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nmr实验
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  nmr experiments
    DESCRIPTION OF THE EVOLUTION OF DENSITY OPERATORS IN NMR EXPERIMENTS FOR THE STRONGLY COUPLED AB SPIN SYSTEMS
    强偶合AB体系NMR实验的密度算符演化描述
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    The Calibration of Chemical Shift in NMR Experiments by External Standards
    外标法NMR实验中化学位移的校正
短句来源
    In this paper we have applied a new procedure to suppress the huge water reso-nanee in the NMR study of HBeAg P3 peptide which is predicted to be an ep itope ofhepatitis B e antigens. Adding water selective relaxation reagents, we have success-fully carried o ut the 1D and 2D NMR experiments of HBeAg P3 pep tide in water so-lution and accomplished the resonanee assignments of the P3 peptide.
    本文利用水质子的选择性弛豫试剂,通过对乙肝病毒e抗原中一个预测的抗原决定簇(HBeAgP3肽)在水溶液中的构象研究,对NMR实验中水峰的抑制进行了新的探索,并完成了HBeAgP3肽的谱峰指定。
短句来源
    A new formalism was proposed to describe the evolution of density operators inmulti-pulse NMR experiments for the strongly coupled AB spin systems(I=1/2); Theevolution formula of spin operators were derived.The polarization transform INEPTexperiment and two-dimensional DQ-INADEQUATE experiment were deseribed. Theformalism is distinct on physical meaning and requires less ealculation。
    提出一种描述自旋为1/2的强偶AB自旋体系多脉冲NMR实验的密度算符演化的方法,推导了自旋算符的自由演化公式,具体描述了极化转移INEPT实验和二维DQ-INADEQUATE实验。 该方法物理意义直观,计算量较小。
短句来源
    The valid magnetic field and the formula of inherent chemical shift in colunm medium under arbitrary conditions for NMR experiments were deduced. The chemical shift calibrations with single-spectrum,double-spectrum and magic-angle experiments were summarized. The medium magnetic effects in parallel and vertical magnetic fields were discussed in detail.
    推导了 NMR实验中任意条件下柱状介质所感受到的有效磁场和固有化学位移的公式 ,概括了通过单谱仪、双谱仪和魔角实验校正化学位移的方法 ,阐述了平行场和垂直场中的介质磁化率效应。
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  “nmr实验”译为未确定词的双语例句
    Study on Experimental Technique of NMR for Determination of Sample in Micrograms
    微克级样品的NMR实验技术研究
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    Product Operator Formalism for Spin Systems with Magnetic Equivalence in FT NMR Experiment Ⅲ. analysis of Spin topology.filtration experiment
    磁等性自旋体系FT—NMR实验的乘积算符描述 Ⅲ.自旋拓扑滤波实验分析
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    1D and 2D NMR (1H NMR, 13C NMR, DEPT, 1H-1H COSY, HSQC, HMBC) methods were used to elucidate the structure of methyl 2, 7, 7-trimethyl-5-oxo-4-(3-methoxy -4-hydroxylphenyl) -1, 4, 5, 6, 7, 8-hexahydroquinolin-3-carboxylate. The 1H and 13C chemical shifts of the compound were assigned.
    应用1H NMR,13C NMR,DEPT,1H-1H COSY,HSQC,HMBC等多种NMR实验测试分析方法,确证了一种新的六氢喹啉衍生物2,7,7-三甲基-4-(4-羟基-3-甲氧基)苯基-5-氧代-1,4,5,6,7,8-六氢喹啉-3-羧酸甲酯的结构,并对它的1H、13C信号进行了归属.
短句来源
    Solvent Suppression in NMR Spectroscopy
    液体NMR实验中溶剂峰的抑制方法
短句来源
    The following issuess were approached:(1) ~1H NMR spectra of protons on the imidazole ring of MI, IE, IP, IMP, and IPP were recorded in D_2O and CDCl_3, respectively. Their ~1H chemical shifts (8) of H_a, H_b and H_c on the imidazole ring exhibit different spectral pattern.
    (1)通过~1H NMR实验观察到了MI,IE,IP,IMP和IPP咪唑环上的H_a,H_b,H_c在D_2O和CDCl_3中~1H化学位移及其变化值随咪唑环上N~1-取代基不同呈现出规律性的变化。
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  nmr experiments
Nucleus cross-polarization technique in a rotating frame of reference is analyzed as applied to NMR experiments with sample magic-angle spinning.
      
