极少量的气体飘进鼻孔……

出自 义务教育教科书 化学 九年级 上册 2012版 第9页,由 人民教育出版社 发行。

实验,在以前,就是炼金术士们每天做的操作。以前的实验室,也就是古代炼金术士与炼丹术士的作坊,条件比现在的中国普通民办初中的实验室的水平还差。靠着对长生不老与“点石成金”的梦想,他们发明了许许多多的实验器具与分离物质的办法。比如我们今天依然使用的过滤与蒸馏。

下面我们做一个简单的实验吧。(不配图片了。)

一、对蜡烛及其燃烧的探究

在点燃前,我们需要观察蜡烛的颜色、状态、形状、硬度,闻一闻气味,等等等等。

用小刀从蜡烛上切下一块石蜡,把它放入水中,观察它是否溶于水,是浮在水面上还是沉入水底,并且你需要判断以下问题:

石蜡的密度与水相比是小还是大。

然后,点燃蜡烛,我们要仔细观察燃着的蜡烛。

蜡烛燃烧时,发生了哪些变化?火焰分为几层?哪一层最亮,哪一层最暗?

取一根火柴梗,拿住一端迅速平放入火焰中,约1秒后取出,根据火柴梗在火焰不同部位被烧的情况,推测火焰哪一部分的温度最高,哪一部分的温度最低。

分别取一个干冷的烧杯和一个内壁涂有澄清石灰水的烧杯,罩在火焰上方,观察烧杯内壁上有什么现象发生,并推测蜡烛燃烧后生成了什么物质。

接着熄灭蜡烛,观察蜡烛熄灭时有什么现象发生。用火柴去点蜡烛刚熄灭时产生的白烟,观察蜡烛是否能够重新燃烧。

探究步骤对现象的观察和描述
点燃前 
燃着时 
熄灭后 

探究完成后,你需要写一份报告。上面要包括日期,实验的操作人,实验(探究)的名称与目的,使用的药品,以及最重要的:

步骤和方法现象分析
1、将石蜡……石蜡在水中……石蜡的密度……
………………

再加上结论,问题与建议,评估与交流。

一个如此简单的实验,需要许多的步骤。这次实验,我们学会了试验的基本步骤。

二、在实验室

开头有一个化学仪器的图片。

化学仪器
化学仪器的图示

看完了吗?上面就是许多我们要掌握的仪器了。

在这之前,我们先要阅读实验室的规则。然后再认识仪器,学习操作。

疑似广告注意。电脑上可以模拟化学实验。查看 NB化学实验 以了解更多信息。

实验室化学药品取用规则

  1. 不能用手接触药品,也不可把鼻孔凑到容器口闻药品的气味,不可以尝任何药品的味道。
  2. 注意节约药品。一般地,必须按照实验规定用量取用药品。若没有说明,按照最少量(即1~2 mL)取用液体,固体只需要盖满试管底部。
  3. 剩余的药品不可放回原瓶,不可随意丢弃,不可拿出实验室,要放入指定的容器(比如废液缸)里。
  4. 不要手抖。

查看药品的标识,比如易燃易爆标志。小心按照上述步骤操作,不要手抖

一件恐怖的实例。女化学家卡伦·韦特豪恩(Karen Wetterhahn)一直以来研究的是有毒金属暴露对有机体的毒性。当卡伦正在做有关二甲基汞(一种有机汞)的实验时,突然,有 2 滴二甲基汞溶液从移液管里滴了下来,正好滴在了她的乳胶手套上。在进了医院急诊室的 3 周后,卡伦就对声音、视觉信号和触碰毫无反应了。1997 年 6 月,卡伦医治无效去世。一切都是因为二甲基汞(二甲基汞很容易被人体吸收,而且具有亲脂性,因此会缓慢富集在身体富含脂质的部位——大脑里,因为大脑的 60% 都是脂质。)能够穿透过乳胶手套,只可惜当时的人们没有意识到,结果让这样一位伟大的科学家过早地结束了她的前程。点击查看出处。

