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排序方式: 共有49条查询结果,搜索用时 15 毫秒
1.
Minimizing entropy generation is a technique that helps improve the effectiveness of real processes by studying the associated irreversibility of system performance of nanofluid. This study examines the entropy generation analysis of electromagnetohydrodynamic radiative Casson flow induced by a stretching Riga plate in a non-Darcian porous medium under the influence of internal energy change, Arrhenius activation energy, chemical reaction, and melting heat transfer. The thermophysical features of the fluid are assumed constant in most of the literature. However, this current research bridges this gap by considering viscosity, conductivity, and diffusivity as temperature-dependent variables. Also, the exponential decaying Grinberg term is used as a resistive force in this investigation due to the electromagnetic properties of the Riga plate in the momentum conservation equation. Some suitable dimensionless variables are introduced to remodel the transport equations into unitless ones and then solved numerically by employing Galerkin Weighted Residual Method. Analyses reveal that the Casson parameter declines the fluid velocity, while the existence of the melting parameter has the opposite effect. Also, this article includes some future recommendations.  相似文献   
2.
BP神经网络在工程机械液压系统故障诊断中的应用研究   总被引:1,自引:0,他引:1  
将BP神经网络理论应用于工程机械液压系统故障诊断中进行研究,通过系统数据的采集、特征向量的提取和分类器的构造,在对网络进行训练的基础上,建立了学习算法,通过试验可以看出神经网络能给出的满意结果。  相似文献   
3.
Detection of light in the eye underlies image-forming vision, but also regulates adaptive responses in physiology and behavior. Typically these adaptive responses do not involve image-forming vision, but depend on a relatively absolute measure of brightness (nonimage-forming irradiance detection). The goal of this study was to further understand how image-forming vision and nonimage-forming irradiance detection contribute to the effects of light on behavior. Three light dependent behaviors were assessed in wild-type, Rpe65-/- and rd1 mice. In Rpe65-/- mice, nonimage-forming irradiance detection is severely attenuated, but rod based visual acuity is relatively preserved. In rd1 mice visual acuity is nonrecordable, but nonimage-forming responses are less severely attenuated than Rpe65-/-. Positive masking, an image-forming vision dependent increase in wheel running, was absent in rd1 and restricted to higher irradiances in Rpe65-/-. Negative masking, a suppression of wheel running sensitivity with nonimage-forming irradiance detection input, was increased in rd1, but reduced in Rpe65-/- mice. By contrast, light aversion, an avoidance of brightly lit areas, was abolished in both Rpe65-/- and rd1. This shows that image-forming vision is not sufficient for light aversion, suggesting nonimage-forming irradiance detection motivates this behavior. Further, the differing effects of disease suggest that negative masking and light aversion are distinct responses with specialized nonimage-forming irradiance detection pathways. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
4.
Methane (CH4) adsorption is investigated on both graphite and in the region between two aligned single-walled carbon nanotubes, which we refer to as the groove site. We exploit the Lennard–Jones potential function and the continuous approximation to determine surface binding energies between a single CH4 molecule and graphite and between a single CH4 and two aligned single-walled carbon nanotubes. Our modelling indicates that for a CH4 molecule interacting with graphite, the binding energy of the system is minimized when the CH4 carbon is 3.83 Å above the surface of the graphitic carbon, while the binding energy of the CH4–groove site system is minimized when the CH4 carbon is 5.17 Å away from the common axis shared by the two aligned single-walled carbon nanotubes. Our results confirm the current view that for larger groove sites, CH4 molecules in grooves are likely to move towards the outer surfaces of one of the single-walled carbon nanotubes. Our results are computationally efficient and are in good agreement with experiments and molecular dynamics simulations, and show that CH4 adsorption on graphite and groove surfaces is more favourable at lower temperatures and higher pressures.  相似文献   
5.
