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排序方式: 共有374条查询结果,搜索用时 15 毫秒
91.
92.
M Martínez Ferro R Milner L Voto J Zapaterio C Cannizzaro S Rodríguez G Bonifacino JM Sanchez NS Adzick 《Canadian Metallurgical Quarterly》1998,13(6):343-347
Studying the electrophysiological characteristics of the various types of Charcot-Marie-Tooth disease is important in the understanding of its pathophysiology. The purpose of this study was to identify the frequency of fibrillation potentials and positive sharp waves (FP/PWs) in HMSN I and II and, since they are indices of denervation, to elucidate whether they are correlated with the amplitude of compound muscle action potentials (CMAP). We reviewed the electrophysiological findings of 47 patients who have been studied in our hospital and found to suffer from Charcot-Marie-Tooth polyneuropathy. FP/PW were graded according to a 4-grade scale and the 38 m/sec criterion for motor conduction velocity (MCV) was used for distinction between HMSN I and II subgroups. Seventy percent of HMSN II patients and 81% of HMSN I patients showed fibrillation potentials in the upper or lower limbs. There was no difference in the frequency of FP/PW appearance between the two groups. In the HMSN II group the FP/PW grade correlated with CMAP amplitude in the upper limbs. In both groups there was no correlation between FP/PW grade and MCV. Our findings might indicate that in HMSN I there is a considerable axonal destruction that occurs concurrently with myelin loss. 相似文献
93.
L Iuliano D Praticò D Ferro V Pittoni G Valesini J Lawson GA FitzGerald F Violi 《Canadian Metallurgical Quarterly》1997,90(10):3931-3935
The mechanism leading to the formation of antiphospholipid antibodies (aPL) is still unknown. Because an in vitro study suggested that aPL may derive from pro-oxidant conditions, we sought a relationship between aPL and isoprostanes, indices of lipid peroxidation in vivo. Thirty patients with systemic lupus erythematosus have been studied. Seventeen (56.6%) were positive for aPL because they had lupus anticoagulant and/or high titer of anticardiolipin antibodies (aCL). Plasma levels of tumor necrosis factor (TNF ) and urinary excretion of two isoprostanes, 8-epi-PGF2alpha and IPF2alpha -I, free radical catalyzed oxidation products of arachidonic acid, were measured. Patients with systemic lupus erythematosus had higher urinary excretion of 8-epi-PGF2alpha and IPF2alpha -I than controls; urinary excretion of the two isoprostanes was highly correlated (Rho = 0.74, P < .0001). Urinary 8-epi-PGF2alpha was highly correlated with both aCL titer (Rho = 0. 70, P < .0001) and TNF (Rho = 0.84, P < .0001), a measure of disease severity. Excretion of this isoprostane was also higher in those patients who exhibited aPL (P < .0001). Comparable correlations were observed with the isoprostane IPF2alpha -I. No difference of 8-epi-PGF2alpha was observed between patients with and without previous history of thrombosis. This study, showing the existence of a close association between aPL and increased in vivo lipid peroxidation, supports the hypothesis that these antibodies may result from pro-oxidative conditions and suggests that inflammation may play an important role. 相似文献
94.
The epidemiologic factors are studied in 584 cases of Hypertonic Dehydration (H.D.) admitted to the Children's Clinic "La Paz" over a period of 5 years. The overall monthly mean (MMT) resulted in 9.75 children a month with a standard deviation of +/- 2.1. The overall monthly evolution is analysed according to the sex, the seasonal incidence, as well as the more relevant etiologic factors: Concentrated diet, diarrhoea, vomiting, respiratory pathology and fever. The epidemiologic peculiarities are discussed according to age. 相似文献
95.
Francesca Licci Giuseppe Turilli Patrizia Ferro Antonio Ciccarone 《Journal of the American Ceramic Society》2003,86(3):413-419
LaMn1− y 3+ Mn y 4+ O3±d and La0.67 R0.33 Mn1− y 3+ Mn y 4+ O3±d (R = Ca, Sr, Ba) phases were synthesized at 350°C by using very reactive, amorphous precursors obtained from the stoichiometric citrate solutions. The chemical process was optimized with respect to the solution concentration, pH, and additives. The precursor reactions were investigated as a function of the cation stoichiometry and the additive by simultaneous thermal and thermogravimetric analysis and X-ray diffraction. The reaction pathway was found to be independent of the cation stoichiometry, but related to the acid or base additive. The annealing temperature was systematically increased in the 350–1200°C interval and the La0.67 Sr0.33 MnO3±d properties (i.e., crystal sizes, Mn average valence, Curie temperature, magnetization, magnetic susceptibility) were measured and found to vary consistently as a function of it. 相似文献
96.
