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81.
MRI-negative rotator cuff tears 总被引:2,自引:0,他引:2
We report two cases of rotator cuff tear in which the T(2)-weighted MRI signal was negative at the first examination, but positive by the second examination without any changes in symptoms. Many authors have reported on correlations between the MRI and operative findings of rotator cuff tears. However, MRI findings, history of symptoms and operative findings in our patients suggest that there was a discrepancy between symptoms and MRI findings dependent on the period from the injury. Operative findings also indicate that intratendinous tears might have occurred first in these patients then progressed to partial or full thickness tears over time. We concluded that physicians should keep rotator cuff pathology in mind even in patients whose MRI findings are negative but symptoms of rotator cuff tear persist. 相似文献
82.
Masaru Sumida 《Experiments in fluids》2007,43(6):949-958
This paper presents the results of an experimental study on the developing pulsatile flow in curved pipes with a long, straight
pipe upstream. In order to examine the dependence of flow-field development on the governing parameters, LDV measurements
were conducted systematically for six cases of flow, where the Womersley number α was varied from 5.5 to 18, the mean Dean number D
m
was 200 and 300, the flow rate ratio η was 0.5 and 1, and the curvature radius ratio Rc was 10 and 30. Peculiar flow phenomena, such as flow reversal for all values of α and a depression in the axial velocity profile for α = 10, were analyzed by decomposing the axial velocity into a time-mean and a varying component, as well as by obtaining the
bias of their profiles. The velocity distributions abruptly change with the phase at turn angles Ω of 15–30°, corresponding to the nondimensional axial length z′ ≅ 1–2 from the bend entrance, and their development along the pipe axis is the most complicated for the flow at a moderate
α of 10 and large η of 1. The entrance length in the case of pulsatile flow is shorter than that for steady flow with the same flow rate as the
maximum pulsatile flow rate. 相似文献
83.
Hayashi M Matsuura Y Nishimura Y Yamasaki T Imai Y Watanabe Y 《The Journal of organic chemistry》2007,72(20):7798-7800
Triethylaluminum-catalyzed/mediated addition of a silylphosphine to aldehydes and epoxides is described. Organophosphines containing a silyloxy group at the alpha- or beta-position on the alkyl substituent are successfully prepared in good yields. 相似文献
84.
85.
The steady, developing turbulent flow in a circular-sectioned 180° bend has been investigated. The bend had a radius of 104 mm
and a curvature radius ratio of 4.0 with long, straight upstream and downstream pipes. Measurements of the longitudinal, radial
and circumferential components of mean velocity, and corresponding components of the Reynolds stress were obtained with a
hot wire anemometer at a Reynolds number of 6×104 and at various longitudinal stations. The velocity fields of the primary and secondary flows and the Reynolds stresses were
illustrated in the form of contour map or vector diagram. Moreover, the mean quantities characterizing the bend flow, i.e.,
the deflection of the primary flow in the cross section, the intensity of the secondary flow and the turbulence energy, were
shown in a graphic form against the longitudinal distances. In the section upstream from a bend angle of about 60°, both the
flows through the 180° and the 90° bend are closely similar in their behavior. In the section from the bend angle of 90°,
the high-velocity regions, however, occur near the upper and lower walls as a result of strong secondary flow and the turbulence
with high level emerges in the central region of the bend. Just behind the bend exit, an additional pair of vortices appears
in the outer part of the cross section owing to the transverse pressure difference. In the downstream tangent, the flow returns
slowly to the proper flow in a straight pipe, but it needs a longer distance for recovery than in the 90° bend.
Received: 23 April 1998/Accepted: 24 April 1999 相似文献
86.
Taishi Uchida Dr. Yasunobu Egawa Takuto Adachi Naoki Oguri Masato Kobayashi Prof. Dr. Takako Kudo Prof. Dr. Nobuhiro Takeda Prof. Dr. Masafumi Unno Dr. Ryoji Tanaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(7):1683-1686
Symmetric and asymmetric (Janus-type) new “lantern cage” siloxanes (PhSiO1.5)4(Me2SiO)4(RSiO1.5)4 (R=Ph or iBu) were synthesized through reaction of all-cis-[PhSi(OSiMe2Br)O]4 with all-cis-[RSi(OH)O]4 (R=Ph or iBu). These precursors were obtained by facile two or three-step reactions from commercially available compounds. The spectroscopic properties of the resulting products were fully characterized and they showed high thermal stability and sublimation without decomposition. The crystal structures clearly indicated that the internal vacancy volumes of the lantern cages are considerably larger than that of octaphenylsilsesquioxane (PhSiO1.5)8. DFT calculations of the lantern cage showed a distinctly different electronic state from that of octasilsesquioxane. These results suggest that lantern cage siloxanes have a characteristic “field” in the molecule. 相似文献
87.
Total Synthesis of the 7,10‐Epimer of the Proposed Structure of Amphidinolide N,Part I: Synthesis of the C1–C13 Subunit
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Dr. Koji Ochiai Dr. Sankar Kuppusamy Yusuke Yasui Tsubasa Okano Yasunobu Matsumoto Dr. Nishant R. Gupta Dr. Yohei Takahashi Prof. Dr. Takaaki Kubota Prof. Dr. Jun'ichi Kobayashi Prof. Dr. Yujiro Hayashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(10):3282-3286
Amphidinolide N, the structure of which has been recently revised, is a 26‐membered macrolide featuring allyl epoxide and tetrahydropyran moieties with 13 chiral centers. Due to its challenging structure and extraordinary potent cytotoxicity, amphidinolide N is a highly attractive target of total synthesis. During our total synthesis studies of the 7,10‐epimer of the proposed structure of amphidinolide N, we have synthesized the C1–C13 subunit enantio‐ and diastereoselectively. Key reactions include an l ‐proline catalyzed enantioselective intramolecular aldol reaction, Evans aldol reaction, Sharpless asymmetric epoxidation and Tamao–Fleming oxidation. To aid late‐stage manipulations, we also developed the 4‐(N‐benzyloxycarbonyl‐N‐methylamino)butyryl group as a novel ester protective group for the C9 alcohol. 相似文献
88.
89.
Yasunobu Iwasaka 《中国颗粒学报》2003,1(5):201-205
1. Introduction The number concentration and size distribution of at-mospheric particles are the two major parameters for aerosol radiative forcing calculation, as the aerosol bur-dens affect the radiative transfer of solar and terrestrial emissions, while the size distribution of atmospheric aerosol is critical to all climatic influences (IPCC, 2001). However most measurements on the characteristics of the number-size distribution were carried out near the earth surface, with only a few exte… 相似文献
90.
Chemical and Electrochemical reductions of bisdehydro[14]- and [18]annu1ened1ones clearly revealed their quinonoid nature. 相似文献