应用电子效应判断有机化学反应主要产物

诱导效应和共轭效应是高等有机化学中两类重要的电子效应,贯穿了大学有机化学的学习,一直是大学有机化学中的重点难点。本文通过分类分析和总结这两类电子效应对π电子的极化作用和中间体稳定性两方面的影响,可确定反应的主要产物,有利于学生的学习和相关内容掌握,为有机化学知识在反应生产中判断主要产物提供了重要的基础保障。涉及的反应包括亲电加成反应、亲核加成反应和亲电取代反应等。     

氮杂环卡宾催化剂在催化多种交叉偶联反应中的应用

由于氮杂环卡宾配体结构特殊,它的金属配合物可以作为催化剂应用于多种偶联反应中。氮杂环卡宾催化剂可以从立体效应,电子效应和平衡配体三个角度出发来进行修饰。通过修饰后的氮杂环卡宾催化剂可以更有效地应用于多种交叉偶联反应中。     

BER还原芳醛的位阻效应和电子效应

使用ＫＢＨ４与７１７＾＃阴离子交换树脂反应，制备了聚合物支载的硼氢化试剂，并用ＢＥＲ对多种芳醛进行了还原。从结构上分析了取代 基对还原结果的影响，并探讨了ＢＥＲ对芳醛还原的位阻效应和电子效应。     

不同取代芳醛Claisen-Schmidt缩合反应活性研究

以取代芳醛和丙酮为原料,合成了7个取代亚苄基丙酮,研究了不同取代芳醛与丙酮之间的Claisen-Schmidt缩合反应的电子效应.产物结构经IR及1HNMR鉴定,并用HPLC测定了含量.研究取代基电子效应对缩合反应影响的实验表明,含推电子取代基芳醛所需的缩合反应温度较高,而含吸电子取代基芳醛的缩合反应在较低温度下就可以进行.     

Cp2TiCl2—i—PrMgBr体系中影响炔烃加氢反应的结构因素

研究了不同结构的炔烃及其在 Cp_2TiCl_2-i-PrM_gBr 存在下催化加氢反应的规律。讨论了反应中取代基的电子效应及炔烃的结构因素。     

贵金属催化剂理性设计在选择性加氢反应中的研究进展

从多相催化的特征出发,综述了多相催化理性设计中典型调控理论和方法的研究进展。同时,以芳香硝基化合物及不饱和醛/酮选择性加氢反应为特征反应,从多相催化剂表面的电子效应、几何效应、界面效应和协同效应等角度进行了全面综述。指出了筛选合适的载体、合成特定尺寸形貌的活性中心、调控金属-载体强相互作用是开发更高效的多相选择性加氢催化剂的重要方向,调控金属-载体强相互作用,优化活性中心的电子效应、空间效应和界面效应,微调N=O及C=O不饱和键的吸附与活化,是实现高效选择性加氢催化体系的理论设计的重要手段。进一步优化氢气的活化裂解方式、活性氢的稳定与迁移,可抑制选择性加氢的副反应。     

表面活性剂介入酵母细胞催化芳香酮的对映选择性还原

以酵母细胞催化4'-氯苯乙酮合成(S)-1-4'-氯苯基乙醇为模型反应,研究了十六烷基三甲基溴化铵、十二烷基硫酸钠和壬基酚聚氧乙烯醚系列表面活性剂对酵母细胞催化4'-氯苯乙酮对映选择性还原反应的影响。结果表明,向反应体系中加入表面活性剂可明显提高4'-氯苯乙酮的转化率,而对产物(S)-1-4'-氯苯基乙醇对映体过量值的影响极小,壬基酚聚四氧乙烯醚(NP-4)是最合适的添加剂。此外,还考察了NP-4对酵母细胞催化系列芳香酮对映选择性还原反应的影响,结果表明,NP-4对产物(S)-1-芳基乙醇的对映体过量值几乎没影响,但对底物芳香酮转化率均有明显的提高,同时还发现底物转化率的提高幅度与芳香环上取代基的电子效应有关,取代基供电子能力越强越有利于底物转化率的增加。     