M.A. Quiroz S. Reyna C.A. Martínez-Huitle S. Ferro A. De Battisti 《Applied catalysis. B, Environmental》2005,59(3-4):259-266
In this work, the elimination of p-nitrophenol (p-NPh) from aqueous solutions by electrochemical oxidation at Pb/PbO2 anodes was investigated. The process was studied under galvanostatic polarization mode in acidic and alkaline media, as a function of the temperature (20, 40 and 60 °C) and of the anodic current density (J = 10, 20 and 30 mA cm−2). In acidic media (0.5 M H2SO4), the oxidation process allowed a 94% p-NPh conversion in 7 h, at 20 °C and with J = 20 mA cm−2, with a wide distribution of degradation products (in particular: 39% p-benzoquinone and 26% hydroquinone, as given by a mass balance at the above electrolysis time). Under these conditions, the current efficiency for the substrate oxidation was 15.4% ([Ah L−1]exp = 7 versus [Ah L−1]theo = 1.08 Ah L−1). In alkaline media (0.1 M NaOH, pH 8.5), the most effective p-NPh elimination (97%) was obtained at 60 °C, 20 mA cm−2 and 420 min of electrolysis time, again with the production of p-benzoquinone and hydroquinone (52.7 and 15.1%, respectively). Under the latter conditions, an almost complete chemical oxygen demand (COD) abatement was attained, with a high level of p-NPh mineralization (>80%), a yield of p-NPh conversion greater than 95% and a scarce formation of aliphatic acids (most probably maleic acid). From the degradation curves ([p-NPh] versus t), in both acidic and alkaline media, the UV analyses and/or COD measurements, a complete oxidation of aliphatic acids to form CO2 could be predicted for electrolysis time >420 min, according to a suggested oxidation pathway. 相似文献
97.
An investigation of the beneficial effects of adding carbon nanotubes to standard injection grout
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L. Restuccia A. Lopez G.A. Ferro D. Liberatore J.M. Tulliani 《Fatigue & Fracture of Engineering Materials & Structures》2018,41(1):119-128
Mortar grouting is often used in masonry constructions to mitigate structural decay and repair damage by filling cracks and voids, resulting in an improvement in mechanical properties. This paper presents an original experimental investigation on grout with added carbon nanotubes (CNTs). The samples were prepared with different percentages of CNTs, up to 1.2 wt% with respect to the binder, and underwent three‐point bending tests in crack mouth opening displacement mode and compressive tests. The results showed that very small additions (up to 0.12 wt% of CNTs) increased not only flexural and compressive strengths (+73% and 35%, respectively, in comparison with plain mortar) but also fracture energy (+80%). These results can be explained on the basis of a reduction in porosity, as evidenced by mercury intrusion porosimetry, as well as by a crack bridging mechanism and by the probable formation of nucleation sites for hydration products, as observed through scanning electron microscopy. 相似文献
98.
Battaglia E. Bonollo F. Ferro P. Fabrizi A. 《Metallurgical and Materials Transactions A》2018,49(5):1631-1640
Metallurgical and Materials Transactions A - High-pressure die castings (HPDCs) cannot normally be heat-treated at a high temperature because of the presence of inner air/gas- or shrinkage-porosity... 相似文献
99.
G. De Maria D. Ferro L. D'Alessio R. Teghil S. M. Barinov 《Journal of Materials Science》2001,36(4):929-935
Hardness of titanium carbide films deposited on silicon (111) substrate by pulsed laser ablation is evaluated in dependence on laser beam fluence and the film thickness. Measurements were performed with the use of a common microhardness testing equipment, the indenter penetartion depth being more than thickness of the coating. Two methods based both on a law-of-mixtures approach were employed to calculate the film hardness from the measured hardness of the composite film-substrate system. One of them accounts for the indentation size effect. The hardness is revealed to reduce significantly with an increase of the film thickness and the laser beam fluence. 相似文献
100.
Ghazaleh Afsahi Estefania Isaza Ferro Kyösti Ruuttunen Tapani Vuorinen 《木材化学与工艺学杂志》2019,39(3):178-186
Contemporary multi-stage bleaching processes partially remove residual lignin and hexenuronic acid from cellulosic pulps. The reactions in the steps could be faster and consume smaller amounts of chemicals. Catalytic bleaching (Hcat), utilizing hypochlorite (H), triethylenediamine (DABCO) and its derivative N-carboxymethyl triethylenediamine (CM-DABCO), is a new discovery that has the potential to improve the chemical and energetic efficiency of bleaching processes in chemical pulp mills, e.g. through reducing the reaction time of the bleaching processes. The objective of this study was to clarify if new kraft pulp bleaching sequences with initial stage of chlorine dioxide (ClO2; D) and an intermediate stage of Hcat could provide fully bleached pulps. The bleaching sequences of the studied eucalyptus pulps include D0E(OP)Hcat(Q)P and HcatZ/DP, which attained a final brightness of 88 and 89% ISO, respectively. HcatZ/DP showed to be the best sequence for the catalytic bleaching of eucalyptus kraft pulps. This study may open new doors to future bleaching of cellulose pulps with fewer towers and decreased use of chemicals. 相似文献