The transitions between the superfluid and nonsuperfluid glass states can be triggered by small magnetic fields and by the change of the tipping angle of the magnetization in NMR experiments.
      
Recent NMR experiments allow us to discuss two regimes of the orientational disorder that have different NMR properties.
      
The states also have different properties in transverse NMR experiments.
      
Manyspin clusters and correlations are created faster in such an experiment than in usual MQ NMR experiments and can be used for the investigation of the many-spin dynamics of nuclear spins in solids.
      
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The polycondensation of p-phenylenediamine and terephthaloyl chloride in amide solvent system has been studied. In order to obtain high molecular weight poly (1,4-phenyleneterephthalamide) (PPTA), the solvation of PPTA with the solvents and the competitive side reaction of the solvents with terephthaloyl chloride in amide-salt system were investigated.We can observed from NMR data, the proton resonance of the amide group of these model compounds shifts markedly to lower field due to the effect of solvation....

The polycondensation of p-phenylenediamine and terephthaloyl chloride in amide solvent system has been studied. In order to obtain high molecular weight poly (1,4-phenyleneterephthalamide) (PPTA), the solvation of PPTA with the solvents and the competitive side reaction of the solvents with terephthaloyl chloride in amide-salt system were investigated.We can observed from NMR data, the proton resonance of the amide group of these model compounds shifts markedly to lower field due to the effect of solvation. The magnitude of these shifts depends on the kind of solvent and the concentration of the salt used. DMAc and NMP are the solvents which react with terephthaloyl chloride comptitively in the polycondensation process.

本文研究了在酰胺-盐溶剂体系中对苯二胺与对苯二甲酰氯的缩聚反应,溶剂对缩聚反应的影响以及溶剂体系与对苯二甲酰氯的副反应。由NMR实验结果表明,聚对苯二甲酰对苯二胺分子中酰胺基团的氢质子由于溶剂化作用向低场方向位移,位移的大小与溶剂的种类及盐的浓度有关。DMAc与NMP两种溶剂体系在缩聚反应过程中皆与对苯二甲酰氟有竞争反应。在该溶剂体系中可得到适于加工成纤的高分子量聚合物。

The acetyl, sulfonyl and phosphoryl are three amino protecting groups. The natural abundance ~(15)N-NMR of their derivatives of the phenylethylglycine and β- phenylethylamine has been studied.We found that there are great differences in the chemical shifts of the three protected compounds.δ~(15)N is shifted to upfield in turn.Among these three amino protecting groups, the diisopropoxyphosphinyl one produces the least deshielding effect, while the acetyl group gives the strongest deshielding effect, and the tosyl...

The acetyl, sulfonyl and phosphoryl are three amino protecting groups. The natural abundance ~(15)N-NMR of their derivatives of the phenylethylglycine and β- phenylethylamine has been studied.We found that there are great differences in the chemical shifts of the three protected compounds.δ~(15)N is shifted to upfield in turn.Among these three amino protecting groups, the diisopropoxyphosphinyl one produces the least deshielding effect, while the acetyl group gives the strongest deshielding effect, and the tosyl group is in the middle.The trend of deshielding effect of the three protecting groups occurred also in the ~1H NMR (Table 1) . Furthermore, we have studied the relation of chemical shifts to the atomic charge and molecular structures by means of semiempirical molecular orbital CNDO/2 and X-ray diffraction of single crystal structure analysis. Model moleculae has been calculated by semiempirical molecular orbital CNDO/2 method. The results were shown in Table 2. The trend of the nitrogen net charges of these moleculae is the same as the ~(15)N NMR chemical shifts.These data show that the phosphoryl group is the most effective nitrogen lone pair electron locali- zing group among the three kinds of protecting groups.And the acetyl one is the least one. By using the data of the single crystal structure of N-diisopropoxypbosphinyl- N-2-(3,4-methylenedioxy) phenyl) ethylglycine.The bonding types of the P-N,S-N and C-N of the related compounds were analyzed.The localizing effect of the pho- sphoryl group on the lone pair electron of nitrogen has been discussed. The one bond coupling constants of the N-phosphoryl system (Table 1) showed that the nitrogen through sp~2 hybrides formed bonds with one phosphorus atom and two carbon atoms.Thus, the nitrogen is in a planar conformation,It is consistent with the results of X-ray diffraction.

