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排序方式: 共有429条查询结果,搜索用时 15 毫秒
91.
OBJECTIVE: Recent clinical studies suggest that the reflex increase in sympathetic nervous activity accompanying a reduction in blood pressure may contribute to the untoward effects of dihydropyridine calcium antagonists. The aim of this study was to examine whether plasma noradrenaline levels and renin activity are increased with the reduction of blood pressure during the initial phase of administration of the long-acting dihydropyridine calcium antagonist amlodipine. METHODS: The effects of amlodipine on ambulatory blood pressure and on diurnal variations in plasma noradrenaline and renin activity were examined 1, 4, and 7 days after the start of amlodipine administration in eight inpatients with essential hypertension. RESULTS: The 24-h mean systolic and diastolic blood pressure on day 7 was significantly lower than it was 1 day before the start of treatment. There was no change in the mean heart rate. The mean trough to peak ratios of systolic and diastolic blood pressure of seven patients were 61% and 71%, respectively. Diurnal patterns of plasma noradrenaline levels and renin activity 1, 4, and 7 days after the start of amlodipine administration were unchanged. CONCLUSION: The antihypertensive effects of amlodipine were of slow onset and long duration and were not accompanied by an increase in sympathetic activity or activation of the renin-angiotensin system. 相似文献
92.
R Otero-Candelera A Cayuela Domínguez M Arenas A Segado Soriano E Barrot Cortés A Verano Rodríguez 《Canadian Metallurgical Quarterly》1997,33(3):118-123
A review of anthropological, sociological, and psychological theories of suicidal behavior indicates that a disruption in social relationships and a breakdown in community networks increase the risk of suicide. Current suicide prevention tactics fail to address these problems, and suggestions are made for tactics that would focus on the underlying causes of suicide, tactics consistent with a communitarian philosophy and tactics that could guide us into the 21st century. 相似文献
93.
Miquel Sànchez Ulises Cortés Javier Béjar Joan De Grácia Javier Lafuente Manel Poch 《Applied Intelligence》1997,7(2):147-165
Although activated sludge process is a very widely used biologicalprocess in wastewater treatment plants (WWTP), and there areproperly functioning control loops such as that of dissolved oxygen,in practice, this type of plant requires a major time investment onthe part of the operator, involving many manual operations.Treatment plants work well most of the time, as long as there are not unforeseen occurrences. Normal operatingsituations (generally similar to design conditions) can be treatedmathematically by using efficient control algorithms. However, there aresituations in which the control system cannot properlymanage the plant, and in which the process can only be efficiently managedthanks to the operators experience. This is a case in which aknowledge-based system may be useful. One of the difficulties inherent tothe development of a knowledge-based system is to obtain the knowledge base(i.e., knowledge acquisition), specially whendealing with a wide, complicated and ill-structured)field.Among the aims of this work arethose to show how semi-automatic knowledge acquisition tools could helphuman experts to organize their knowledge about their domain and also, tocompare the power of different approaches of knowledge acquisition) to the same database.In this paper are presented the results obtained fromapplying two different classification techniques to the development of knowledge-bases for the management of an activated sludge process. 相似文献
94.
This paper introduces a novel continuous‐time dynamic average consensus algorithm for networks whose interaction is described by a strongly connected and weight‐balanced directed graph. The proposed distributed algorithm allows agents to track the average of their dynamic inputs with some steady‐state error whose size can be controlled using a design parameter. This steady‐state error vanishes for special classes of input signals. We analyze the asymptotic correctness of the algorithm under time‐varying interaction topologies and characterize the requirements on the stepsize for discrete‐time implementations. We show that our algorithm naturally preserves the privacy of the local input of each agent. Building on this analysis, we synthesize an extension of the algorithm that allows individual agents to control their own rate of convergence towards agreement and handle saturation bounds on the driving command. Finally, we show that the proposed extension additionally preserves the privacy of the transient response of the agreement states and the final agreement value from internal and external adversaries. Numerical examples illustrate the results. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
95.
