小的环

Moreover, we found that N-heterocyclic carbene could served as an efficient and novel catalyst for the reactions of aziridines with silylated nucleophiles or acid anhydrides.

随后，我们发现氮杂环卡宾也可以作为一种有机小分子催化剂，分别催化各类硅试剂或酸酐对氮杂环丙烷化合物的开环。

So before applying Mather's theorem of connecting orbits to concrete Hamiltonian system, we have to check whether the set W〓 is empty or not, and which cohomology classes are C-equivalent. In present paper, by investigating the topological structure of action minimizing sets near a co-dimensional one torus which is preserved under generic perturbations and becomes hyperbolic in nearly integrable Hamiltonian system.

与传统的Poincaré-Melnikov方法相比，我们方法明显优越之处在于，一方面我们的方法不仅可以得到双曲环面之间的异宿轨道，而且当该环面附近的其它环面破裂时，可以得到不同Mather集之间的连接轨道，另一方面，我们把异宿轨的存在性的证明转化为双曲环面极小同宿轨的某种弱孤立性的证明，所需条件比Poincaré-Melnikov方法弱得多。

On the condition of "many-head" and "small drive ratio",the plane double enveloping hourglass worm can not settle the problem of undercutting and sharpening simultaneously.It has devoted to a new type hourglass worm_sphere double enveloping hourglass worm.

考虑到平面二次包络环面蜗杆传动在多头小传动比条件下根切与齿顶变尖的矛盾很难同时解决且啮合性能较差，介绍了一种新型环面蜗杆传动——球面二次包络环面蜗杆传动。

PECH based PUs showed higher phase separation than that of PPG base PUs owing to that the -Cl groups in PECH reduced the flexibility of molecule chain and hindered the formation of hydrogen bonds between ether groups in soft segments and -NH groups in hard segments. As a result, PECH based PUs have lower free volume content, diffusion coefficient and equilibrium adsorption of CO〓, benzene and ethanol through them than through PPG based PUs.

聚环氧氯丙烷醚聚氨酯的氯基降低了链段柔性，妨碍了软段中醚基与硬段中氨基的氢键作用，导致其相分离程度较聚环氧丙烷醚聚氨酯大，并使CO〓、苯和乙醇蒸汽在聚环氧氯丙烷醚聚氨酯中的渗透系数和扩散系数较聚环氧丙烷醚聚氨酯小，而偏离费克扩散的程度大。

So, the aromaticity of acenaphthenyl groups in C_2 gum should be the least. In order to explain the reason, quantum chemical calculation is utilized. The optimized geometrical structrures of condensed aromatics in C_1 gum, C_2 gum and C_3 gum are calculated at B3LYP/6-31G* levels. We find that some phenyl groups in acenaphthenyl groups are coplanar and have the largest conjugated structure.

为了解释其原因，我们利用量子力学方法进行了计算，研究了三种稠环基团在B3LYP／6-31G*基组水平下优化得到的几何结构，发现苊式多苯基苯基中的萘环和中间的苯环共面，电子离域性最大，而其他二者所有苯环都不共面，发生了明显地扭曲；同时，在优化几何结构的基础上，对三种化合物进行了前线分子轨道的分析，利用密度泛函理论方法(density function theory，DFT)计算了稠环基团的最高占有轨道和最低未占轨道之间的能量差，即能隙，发现C_2胶上苊式多苯基苯基的Eg最小，解释了C_2胶具有最好的辐射保护效果的原因。

The main characteristics include: the quiet Sun corona has a rapid response to the flare heating, within 2 second the corona temperature increases nearly one order of magnitude, but later such increase becomes very slowly; the downward velocity at early stage of impulsive phase is too small to be negnected; chromospheric evaporation made by conduction shows some intensely, the maximum evaporated velocity may be as large as 1000 km/s; the chromospheric condensation appears just when the chromospheric evaporation takes place and its place always coincide with that of transition region in the early stage; the maximum of chromospheric condensation occurs also in the early stage of impulsive phase, at which the density in condensation may be larger two order of magnitude than that of surround and the downward velocity may be as large as 100 km/s; after the maximum of chromospheric condensation, its strongth decreases gradually but its width becomes greater with time and have a tendency to transport into deep chromosphere; the front of chromospheric condensation heats atmosphere obviously and the temperature in the chromospheric condensation is higher than the original case; the downware velocity of transition region may be greater than 100 km/s at the early stage; when the evaporated material collide at the top of loop, the densityand the presure there increase rapidly, which result in the formation of a shock wave; and so on.

