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991.
992.
Masahiro Tanabe Katsuyoshi Ito Ayame Shimizu Takeshi Fujita Hideko Onoda Shigenari Yamatogi Yasuo Washida Naofumi Matsunaga 《Magnetic resonance imaging》2009
Purpose
The aim of this study was to determine the adequate MR sequence for the lesion conspicuity of hepatocellular lesions with increased iron uptake on superparamagnetic iron oxide (SPIO)-enhanced MRI.Materials and Methods
SPIO-enhanced MRI was performed using a 1.5-T system. Among 25 patients with hypovascular hepatocellular nodules on contrast-enhanced dynamic CT (no early enhancement at arterial phase and hypoattenuation at equilibrium phase), 39 lesions with increased iron uptake on SPIO-enhanced MRI were evaluated. SPIO-enhanced MRI included (1) T1-weighted in-phase gradient recalled echo (GRE) images, (2) T2-weighted fast spin echo (FSE) images, (3) T2*-weighted GRE with moderate TE (7 ms) and (4) long TE (12 ms). The lesion-to-liver contrast-to-noise ratios of the hepatocellular nodule and the signal-to-noise ratio (SNR) of the hepatic parenchyma were calculated by one radiologist for a quantitative assessment. MR images were reviewed retrospectively by two independent radiologists to compare the subjective lesion conspicuity in each image set based on a four-point rating scale.Result
The mean lesion-to-liver contrast-to-noise ratios with T2*-weighted GRE with moderate TE (7 ms) was highest (5.79±3.71) and was significantly higher than those with T1-weighted, in-phase images (3.79±3.23, P<.01), T2-weighted images (2.72±1.52, P<.001) and T2*-weighted GRE with long TE (12 ms) (3.93±2.69, P<.05). The subjective rating of lesion conspicuity was best on the T2*-weighted GRE with moderate TE (7 ms), followed by that on the T2*-weighted GRE with moderate TE (7 ms; P<.05).Conclusion
T2*-weighted GRE sequence with moderate TE (7 ms) showed high lesion-to-liver contrast-to-noise ratios in hepatocellular lesions with increased iron uptake on SPIO-enhanced MRI, indicating better lesion conspicuity of hypointense hepatocellular nodules in cirrhosis or chronic hepatitis. 相似文献993.
Haruko Takechi Yasuo Goto Hajime Takahashi Minoru Machida 《Journal of heterocyclic chemistry》2001,38(2):333-338
4‐(7‐Diethylaminocoumarin‐3‐yl)benzeneisocyanate (DACB‐NCO) was synthesized as a new fluorescent derivatization reagent for alcohols for use in high‐performance liquid chromatography (hplc). Saturated alcohols (C6‐C22) were derivatized in good yields into the corresponding fluorescent DACB‐carbamic esters by treating with DACB‐NCO. The DACB‐carbamic esters of these alcohols were clearly separated on a reversed‐phase hplc column (Inertsil ODS‐2, mobile phase: methanol‐water, excitation wavelength 402 nm; emission wavelength 488 nm). The detection limit (S/N = 3) of cetyl alcohol, as a test compound, was 5 fmol/10 μl. 相似文献
994.
Yasuo Ohta Matsumi Doe Yoshiki Morimoto Takamasa Kinoshita 《Journal of heterocyclic chemistry》2000,37(4):751-755
The Birch reduction of 2‐ and 5‐acylfuran‐3‐carboxylic acid 1 and 4 gave 2‐acyl‐2,3‐dihydrofuran‐3‐carboxylic acid 2 and 5‐acyltetrahydrofuran‐3‐carboxylic acid 5 , respectively. Further examination of the reductive elimination was also studied on 2‐(arylmethoxymethyl)furan‐3‐carboxylic acids 7. 相似文献
995.
Wakayama Tatsuki Nakada Eiju Asada Yasuo Miyake Jun 《Applied biochemistry and biotechnology》2000,84(1-9):431-440
Hydrogen production by photosynthetic bacteria provides an efficient energy conversion method under low light intensity. However,
under strong illumination, such as midday sunlight, the efficiency drops. This prevents the method from being applied industrially.
To overcome this problem, we examined a method to thin out the excessive illumination. Light was given intermittently to reduce
the total energy flux. The on/off ratio was set at 1/1 throughout the study, so that the time average of the light energy
flux became half the continuous illumination. By keeping the time-average light flux constant (0.6 kW·m−2), the effects of the cycle period were examined in the range of hours to seconds. The hydrogen production rate was greatly
affected by the cycle period, but cell growth and substrate consumption rates remained almost constant. The 30-min light/dark
cycle (30 min on and 30 min off) provided the highest rate of hydrogen production (22 L·m−2·24 h−1). At the shorter cycles, the rate decreased except that there was a suboptimum at about 40 s. Under excessive light intensity
(1.2 kW·m−2), the light-to-hydrogen conversion efficiency was greatly enhanced. The hydrogen production rate during the 30-min cycle
was twice as high as during a 12-h cycle under the same conditions. 相似文献
996.
Examples of isotropic Kähler manifolds (i.e., J2=0) which are neither complex nor symplectic, and therefore not indefinite Kähler, are constructed. 相似文献
997.
A new sesquiterpene, named baccharisketone (1), and a new monoterpene, p-methoxythymol acetate (2), were isolated from the leaves of Baccharis dracunculifolia along with seventeen known compounds (3-19). The structures of the new compounds were determined by spectroscopic means. The growth inhibitory activity of the isolated compounds against leukemia cells (L 1210) was tested and three terpene phenols (4, 6, 17) and five sesquiterpene alcohols (8, 10, 11, 13, 16) were found to exhibit strong cytotoxic activity. 相似文献
998.
This paper presents an analytical method for minimum cost design of regular rectangular building frames for constrained elastic compliance. The method, consisting of a semi-inverse method and a design region extension procedure, is illustrated by two classes of exact solutions. It is shown that the relative story displacements are almost uniformly distributed in an optimally designed frame with almost uniform story heights and that the solutions enable one to calculate all maximum member-end stresses from member-end curvatures. It is suggested that the proposed design formulas may be utilized for design problems, subject to relative story displacement and stress constraints. Since these solutions are shown to be dependent upon the nature of the prescribed minimum stiffnesses, a method of finding a practically reasonable set of minimum stiffnesses is also presented. 相似文献
999.
1000.
Yasuo Teranishi 《Discrete Mathematics》2002,257(1):183-189