共查询到20条相似文献，搜索用时 125 毫秒
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以1—溴己烷,丙二酸二乙酯和丙烯醛为原料,经五步反应首次合成了溴化[2—(5—己基—1,3—二氧环己烧—2—基)乙基]三乙基铵(h). 相似文献
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该实验以BA、AA为核单体,并加入SiO2溶胶对其改性,以MMA、BA、AA为壳单体采用半连续核-壳乳液聚合法制备纳米SiO2溶胶改性纯丙乳液,着重探讨了引发剂用量对SiO2溶胶改性纯丙乳液的合成及性能的影响,并且进行凝胶率、吸水率、固含量等指标的检测.实验结果表明:在引发剂含量占单体的0.65%时,乳液性能最佳,其中凝胶率为10.77%,固含量为39.38%,吸水率为24.11%,离心稳定率为3.66%,各稳定性均合格. 相似文献
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利用同时蒸馏-萃取装置提取北五味子叶挥发油,其提取率为5.05%,并用气相色谱-质谱联用仪对北五味子叶挥发油化学成分进行分析鉴定.从分离到的132个成分中,鉴定出68个成分,占挥发油总含量的53.84%,其中主要成分为1-乙烯基-1-甲基-2,4-二（丙-1-烯-2-基）环己烷（6.33%）,2,6-二甲基-6-（4-甲基-3-戊烯基）-双环[3.1.1]庚-2-烯（4.40%）和1-甲基-5-亚甲基-8-（1-甲乙基）-1,6-环癸二烯（3.98%）. 相似文献
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两性聚丙烯酰胺在污泥脱水中的应用研究 总被引：1，自引：0，他引：1
本论文首先以氨基乙酸和丙烯酰氯为原料制备丙烯酰胺基乙酸钠(NaSAA)单体,然后以丙烯酰胺(AM)丙烯酰胺基乙酸钠(NaSAA)和二甲基二烯丙基氯化铵(DMDAAC)为单体,(NH4)2S2O8和NaHSO3为自由基引发剂,采用水溶液聚合法合成丙烯酰胺/丙烯酰胺基乙酸钠/二甲基二烯丙基氯化铵共聚物.通过研究AM/NaSAA/DMDAAC共聚物絮凝和脱水性能,发现丙烯酰胺/丙烯酰胺基乙酸钠/二甲基二烯丙基氯化铵共聚物是一种优良的絮凝剂. 相似文献
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简要介绍了用原位聚合合成PET及PET／SiO2纳米复合材料的方法,并对合成材料的力学性能和摩擦性能进行了研究。研究表明：PET／SiO2纳米复合材料的拉伸强度、冲击强度、弯曲强度等较纯PET有较大提高。当SiO2含量为2％时,复合材料的拉伸强度、弯曲强度分别比纯PET提高26．4％、25．2％,当SiO2用量为1％时,其冲击强度是纯PET的1-31倍。PET／SiO2纳米复合材料比纯PET具有较好的耐磨性。 相似文献
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运用MP2方法对N-H…O=C氢键二聚体中氢键强度进行了研究,探讨了氢键受体分子中不同取代基对N-H…O=C氢键强度的影响.研究发现,可以通过改变取代基来调节二聚体中N-H…O=C氢键强度.取代基为供电子基团,氢键强度增强.取代基为吸电子基团,氢键强度减弱.自然键轨道(NBO)分析表明,N-H…O=C氢键强度越强,参与形成氢键的氢原子的电荷越正,氧原子的电荷越负,单体分子间电荷转移越多,N-H…O=C氢键中氧原子的孤对电子n(O)对N-H的反键轨道σ*(N-H)的二阶稳定化能越大. 相似文献
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简要介绍了用原位聚合合成PET及PET/SiO2纳米复合材料的方法,并对合成材料的力学性能和摩擦性能进行了研究.研究表明:PET/SiO2纳米复合材料的拉伸强度、冲击强度、弯曲强度等较纯PET有较大提高.当SiO2含量为2%时,复合材料的拉伸强度、弯曲强度分别比纯PET提高26.4%、25.2%,当SiO2用量为1%时,其冲击强度是纯PET的1.31倍.PET/SiO2纳米复合材料比纯PET具有较好的耐磨性. 相似文献
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利用含有新型的吡啶基的二硫纶配体合成了两种新型的三羰基金属铼配合物[（L1）Re（CO）3Cl]（1）和[（L1）Re（CO）3Cl]（2）,其中L1=4,5-二（3-吡啶基甲基硫基）-1.3-苯二硫纶基,L2=4,5-二（3-吡啶基甲基硫基）-1,3-乙基二硫纶基。对二者进行了元素分析、1H NMR、IR、UV和MS等多项表征,解析出了化合物L1的晶体结构,并对化合物1,2,L1和L2的荧光性质和电化学行为做了初步的研究和探讨。 相似文献
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罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
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Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
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Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 相似文献
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《海外英语》2007,(5):10-11
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? 相似文献
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陈美曦 《山东教育学院学报》2008,23(2):103-107
Different nations have different social cultures, and the social culture of every nation is developing with the development of the nation, language is greatly influenced by social culture, which enables language to possess national and historical characteristics. Word is the smallest, independent, meaningful linguistic unit of language. It can well reflect the national and historical characteristics. From synchronic aspect, the social and cultural influence on word meaning is mainly embodied in conceptual and associative meanings of word. The incorrespondence of word meaning is a phenomenon that exists in both conceptual and associative meanings of word among different languages. From diachronic aspect, the development of social culture causes some changes of word meaning to some extent. Therefore, social culture plays a key role in vocabulary learning and mastery of a language. 相似文献
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邱崇丙 《唐山师范学院学报》2014,(1):21-23
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。 相似文献
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《海外英语》2007,(4):36
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. 相似文献