1. 固体药品的取用

固体药品通常保存在广口瓶里,取用固体药品一般使用药匙。块状的固体药品也可以使用镊子夹取。用过的药匙或者镊子要立刻用干净的纸擦拭干净,以备下一次使用。

把密度较大的块状药品或金属颗粒放入玻璃容器时,应该先把容器横放,把药品或金属颗粒放入容器口后,再将容器慢慢地竖立起来,使其缓缓地滑到容器的底部,以免打破容器。简记作“一横二放三慢竖”。

而加入固体粉末时,为了避免药品粘在管口和管壁上,可以先使试管倾斜,把盛有药品的药匙,或者纸槽小心地送进试管的底部,然后使试管直立起来。也简记作“一斜二送三直立”。

2. 液体药品的取用

液体药品通常盛放在细口瓶里,一般来说,较多量的,使用倾倒法取用。一般简记作“一斜二靠三倒”。

注意,打开细口瓶的塞子要倒放在桌面上,防止瓶塞与药品被污染。将瓶子上有标签的一面朝向手心,防止瓶口残留液流下腐蚀标签。(标签一旦损坏,内部盛放所有的药品,不管有多贵,必须全部废弃。)取用完后,要立即盖上塞子,防止污染试剂,防止试剂损耗。

较少量的,使用胶头滴管。先挤出滴管内空气,然后放入细口瓶,放开胶帽,再垂直悬空置于试管上方,按住胶帽。取用完毕后,保持胶帽在上,不要平放或是倒置,防止液体倒流腐蚀胶帽,污染药品,并且(除去滴瓶上的滴管一定不要清洗并且专瓶专用多余液体不需要送至废液缸外)一定要用清水冲洗干净(除去取用蒸馏水的滴管,因为蒸馏水比自来水干净)。

当需要取用一定量药品时,我们会使用量筒(分度值为0.1 mL)和滴管(用于添加微量液体,使其达到所需要的体积)。量取时,量筒必须放平,视线与量筒内凹液面最低处保持水平后再读出体积。先倒再滴,怎么滴怎么倒都和上面的内容一致。

3. 仪器

接下来我们讲讲仪器。顺便复习一些内容。

化学仪器
化学仪器的图示

1、试管:用作少量试剂的反应容器,在常温或加热时使用。注意,加热后不能骤冷,防止炸裂。

2、烧杯:用作配制溶液和较大量溶剂的反应容器,在常温或加热时使用。加热时,应放置在石棉网上,使受热均匀。

3、量筒:量度液体体积。注意,不能加热,不能作反应容器。

4、集气瓶:用于收集或贮存少量气体。可以用做部分反应的反应容器。

5、酒精灯:用于加热。注意:用完酒精灯后,必须用灯帽盖灭,不可用嘴去吹;绝对禁止向燃着的酒精灯里添加酒精,以免失火,绝对禁止用酒精灯引燃另一只酒精灯。高温可以使用灯罩达到目的。

补充:酒精喷灯:常用的酒精喷灯有座式酒精喷灯和挂式酒精喷灯两种。座式酒精喷灯的酒精贮存在灯座内,挂式喷灯的酒精贮存罐悬挂于高处。酒精喷灯的火焰温度可达1000℃左右。反应条件为高温时(例如碳还原氧化铜)使用。

6、试管夹:用于夹持试管。

7、玻璃棒:用于搅拌或转移液体时引流。

8、胶头滴管:用于吸取和滴加少量液体,用过后应立即洗净,再去吸引其他药品。

9、滴瓶:用于盛放液体药品。滴瓶上配套使用的滴管不用清洗。

10、铁架台:用于固定和支持各种仪器,一般常用于过滤、加热等实验操作。

11、水槽:用于排水法收集气体、或用来盛大量水的仪器,不可加热。

12、燃烧匙:燃烧匙由铁丝和铜质小勺铆合而成。用于盛放可燃性固体物质作燃 烧试验,特别是物质在气 体中的燃烧反应。

13、托盘天平:用于称量药品的质量。如何秤量与物理相反。

14、平底烧瓶圆底烧瓶:常用作反应容器。

15、锥形瓶:常作为反应容器。

16、带导管的橡皮塞:一般在制取气体时连接发生装置和收集装置。

17、广口瓶:一般用于实验室盛放固体药品。

18、细口瓶:一般用于实验室盛放液体药品。 

19、蒸发皿:通常用于溶液的浓缩或蒸干。

20、漏斗:用于向试管、酒精灯等添加液体。有普通漏斗、分液漏斗(可以控制流速)和长颈漏斗

补充:坩埚钳(crucible tongs),一种常见的化学仪器。通常用来夹取坩埚。一般由不锈钢,或不可燃、难氧化的硬质材料制成。

上面的第五点就是我们接下来要说的。

4. 给物质加热

一般使用酒精灯。除了上述的注意事项以外,我们还需要注意:

