A,C-Bridged Calix[6]arene： Relationship between the Length of Bridge and Conformation

Three new A,C-diamide bridged p-tert-butylcalix[6]arenes were synthesized from p-tert-butylcalix[6]arenes by bridging ClCH2CONH(CH2)nNHCOCH2Cl(n=3,4,6) in acetonitrile using K2CO3 as a base in 17%-25% yields.It was found that the bridged calix[6]arenes with shorter bridges (n=2,3,4 in N′,N′-bischloroacetodiamines) adopt cone conformation, but the last one (n=6) adopts alternate conformation, i.e., accompanying the lengthening of bridge, the conformation of A,C-bridged calix[6]arenes changes from cone to alternate.     

室温无溶剂条件下醋酸锌催化的Knoevenagel缩合反应

以醋酸锌作为催化剂, 在室温无溶剂条件下催化芳香醛与活泼亚甲基化合物发生Knoevenagel缩合反应, 其反应条件温和, 产率最高可达100%, 产品纯度好, 操作和后处理简单.     

Effect of La2O3／γ—Al2O3 Catalyst on the Activation of CH4 and CO2 to C2 Hydrocarbons under Non—equilibrium Plasma

In the reaction of methane and carbon dioxide to C2 hydrocabons under non-equilibrium plasma, methane conversion was decreased,but selectivity of C2 hydroxarbons was increased when using La2O3/γ-Al2O3 as catalyst. So the yield of C2 hydrocarbons was higher than using plasma alone. The synergism of La2O3/γ-Al2O3 and plasma gave methane conversion of 24.9% and C2 yield of 18.1%. The distribution of C2 hydrocarbons changed when Pd-La2O3/γ-Al2O3 was used as catalyst,the major C2 product was ethylene.     

An Interesting Approach to Bis-calix[5]arene Analogue from Calix[6]arene

Calix [n] arenas {n = 4, 6 or 8} are easily prepared from formaldehyde and para-substituted phenols via cyclic condensation under alkaline conditions in one step. It is not surprising that the calyx [n] arene (n = 4, 6, 8) chemistry has been developing very rapidly during the latest 20 years1. However, it is not the case for calixarenes with odd benzene rings (for example, n = 5). The yield of p-tert-butylcalix [5] arene synthesized in one-step from p-tert-butylphenol and formaldehyde was a…     

环形装置中三维MHD平衡与稳定性的计算机模拟

一、引 言 在聚变研究中,环形等离子体的磁约束起着重要作用。目前托卡马克研究的进展令人鼓舞,其理论与实验比较符合,定标关系清楚。但是无论从聚变的最终目标来看,还是从实验的安排考虑,完全轴对称的几何形状给各方面部带来许多不便。人们希望知道如果把环形几何中加进直线段,或者把圆环改成不具有对称性的环形,会对等离子体约束产生何种影响?     

Theory on the molecular characteristic contour (II)--Molecular intrinsic characteristic contours of several typical organic molecules

The molecular intrinsic characteristic contour (MICC) is defined based on the classical turning point of electron movement in a molecule. Three typical organic molecules, I.e. Methane, methanol and formic acid, were employed as examples for detailed introduction of our method. Investigations on the cross-sections of MICC provide important information about atomic size changing in the process of forming molecules. The electron density distributions on the MICCs of these molecules were calculated and shown for the first time. Results showed that the electron density distribution on the MICC correlates closely with molecular chemical properties, and it provides a new insight into molecular boundary.     