测定了九种苯乙基甘氨酸和β苯乙氨衍生物天然丰度的~(15)N及1HNMR参数,结合量子化学计算结果和X射线衍射结构分析对NMR实验结果进行了研究,氮原子净电荷与~(15)N化学位移趋势相一致;对氨基保护基磷酰基定域氮孤对电子的作用优于乙酰基、磺酰基作了理论分析;1J15N-31P研究结果与单晶结构的结论一致。

The distribution of acid sites of difforent acid strengths on zeolite Y with different Si/Al ratios prepared by secondary synthesis with (NH_4)_2SiF_6 have been studied by ~(20)Si MAS NMR, statistic calculation and NH_3-TPD methed, and the data obtained have been correlated with the activities of the zeolites toward typical acid-catalyzed reactions It has been proved that the acid strength of the aluminum sites in zeolite Y framework depends on their local framework environment, i. e. the number of next nearest...

The distribution of acid sites of difforent acid strengths on zeolite Y with different Si/Al ratios prepared by secondary synthesis with (NH_4)_2SiF_6 have been studied by ~(20)Si MAS NMR, statistic calculation and NH_3-TPD methed, and the data obtained have been correlated with the activities of the zeolites toward typical acid-catalyzed reactions It has been proved that the acid strength of the aluminum sites in zeolite Y framework depends on their local framework environment, i. e. the number of next nearest Al neighbors n-NNN. Strong acidity arises from AlO_4~- tetrahedras with no close Al neighbor in the second layer of T sites. Changes in zeolite acidity and acid strength with Al content measured by NH_3 TPD method are in good agreement, with the result, of ~(29)Si MAS NMR and the distribution of Al sites with different n-NNN obtained from statistic calculation. As the Al content decreases, the total acidity of zeolite Y decreases monotonously, but the strong acidity increases first and then decreases. The maximum of the volcano curve of the strong acidity is Iocated at Al/(Al+Si) ratio 0.15. The catalytic activity of the zeolites toward isopropanol dehydration which requires on]y weak acidity and the total acidity vary similarly with A content, whilo the catalytic activity toward cumene cracking which needs strong acldity parallels that of the strong acidity.

用~(29)Si MAS NMR(MAS为Magic Angle Spinning),统计计算,NH_3-TPD等方法对(NH_4)_2·SiF_6去铝补硅得到的高硅Y型沸石的酸位分布情况进行了研究,并与典型酸催化反应数据相关联,证实了Y型沸石的酸位强度取决于Al原子的周围环境,即与次邻位Al原子数目n-NNN(NNN为Next Nearst Neighbor)有关,沸石的强酸性来自次邻位无Al原子的AlO_4~-四面体,NH_3-TPD法测量的沸石酸量和酸强度数据与~(29)Si MAS NMR实验结果和统计计算得到的不同n-NNN Al位的分布是一致的,随着Al含量减少,Y型沸石表面的总酸量是单调下降的,但强酸量却是先增加后下降,在Al/(Al+Si)为0.15左右出现极大值,不同硅铝比的Y型沸石对典型的强酸性和弱酸性催化反应的活性变化规律亦与酸性相吻合。

 
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