1、 酒精灯内的酒精,量不得少于四分之一,不得多于三分之二。

2、不用时盖上灯帽,以防酒精挥发点不着。

3、加热液体:

  • 试管外壁要干燥。试管内液体不超过试管容积的三分之一。
  • 试管夹应从试管底部套上取下,夹持在其上方约三分之一处。
  • 加热时要先使试管均匀受热(预热),然后固定用外焰加热。
  • 试管口要对着没人的地方。
  • 加热后的试管需要等待其冷却后,方可接触冷水或清洗。

违反上述条例,可能会使试管炸裂,或者受伤。

4、加热固体时,试管口要微微向下,防止试管口冷凝水回流炸裂试管。

5. 连接仪器装置

初中化学实验中,一般需要连接玻璃导管、橡胶塞、胶皮管,连接好后要检查装置气密性。装置的正确连接十分重要。

  1. 将玻璃管插入有孔的橡皮塞时,先将玻璃管口用水润湿,对准橡胶塞上的孔稍稍用力转动插入即可。
  2. 连接玻璃管和胶皮管时也需要先把玻璃管口用水润湿,然后稍稍用力,把玻璃管插入胶皮管。
  3. 在容器口塞橡胶塞时,应该把橡胶塞慢慢转动着塞进容器口,千万不可以把容器放在桌子上再使劲塞进塞子,以免压破容器。
  4. 检查装置的气密性,一般有以下的一种通法。先将导管放入水中,用手紧握试管,观察导管口有没有气泡冒出。如果有气泡冒出这说明装置不漏气,但如果没有气泡冒出,你需要仔细的查找原因,比如说是否应该塞紧或更换橡胶塞。直到不漏气以后才可以进行实验。

6. 洗涤玻璃容器

做实验也必须要使用干净的仪器,否则也会影响实验的效果。现在我们以洗涤试管为例,说明洗涤玻璃仪器的方法。

首先先倒净试管内的废液,再注入半试管水,振荡以后将水倒掉,再注入水,振荡后再倒掉,这样连续重复几次。如果内壁附有不易洗掉的物质,要使用试管刷来刷洗。刷洗时须转动或上下移动试管刷,但用力不能过猛,以防损坏试管。

洗干净的玻璃容器有一个标志,那就是内壁附着的水既不聚成水滴,也不成股留下。洗干净的玻璃容器应放在指定的地方。

下一期关于空气,记得来看哦。

Lake桑

2018.12.29

每日一词:fulcrum(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for December 29, 2018 is:

fulcrum • \FULL-krum\  • noun

1 a : prop; specifically : the support about which a lever turns

b : one that supplies capability for action

2 : a part of an animal that serves as a hinge or support

Examples:

“Normally, bending involves using the hip as a fulcrum, and erector spinae muscles to support our trunk. When Jackson leaned over, he transferred the fulcrum to the ankle, with the calf and Achilles tendon under strain.” — Jake Rossen, Mental Floss, 22 May 2018

“In 2014, then-Attorney General Greg Abbott issued a nonbinding opinion advising that bag bans are legal if they are not aimed at ‘solid waste management.’ That murky phrase, which appears in the Texas Health and Safety Code, has become the fulcrum for debate on the issue.” — Emma Platoff, The Texas Tribune, 22 June 2018

Did you know?

Fulcrum, a word that means “bedpost” in Latin, derives from the verb fulcire, which means “to prop.” When the word fulcrum was used in the 17th century, it referred to the point on which a lever or similar device (such as the oar of a boat) is supported. It did not take long for the word to develop a figurative sense referring to something used as a spur or justification to support a certain action. In zoology, fulcrum can also refer to a part of an animal that serves as a hinge or support, such as the joint supporting a bird’s wing.


