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排序方式: 共有1809条查询结果,搜索用时 15 毫秒
111.
A Guimar?es A Machado S Carvalho H Alaiz L Vieira M Abecasis 《Canadian Metallurgical Quarterly》1998,22(6):595-597
The authors calculated the shunt revision rate for 77 consecutive patients with tumoural obstructive hydrocephalus. At a mean follow up of 23.7 months, the annual revision rate was 0.06 which is significantly lower than the annual revision rate of 0.39 for other hydrocephalic patients treated during the same period. Shunted patients who had total excision of their lesions had a significantly lower revision rate than patients who had a partial excision or a biopsy. It is therefore, suggested that cases with tumoural obstructive hydrocephalus may represent a subset of hydrocephalic patients who are associated with a relatively low risk of shunt complications. The observation has to be addressed when the role of endoscopic third ventriculostomy in these patients is being considered. 相似文献
112.
113.
Evaluation and optimization of chromium removal from tannery effluent by microemulsion in the Morris extractor 总被引:2,自引:0,他引:2
Dantas Neto AA de Castro Dantas TN Alencar Moura MC 《Journal of hazardous materials》2004,111(1-3):115-122
A multidisciplinary Road Accident Analysis Group with the objective of conducting in-depth investigations of specific types of accidents has existed in Denmark for some years. The group has analysed head-on collisions, left-turn accidents, truck accidents and single vehicle accidents. The data collection included police reports, the group's investigation of accident sites and vehicles involved, and interviews with the involved road users and witnesses. The main accident factors in the head-on collisions and in the single vehicle accidents were excessive speed, drunk driving and driving under the influence of illegal drugs. The primary accident factors in left-turn accidents were attention errors or misjudging the amount of time available to complete the left turn. In the truck accidents insufficient searching for visual information as well as speeding were major factors. For all the accident themes the primary injury factor was failure to wear seat- belts. The multidisciplinary approach has provided a rather precise knowledge of the contributing factors leading up to the accident. The method requires a lot of resources, which is a limiting factor for the number of accidents to be analysed in this way. However, the method is suitable for analysis of common occurring or very serious types of accidents. 相似文献
114.
Papo MJ Catledge SA Vohra YK Machado C 《Journal of materials science. Materials in medicine》2004,15(7):773-777
We used microwave plasma chemical vapor deposition to deposit nanocrystalline and multilayer (nanocrystalline/microcrystalline/nanocrystalline) diamond thin films on Ti-6AI-4V substrates imitating the condyle and fossa components of the temporomandibular joint. We tested the condyle/fossa pairs for wear in a mandibular movement simulator for an equivalent of two years of clinical use. Analysis of the wear surfaces by optical microscopy, scanning electron microscopy (SEM), and Raman spectroscopy showed that damage in both the films was minimal, no loss of film occurred and the wear performance was superior for the multilayer film. Comparisons with an uncoated condyle/fossa pair showed that the coated temporomandibular joint pairs had improved wear performance. 相似文献
115.
Machado JC Foster FS 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2001,48(1):17-27
A theoretical formulation for the profile of the integrated backscatter coefficient (IBC) is derived. This new formulation is based on a theoretical treatment. It includes correction for the diffraction of the ultrasonic beam and correction for the non-ideal nature of the reference signal. The inclusion of these correction factors permits accurate quantitative profiling of the IBC over the transducer focal zone. Experimental measurements are first performed on well-calibrated vessel-equivalent phantom materials and subsequently on human coronary arteries in vitro. A spherically focused 50.0 MHz f/1.83 transducer is used. IBC profiles are shown for three samples that are representative of early, mid, and advanced atherosclerotic coronary disease. The IBC profiles clearly differentiate the arterial tissues. However, variation between samples with histologically confirmed intimal thickening (N=24) was large. The mean IBC (±1 standard deviation), in (Sr.mm)-1, for media, adventitia, and thickened intima were 3.86×10-3, 1.53×10-2, and 2.24×10-2, respectively. The mean IBC of thickened intima is larger than previous measurements obtained from femoral arteries, and the mean IBC for media and adventitia layers are lower, reflecting differences in tissue composition between coronary and femoral vessels 相似文献
116.
Removal of chromium from aqueous solutions by diatomite treated with microemulsion 总被引:10,自引:0,他引:10
In order to evaluate the sorption of heavy metals, a crude diatomite was impregnated with a microemulsion which showed remarkable increase in chromium sorption capacity as compared to untreated diatomite. Samples with two different granulometries were investigated, both yielding practically complete adsorption. The adsorption process is pH dependent and the best results for the initial Cr (III) concentration of 1.5 g/L were obtained at pH 2.95. The effect of the concentration of the chromium synthetic solution was also investigated. The adsorption isotherms were obtained (30. 40 and 50 degrees C) and the Freundlich and Langmuir models were used to determine the adsorption capacity of the adsorbent. Following the adsorption step, a desorption process was carried out using several eluant solutions. The best results were obtained using hydrochloric acid (100%) as eluant. 相似文献
117.
