成对的

In this thesis, we developed chiral proton N-O type ligands and employed them in the enantioselective addition of diethylzinc to N-diphenylphosphinoyl imines. The relationship between the structure of the ligands and the enantioselectivity was systematically studied. Furthermore, enantioselective butylation of N-diphenylphosphinoyl imines withBu〓Zn and enantioselective diphenylzinc addition to imine were also examined.

本文致力于亚胺的不对称催化有机锌试剂加成反应的研究：以手性质子型N-O配体为促进剂，对N-二苯基次膦酰亚胺进行不对称乙基锌加成反应而展开研究工作，系统地考查了手性配体的结构对反应的影响；另外，对N-二苯基次膦酰亚胺的不对称催化丁基锌加成进行了研究，并首次对亚胺的不对称苯基锌加成反应进行了初步探索。

Interaction designers have always designed in pairs, have always rapidly iterated in a discardable medium, have constantly refactored their work, always begin with a fuzzy, out of focus, yet complete image of the final product, always are open to outside advice, suggestion, and direction, and have always judged that advice on its merit, not on the authority of its source.

交互设计师总是成对的设计，总是快速在中间交付物中迭代，总是不断的重构他们的工作，总是在最终产品的未完成形态、模糊形态、没有焦点的状态中开始工作，总是开放的听取外人的建议和指导，也总是判断这些建议的优点，而不迷信建议来源的权威性。

For very long time, many research groups focus on using more than a stoichiometric amount of a chiral auxiliaries to obtain high enantioselectivity. There were mainly two sorts of processes reported on highly catalytic asymmetric addition of Grignard reagents to aldehydes. The former case was to transform Grignard reagent RMgX into other organometal reagents such as R_2Zn and R-Ti derivatives via complicated procedures at extremely low temperature. The later case was to link a chiral ligand to Mg in the form of organomagnesium amides or use chiral amine ligand catalyzing the alkylation of aldehydes.

格氏试剂对醛的不对称加成的报道大多需要大量的手性助剂以获得高的光学活性，而高度催化的格氏试剂对醛的不对称加成主要通过两种途径进行：一种是把格氏试剂转化成其他的有机金属试剂如R_2Zn和R-Ti化合物再对醛进行加成，反应通常在低温下进行；另一种是利用手性镁胺作为中间体或直接用手性胺催化来完成此反应。

It introduced the classical theory of bubble nucleation during the process of foam plastics , and presented the calculation formulas about the radius of critical nucleation , required Gibbs free energy and nucleation rate of some kinds of nucleation. It reviewed the development of classical theory of bubble nucleation , including the influence of free volume and oversaturation on bubble nucleation , and pointed out the existing deficiencies in explanation of classical theory of bubble nucleation to bubble nucleation of dynamic polymer melt.

介绍了泡沫塑料加工过程中气泡成核的经典理论，给出了几种成核方式的临界成核半径、所需克服的吉布斯自由能及成核速率的计算公式；评述了经典成核理论的发展，包括自由体积和气体过饱和度对气泡成核的影响，并分析指出了经典成核理论对动态聚合物熔体气泡成核解释存在的不足。

ResultsCyromazine had a great toxicity to firs t-instar larvae of housefly with LC 50 value of 43.896 mg/L, and showed less toxic actio n to third-instar larvae and adults of housefly, but reduced the pupate, ecl osion, female oviposition and egg hatch.

结果 灭蝇胺对家蝇 1日龄幼虫的 48h的LC5 0 值为 43 。896mg/L ，对 3日龄幼虫和成蝇的毒杀效果较差，但可引起幼虫化蛹率、羽化率以及雌成蝇产卵量和卵孵化率明显下降；阿维菌素对家蝇 1日龄、3日龄幼虫和成蝇表现出较强的急性毒杀作用，其 48hLC5 0 值分别为 0 。162 1mg/L、1.5546mg/L和 0 。2 10 3mg/L ，而对家蝇生长发育无不良影响。

Shim current calculation When shim coils are excited by appropriate current, they can generate correcting magnetic field to compensate the imaging magnetic field unhomogeneity. Based on the indirect calculation method, we proposed a novel iterative optimization algorithm to calculate shim current. Because there is a direct proportion relationship between FID signal and magnetic field homogeneity, we use the intensity of FID signal as feedback information to the calculation. Shim current can be worked out in less than 3 minutes. This satisfied the requirement that active shimming should be performed in real time.