Lake桑

December 29, 2018 at 01:00PM

化学相关:从认识开始

目录:化学相关:开坑预告及目录

下一期:化学相关:走进化学实验室

化学就在我们身边。衣食住行,一样也离不开化学。

化学是一门研究物质的科学。它研究自然界本身有的物质,也创造新的物质。

首先,我们得对变化分个类,这样就可以更好地理解什么是物质的变化,什么样物质的变化会产生新的物质。

一、物质变化

首先是物理变化。

物理变化:没有生成其他新物质的变化。其中,加粗部分是它的特征。一般来说,物理变化伴随形状与状态(物态)的改变。

还有一类就是化学变化。

化学变化:生成其他新物质的变化。也叫做化学反应。加粗的是其特征。一般会伴随物理变化。与此同时,可能伴随发光,放热,吸热,变色,产生气泡,生成沉淀,等等等等。但是这些不可以看作判断的依据(e.g. 白炽灯发光是因为电流的热效应),判断依据有且只有一个,也就是:

是否有新物质生成。

他们的本质区别就在于是否有其他物质生成。联系则在于化学变化过程中,一定伴随着物理变化。

比如说,蜡烛燃烧时,石蜡熔化是物理变化,燃烧则是化学变化。

由于燃烧这一现象的特殊性(以后的某一期内容会专门讲燃烧),你可以死板的记住,所有的燃烧都是化学变化。

剧透?

燃烧的狭义上的定义是:可燃物与氧气反应发生的一种发光、放热的剧烈氧化反应。所以燃烧是化学变化。但是部分活泼金属(比如镁)可以在氟气,氯气,甚至是不可燃不助燃的氮气与二氧化碳中燃烧。这就是广义上的燃烧了。爆炸则不一定是,主要是气球爆炸不是,其他的,比如可燃性气体的爆炸,可燃性粉尘的爆炸,都是化学变化。

二、物质的性质

首先是化学性质。

化学性质:物质在化学变化中才能表现出来的性质。

即:物质A能与物质B发生反应。

例:镁能与氧气发生反应。

再例如:可燃性,助燃性,氧化性,还原型,稳定性,毒性,酸碱性……

物理性质:物质不需要发生化学变化就表现出来的性质。

即:感官可以感知的,或者物理仪器可以测定的。

例:溶解性,挥发性,导热性,导电性,延展性。

再例如:颜色,状态,气味,密度,熔点,沸点,硬度……

三、性质与变化的区别

1. 性质是物质本身的属性。

一般地,描述物质的性质,通常会有关键词:“能”,“易”,“会”,“可”,“可以”,以及其否定形式。

比如说,酒精燃烧是化学变化,而酒精能燃烧是化学性质。

描述性质时,需要表明具体的条件

比如说,常温下,水是无色液体。

1013\, \mathrm{hPa} ,水的熔点是0 ℃。

一般来说,性质决定用途,用途体现性质。

比如铜的导电性好,用作导线,二氧化碳用于灭火,酒精作为燃料,等等等等。

下一篇,浸泡在(不是)走进化学实验室,记得来看哦。

Lake桑

2018.12.28

每日一词:canorous(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for December 28, 2018 is:

canorous • \kuh-NOR-us\  • adjective

: pleasant sounding : melodious

Examples:

“His artistry, technical proficiency, and canorous melodies have an introspective yet uplifting feeling by virtue of the beauty and honesty that so naturally accompany the acoustic guitar.” — Kevin Gillies, Noozhawk (Santa Barbara, California), 26 Nov. 2018

“There is an element of truth to that, but Zephyr—such a canorous hippie-child name—sang a populist tune not found in any Beltway progressive songbook.” — Bill Kauffman, American Conservative, 1 Nov. 2014

Did you know?