Electricity supplies an increasing share of the world’s total energy demand and that contribution is set to increase. At the same time, there is increasing socio-political will to mitigate impacts of climate change as well as to improve energy security. This, in combination with the desire to ensure social and economic prosperity, creates a pressing need to consider the sustainability implications of future electricity generation. However, approaches to sustainability assessment differ greatly in their scope and methodology as currently there is no standardised approach. With this in mind, this paper reviews sustainability indicators that have previously been used to assess energy options and proposes a new sustainability assessment methodology based on a life cycle approach. In total, 43 indicators are proposed, addressing the techno-economic, environmental and social sustainability issues associated with energy systems. The framework has been developed primarily to address concerns associated with nuclear power in the UK, but is applicable to other energy technologies as well as to other countries.  相似文献   
6.
There is currently an international drive to build new nuclear power plants, bringing about what is being termed a “nuclear renaissance”. However, the public perception of nuclear energy has historically been, and continues to be, a key issue, particularly in light of the Fukushima nuclear incident. This paper discusses the disparity between perceived and calculated risks based on the last four decades of research into risk perception. The leading psychological and sociological theories, Psychometric Paradigm and Cultural Theory, respectively, are critically reviewed. The authors then argue that a new nuclear-build policy that promotes a broader approach to design incorporating a wider range of stakeholder inputs, including that of the lay public, may provide a means for reducing the perceived risk of a nuclear plant. Further research towards such a new approach to design is proposed, based on integrating expert and lay stakeholder inputs and taking into account broader socio-cultural factors whilst maintaining the necessary emphasis on safety, technological development, economics and environmental sustainability.  相似文献   
7.
Studies on the amylase activities and tolerance to cyanide by five spoilage molds of cassava tuber were carried out. None of the test fungi grew in 0.1 g/ml concentration of potassium cyanide while only Aspergillus aculeatus and A. niger grew in 0.05 g/ml. Except for B. theobromae, all the other four molds synthesised amylases on the 2nd day of incubation. Highest amylase activities by the molds were recorded between pH 6–7 and at 25°C. The molds degraded satisfactorily the raw starch and protein contents of the blended cassava tuber pulp. Total reducing sugars were detected in large quantities from the mold deteriorated cassava tuber.  相似文献   
8.
The effects of captan on the production of mycelia and cellulolytic enzymes of Aspergillus aculeatus and Botryodiplodia theobromae were investigated in culture. There was decrease in mycelia of both fungi with increase in captan concentration in ppm. No fungal growth was recorded at 400 ppm. Captan at 10–50 ppm at 25 and 30 °C induced both fungi to produce more mycelia than in control cultures. The effect of captan concentration on the production of cellulases showed a decrease in quantity with increase in concentration. At 400 ppm no cellulase was produced by both fungi. There was a general decrease in cellulase production with increase in temperature either in control or experimental cultures. In cultures incorporated with captan, the cellulolytic activities of A. aculeatus (at 10 ppm) and B. theobromae (at 10 ppm, 50 ppm) were found to be relatively high.  相似文献   
9.
The electroplating of Ni-Cd alloy coatings was carried out from alkaline baths (pH 10). For comparison, electroplating of the parent metals, Ni and Cd, was performed individually under the same conditions. The cathodic current efficiency for codeposition was high and decreased with increasing current density. The codeposition process is an anomalous type of plating with Cd being the preferentially deposited metal. The Ni content in the deposits increased with increasing current density. This increase in Ni content improves the corrosion resistance and microhardness of the deposits. X-ray diffraction analysis showed that the deposits consist of a mixture of Ni, β, γ, γ1 phases.  相似文献   
10.
Abstract

Cross-validation of soft computing techniques needs to be done efficiently to avoid overfitting and underfitting. This is more important in petroleum reservoir characterisation applications where the often-limited training and testing data subsets represent Wells with known and unknown target properties, respectively. Existing data stratification strategies have been haphazardly chosen without any experimental basis. In this study, the optimal training–testing stratification proportions have been rigorously investigated using the prediction of porosity and permeability of petroleum reservoirs as an experimental case. The comparative performances of seven traditional and advanced machine learning techniques were considered. The overall results suggested a recommendable optimum training stratification that could serve as a good reference for researchers in similar applications.  相似文献   
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