胺烷基二茂铁环钯化反应研究

研究了胺烷基二茂铁环钯化反应，探讨了反Ｃｏｐｅ准则的现象，阐明了胺组分的电子效应和空间结构、体系的酸碱度和体系的温域是决定生成环钯产物的重要因素。     

聚乙二醇中氯苯的Suzuki偶联反应研究

系统地研究了聚乙二醇体系中纳米钯催化氯苯的Suzuki偶联反应。通过对温度、聚乙二醇(PEG)链长以及碱等条件的优化,得出了最优化反应条件。研究发现,在100℃下,以PEG2000为反应介质,以Pd(OAc)2为钯源,以Na2CO3或K3PO4为碱,氯苯尤其是活化氯苯均能顺利发生反应。同时也研究了苯硼酸上取代基的电子效应和位阻效应对反应的影响,结果表明,当苯硼酸上具有给电子效应的基团时,反应更容易发生,取代基的位阻效应对反应无影响。研究还发现,在此催化体系中溴苯除发生Suzuki偶联反应外,还可发生还原去卤反应。同时,对反应机理进行了研究,TEM显示,在氯苯反应过程中有纳米钯的生成。最后研究了该催化体系的循环使用情况,研究表明该催化体系可以循环使用3次。     

含氟精细化工产品的开发和应用

一、氟化工产品介绍1.氟的特性1)模拟效应2)脂溶性和渗透性3)电子效应4)阻塞效应2.氟化工产品的分类1)含氟聚合物2)CFC及其代用品3)氟无机盐4)精细氟化工产品:①精细氟化工产品:     

纳米碳酸钙四大纳米效应应用表现

介绍了纳米碳酸钙四大纳米效应：量子尺寸效应、小尺寸效应、表面效应和宏观量子隧道效应，及其在应用过程中表现出与普通轻质碳酸钙所不同的、反常的物理化学特性。对进一步拓展纳米碳酸钙的应用领域、不断优化其生产工艺参数、突出其纳米特性、提升产品品质等都具有一定的指导意义。     

POOL BOILING OF BINARY MIXTURES

Nucleate pool boiling heat transfer coefficients for pure water, pure n-propanol and eight of their mixtures including the azeotrope were measured by using a horizontal electrically heated stainless steel tube of 3.35 mm O.D. and 9.8 cm long as heating element. This binary system was chosen for the reason that it is suitable for simultaneous investigation of the mass diffusion effect (the F effect), the effect of slowing down in bubble growth rate caused by the exhaustion of the volatile component near the vapor-liquid interface, the Marangoni effect (the M effect), the effect of surface tension gradient caused by the evaporation of the component of lower surface tension, and the dynamic surface effect (the Y effect), the effect of surface tension gradient caused by the stretching of vapor-liquid interface, on the boiling heat transfer rate in mixture. It is concluded that the mass diffusion effect can qualitatively account for the experimental results of the system. The discrepancy between the experimental data and the theoretical prediction by considering the F effect is due to taking no account of the intercorrelated effects of M and Y.

The effect of interfacial properties such as surface tension and contact angle on boiling heat transfer rate and the incipience of boiling were also evaluated.     

The bulk photovoltaic effect in photorefractive K1-xLixTa1-yNbyO3 crystals

Experimental evidence of the bulk photovoltaic effect in photorefractive K_1-xLi_xTa_1-xNb_yO₃ (KLTN) crystals is shown. The dependence of the bulk photovoltaic effect on the pbotorefractive impurities type is presented. The current voltage characteristic is presented for different temperatures. It was found that, in Fe-doped KLTN crystals at low temperature, the bulk photovoltaic effect is the dominant transport mechanism contributing to the photorefractive process.     

工业废水排放量变化的密度效应和增长效应

以可持续发展理论为基础,运用物质减量反弹效应的方法,给出了工业废水排放量变化的密度效应和增长效应计算公式,并根据1991～2004年<中国统计年鉴>中公布的数据,对全国工业废水排放量变化的密度效应和增长效应进行了计量分析.结果表明,1997年以前,密度效应比增长效应作用明显,全国工业废水排放量呈现下降趋势;1997年以后,增长效应比密度效应作用明显,全国工业废水排放量呈现上升趋势,特别是近3年增长显著.     