In Confessions of an English Opium-Eater (1821), the author Thomas de Quincey describes a manservant who, after accidentally letting a loaded trunk fall down a flight of stairs, “sang out a long, loud, and canorous peal of laughter.” Canorous typically describes things, such as church choirs or birds in the spring, that are a pleasure to listen to. It derives from the Latin verb canere (“to sing”), a root it shares with a number of words that evoke what is sweet to the ear, such as chant, canticle (“a song”), cantor (“a leader of a choir”), carmen (“a song, poem, or incantation”), and even accent.


Lake桑

December 28, 2018 at 01:00PM

又一个周五!


周五中午啦~ 吃完午饭,下午继续工作! (由 IFTTT 发送)

Lake桑

December 28, 2018 at 12:00PM

化学相关:开坑预告及目录

终于要开始写初中化学了。

以下是目录。

文章中以向右的三角形开头的行是选读内容,可以被点击并展开。


  • 化学相关:从认识开始
  • 化学相关:走进化学实验室
  • 化学相关:我们周围的空气
  • 化学相关:氧气
  • 化学相关:我们需要更深入些
  • 化学相关:水
  • 化学相关:化学方程式
  • 化学相关:碳与碳的氧化物
  • 化学相关:燃料

  • 定期查看此页面,看看有没有新条目。

    Lake桑

    每日一词:enervate(转自 韦氏词典)

    原文链接


    Merriam-Webster’s Word of the Day for December 27, 2018 is:

    enervate • \EN-er-vayt\  • verb

    1 : to reduce the mental or moral vigor of

    2 : to lessen the vitality or strength of

    Examples:

    Dehydration and prolonged exposure to the sun had enervated the shipwrecked crew, leaving them almost too weak to hail the passing vessel.

    “In contrast, there was dignity in the Joad family (of John Steinbeck’s The Grapes of Wrath). When the Dust Bowl smothered Oklahoma, the Joads were not enervated, they moved west in search of work.” — George Will, The Washington Post, 7 Dec. 2016

    Did you know?

    Enervate is a word that some people use without really knowing what it means. They seem to believe that because enervate looks a little bit like energize and invigorate it must share their meaning—but it is actually their antonym. Enervate comes from the Latin enervatus,the past participle of the verb enervare, which literally means “to remove the sinews of,” but is also used figuratively in the sense of “to weaken.” The Latin enervare was formed from the prefix e-, meaning “out of,” and nervus, meaning “sinew or nerve.” So etymologically, at least, someone who is enervated is “out of nerve.”


    Lake桑

    December 27, 2018 at 01:00PM

    语文相关:耄耋

    màodié

    解释:八九十岁。耄,形声字,音“冒”。耋,音“迭”。

    使用:耄思(思绪纷乱);耄耄(纷乱貌);耄乱(谓年老昏乱的人);耄夫(年老昏庸之人);耄昏(年老昏愦);耄聩(年老糊涂);耄朽(老朽;衰老);耄衰(衰老);耋老(年老;老年人);耋吏(老吏);耋耄(高寿);耋寿(指高寿的人;老人);耋耄之年

    出处:
    语出《汉·曹操·对酒歌》:“人耄耋,皆得以寿终。恩泽广及草木昆虫。”

    Lake桑

    2018.12.26

    每日一词:utmost(转自 韦氏词典)

    原文链接


    Merriam-Webster’s Word of the Day for December 26, 2018 is:

    utmost • \UT-mohst\  • adjective

    1 : situated at the farthest or most distant point : extreme

    2 : of the greatest or highest degree, quantity, number, or amount

    Examples:

    “The refuge, which is bordered by the Centennial Mountains and Continental Divide to the south and the Gravelly Mountains to the north, is also home to the utmost point of the Missouri and Mississippi rivers.” — Kelley Christensen, The Montana Standard, 25 Nov. 2013

    “The Richmond football team is one of eight 4AA squads with a bye this week, but head coach Bryan Till is still preaching … that keeping a sense of urgency is of the utmost importance.” — Leon Hargrove Jr., The Richmond County (North Carolina) Daily Journal, 15 Nov. 2018

    Did you know?

    Utmost traces back to the Old English ūtmest, a superlative adjective formed from the adverb ūt, meaning “out.” Ūtmest eventually evolved into utmost, perhaps influenced by the spelling of the word most. Not surprisingly, the earlier sense of utmost carries the same meaning as outermost. The second sense of utmost, meaning “of the greatest or highest degree,” first appeared in English in the 14th century. A related word is utter, meaning “absolute” or “total,” as in the phrase “utter chaos”; it comes from Old English utera, meaning “outer,” and ultimately from ūt.