Fe3(CO)12与P(NEt2)2Cl的反应--两核和三核铁羰基簇合衍生物的合成和晶体结构

Fe_3(CO)_(12)与配位基前体P(NEt_2)_2Cl反应,给出4个新的两核和三核铁羰基簇合衍生物:Fe_2(CO)_6(μ-Cl)[μ-P(NEt_2)_2](Ⅰ),Fe_2(CO)_6[μ-P(NEt_2)_2]_2(Ⅱ),Fe_3(CO)_9(μ-CO)(μ_3-PNEt_2)(Ⅲ)和Fe_3(CO)_9(μ_3-PNEt_2)[P(NEt_2)_3](Ⅳ)。在反应期间,配前体分子中的P-Cl和P-N键劈开,形成的分子片Cl、PNEt_2、P(NEt_2)_2和P(NEt_2)_3作为配体与铁羰合物重新组建成上述簇合物。利用X射线衍射法测定了它们的晶体结构。Ⅰ属三斜晶系,P1空间群,晶胞参数a=0.8745(6)nm,b=0.9601(7)nm,c=1.3996(10)nm,α=74.131(11)°,β=79.480(12)°,γ=69.727(12)°,V=1.0553(13)nm~3,D_c=1.543g·cm~(-3),Z=2,R=0.0443,wR=0.0831。Ⅱ属正交晶系,Pbcn空间群,晶胞参数a=1.0153(3)nm,b=1.7543(5)nm,c=1.6860(5)nm,V=3.0031(15)nm~3,D_c=1.394g·cm~(-3),Z=4,R=0.0519,wR=0.1035。Ⅲ属单斜晶系,P2_1/c空间群,晶胞参数a=1.0280(5)nm,b=1.2113(5)nm,c=1.9192(7)nm,β=93.560(7)°,V=2.1366(16)nm~3,D_c=1.712g·cm~(-3),Z=4。Ⅳ属单斜晶系,Cc空间群,晶胞参数a=1.5875(7)nm,b=1.0359(5)nm,C=2.1919(9)nm,β=101.266(8)°,V=3.535(3)nm~3,Dc=1.443g·cm~(-3),Z=4。Ⅰ和Ⅱ为两核铁簇,其簇骨架Fe_2PCl和Fe_2P_2呈蝶状。Ⅲ和Ⅳ     

大气相干长度的昼夜观测

 介绍了利用差分像运动测量法测量光波到达角起伏方差来确定大气相干长度的方法，阐述了一种能对大气相干长度进行昼夜测量的日夜两用型大气相干长度仪的测量原理与结构,经过长期昼夜观测分析得知: 整层大气湍流强度有随时间变化的趋势，这种趋势与近地面层的湍流强度的时间变化特征基本吻合，即在日出后和日没前两段时间内的相干长度值远大于其它时间段内的值。     

原子荧光光谱法测定食品添加剂磷酸中的砷

建立了原子荧光光谱法测定食品添加剂磷酸中砷的方法.并对负高压、灯电流、载气流量、屏蔽气流量、硫脲与抗坏血酸浓度、载流介质浓度、硼氢化钠浓度等作了研究并予以优化.方法的线性范围为0.0-40.0ng/mL,相关系数为1.0000,检出限为0.02ng/mL,相对标准偏差在0.82％-1.86％之间,试样加标回收率在95.10％-102.20％之间.方法操作简便、灵敏度高、检出限低、重复性和再现性好,完全适用于食品添加剂磷酸中砷的检测.     

托卡马克中局域磁扰动引起的高能量离子损失研究

基于单粒子导心运动代码ORBIT，采用测试粒子模拟方法，研究了托卡马克等离子体内部不同径向位置处局域磁场扰动对高能量离子的损失的影响。研究表明，在局域磁扰动主要分布在某磁面附近、其环向具有类似纹波场形式下，可造成一些靠近等离子体中心区域的高能量离子损失，但对靠近等离子边界的离子损失影响相对不大。这些损失的高能量离子均为捕获离子，离子的投掷角越大就越容易损失。此外，造成高能量离子最大损失率的局域场径向位置与这些损失离子的初始径向位置通常存在一定的偏移，而且这个偏移与这些离子的能量密切相关。当局域场出现在某些位置时，能量较低的离子会有一定的损失，能量较高的离子反而不会损失。