Francisco Andrade Paulo Novais José Machado José Neves 《Artificial Intelligence and Law》2007,15(4):357-373
The combined use of computers and telecommunications and the latest evolution in the field of Artificial Intelligence brought along new ways of contracting and of expressing will and declarations. The question is, how far we can go in considering computer intelligence and autonomy, how can we legally deal with a new form of electronic behaviour capable of autonomous action? In the field of contracting, through Intelligent Electronic Agents, there is an imperious need of analysing the question of expression of consent, and two main possibilities have been proposed: considering electronic devices as mere machines or tools, or considering electronic devices as legal persons. Another possibility that has been frequently mentioned consists in the application of the rules of agency to electronic transactions. Meanwhile, the question remains: would it possible, under a Civil Law framework, to apply the notions of “legal personhood” and “representation” to electronic agents? It is obvious that existing legal norms are not fit for such an endeavouring challenge. Yet, the virtual world exists and it requires a new but realistic legal approach on software agents, in order to enhance the use of electronic commerce in a global world. 相似文献
118.
Claudia Giovedi Luci Diva Brocardo Machado 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2007,265(1):256-259
Fluoroelastomer can be used as a sealing material for different purposes. The aim of this work is the evaluation of the effects of the ionizing radiation of an electron beam (EB) on the mechanical, thermal and surface properties of a commercial fluoroelastomer containing carbon black and inorganic fillers. The material was irradiated with overall doses between 10 and 250 kGy. Tensile strength (stress and strain at break), hardness (Shore A) and compression set were evaluated. Thermal behavior was evaluated by thermogravimetric analysis and differential scanning calorimetry. Surface modifications were inspected using scanning electron microscopy (SEM) and optical microscopy. The experiments have shown that EB irradiation promotes beneficial changes in the fluoroelastomer tensile strength behavior while compression set remain constant and the glass transition temperature increases. The SEM micrographs have shown compactness in the irradiated samples, although optical observations showed no surface morphology changes. 相似文献
119.
Machado Liana; Wyatt Natalie; Devine Amy; Knight Benjamin 《Canadian Metallurgical Quarterly》2007,33(5):1045
Humans have a remarkable capability to respond efficiently to a stimulus of interest despite other stimuli competing for neural resources. The current study investigated how the human system copes with distracting stimuli. During each trial, participants viewed 2 sequential stimuli that were each associated with a specific action based on an arbitrary mapping. The 1st stimulus served as a distractor, and the 2nd stimulus required a response (target). When the distractor preceded the target by more than a few hundred milliseconds, response latencies were slower when the 2 stimuli were associated with the same response. The authors propose that this negative compatibility effect stemmed from an inhibitory mechanism that the human system utilizes to prevent the distractor from eliciting an unwanted response. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
120.
Voltammetric and chronoamperometric studies of silver electrodeposition from a bath containing HEDTA
G. M. de Oliveira M. R. Silva Ivani Aparecida Carlos 《Journal of Materials Science》2007,42(24):10164-10172
The electrodeposition of silver on platinum from ammonium-buffered solutions containing HEDTA (N-(2-hydroxyethyl)ethylenediaminetriacetic
acid) at various concentrations was investigated. Potentiometric titration and voltammetric studies indicated that in the
presence of 2.0 × 10−1 M HEDTA, the deposited silver was reduced from a mixture of [AgHEDTA]2− and [Ag(NH3)2]+ complexes, whereas at 2.0 × 10−2 M and 2.0 × 10−3 M HEDTA in the electrolyte, the silver was reduced from the [Ag(NH3)2]+ complexes alone. Hydrodynamic studies showed variation in the diffusion coefficient for the electroactive species in solution,
depending on the HEDTA concentration. Chronoamperometric study in a solution containing 2.0 × 10−1 M HEDTA at low overpotential (0.000 V to –0.050 V) showed a transition from progressive to instantaneous nucleation in a single
current transient, whereas, at −0.200 V only 3D-progressive nucleation controlled by mass transport was observed. Scanning electron microscope images showed that the silver
films produced in silver baths with HEDTA were uniform, without cracks, and fine-grained, regardless of its concentration,
while in the absence of HEDTA the morphology was rough and dendritic. X-ray diffraction analysis of the films obtained at
various HEDTA concentrations revealed polycrystalline silver, similar to film obtained in cyanide and EDTA/ammonia baths. 相似文献