    Lake桑

    December 26, 2018 at 01:00PM

    每日一词:benison(转自 韦氏词典)

    原文链接


    Merriam-Webster’s Word of the Day for December 25, 2018 is:

    benison • \BEN-uh-sun\  • noun

    : blessing, benediction

    Examples:

    “I offer thanks for the little things and the big things, everyday benisons and once-in-a-blue-moon moments of grace.” — Kati Schardl, The Tallahassee (Florida) Democrat, 17 Nov. 2017

    “In the second half of the second act, the show shrinks and darkens as Hamilton’s life does. The last song, describing the 50-year widowhood of Eliza, gives an unexpected benison.” — Richard Brookhiser, The National Review, 6 Apr. 2015

    Did you know?

    Benison and its synonym benediction share more than a common meaning; the two words come from the same root, the Latin benedicere, meaning “to bless.” (Benedicere comes from the Latin bene dicere—”to speak well of”—a combination of the Latin bene, meaning “well,” and dicere, “to say.”) Of the two words, benediction is more common today, but benison has a longer history in English. Records show that benison has been used in our language since the 13th century, whereas benediction didn’t appear in print until the 15th century.


    Lake桑

    December 25, 2018 at 01:00PM

    又一个圣诞节。

    又是一个圣诞节。

    这篇文章由IFTTT发布。

    Lake桑

    December 25, 2018 at 12:00AM

    语文相关:亡佚

    wáng

    解释:散失,失传。亡、佚,都是散失、丢失的意思。

    例句:这几本书久已亡佚。(这几种书很久以前就已经失传了。

    出处:

    • 章炳麟 《文学总略》:《汉高祖手诏》、 匡衡 王凤 镏隗 孔羣 诸家奏事,书既亡佚,复传其録。
    • 田北湖 《论文章源流》:今民史亡佚,国史亦残缺不完。

    Lake桑

    2018.12.24

    每日一词:grinch(转自 韦氏词典)

    原文链接


    Merriam-Webster’s Word of the Day for December 24, 2018 is:

    grinch • \GRINCH\  • noun

    : one who spoils the pleasure of others : killjoy, spoilsport

    Examples:

    “Chalk it up to a weary world eager for uplifting entertainment, the surprise of a diamond-in-the-rough performer or simply the sheer delight of watching Britain’s Got Talent judge and notorious grinch Simon Cowell grow a heart right before the audience’s eyes.” — Michelle Tauber et al., People, 4 May 2009

    “Not content with banning Christmas in 2016, the country’s supreme grinch, Kim Jong Un, went further by prohibiting gatherings that involve alcohol and singing, according to South Korea’s National Intelligence Service (NIS).” — John Onyanga-Omara, The Argus Leader (Sioux Falls, South Dakota), 20 Dec. 2017

    Did you know?

    When Theodor Geisel, better known as Dr. Seuss, wrote the children’s book How the Grinch Stole Christmas in 1957, he probably had no idea that grinch would soon enter the general lexicon of English. Like Charles Dickens’ Ebenezer Scrooge (whose name has become synonymous with miser), the Grinch changes his ways by the story’s end, but it’s the unreformed character who “hated Christmas! The whole Christmas season!” who sticks in our minds. The ill-natured Grinch, with his heart “two sizes too small,” provides us with a lively symbol of someone we love to hate, and his name has thus come to refer to any disgruntled grump who ruins the pleasure of others.


    Lake桑

    December 24, 2018 at 01:00PM

    又一个周一。

    一周又开始了。加油工作!(由 IFTTT 发送)

    Lake桑

    December 24, 2018 at 07:00AM

    每日一词:assuage(转自 韦氏词典)

    原文链接


    Merriam-Webster’s Word of the Day for December 23, 2018 is:

    assuage • \uh-SWAYJ\  • verb

    1 : to lessen the intensity of (something that pains or distresses) : ease

    2 : to make quiet : pacify

    3 : to put an end to by satisfying : appease, quench

    Examples:

    “Prince wrote often and eagerly about the idea of sanctuary—places where his spiritual anxieties were assuaged.” — Amanda Petrusich, The New Yorker, 25 June 2018

    “The interview offers a rare glimpse of what Charles might be like as king, and is perhaps an effort to assuage critics who have worried that he would diverge from British monarchs, who are bound by tradition to reign, not rule, over their subjects.” — Palko Karasz, The New York Times, 8 Nov. 2018

    Did you know?