V. Cortés J. Blasco N. Aleixos S. Cubero P. Talens 《Food and Bioprocess Technology》2017,10(10):1755-1766
Visible and near-infrared spectroscopy has been widely used as a non-invasive and rapid-assessment technique for the quality control of agricultural products. In this study, 325 samples of nectarines representing two commercial varieties, cv. ‘Big Top’ and cv. ‘Magique’, were analysed by visible and near-infrared diffuse reflectance spectroscopy (VIS-NIR). The spectral data were pre-treated and analysed to predict the internal quality of the samples and to discriminate between the two varieties. Good prediction of the internal quality of the samples, using partial least-squares regressions, was observed for both (R 2 P of 0.909 and 0.927 and RMSEP of 0.235 and 0.238 for cv. Big Top and Magique, respectively). Discriminant models, using linear discriminant and partial least-squares discriminant analyses, were built to classify the nectarines. Both methods provided good results with rates of 97.44 and 100% of correctly classified samples. The results indicated that visible and near-infrared techniques can be useful and simple methods for quality control and for the correct identification of nectarines in commercial lines as an alternative to the slower and less accurate manual classification. 相似文献
96.
High-rise buildings require the installation of complex elevator group control systems (EGCSs). In vertical transportation, when a passenger makes a hall call by pressing a landing call button installed at the floor and located near the cars of the elevator group, the EGCS must allocate one of the cars of the group to the hall call. We develop a particle swarm optimization (PSO) algorithm to deal with this car-call allocation problem. The PSO algorithm is compared to other soft computing techniques such as genetic algorithm and tabu search approaches that have been proved as efficient algorithms for this problem. The proposed PSO algorithm was tested in high-rise buildings from 10 to 24 floors, and several car configurations from 2 to 6 cars. Results from trials show that the proposed PSO algorithm results in better average journey times and computational times compared to genetic and tabu search approaches. 相似文献
97.
Mario Ponce-Silva Juan A. Aquí-Tapia María C. Arellano Edwing A. Moreno Claudia Cortés-García 《International Journal of Circuit Theory and Applications》2019,47(2):254-274
In this paper, the analysis, design, and implementation of a power supply based on a multi-stage-shunt class E amplifier applied to ozone generation are presented. The proposed topology operates with pulsating waveforms and allows unidirectional energy flow from the power supply to the load with no energy return. Furthermore, due to the multi-stage operation, it presents a lower stress in the switches compared with other similar topologies. To validate the proposed topology, a prototype was designed to feed a set of ozone generating cells in a power range of 0 to 500 W. This prototype provides an efficiency of 95% with an ozone production of 10.5 g/h and efficacy of 22.89 g/kWh. The proposed power supply is an alternative to feed any other type of dielectric barrier discharge load while keeping the efficiency of the power supply above 90%. 相似文献
98.
99.
W. Ortega-Lara D.A. Cortés-Hernández S. Best R. Brooks A. Hernández-Ramírez 《Ceramics International》2010,36(2):513-519
Titania–wollastonite materials that show high in vitro bioactivity, appropriate cell proliferation and antibacterial behavior have been developed. Titania–wollastonite compounds were synthesized by two different routes: (i) solid state reaction and (ii) sol–gel. The in vitro bioactivity assessment was performed by immersing samples in a simulated body fluid (SBF). The materials characterization, before and after immersion in SBF, was performed by SEM and EDS. Cytotoxicity was assessed by estimating cell proliferation and the antibacterial properties were evaluated by performing a kinetic study of a bacterium growth (Burkhoderia cepacia). In order to evaluate the band gap value UV–vis spectroscopy was performed. A faster apatite layer formation was observed on the samples processed by sol–gel. However, these agglomerates were smaller than those formed on the solid state reaction substrates. The highest inhibition of the bacteria growth and the highest cell proliferation were observed on the samples synthesized by solid state reaction. 相似文献
100.