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11.
Volume Contents
Contents of Volume 68 (2002) 相似文献12.
A DWBA analysis mixing single-particle and core excitations shows that the experimentally observed spin dependent effect in the inelastic proton scattering reflects an intermediate coupling situation in the structure of odd 2p, 1f-shell nuclei. 相似文献
13.
A. Niemann W. H. Mennicke H. Meyer H. Reif E. Müller K. Jeney R. H. Sterzel H. Rüssel U. Anders A. E. Bühler F. Kreuzig W. Czysz R. Kaliszan R. Wennig F. Knorr U. Gerhardt und C. Martin 《Fresenius' Journal of Analytical Chemistry》1978,290(4):347-352
Ohne Zusammenfassung 相似文献
14.
15.
We describe new correlation experiments suitable for determining long-range 1H-1H distances in 2H,15N-labeled peptides and proteins. The approach uses perdeuteration together with back substitution of exchangeable protons during sample preparation as a means of attenuating the strong 1H-1H dipolar couplings that broaden 1H magic angle spinning (MAS) spectra of solids. In the approach described here, we retain 100% of the 1H sensitivity by labeling and detecting all exchangeable sites. This is in contrast to homonuclear multiple pulse decoupling sequences that are applied during detection and that compromise sensitivity because of the requirement of sampling between pulses. As a result 1H detection provides a gain in sensitivity of >5 compared to the 15N detected version of the experiment (at a MAS frequency of 13.5kHz). The pulse schemes make use of the favorable dispersion of the amide 15Ns resonances in the protein backbone. The experiments are demonstrated on a sample of the uniformly 2H,15N-labeled dipeptide N-Ac-Val-Leu-OH and are analogous to the solution-state suite of HSQC-NOESY experiments. In this compound the 1H amide linewidths at 750MHz vary from approximately 0.67 ppm at omega(r)/2pi approximately 5kHz to approximately 0.20 ppm at omega(r)/2pi approximately 30kHz, indicating that useful resolution is available in the 1H spectrum via this approach. Since the experiments circumvent the problem of dipolar truncation in the 1H-1H spin system, they should make it possible to measure long-range distances in a uniformly labeled environment. Thus, we expect the experiments to be useful in constraining the global fold of a protein. 相似文献
16.
We examine the smoothness properties of the principal curvatures of subdivision surfaces near irregular points. In particular we give an estimate of their L
p
class based on the eigenstructure of the subdivision matrix. As a result we can show that the popular Loop and Catmull–Clark schemes (among many others) have square integrable principal curvatures enabling their use as shape functions in FEM treatments of the thin shell equations. 相似文献
17.
Reif B Jaroniec CP Rienstra CM Hohwy M Griffin RG 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2001,151(2):320-327
In this Communication, we demonstrate the use of deuteration together with back substitution of exchangeable protons as a means of attenuating the strong 1H-1H couplings that broaden 1H magic angle spinning (MAS) spectra of solids. The approach facilitates 15N-1H correlation experiments as well as experiments for the measurement of 1H-1H distances. The distance measurement relies on the excellent resolution in the 1H MAS spectrum and homonuclear double quantum recoupling techniques. The 1H-1H dipolar recoupling can be analyzed in an analytical fashion by fitting the data to a 2- or 3-spin system. The experiments are performed on a sample of the dipeptide N-Ac-Val-Leu-OH, which was synthesized from uniformly [2H, 15N] labeled materials and back-exchanged in H2O. 相似文献
18.
An ultrafast transient refractive index grating, produced in barium fluoride, a material with positive dispersion, promotes
very efficient third harmonic generation. The significant enhancement of the generation up to a conversion efficiency of about
3% is due to self phase matching, involving the instantaneous grating. At the same time several diffraction orders of the
third harmonic signal are observed behind the sample.
Received: 17 October 2000 / Published online: 21 February 2001 相似文献
19.
20.
M. Schade O. Varlamova J. Reif H. Blumtritt W. Erfurth H. S. Leipner 《Analytical and bioanalytical chemistry》2010,396(5):1905-1911
We report on the structural investigation of self-organized periodic microstructures (ripples) generated in Si(100) targets
after multishot irradiation by approximately 100-fs to 800-nm laser pulses at intensities near the single shot ablation threshold.
Inspection by surface sensitive microscopy, e.g., atomic force microscopy (AFM) or scanning electron microscopy (SEM), and
conventional and high-resolution transmission electron microscopy reveal complex structural modifications upon interaction
with the laser: even well outside the ablated area, the target surface exhibits fine ripple-like undulations, consisting of
alternating crystalline and amorphous silicon. Inside the heavily modified area, amorphous silicon is found only in the valleys
but not on the crests which, instead, consist of highly distorted crystalline phases, rich in defects. 相似文献