在改善色球辐射损失和精确分辨过渡区的基础上，通过联立求解连续性方程、动量方程和能量方程，构造了一维磁限制性耀斑环在热沉积作用下的大气动力学模型，获得了耀斑热模型下脉冲相早期较为细致的大气演化理论图象，其主要特征是：耀斑对宁静日冕的加热相当迅速，仅2秒钟日冕温度增加即达一个量级，之后日冕温度增加缓慢；脉冲相早期日冕向下速度很小，几乎可以忽略，热传导驱动色球蒸发，其过程较为激烈，蒸发极大速度可达到1000km/s；色球压缩区与色球蒸发几乎同时形成，且在早期其位置总是与过渡区位置重合；色球压缩极大发生在脉冲相早期，其时密度可高于周围约2个量级，向下速度可超过100km/s；色球压缩极大后，其强度逐渐减弱，但宽度明显增大，且渐渐脱离过渡区往色球传播；压缩区内物质温度要高于原先的大气温度；过渡区下降在脉冲相早期相当迅速，可超过100km/s；当蒸发物质在环顶高速相碰时，环顶的密度、压力迅速增大，且温度也有所增加，导致形成激波，其波面以每秒上百公里的速度自环顶向下传播；在脉冲相前期，日冕软x辐射对色球的加热作用可以忽略；等。

OH radicals produced by ultrasound in aqueous solution attack phenolic cycle at adjacent or para position of the hydroxyl on phenol so that phenol is changed into small organic molecules such as muconic acid, maleic acid and ethane diacid. These small organic molecules will be oxidized to form carbon dioxide and water by.

苯酚超声降解的作用机理是，超声空化在水溶液中产生的·OH自由基进攻苯酚苯环上羟基的邻位或对位而使苯环断裂生成己二烯酸、顺式丁烯二酸和乙二酸小分子有机物而使苯酚得以降解，这些小分子有机物在·OH自由基的进一步作用下最终被氧化成CO〓和H〓O。

The following exciting results are revealed: 1 When considering the influence of some nonlinear elements such as hard-limit of exciters, the effects of some devices such as Power System Stabilizer and Static Var Compensator which can introduce positive damping in power system, the reasonability of system parameter values in simulation, the SNB surface and HB surface on the boundary of SSSR will turn close to each other and even coalesce together; 2 Under some conditions, coupling between slow exciters and shunt capacitors will bring negative damping in power system dynamics, which increases the possibility of oscillatory instability. So the power system with mass shunt compensators is easily subjected to the oscillatory instability. In recent years, chaotic phenomena of power system have been reported many times. Some simulation studies even found chaos existing inside the power system SSSR. In this dissertation, chaotic phenomena in power systems are thoroughly studied in order to make clear the relation of chaos and SSSR. The following results are derived: 1 Based on Li-Yorke Theorem and their definition on the chaos, the existence of chaos in power system is verified; 2 Three possible routes of causing chaos in power system are found and deeply investigated. They are route of cascading period doubling, route of directly initial energizing and route of torus bifurcation (or quasi-periodicity). The latter two routes are investigated for the first time in power system stability studies; 3 When the stability conditions of chaos are broken, it is found they can lead to voltage collapse, angle divergence, or voltage collapse with angle divergence simultaneously.

针对在电力系统小扰动稳定区域内可能存在混沌吸引域的有关报道，本文深入研究了电力系统混沌现象的出现途径和与系统失稳模式之间的关系：1利用Li-Yorke定理和Li-Yorke的混沌定义，从理论上证明了电力系统混沌现象的存在性；2发现了电力系统中导致混沌出现的三种可能途径：倍周期分岔导致混沌、初始能量直接激发混沌和经由环面分岔导致混沌，并对后两种新发现的途径进行了较为细致的研究；3发现了混沌极限环破裂导致电压崩溃、角度失稳以及电压崩溃和角度失稳同时出现的现象，其中混沌极限环破裂导致系统角度失稳和电压崩溃及角度失稳同时出现的现象均属首次报道；4证明由微分-代数方程描述的系统模型，其小扰动稳定域的边界只包含HB、SNB和SIB三种分岔界面，在SSSR的内部和边界上，均不可能存在会导致混沌的点，从而将混沌现象排除在小扰动稳定域的研究之外，简化了后者的研究工作。

The tests showed that the tension of each hoop cable and radial cable distributed unevenly under various working conditions,because of the friction between hoop cable and joints.Compared with the traditional joints,using new joints in structure could make the friction between hoop cable and joints reduce obviously,and friction loss on hoop cable at joints was small.

试验表明，由于环索与节点间存在摩擦，使得各工况下结构各圈环索和斜索张力分布不均匀；与传统节点相比，采用新型节点的结构环索与节点间的摩擦大幅降低，环索预应力损失较小，预应力传递效率更高。

The stability constants for the new macrocycle and binary complexes of the amino acid with the macrocyclic ligand are reported.

大环多胺配体对各种小分子的识别与大环的腔体大小、环的刚性程度及环上取代基的性质有关。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了