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排序方式: 共有1460条查询结果,搜索用时 15 毫秒
151.
E. Ferrari A. Pareschi A. Regattieri A. Persona 《The International Journal of Advanced Manufacturing Technology》2003,21(12):917-922
Markets are affected by strong competition in terms of continuous innovation of products and processes, high customer satisfaction and low cost of production. In order to achieve these strategic results it is recommended, or necessary, to rectify lack of organisation. For instance, the increasing costs due to material handling, force factories to check the facility layout and, when necessary, to improve it. The evaluation of a prospective improvement requires a large effort and a well-established skill. The study and the optimisation of plant layout is a strategic activity. This paper represents the last step of a research program on the automatic design of plant layout. The aim is to support the design activity of plant layout by means of an integrated approach, taking into account many criteria, both quantitative and qualitative. In particular, this paper presents a global approach, based on material flow and activity relationships. It is carried out using new software, called LRP (layout and re-layout program), introduced by the authors. A real application in a factory, specialising in the production of electronic devices, is presented. 相似文献
152.
The effect of cocaine (7.5, 15 and 30 mg/kg) administered in acute or subchronic mode, on the mating behaviour of sexually active male rats varied in a dose- and mode-dependent manner. Regardless of mode of treatment, 30 mg/kg markedly impaired the rats copulatory ability and impairment continued for a week after suspension of subchronic treatment. An acute dose of 15 mg/kg reduced intromission frequency, while in subchronic mode it also reduced ejaculation latency. Mount frequency was increased by 7.5 and 15 mg/kg, but only on first injection. In the case of sexually-naive male rats, acute administration of cocaine (3-30 mg/kg) stimulated penile erections at 7.5 mg/kg and motor hyperactivity at all doses. (-) Eticlopride (0.025 and 0.05 mg/kg), a DA D2 antagonist, counteracted cocaine-induced motor hyperactivity but not penile erection, which it enhanced. (-) Eticlopride at the same doses also antagonized cocaine potentiation of lisuride (0.2 mg/kg)-induced behavioural effects. When male rats treated with subchronic cocaine (15 mg/kg) were injected with the DA D2 agonist SND 919 (0.1 mg/kg), they displayed a more marked stretching-yawning behaviour than control animals receiving SND 919 at the same dose. The involvement of DA D2 receptors in cocaine-induced effects is suggested. 相似文献
153.
E Melillo L Iabichella R Berchiolli M Ferrari G Catapano G Dell'Omo R Pedrinelli 《Canadian Metallurgical Quarterly》1995,15(2):60-64
The effect of intravenous iloprost treatment (median rate: 1.6; range 1-2 ng/kg/min; 6 h daily over 4 weeks) on transcutaneous pO2 and pCO2 was studied in 8 patients with bilateral peripheral obstructive arterial disease and monolateral critical limb ischemia. Tensiometric determinations were obtained at both metatarsi in the supine and dependent position. In critically ischemic limbs, supine transcutaneous p)2 changed erratically during iloprost treatment, increasing in only three out of eight lower limbs. At variance with its inconsistent behavior in the supine position, dependent pO2 increased during drug administration (p<0.02). Transcutaneous pCO2 was unchanged by iloprost. In the contralateral, non-symptomatic limb, both supine and dependent pO2 values were increased by the drug, suggesting that systemic hemodynamic changes may participate in its effect on transcutaneous gas tension, even at infusion rates clinically titrated to avoid evident changes in blood pressure and heart rate. 相似文献
154.
155.
D. Pereira C. A. Ferrari A. Scalabrin 《Journal of Infrared, Millimeter and Terahertz Waves》1986,7(8):1241-1250
In this work we report laser action in 69 new FIR laser lines in CD3OH optically pumped by a regular cw CO2 laser. We have performed measurements of laser wavelength, optimum pressure of the gas, relative polarization and intensity on all lines, including some previously known. 相似文献
156.
