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排序方式: 共有891条查询结果,搜索用时 187 毫秒
101.
102.
H Kagawa Y Komiyama S Nakamura T Miyake Y Miyazaki K Hamamoto M Masuda H Takahashi S Nomura S Fukuhara 《Canadian Metallurgical Quarterly》1998,91(6):297-304
An autopsy case of Sj?gren-Larsson syndrome (SLS), an 8-year-old boy, is presented with neuropathological investigations. Widespread deposition of 2 different types of unusual substances, stained lightly or strongly with periodic acid Schiff (PAS) was most conspicuous in this case. The first type of them, lightly stained with PAS at room temperature, was widely distributed in the central nervous system (CNS): the white matter of cerebrum and brainstem, subpial and subependymal glial layers, subpial space, perivascular space of small blood vessels, and their adjacent nervous tissue. The second type, strongly stained with PAS, small round or ellipsoid bodies, was found in the subpial, subependymal and perivascular glial layers. The first type of PAS-positive substances might be fatty alcohols or their metabolites, and the second type, some degraded products of lipids in astrocytic processes. Lipofuscin-like substances were accumulated in perivascular macrophages located around small blood vessels. Spheroid bodies (axonal swellings) were frequently observed in relay nuclei: lateral geniculate body (LGB), pontine nuclei, inferior olivary nuclei, posterior funicular nuclei, or cerebellar dentate nuclei. A lot of PAS-positive fine granules were contained in a spheroid body of LGB. Scarcity of myelinated nerve fibers was recognized in the cerebral and cerebellar white matter and the corticospinal tracts of spinal cord. Focal cortical dysgenesis, resembling that of unlayered polymicrogyria, was observed in bilateral insular cortices. Further histochemical studies are needed to explore the exact pathogenesis, but widespread deposition of PAS-positive substances in CNS may support the supposition that SLS is one of congenital errors of lipid metabolism. 相似文献
103.
Recent studies indicate that centrally released arginine vasopressin (AVP) facilitates brain water permeability in normal and pathological conditions. The effects of central administration of arginine vasopressin (AVP) receptor antagonists on vasogenic brain edema were studied in rats. V1 or V2 receptor antagonists were stereotactically injected into the lateral ventricle 10 min prior to or 1 h after cold brain injury. The injury resulted in significant increases in the mean water content of the lesion and the contralateral hemispheres by 1.15 and 0.38%, respectively. Twenty-four hours after injury, the brain water and sodium contents, the brain swelling, and plasma osmolality were measured. V1 receptor antagonist of 50 ng significantly decreased the brain water and sodium contents and the brain swelling in the adjacent cortex of the lesion without changes in serum osmolality. On the other hand, 5 ng of V1 receptor antagonist and V2 receptor antagonist had no effect on edema. The V1 receptor of AVP is thought to act predominantly on water permeability of the brain. Peptide therapy may become an additional tool for brain edema treatment. 相似文献
104.
Takayuki Tomaru Shinji Miyoki Masatake Ohashi Kazuaki Kuroda Takashi Uchiyama Toshikazu Suzuki Akira Yamamoto Takakazu Shintomi Akitoshi Ueda Daisuke Tatsumi Shuichi Sato Koji Arai Masaki Ando Koji Watanabe Kenji Nakamura Masahiko Watanabe Kazuhiko Ito Izumi Kataoka Hiroaki Yamamoto Brett Bochner Yaron Hefetz 《Applied optics》2003,42(7):1306-1307
105.
Takashi Hirano Yuiko Kazahaya Akio Nakamura Toshihiro Miyao Shuichi Naito 《Catalysis Letters》2007,117(1-2):73-78
The effect of addition of In and Pb on the reduction of N2O by CO was studied over SiO2 supported Pd catalysts, using a closed gas circulation system as well as in-situ infrared spectroscopy. Formation of intermetallic
compounds such as Pd0.48In0.52, Pd3Pb and Pd3Pb2 was observed which caused a drastic enhancement of the rate of N2 formation. The infrared spectroscopic analyses revealed a weakening of the adsorption strength of CO on Pd metal by the formation
of intermetallic compounds, which is likely the main reason for the enhancement of the reaction rate. From a kinetic investigation
as well as in situ FT-IR observation during the N2O-CO reaction, a redox mechanism was proposed involving the oxidation of the surface by N2O followed by its reduction by CO. Over Pd/SiO2, the former process seems to be the rate limiting step because of the inhibition of N2O activation by strongly adsorbed CO. By adding In or Pb, the rate limiting step shifted to the latter process, which resulted
in a large enhancement in the rate of N2 formation. 相似文献
106.