    Scholars assume that the word assuage derives from assuaviare, a Vulgar Latin term that combines the prefix ad- (“to” or “toward”) and the Latin suavis, meaning “sweet,” “pleasant,” or “agreeable.” (Suavis is also the source of the adjective suave.) To assuage is to sweeten or make agreeable or tolerable, and it is far from the only English word for relieving or softening something difficult. Others include allay, alleviate, and mitigate. Allay implies an effective calming or soothing of fears or alarms, while alleviate implies temporary or partial lessening of pain or distress. Mitigate suggests moderating or countering the force or intensity of something painful.


    Lake桑

    December 23, 2018 at 01:00PM

    A scheduled post.

    You are supposed to see this post at 0:00 on December 23rd.

    L.

    December 22nd, 2018

    自热拉面。

    No comment.

    Lake桑

    2018.12.22

    每日一词:compendious(转自 韦氏词典)

    原文链接


    Merriam-Webster’s Word of the Day for December 22, 2018 is:

    compendious • \kum-PEN-dee-us\  • adjective

    : marked by brief expression of a comprehensive matter : concise and comprehensive

    Examples:

    Noah Webster’s style of defining for the first American dictionary was compendious.

    “For the past few years his writing has been an elegant and compendious ongoing exploration of Britain’s social history through its council estates.” — Lynsey Hanley, The Guardian, 19 Apr. 2018

    Did you know?

    Compendious is applied to things that are brief in statement or expression, but oftentimes the brevity is chock-full of meaning. Its synonyms run the gamut, giving us concise, terse, succinct, pithy, laconic, and summary. Concise simply suggests the removal of all that is superfluous or elaborative (“a concise description”). Terse implies pointed conciseness (“a terse reply”). Succinct implies the greatest possible compression (“a succinct letter of resignation”). Pithy adds the implication of richness of meaning or substance (“pithy one-liners”). Laconic implies brevity to the point of seeming rude or indifferent (“a laconic stranger”). Summary suggests the stating of main points with no elaboration (“a summary listing of the year’s main events”).


    Lake桑

    December 22, 2018 at 01:00PM

    每日一词:solstice(转自 韦氏词典)

    原文链接


    Merriam-Webster’s Word of the Day for December 21, 2018 is:

    solstice • \SAHL-stiss\  • noun

    1 : either of the two points on the ecliptic at which its distance from the celestial equator is greatest

    2 : the time of the sun’s passing one such point on the ecliptic which occurs about June 21 to begin summer in the northern hemisphere and about December 21 to begin winter in the northern hemisphere

    Examples:

    People all over the world have observed celebrations linked to the summer and winter solstices since ancient times.

    “The Earth wobbles on its axis once every 27,000 years…. This alters the relationship between the solstices and the distance from the Earth to the Sun.” — Steven A. Ackerman and Jonathan Martin, The Chippewa Herald, 8 Oct. 2018

    Did you know?

    In the Northern Hemisphere, the summer solstice usually occurs on June 20 or 21 and the winter solstice on December 21 or 22. In the Southern Hemisphere, where the seasons are reversed, the solstices are exactly the opposite. For several days around the time of the solstices, the sun’s appearance on the horizon at sunrise and sunset seems to occur at the same spot, before it starts drifting to the north or south again. Solstice gets its shine from sol, the Latin word for “sun.” The ancients added sol to -stit- (a participial stem of sistere, which means “to stand still”) and came up with solstitium. Middle English speakers shortened solstitium to solstice in the 14th century.


    Lake桑

    December 21, 2018 at 01:00PM

    又一个周五!


