槟榔嚼块对神经系统的影响及其依赖性

槟榔嚼块（betel quid）是一种由槟榔果和多种添加物组成的混合物,含有槟榔碱、槟榔次碱、去甲槟榔次碱等多种生物碱,对中枢和外周神经系统均产生明显的药理作用,具有一定的滥用潜力和依赖性。     

解析几例习题

例1 某氯酸钾样品中混入了氯化钾杂质，经分析知氯元素的质量分数为35．5％．氯酸钾的纯度为（ ）     

一道中考计算题的“歪打正着”与正解

题目 （2005年盐城市中考题）有由氯化钾和盐A组成的固体混合物，其中A的质量分数为69％．现取10g该固体混合物，加入50g质量分数为7．3％的盐酸，它们可恰好完全反应，得无色溶液，     

溴代正辛烷的合成

以正辛醇和氢溴酸为原料，以浓Ｈ２ＳＯ４为催化剂，以９８％的高收率合成溴代正辛烷，反应具有条件温和，配比合理、操作方便和后处理简单等优点，十分适宜于工业生产．     

巧解两例有关中和反应的计算型选择题

例1为恰好中和某一强碱溶液，需用加g溶质质量分数为a％的盐酸．若改用加g溶质质量分数仍为a％的硫酸，并在反应后向所得溶液中滴入石蕊试液，则所得溶液显（ ）     

粉丝浆液提取蛋白质

用３７％的盐酸，把粉丝浆液调至ＰＨ为４．２－４．５，在３１８Ｋ凝聚３０－５０分钟，分离，加碱调至ＰＨ为６．８－７．０，在３３３Ｋ，真空度５８０ｍｍＨｇ下，真空脱水干燥６０－９０分钟，得优质蛋白，可用作蛋白饲料或制绿豆蛋白食品。     

冬天捞碱 夏天晒盐

例 在我国青海湖地区有一种说法：冬天捞碱，夏天晒盐．这里的碱是指Na2CO3，盐是指NaCl,人们从盐湖中捞得的碱会含有少量的NaCl．     

槟榔碱对未孕大鼠离体子宫平滑肌运动的影响

利用二道生理记录仪记录大鼠离体子宫平滑肌的运动，观察不同浓度的槟榔碱对子宫平滑肌条的作用，以及M-受体、a-受体、组胺H1受体、L-型钙通道和前列腺素合成酶分别被阻断或抑制后，这种作用受到的影响，以探讨槟榔碱对大鼠离体子宫平滑肌的作用和机制。结果表明：槟榔碱可促进离体子宫平滑肌的收缩，对收缩波的频率、振幅、收缩波面积作用显著，且呈显著正相剂量效应关系，而对收缩波的持续时间影响很小。槟榔碱的这种作用可被阿托品阻断，即证明该作用可能是通过M-受体发挥作用，与a-受体、组胺Hl受体、L-型钙通道及前列腺素合成酶的释放无关。     

CaO脱酸合成二辛基二甲基季铵盐

以二辛胺为原料,硫酸二甲酯为烷基化试剂,CaO为缚酸剂,通过非均相的液—固反应,常压下合成了二辛基二甲基氢氧化铵,二辛胺能定量转化。将二辛基二甲基氢氧化铵与盐酸或氢溴酸中和得到二辛基二甲基季铵盐。此方法反应时间短,反应产率高,一般可达98.2％,所得产品纯度高。     

茶树中茶多糖含量测定及提取研究

考察了温度、酸碱盐介质及微波提取对茶多糖提取的影响，实验表明，用氯仿、乙酸乙酯将茶叶、茶树枝梢、茶树根粉末进行回流提取之后，再用质量分数2％的碳酸钠溶液在微波提取器中浸提3次，可将茶多糖及其它有效成分充分提取出来，其中茶树根多糖提取率高达7．25％，茶树枝梢可达6．34％，粗老叶子可达6．07％。     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

胡主席在印度,我却在中国

Today, Sunday morning, I sit thinking and typing at my computer. My thoughts are in my homeland, India and my body is in China. The body is here and mind there for a good reason. Mr. Hu is president and I am resident and both are in each other's countries (what a difference the absence of one small letter makes!). Mr. Hu will return in a few days and I will stay on longer.     

STORIES

正A One day a pig went to the stable(马棚)to see his good friend,an oldhorse,and was going to stay there forthenight.Night came and it was time forsleep.The pig went into the straw heap(稻草堆)and lay comfortably.A longtime passed,but the horse was stillstanding there and did not move.Thepig asked the horse why he did not go tosleep."Standing like this is the begin-ning ofsleeping,"answered the horse.     

巧妙引语(英文)

正1.Any fool can count the seeds in an apple.Only God can count all the apples in one seed.2.Happy families are all alike;every unhappy family is unhappy in its own way.3.Memories are the key not to the past,but to the future.4.Sometimes in the dark you see what you want to see.5.There is a great difference between     

Information for Authors

正Scope and Policy The Journal of Chongqing University-English Edition(JCQU-E)is a peerreviewed journal publishing research articles in multiple disciplines of science and technology,covering civil and environmental engineering,chemical engineering,biotechnology,mechanical and electrical engineering,computer and data processing,mining,metallurgy,materials science,and interdisciplines thereof.