多联吡啶衍生物化学修饰碳糊电极的制备及其循环伏安行为的研究

利用合成的多联吡啶衍生物6，6″－二甲基－4′－苯基－2，2′：6′，2″－三联吡啶（TPY）制备了新型的化学修饰碳糊电极并研究了 Cu（Ⅱ）、Co（Ⅱ）在该电极上的循环伏安行为。结果表明，TPY化学碳糊电极对Cu（Ⅱ）、Co（Ⅱ）有显的富集作用，且电极的稳定性和重现性良好。     

小麦幼胚愈伤组织诱导及植株再生

选取23个品种（系）及8个杂交组合F1的幼胚作为供试材料，取12－16日龄的幼胚接种在附加2，4－D2.0mg/L和6－BA1.0mg/L的MS培养基上，诱导3－5d后所有供试材料都具有愈伤组织。筛选出适宜的继代培养基为：MS＋2，4－D4.0mg/L NAA0.5mg/L LH500mg/L 0.5%蔗糖＋0.85%琼脂；大穗2、昌乐2号、抗锈204、品系38等材料愈伤组织生长较好。植株再生适宜的培养基为1／2MS＋NAA0.5mg/L 6-BA0.5mg/L 0.3%蔗糖＋0.85%琼脂。抗锈204、昌乐2号、优265／昌乐2号、优265／京选6号、优265／有芒白4号等5个供试材料分化率较高；杂交胚与常规品种比较，幼苗分化表现出较强的杂种优势。     

第19届美国数学奥林匹克试题解答

1.至多可以发行10~5个.我们可以造出10~5个互不相同的五位数证号 a_1a_2a_3a_4a_5.第6位数字 a_6规定为和a_1 a_2十a_3 a_4 a_5的个位数字.这时,如果两个号码的前5位数字 a_1a_2a_3a_4a_5与a_1~′a_2~′a_3~′a_4~′a_5~′中仅有一处不同,那么第6位     

N-苯甲酰基-N′-(4-溴苯基)硫脲的合成

用二氯甲烷作溶剂，以PEG－400为催化剂，合成N－苯甲酰基－N′－（4－溴苯基）硫脲，并用红外光谱对其结构进行表征。     

四核锰配合物[Mn4O2(O2CCH:CHCH3)7(Me2bipy)2]ClO4的合成与磁性质

本用[Mn4O2(O2CCH:CHCH3)7(Me2bipy)2]ClO4和4，4′－二甲基－2，2′联吡啶在CH3CN溶液反应，合成了一个四核的锰配合物[Mn4O2(O2CCH:CHCH3)7(Me2bipy)2]ClO4。对化合物进行了元素分析及红外表征，在2，2－300K温度范围内测定了其变温磁化率，实验结果表明化合物存在反铁磁性交换作用。     

"凸透镜成像规律"记忆法

凸透镜成像的规律是光学的重点之一,而同学们对其成像规律往往是掌握不准,记的不牢而导致用的混淆。为了帮助同学们更好地理解和记忆,大家不妨采用以下方法和步骤试一试。1 画一幅示意图。在图中,1、2、3、4、5、6为物体,1′、2′、3′、4′、5′、6′是与物体对应的像。其中物体4不能成像。     

确定n^（n^n）末位数的一个简易数表

以n′、n″分别表示n的末 1和末 2位数码 ,N′表示nnn的末位数 ,则有定理　设n′≠ 0 .(1 )若n≡ 1 (mod 4) ,则n′=N′;(2 )若n≡ 3 (mod 4) ,则N′≡ (n′) 3(mod 1 0 ) ;(3 )若n≡ 0或 2 (mod 4) ,则N′ =6.引理 1 [1] 　n4 q r的末位数与nr 同 .引理 2　n′为非零偶数 ,则n4 q末位为 6.证明 :n′=2 ,4,6,8和n4 ≡ (n′) 4≡ 6(mod 1 0 ) .故n4q=(n4 ) q≡ 6q≡ 6(mod 1 0 ) .定理的证明 :(1 )有n =4k 1 ,由引理 ,nn 末位 =(4k 1 ) 1的末位≡ 1 (mod 4) ,故nn=4q 1 .再用引理 ,nnn=n4q 1≡n≡n′(mod 1 0 ) ,即N′ =n′ .(2 )当n≡ …     

BCI—代数弱左自映射集合的一个性质

证明如果X是一个弱正定关联BCI－代数，L′（X）是X的所有弱左自映射集合，则（1）L′（X）是一个弱正定关联BCI－代数；（2）L′（X）同构于X。这推广了[3]中的主要结果。     

弱极值的充分条件

欧拉方程Ｆｙ－Ｆｙ′ｘ－Ｆｙ′ｙｙ′－Ｆｙ′ｙ′ｙ″＝０若它的解为ｙ＝ｙ（Ｘ）找出泛函Ｔ（ｙ）达到弱极小值的充分条件，若曲线ｙ＝ｙ（ｘ）∈Ｖ满足：１）Ｆｙ－ｄ／ｄｘｆｙ′＝０，２）Ｐ（ｘ）＝１／２Ｆｙ′ｙ′＞０，３）区间（ａ，ｂ）不含ｘ＝ａ的共轭点，则此曲线ｙ＝ｙ（ｘ）使泛函Ｔ（ｙ）达到弱极小值。     

H——矩阵的性质

设H是Hermite正定矩阵，定义矩阵A的H－－共轭为A′=A^-1AH，若AA′＝A′A，则称A为H－－正规定矩阵。本文得到了H－－正规矩阵的一些性质。     

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,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

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…     

库克斯顿城堡

城堡, 是欧洲典型的建筑之一, 每个城堡都有一个美丽的传说或是一段历史。从本期开始, 我们将推出“城堡之旅”, 带各位读者去浏览、观赏欧洲各地的城堡, 开始一段文化与历史的旅途!     

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.