    周五中午啦~ 吃完午饭,下午继续工作! (由 IFTTT 发送)

    Lake桑

    December 21, 2018 at 12:00PM

    每日一词:frenetic(转自 韦氏词典)

    原文链接


    Merriam-Webster’s Word of the Day for December 20, 2018 is:

    frenetic • \frih-NET-ik\  • adjective

    : marked by excitement, disorder, or anxiety-driven activity :
    frenzied, frantic

    Examples:

    “For Youse and the roughly 90 employees who work at the store, the 5-mile move capped more than a half-year of planning, followed by a frenetic two days in which everything from the one store was transferred to the other.” — Chad Umble, LancasterOnline.com, 22 Oct. 2018

    “During his years as a sports broadcaster in Chicago, Adam Harris realized his volunteer work as a youth baseball coach often would provide a welcome break from the frenetic world of media.” — Karen Ann Cullotta, The Chicago Tribune, 18 Oct. 2018

    Did you know?

    When life gets frenetic, things can seem absolutely insane—at least that seems to be what folks in the Middle Ages thought. Frenetik, in Middle English, meant “insane.” When the word no longer denoted stark raving madness, it conjured up fanatical zealots. Today, its seriousness has been downgraded to something more akin to “hectic.” But if you trace frenetic back through Anglo-French and Latin, you’ll find that it comes from Greek phrenitis, a term describing an inflammation of the brain. Phren, the Greek word for “mind,” is a root you will recognize in schizophrenic. As for frenzied and frantic, they’re not only synonyms of frenetic but relatives as well. Frantic comes from frenetik, and frenzied traces back to phrenitis.


    Lake桑

    December 20, 2018 at 01:00PM

    每日一词:tchotchke(转自 韦氏词典)

    原文链接


    Merriam-Webster’s Word of the Day for December 19, 2018 is:

    tchotchke • \CHAHCH-kuh\  • noun

    : knickknack, trinket

    Examples:

    “How someone organizes their desk can tell you a lot about how they get work done. That’s why we’re stepping into the offices of enviably creative (and productive) people to look at what’s on their desks—pens and notebooks and gadgets, but also décor and tchotchkes.” — Deva Pardue and Maxine Builder, The New York Magazine, 10 Sept. 2018

    “… a review from WireCutter … called it the best 3D pen of the lot. While we’re debating whether any home needs the flood of tchotchkes that will inevitably pour forth as a result of this gadget, the idea of drawing something into existence is pretty appealing.” — Talia Milgrom-Elcott, Forbes, 1 Nov. 2018

    Did you know?

    Just as trinkets can dress up your shelves or coffee table, many words for “miscellaneous objects” or “nondescript junk” decorate our language. Knickknack, doodad, gewgaw, and whatnot are some of the more common ones. While many such words are of unknown origin, we know that tchotchke comes from the Yiddish tshatshke of the same meaning, and ultimately from a now-obsolete Polish word, czaczko. Tchotchke is a pretty popular word these days, but it wasn’t commonly used in English until the 1970s.


    Lake桑

    December 19, 2018 at 01:00PM

    每日一词:millefleur(转自 韦氏词典)

    原文链接


    Merriam-Webster’s Word of the Day for December 18, 2018 is:

    millefleur • \meel-FLER\  • adjective

    : having an allover pattern of small flowers and plants

    Examples:

    The museum’s collection includes several medieval tapestries with millefleur designs.

    “An early 16th century millefleurs tapestry is a charmer, with children playing amidst the birds and animals and the thousand flowers of the style’s name.” — Sherry Lucas, The Clarion-Ledger (Jackson, Mississippi), 29 Sept. 2002

    Did you know?

    Millefleur (which can also be spelled millefleurs) came directly from French into English in the 17th century as a word for a perfume distilled from several different kinds of flowers. The literal meaning of mille fleurs in French is “a thousand flowers,” so it is easy to see how millefleur came to be applied to patterns or backgrounds of many tiny flowers or plants. A similarly colorful extension of “a thousand flowers” can be seen in the word millefiori. That term, which refers to ornamental glass characterized by multicolored flower-like designs, comes from mille fiori, the Italian phrase meaning “a thousand flowers.”


    Lake桑

    December 18, 2018 at 01:00PM