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111.
Szyczewski A Hołderna-Natkaniec K Natkaniec I 《Solid state nuclear magnetic resonance》2004,25(1-3):21-27
Internal dynamics of 17- and 21-substituted progesterone derivatives was studied by the methods NMR, inelastic incoherent neutron scattering (IINS) and quantum chemical calculations. Comparison of the computer simulation of the phonon density of states (PDS) spectrum performed by the density functional theory (DFT) method with the spectrum obtained after a transformation of the experimental results permits an interpretation of subsequent modes. Only for 17OH prg the second moment of NMR line decreases to 10 G2 near room temperature, most probably because of the oscillations about direction of inter-molecular hydrogen bond. Significant mobility of protons in this compound is also confirmed by a low intensity of the elastic peak in INS and broadening of this spectrum. 相似文献
112.
Weglarz WP Tanasiewicz M Kupka T Skórka T Sułek Z Jasiński A 《Solid state nuclear magnetic resonance》2004,25(1-3):84-87
A 3D spin-echo (3D SE) pulse sequence was used on a 4.7 T research MRI system to produce images of extracted human first molar tooth placed in CuSO4 water solution. The maximal resolution achieved was 35 x 63 x 300 microm3 in read and two phase directions, respectively. The high-intensity signal from water in solution together with the lack of signal from mineralized tooth tissue produce very good contrast allowing to visualize topography of outer and inner surfaces of the tooth. The 3D MR data were median filtered, binarized and then divided into separate segments corresponding to the inner tooth cavities and the hard tooth tissue. The topography of the root canals was visualized and the canals volume was calculated. The presented technique may be used for quantitative analysis of the root canal cavities shape and volume. The results of such an analysis may be applied for estimation of the quality of the impressional mapping methods in restorative dentistry or as an alternative non-impressional 3D mapping method. 相似文献
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Krzysztof Bartkowski Maria Dimitrova Prof. Piotr J. Chmielewski Prof. Dage Sundholm Dr. Miłosz Pawlicki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(68):15477-15482
Understanding of the aromatic properties and magnetically induced current densities of highly conjugated chromophores is important when designing molecules with strongly delocalized electronic structure. Linear extension of the triphyrin(2.1.1) skeleton with an annelated benzo[b]heterocycle fragment modifies the aromatic character by extending the electron delocalization pathway. Two-electron reduction leads to an antiaromatic triphyrin(2.1.1) ring and an aromatic benzo[b]heterocycle subunit. Current-density calculations provide detailed information about the observed pathways and their strengths. 相似文献
116.
Structural Chemistry - It is obvious and well known that the hydrogen bond plays a crucial role in numerous physical, chemical and biochemical processes. However, the significance of other... 相似文献
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Majchrzak-Kucęba Izabela Ściubidło Aleksandra 《Journal of Thermal Analysis and Calorimetry》2019,138(6):4139-4144
Journal of Thermal Analysis and Calorimetry - The paper presents the effect of the tabletting pressure and time on the chemical structure and crystallinity of the CuBTC and MIL-53(Al)... 相似文献
118.
Gidlewski Mirosław Prochowski Leon Jemioł Leszek Żardecki Dariusz 《Nonlinear dynamics》2019,97(3):1877-1893
Nonlinear Dynamics - The reconstruction of a road accident can be treated as the resolution of an “inverse problem” in mechanics using analytical or numerical models. In the road... 相似文献
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Nonlinear Dynamics - We present a model—a modified standard map. This model has interesting properties that allow quantum–classical correspondences to be studied. For some range of... 相似文献
120.
Martowicz Adam Bryła Jakub Staszewski Wieslaw J. Ruzzene Massimo Uhl Tadeusz 《Nonlinear dynamics》2019,97(3):1911-1935
Nonlinear Dynamics - The work is primarily devoted to the peridynamic model elaborated for a solid body made of shape memory alloys (SMAs). The superelasticity effect is taken into consideration as... 相似文献