排序方式: 共有12条查询结果,搜索用时 15 毫秒
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以尿素为原料,通过高温热缩聚法制备出石墨相氮化碳(g-C_3N_4),并通过超声剥离,破坏g-C_3N_4层状结构,得到分散的片状结构。将不同量的硝酸银配成银氨溶液,抗坏血酸将其还原成银,并在搅拌下沉积在g-C_3N_4的表面,得到不同银负载量的Ag/g-C_3N_4。利用X-射线衍射仪、纳米粒度仪以及红外光谱仪对其进行表征。最后在紫外-可见光谱仪的测试下,通过降解甲基橙和罗丹明B,比较光催化剂对降解物的选择性降解。结果表明:在可见光的照射下,由90 mg硝酸银与100 mg g-C_3N_4制备的复合光催化材料表现出最佳的降解效果,远大于复合之前g-C_3N_4的降解效果。而且对罗丹明B的降解性大于甲基橙,表明光催化材料对降解物具有选择性。 相似文献
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电阻的T形网络与∏形网络间的等效变换是电路计算中经常遇到的问题.一般教材都根据等效的概念采用基尔霍夫定律得到转换公式,过程复杂,不利于学生的理解和掌握.这里介绍一种更为简便易懂的推导方法. 相似文献
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电阻的T形网络与П形网络间的等效变换是电路计算中经常遇到的问题.一般教材都根据等效的概念采用基尔霍夫定律得到转换公式,过程复杂,不利于学生的理解和掌握.这里介绍一种更为简便易懂的推导方法. 相似文献
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水合稀土二氯醋酸盐的合成及热分解研究 总被引:1,自引:0,他引:1
合成了La,Ce,Nd,Sm,Eu,Gd二氯醋酸盐,经化学分析,热重法和五氧化二磷真空千燥脱水法确定组成为Ln(CHCl2COO)3.nH2O(n=2,Ln=La,Ce,Nd;n=1.5,Ln=Sm;n=1.25,Ln=Eu;n=1,Ln=Gd),它们均属新水合物.用DTA-TG-DTG并用技术并辅以化学分析和红外光谱技术研究了其热分解机理,实验证明,由室温至600℃范围内,它们均发生三步主要反应:水合盐脱水变为无水盐;无水盐分解为中间产物,Ln2(OH)Cl5.3H2O[Eu盐分解为Eu2(OH)Cl5.2H2O];中间产物进一步分解为LnOCl[Ce盐为CeO2].并观察到无水盐和氯氧化物形成温度皆与原子序数呈现镧系"双一双效应". 相似文献
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结构复杂(但电阻间具有串、并联关系)的线性混联电阻电路的等效,对学生来说是个难点,学生面对结构复杂的电路无从下手,讲解时需要调动学生的想像力,教、学都感吃力. 相似文献
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提出了均三甲苯及其液相氧化目标产物均苯三甲酸的色谱分析方法.通过甲醇酯化将均苯三甲酸转化为均苯三甲酸三甲酯再进行色谱分析,分别以异丙苯和苯甲酸苄酯为内标对均三甲苯和均苯三甲酸三甲酯进行气相色谱分析.结果表明:均三甲苯和均苯三甲酸三甲酯的相对标准偏差分别为0.68%,2.84%,均三甲苯和均苯三甲酸三甲酯、均苯三甲酸的回收率分别为97.72%~104.27%,98.41%~104.72%,98.38%~102.51%. 相似文献
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Effects of polarons on static order hyperpolarizabilities polarizabilities and second of conjugated polymers 下载免费PDF全文
According to the one-dimensional tight-binding Su-Schrieffer-Heeger model, we have investigated the effects of charged polarons on the static polarizability, axx, and the second order hyperpolarizabilities, γxxxx, of conjugated polymers. Our results are consistent qualitatively with previous ab initio and semi-empirical calculations. The origin of the universal growth is discussed using a local-view formalism that is based on the local atomic charge derivatives. Furthermore, combining the Su Schrieffer-Heeger model and the extended Hubbard model, we have investigated systematically the effects of electron-electron interactions on αxx and γxxxx of charged polymer chains. For a fixed value of the nearest-neighbour interaction V, the values of αxx and γxxxx increase as the on-site Coulomb interaction U increases for U 〈 Uc and decrease with U for U 〉 Uc, where Uc is a critical value of U at which the static polarizability or the second order hypcrpolarizability reaches a maximal value of αxx or γxxxx. It is found that the effect of the e-e interaction on the value of αxx is dependent on the ratio between U and V for either a short or a long charged polymer. Whereas, that effect on the value of γxxxx is sensitive both to the ratio of U to V and to the size of the molecule. 相似文献
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The migration of a polaron at polymer/polymer interface is believed to be of fundamental importance for the transport and light-emitting properties of conjugated polymer-based light emitting diodes. Based on the one- dimensional tight-binding Su-Schrieffer-Heeger (SSH) model, we have investigated polaron dynamics in a one- dimensional polymer/polymer system by using a nonadiabatic evolution method. In particular, we focus on how a polaron migrates through the conjugated polymer/polymer interface in the presence of external electric field. The results show that the migration of polaron at the interface depends sensitively on the hopping integrals, the potential barrier induced by the energy mismatch, and the strength of applied electric field which increases the polaron kinetic energy. 相似文献
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Effects of polarons on static polarizabilities and second order hyperpolarizabilities of conjugated polymers 下载免费PDF全文
According to the one-dimensional tight-binding Su-Schrieffer-Heeger model,we have investigated the effects of charged polarons on the static polarizability,α xx,and the second order hyperpolarizabilities,γ xxxx,of conjugated polymers.Our results are consistent qualitatively with previous ab initio and semi-empirical calculations.The origin of the universal growth is discussed using a local-view formalism that is based on the local atomic charge derivatives.Furthermore,combining the Su-Schrieffer-Heeger model and the extended Hubbard model,we have investigated systematically the effects of electron-electron interactions on α xx and γ xxxx of charged polymer chains.For a fixed value of the nearest-neighbour interaction V,the values of α xx and γ xxxx increase as the on-site Coulomb interaction U increases for U U c and decrease with U for U U c,where U c is a critical value of U at which the static polarizability or the second order hyperpolarizability reaches a maximal value of α max or γ max.It is found that the effect of the e-e interaction on the value of α xx is dependent on the ratio between U and V for either a short or a long charged polymer.Whereas,that effect on the value of γ xxxx is sensitive both to the ratio of U to V and to the size of the molecule. 相似文献