Takao Yamamoto Shuichi Okuda Masatoshi Fujishiro 《Journal of Nuclear Materials》1988,160(2-3):247-252
A thin titanium layer with uniformly absorbed tritium (T/Ti ˜1.0) was bombarded by 390 keV D3+ ions (130 keV per deuteron). Bombardment was performed at low (111 K) and room temperatures up to fluences of 5.9 × 1018 D/cm2 and 3.0 × 1018 D/cm2, respectively. Depth profiles of tritium up to a depth of 0.8 mg/cm2 (˜1.8 μm) were measured and the change of the profile with fluence was investigated by means of the T(d, )n nuclear reaction. At both of the temperatures, a dip was formed on the depth profile of tritium at the depth around the projected range, indicating that the deuteron bombardment induced the migration of tritium against the concentration gradient. At the low temperature, the dip showed a gradual growth with fluence and saturation of the growth at the higher fluences, which could not be described by the existing model for isotope mixing. The spectrum of protons from the D(d, p)T reaction obtained in the same measurement suggested that the release of deuterium suddenly started at the final stage of the present bombardment. The dip formed at room temperature was larger than that at the low temperature. The migration of tritium induced by the bombardment is discussed on the basis of the experimental results obtained. 相似文献
107.
Y Nonaka T Fujii N Kagawa MR Waterman H Takemori M Okamoto 《Canadian Metallurgical Quarterly》1998,258(2):869-878
Dahl's salt-resistant normotensive rats (DR rats) have been previously reported to express cytochrome P-450 (CYP11B1) containing five missense mutations [Matsukawa, N., Nonaka, Y., Higaki, J., Nagano, M., Mikami H., Ogihara, T. & Okamoto, M. (1993) J. Biol. Chem. 268, 9117-9121]. To investigate structure-function relationships of CYP11B, wild-type rat CYP11B1 and CYP11B2 and DR-CYP11B1 (mutant CYP11B1 in Dahl's salt-resistant rats) have been successfully expressed in Escherichia coli. Steroid 11beta-hydroxylase (11beta-OHase) activity observed with DR-CYP11B1 was similar to that of wild-type CYP11B1, while 18-hydroxylase (18-OHase) activity of DR-CYP11B1 was lower than that of wild-type CYP11B1. Mutant CYP11B1s containing a single or a double amino acid substitution associated with DR-CYP11B1 have been also expressed in E. coli to investigate effects of the substitutions on enzymatic activity. Each of the single mutant enzymes showed lower 18-OHase activity than wild-type CYP11B1, but not as low as DR-CYP11B1. A double mutant CYP11B1 with V381L and I384L showed 18-OHase activity at a similar low level to that of DR-CYP11B1. The 19-hydroxylation (19-OHase) activity of DR-CYP11B1 was about one-third of that of the wild-type enzyme and this low activity appeared due to the V443M mutation. These results suggest that three of five amino acid substitutions present in DR-CYP11B1 account for the decreased 18-OHase and 19-OHase activities. A decrease in these enzyme activities may be responsible for the normotension of the DR rats when fed a high-salt diet. 相似文献
108.
Shunichi Hasegawa Takahiro Nishiwaki Hitoe Habuchi Shoji Nitta Shuichi Nonomura 《Fullerenes, Nanotubes and Carbon Nanostructures》1995,3(2):163-178
CPM spectra of the fullerene film was measured to obtain the below gap absorption. The optical energy gap Eo was obtained by using the Tauc's plots. Eo did not change so much with the intercalated impurities. The absorption due to intercalated impurities was found below 1.6eV. 相似文献
109.
110.
The basic characteristics and charge storage behavior of metal-alumina-silicon dioxide-silicon(MAOS) field effect transistors have been investigated as a function of the oxide thickness. The typical charge storage behaviors have also been measured on devices with SiO2 films of 50 Å and Al2O3 films of 700 Å and the results are interpreted in terms of electron and hole transport processes across thin SiO2 layer and electron injection from Al electrode by tunneling mechanism. In the MAOS structure, the shift of threshold voltage from initial state is within about 23 V and can be reversibly controlled, more than 106-times at least, by alternate electric fields under suitable stressing condition. It is considered that the charge storage time is practically infinite at room temperature and of the order of 106 hr at 150°C. The failure behaviors of device parameters under the repeated field stressing and cycles can be also accounted for in terms of electron accumulation within Al2O3 films and at interfaces between Al2O3 and SiO2 films. 相似文献