不对称的
- 与 不对称的 相关的网络例句 [注:此内容来源于网络,仅供参考]
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It is demonstrated that the chiral quaternary ammonium salts catalysts exhibit promising catalytic properties for the substrate. Part III: The synthesis and the characterizing of the macroporous aminomethyl resin-supported cinchona alkaloid complexes and the study on its catalytic properties The part consists of two subsections. the macroporous aminomethyl resin -supported cinchona alkaloid complexes were synthesized by the stuff (cinchonine, quinine and macroporous aminomethyl resin). Their structures were characterized by means of elemental analysis, XPS, TG/DTA; the chiral polymer-supported complexes were first used as catalysts for the reduction of ketones. Their catalytic properties for the reduction processes were investigated. The comparison of the products e.e., the conversion of the substrate among different reduction processes was employed with determined by HPLC. The effects of the time, the temperature, the ratio of catalyst to substrate, reaction solvent as well as the recycle times were also discussed.
第三章聚-4-氨甲基苯乙烯负载金鸡纳碱金属络合物的合成与表征及其不对称催化性能研究本章分为两节,以辛可宁和奎宁及聚-4-氨甲基苯乙烯为原料,合成了4种聚-4-氨甲基苯乙烯负载金鸡纳碱络合物催化剂,并对它们的结构用元素分析、X-射线光电子能谱、TG/DTA等几种测试手段进行了表征;首次将所合成的手性高分子负载的金属络合物用于催化芳香酮不对称还原反应,详细研究了所得的手性高分子负载的金属络合物对不同底物的催化性能,用HPLC等分析手段定量检测了还原过程的底物转化率及其产物对映异构体选择性,并考察了反应时间、反应温度、催化剂和底物投料比、反应溶剂和循环次数对催化性能的影响。
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These dendritic NOBIN derived Schiff base ligands have been applied to titanium catalyzed hetero-Diels-Alder reaction of Danishefshy's diene and aldehydes, affording the corresponding 2-substituted 2, 3-dihydro-4H-pyran-4-one in quantitative yields and excellent enantioselectivities (up to 97. 2%ee). Comparing the reactivities and enantioselectivities of reaction catalyzed by the titanium complexes of these Schiff base ligands, it was found that a series of ligands L〓 were superior to the other three series of ligands L〓, L〓 and L〓, a significant positive NLE and a dendrimer effect existed in the L〓 dendritic catalyst system. The disposition of the dendritic wedges and the dendron size in the ligands were observed to have a significant impact on the enantioselectivity of the reaction.
NOBIN衍生的树枝状大分子希夫碱手性配体与钛形成的配合物在催化不对称杂Diels-Alder反应中的应用将得到的四个系列NOBIN衍生的树枝状希夫碱三齿手性配体与四异丙氧基钛形成的配合物用于催化Danishefsky's diene与醛的不对称杂Diels-Alder反应,通过反应条件的优化,获得了定量的收率和最高达97.2%ee值的对映选择性;考察了这四个系列NOBIN衍生的树枝状希夫碱钛配合物的催化活性和对映选择性,结果发现它们的活性次序依次为L〓≈L〓>L〓>L〓,对映选择性次序依次为L〓>L〓>L〓>L〓。
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If the fingers are asymmetric than that means that the person has a creative, artistic character but if there are very symmetric with each other, that means the person is the hunter and gatherer type, created for business life.
如果手指不对称,说明他有创造力,艺术家的性格;如果手指对称,意味著他是猎人或采猎者型,即为事业而生的人。
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The nonlinearity and discrete gradient inherited in CAViaR model is a conundrum for parameter estimation. We take the asymmetric Laplace distribution with scale parameter as the error process; indicate the variance has a minimum positive value when the scale parameter is a constant, conflicting with the distribution of real financial data. Further we estimate the parameters of indirect TARCH-CAViaR model base on Bayesian framework and Markov chain Monte Carlo method. The optimal scale parameter can also be obtained by Markov chain Monte Carlo method.