Felipe Thomaz Aquino Rafael R. Pereira Jefferson Luis Ferrari Sidney José Lima Ribeiro Alban Ferrier Philippe Goldner Rogéria Rocha Gonçalves 《Materials Chemistry and Physics》2014
This paper reports on the preparation of novel sol-gel erbium-doped SiO2-based nanocomposites embedded with Nb2O5 nanocrystals fabricated using a bottom-up method and describes their structural, morphological, and luminescence characterization. To prepare the glass ceramics, we synthesized xerogels containing Si/Nb molar ratios of 90:10 up to 50:50 at room temperature, followed by annealing at 900, 1000, or 1100 °C for 10 h. We identified crystallization accompanying host densification in all the nanocomposites with orthorhombic (T-phase) or monoclinic (M-phase) Nb2O5 nanocrystals dispersed in the amorphous SiO2 phase, depending on the niobium content and annealing temperature. A high-intensity broadband emission in the near-infrared region assigned to the 4I13/2 → 4I15/2 transition of the Er3+ ions was registered for all the nanocomposites. The shape and the bandwidth changed with the Nb2O5 crystalline phase, with values achieving up to 81 nm. Er3+ ions were located mainly in Nb2O5-rich regions, and the complex structure of the different Nb2O5 polymorphs accounted for the broadening in the emission spectra. The materials containing the T-phase, displayed higher luminescence intensity, longer 4I13/2 lifetime and broader bandwidth. In conclusion, these nanostructured materials are potential candidates for photonic applications like optical amplifiers and WDM devices operating in the S, C, and L telecommunication bands. 相似文献
157.
Electronic structure of rapidly quenched ribbons of nominal composition NdyFe(86−y−x)B14Tix (x = 0, 2, 4; y = 7, 8 at.%) was studied by X-ray absorption (Fe and Ti K-edge) and X-ray photoelectron spectroscopy. It was found by XANES that Ti addition promotes modifications of the electronic structure of Fe sub-band. From the analysis of differences in the pre-edges structure areas, coming from variations in the 3d density of states near the Fermi level, the evidences of acceptor nature of Ti and Fe atoms in NdFeB alloys are present. Using photoelectron spectroscopy, we found that neodymium, iron and titanium are in both, metallic and oxidized, states on the surface of the ribbons. A higher Ti0 content (at high vacuum) is characteristic of the annealed samples. The presence of oxidized titanium states was corroborated by XANES. 相似文献
158.
Signatures of a Two‐Dimensional Ferromagnetic Electron Gas at the La0.7Sr0.3MnO3/SrTiO3 Interface Arising From Orbital Reconstruction
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159.
Laura Mayol Daniela De Stefano Virginia Campani Francesca De Falco Eleonora Ferrari Claudia Cencetti Pietro Matricardi Luigi Maiuri Rosa Carnuccio Angela Gallo Maria Chiara Maiuri Giuseppe De Rosa 《Journal of materials science. Materials in medicine》2014,25(6):1483-1493
In this study, a sterile and biocompatible chitosan (CHI) gel for wound healing applications was formulated. CHI powder was treated in autoclave (ttCHI) to prepare sterile formulations. The heat treatment modified the CHI molecular weight, as evidenced by GPC analysis, and its physical–chemical features. Differential scanning calorimetry studies indicated that the macromolecules, before and after thermal treatment, differ in the strength of water-polymer interaction leading to different viscoelastic and flow properties. Thermally treated CHI exhibited the following effects: (i) increased the proliferation and migration of human foreskin foetal fibroblasts at 24 h; (ii) accelerated wound healing (measured as area of lesion) at 3 and 10 days in an in vivo model of pressure ulcers. These effects were linked to the increase of the hydroxyproline and haemoglobin content as well as Wnt protein expression. Moreover, we found a reduction of myeloperoxidase activity and TNF-α mRNA expression. These observations suggest the potential of this novel CHI gel in wound healing and other therapeutic applications. 相似文献
160.