Y_1Ba_2Cu_3O_(7—δ)超导体磁化率曲线研究

研究了不同工艺条件下的Y_1Ba_2Cu_3O_(7-δ)陶瓷超导体的磁化率曲线k(T),发现在Tc以下χ(T)曲线存在两个不同的跳变区:第一跳变区为超导晶粒的Meissner效应;第二跳变区来自晶粒和晶界形成超导连接后的抗磁屏蔽效应。超导相含量可以由第一跳变区的信息量进行估算。     

一种粘泥剥离杀菌剂GA-101的合成及现场应用研究

利用二乙烯三胺、盐酸胍、氯代十二烷,合成一种高效粘泥剥离杀菌剂GA-101。对其杀菌效果及粘泥剥离效果进行考察,并在天津滨海新区某大型化工企业现场应用。研究表明,粘泥剥离杀菌剂GA-101杀菌效率高,抑菌时间长,使用广谱。对循环冷却水系统中的粘泥,有较强剥离效果。     

Thickness effect on fracture energy of cementitious materials

This paper studies the thickness effect on the fracture energy of cementitious materials based on a local fracture energy concept. Similar to the specimen back boundary, the presence of two free surfaces in the thickness direction also influences the local fracture energy dissipation, leading to the boundary or thickness effect. A bilinear local fracture energy model originally developed to characterise the ligament or back boundary effect on the fracture energy is further developed to consider variations of the local fracture energy in the thickness direction. The proposed model is used to analyse available experimental data from the literature. The predictions from the model are in a good agreement with the experiments.     

微波辐照污泥杀菌的生物学效应

通过在不同温度、时间条件下对硝化污泥进行微波辐照,得出温度是细菌致灭的主要原因。同时,从理论上阐述了除生物热效应的作用之外,微波辐照所产生的场力效应对杀灭细菌所产生的作用也不应忽略。     

Effect of pores on dielectric breakdown strength of alumina ceramics via surface and volume effects

To investigate the effect of pores on the dielectric breakdown (DB) of alumina ceramics under AC voltage, we implant pores at different positions (surface, interior, and the whole body) of the ceramic samples by adding the polyvinyl alcohol solid particles at different positions in the green bodies. Meanwhile, two electrode setups are used to test the dielectric breakdown strength (DBS), in order to analyze the effect of pore distribution on the DB, and the morphology of the DB channels is characterized. The results reveal both the pores on the surface and in the bulk reduce the DBS, and the pore distribution affects the shape and position of the DB channel. Besides, pre-breakdown in a low-DBS layer is found when the voltage is not high enough to produce DB. It confirms that the effect of pores on the DB is a combination of the volume effect and the surface effect.     

Abscopal Effect of Frozen Autograft Reconstruction Combined with an Immune Checkpoint Inhibitor Analyzed Using a Metastatic Bone Tumor Model

We evaluated the abscopal effect of re-implantation of liquid nitrogen-treated tumor-bearing bone grafts and the synergistic effect of anti-PD-1 (programmed death-1) therapy using a bone metastasis model, created by injecting MMT-060562 cells into the bilateral tibiae of 6–8-week-old female C3H mice. After 2 weeks, the lateral tumors were treated by excision, cryotreatment using liquid nitrogen, excision with anti-PD-1 treatment, and cryotreatment with anti-PD-1 treatment. Anti-mouse PD-1 4H2 was injected on days 1, 6, 12, and 18 post-treatment. The mice were euthanized after 3 weeks; the abscopal effect was evaluated by focusing on growth inhibition of the abscopal tumor. The re-implantation of frozen autografts significantly inhibited the growth of the remaining abscopal tumors. However, a more potent abscopal effect was observed in the anti-PD-1 antibody group. The number of CD8+ T cells infiltrating the abscopal tumor and tumor-specific interferon-γ (IFN-γ)-producing spleen cells increased in the liquid nitrogen-treated group compared with those in the excision group, with no significant difference. The number was significantly higher in the anti-PD-1 antibody-treated group than in the non-treated group. Overall, re-implantation of tumor-bearing frozen autograft has an abscopal effect on abscopal tumor growth, although re-implantation of liquid nitrogen-treated bone grafts did not induce a strong T-cell response or tumor-suppressive effect.