共查询到20条相似文献,搜索用时 109 毫秒
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从产于甘肃的高山绣线菊植物中分离出一种新的化合物:白桦酯酸7',8'-二羟基肉桂酸脂.利用MS,IR,1D和2D NMR技术,其中包括1H-1H COSY,1H-13C COSY,1H-13C COLOC等对1H和13C谱进行了归属. 相似文献
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从雷公藤分离出二种新的萜化合物,利用1H-1H COSY,1H-13H COSY和COLOC等2DNMR技术,分析了雷酚萜甲醚和雷酚萜的1H和13C NMR谱,明确地指认出这三种化合物的全部1H和13C共振峰. 相似文献
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南蛇藤中倍半萜生物碱的二维NMR研究 总被引:1,自引:0,他引:1
用DEPT和二维NMR技术包括:1H-1H COSY,1H-13C COSY,NOESY,特别是1H-13C COLOC对两个多酯基取代的倍半萜生物碱的化学及立体结构进行了研究,并对其1H和13C NMR谱峰进行了归属。 相似文献
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本文用NOE和二维核磁共振技术-COSY,C-H化学位移相关,C-H远程化学位移相关(COLOC),DEPT对二个倍半萜分子的立体化学结构进行了研究,并对其1H和13C化学位移进行了归属。 相似文献
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A method for enhancing the sensitivity of 15N spectra of nonspinning solids through 1H indirect detection is introduced. By sampling the 1H signals in the windows of a pulsed spin-lock sequence, high-sensitivity 1H spectra can be obtained in two-dimensional (2D) spectra whose indirect dimension yields the 15N chemical shift pattern. By sacrificing the 1H chemical shift information, sensitivity gains of 1.8 to 2.5 for the 15N spectra were achieved experimentally. A similar sensitivity enhancement was also obtained for 2D (15)N-(1)H dipolar and 15N chemical shift correlation spectroscopy, by means of a 3D 1H/15N-1H/15N correlation experiment. We demonstrate this technique, termed PRINS for proton indirectly detected nitrogen static NMR, on a crystalline model compound with long 1H T(1rho) and on a 25-kDa protein with short 1H T(1rho). This 1H indirect detection approach should be useful for enhancing the sensitivity of 15N NMR of oriented membrane peptides. It can also be used to facilitate the empirical optimization of 15N-detected experiments where the inherent sensitivity of the sample is low. 相似文献
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偶合常数是一个重要的NMR参数,其数值与分子中化学键的二面角有关,可以为分子结构研究提供很重要的信息.多维NMR谱由于具有较大的化学位移分辨率,因此常常被用来测定同核或异核自旋-自旋偶合常数.本文介绍了利用最高量子相关技术(MAXY)测定同核偶合常数的方法.MAXY是最近发展的一种多维NMR谱编辑技术,可以使不同官能团(CH,CH2,CH3)的相关峰分布于不同的图谱区域,因此比常规的二维谱具有更高的化学位移分辨率.而且被分离开来的NMR相关峰呈吸收性线型,能清楚地展示各自的偶合分裂特征,可以直接用于测定偶合常数. 相似文献
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偶合常数是一个重要的NMR参数,其数值与分子中化学键的二面角有关,可以为分子结构研究提供很重要的信息.多维NMR谱由于具有较大的化学位移分辨率,因此常常被用来测定同核或异核自旋-自旋偶合常数.本文介绍了利用最高量子相关技术(MAXY)测定同核偶合常数的方法.MAXY是最近发展的一种多维NMR谱编辑技术,可以使不同官能团(CH,
CH 相似文献
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D. S. Blokhin S. V. Efimov A. V. Klochkov A. R. Yulmetov A. V. Filippov O. N. Antzutkin A. V. Aganov V. V. Klochkov 《Applied magnetic resonance》2011,41(2-4):267-282
We have studied the spatial structure of the decapeptide Val-Ile-Lys-Lys-Ser-Thr-Ala-Leu-Leu-Gly in aqueous solution and in a complex with sodium dodecyl sulfate (SDS) micelles by 1H nuclear magnetic resonance (NMR) spectroscopy and two-dimensional (2-D) NMR spectroscopy (total correlation spectroscopy and nuclear Overhauser effect spectroscopy (NOESY)). The approach used to determine the decapeptide spatial structure was based on analysis of the 1H?C13C residual dipolar couplings in the molecules partially aligned in lyotropic liquid crystalline media. Analysis of the interproton distances obtained from the 2-D NOESY NMR spectrum was used to reveal the spatial structure of the decapeptide in a complex with SDS micelles. Complex formation was confirmed by analysis of 1H chemical shifts in the NMR spectrum of the decapeptide and analysis of the signs and values of NOEs in a solution with SDS micelles. 相似文献
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Heise H Sakellariou D Meriles CA Moulé A Pines A 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2002,156(1):146-151
In a recent publication we presented a method to obtain highly resolved NMR spectra in the presence of an inhomogeneous B(0) field with the help of a matched RF gradient. If RF gradient pulses are combined with "ideal" 90 degrees pulses to form inhomogeneous z rotation pulses, the line broadening caused by the B(0) gradient can be refocused, while the full chemical shift information is maintained. This approach is of potential use for NMR spectroscopy in an inhomogeneous magnetic field produced by an "ex-situ" surface spectrometer. In this contribution, we extend this method toward two-dimensional spectroscopy with high resolution in one or both dimensions. Line narrowing in the indirect dimension can be achieved by two types of nutation echoes, thus leading to depth-sensitive NMR spectra with full chemical shift information. If the nutation echo in the indirect dimension is combined with a stroboscopic acquisition using inhomogeneous z-rotation pulses, highly resolved two-dimensional correlation spectra can be obtained in matched field gradients. Finally, we demonstrate that an INEPT coherence transfer from proton to carbon spins is possible in inhomogeneous B(0) fields. Thus, it is possible to obtain one-dimensional (13)C NMR spectra with increased sensitivity and two-dimensional HETCOR spectra in the presence of B(0) gradients of 0.4 mT/cm. These schemes may be of some value for ex-situ NMR analysis of materials and biological systems. 相似文献
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Peter Trautner Klaus Woelk Joachim Bargon Rex E. Gerald II 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2001,151(2):284
NMR signals from samples that rotate uniformly about the central conductor of a TCD (toroid cavity detector) exhibit frequency shifts that are directly proportional to the sample's angular velocity. This newly observed effect is based on the unique radiofrequency field inside TCDs, which is variable in direction. If a liquid sample is pumped through a capillary tube wound about the central conductor, the frequency shift is proportional to the flow rate. A mathematical relationship between a volumetric flow rate and the frequency shift is established and experimentally verified to high precision. Additionally, two-dimensional flow-resolved NMR spectroscopy for discrimination between components with different flow velocities yet retaining chemical shift information for structural analysis is presented. The application of the two-dimensional method in chromatographic NMR is suggested. Furthermore, utilization of the frequency-shift effect for rheologic studies if combined with toroid-cavity rotating-frame imaging is proposed. 相似文献