CAViaR一般模型中递归分位回归方程的非线性和非连续可微性是参数估计的一个难题,基于含有尺度参数的不对称拉普拉斯分布作为误差过程,指出将尺度参数固定为常数会导致不对称拉普拉斯分布随机变量的方差存在最小正值的限制,与实际金融数据分布不符;进而提出采用贝叶斯分析和马尔科夫链蒙特卡罗模拟方法,估计间接TARCH-CAViaR模型的参数,并可获得尺度参数的合理估计。
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Diffusive fluxes are roughly symmetric around the magnetic equator during equanoxes. But they are asymmetric during solstices, the winter hemisphere has smaller fluxes than the summer hemisphere does.
在分点,南北半球的扩散通量和扩散速度大致对称;而在至点,扩散通量存在着明显的南北半球不对称现象。
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The multicycle laser pulse is synthesized by a 10 fs/800 nm fundamental pulse and a 15 fs/1200 nm control pulse.
利用波长为800 nm,脉宽为10 fs的基频场和波长为1200 nm的控制场组成的双色场作用于不对称分子,发现不对称分子的高次谐波在平台区的末端呈现出光滑的超连续结构。
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The vibration modes in ABA sandwich 180°domain structure have been analysized, it was found that the FDLW includes symmetric vibration mode and aymmetric vibration mode. A new asymmetric vibration mode have been found in the two Layer 180°domain structure with two metalized surfaces.
并指出基模色散特性的差别主要来自于畴层结构的不对称,铁电畴层波是畴最不对称情况下压电耦合的结果,随着层数目的增加,奇数层和偶数层的这种基模色散的差异将逐步减少,最终趋于铁电畴层弯曲波。
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In recent years, optically active polymers have attracted much attention because of their unique functions such as molecular recognition, optical resolution for racemates and catalytic activity in asymmetric transformations as well.
近年来,光学活性聚合物的合成与结构—性能研究深受国内外学者的高度关注,这是由于这些合成材料具有潜在的应用前景,如:光学活性聚合物可应用于外消旋混合物的对映异构体分离,即光学拆分过程;不对称吸附、手性诱导及许多有机化学反应过程中的不对称催化。
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This thesis mainly calculate and analyze the effect of gravitational gradient based on the torsion pendulum, the result showed that for the modulated torsion pendulum, the torque caused by the gravitational gradient reached to 10~(-12)Nm, while the dissymmetry of round gravitational field can also affect the experiment.
本文主要计算和分析引力梯度效应对弱等效原理实验的影响,结果发现对于调制的扭秤,由于系统的不对称所引起的引力梯度效应达到了10~(-12)Nm,而周围引力场的不对称同样也会对实验产生不同程度的影响。
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There are several ways toobtain the DBHF self-energy from the G matrix used before, such as a simple method,where the Dirac structure of the nucleon self-energy is obtained from the momentumdependence of the single-particle energy, and a projection method.
在不同的不对称系数条件下,我们计算出的各密度处的核子平均结合能满足经验的抛物线规律,给出了密度依赖的不对称能。
- 推荐网络例句
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And discuss some key point of integrated management system design, include hazard identification and risk assessment and risk control in the occupational health and safety management, the measure of satisfaction target of customer, the flawlessness of law system, the integration of the integrated management system and enterprise standardization system, unify lead institution and work orgnization, integreted internal audit and integrated management review.
同时,论述了一体化管理体系构建中的几个主要问题,包括职业健康安全管理中的危险源辨识、风险评价和风险控制、顾客满意度的科学监测、法律、法规体系的完善、一体化管理体系与企业标准化体系的有机结合、统一的领导机构和工作机构、一体化的内部审核和管理评审。
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Deepwater Taranaki is investigated for its petroleum potential, using all available seismic data tied to shallow-water wells.
运用与浅水井相关的现有全部震波探测数据考察了深海区塔拉纳基盆地的油藏前景。
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If you're huffing and puffing at any point during the run, slow down and make sure you can take deep breathes.
如果你任何时候在跑步过程中气喘如牛,降低速度并且确保你能够深呼吸。