5匀场电流计算对匀场线圈施加适当的电流后才能产生校正磁场消除成像磁场的非均匀分量，本文在匀场电流间接计算方法的基础上，利用磁共振成像原理中磁场均匀性与系统FID信号强度成正比的关系提出了一种电流迭代优化算法，将系统FID信号强度的变化作为反馈信息，能够快速计算出匀场电流对成像磁场进行补偿校正，平均耗时不到三分钟，满足磁共振成像系统对有源匀场的实时性要求。

Shim current calculationWhen shim coils are excited by appropriate current, they can generate correcting magnetic field to compensate the imaging magnetic field unhomogeneity. Based on the indirect calculation method, we proposed a novel iterative optimization algorithm to calculate shim current. Because there is a direct proportion relationship between FID signal and magnetic field homogeneity, we use the intensity of FID signal as feedback information to the calculation. Shim current can be worked out in less than 3 minutes. This satisfied the requirement that active shimming should be performed in real time.

5匀场电流计算对匀场线圈施加适当的电流后才能产生校正磁场消除成像磁场的非均匀分量，本文在匀场电流间接计算方法的基础上，利用磁共振成像原理中磁场均匀性与系统FID信号强度成正比的关系提出了一种电流迭代优化算法，将系统FID信号强度的变化作为反馈信息，能够快速计算出匀场电流对成像磁场进行补偿校正，平均耗时不到三分钟，满足磁共振成像系统对有源匀场的实时性要求。

To enlarge the measurement range of a potential vision meter and improve its measurement accuracy for patients with high error of refraction, the imaging characteristics of its optical system were investigated. The visual magnification equation of the system was derived. The influence of the focal length variation of the collimating lens and the imaging lens on the magnification was analyzed respectively.

针对潜在视功能检测仪临床使用中量程有限和对高度屈光不正患者检测结果有一定误差的现象，研究了其光学系统成像特性，建立了系统对视力板成像的视觉放大率公式，分析了准直透镜、成像透镜焦距变化对视觉放大率的影响。

There're kids learning to walk and children flying kates, there're couples of young lovers and pairs of middle-aged spouses, and also oldsters with grey hair. Seeing from high land, the park, which has few visitors in usual time, had been full of people, even the stone boards used as decoration for the passages were occupied by passers-by.

有蹒跚学步的小孩，也有放风筝的儿童，有成对的情侣，也有手牵手的中年夫妇，还有头发花白的老人，放眼望去，平日冷清的公园几乎被人填满，连用作装饰的回廊石板上也坐满了过往的游客。

In summary, various key experimental conditions in electron acoustic imaging of ferroelectric domains were systematically studied. The optimum experimental conditions to obtain EAI of domains with good quality and the factors important to image analysis have been presented. The piezoelectric vibrator model and calculation of motion equation are helpful for explaining the imaging mechanism and related experimental phenomena. The sample holder with variable electric field was designed. The domain movement of BaTiO〓 ceramics and crystal under lateral and longitudinal applied electric field and domain movement of PMN-PT crystal under longitudinal poling electric field were observed. The application of SEAM on revealing of ferroelastic domains, imaging of residual stress distribution in ceramics coatings and around the pores on the surface of ferroelectric ceramic composite have been reported respectively. All these works enriched the study of electron acoustic imaging and extended the application of SEAM in the characterization of materials.

综上所述，本文系统地研究了各项关键实验条件对电畴电声成像的影响，指出了获得最佳畴结构电声像的条件和成像分析中应当考虑的各种影响因素；提出了解释电畴电声成像的压电振子模型，在此基础上推导并求解了压电振子运动方程，并对一些实验现象作出了解释；成功地设计了可变电场的样品台，观察了BaTiO〓陶瓷和晶体在横向电场作用下的畴运动，PMN-PT晶体在纵向极化电场作用下的畴运动；探索了电声显微镜在铁弹畴成像，陶瓷涂层应力观察，陶瓷自然表面气孔周围应力成像的应用，这些研究，丰富了电声成像的学术内涵，拓展了电声显微镜的应用领域。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。