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1.
试图构建企业以顾客为中心的营销策略过程的一般模型,并利用已有的研究成果对其构成要素进行了深入分析.在此基础上,对此模型所形成的企业营销策略循环进行分类分析,并以实例说明它们所代表的现实意义,从而为企业的决策提供帮助. 相似文献
2.
An experimental study of heat transfer to boiling liquids under natural convective flow has been carried out in a single tube vertical thermosiphon reboiler to investigate the effect of heat flux and submergence on circulation rates. The test liquids used were distilled water, various concentrations of propan-2-ol in water and their azeotrope. The test section was an electrically heated stainless steel tube of 25.56 mm i.d., 28.85 mm o.d. and 1900 mm long with twenty-one spot welded copper constantan thermocouples to measure the variations in wall temperature along its axis. The uniform heat fluxes in the range of 3.5–42.4 kW/m2 were employed while inlet liquid sub-cooling varied from 0.2 to 30.7 °C. The liquid submergence levels were maintained in the range 30–100%. The typical experimental data has been graphically presented and discussed. An empirical correlation has been developed from the experimental data of the present study through regression analysis. 相似文献
3.
An experimental investigation under cold condition was made to study the effects of some operating/design parameters and non-mechanical L valve configuration on the solid circulation rate in a 4.5 m tall, 0.15 m diameter circulating fluidized bed with riser flow rate varying from 1400 litres/min to 2000 litres/min and bed inventory from 15 kg to 25 kg of sand of average sizes 200 μm, 400 μm and 500 μm. Solid circulation rate was estimated by measuring velocity of sand particle travelling through a vertical Perspex tube section at the bottom of the return leg. It was found to be in the range of 2.8 to 12.3kg/m2s, 0.07 to 9.1kg/m2s and 0.12 to 2.23kg/m2s for sand sizes of 200 μm, 400 μm and 500 μm, respectively for a horizontal L valve. Two mathematical correlations have been developed from the experimental results to predict solid circulation rate as a function of riser flow rate, aeration flow rate, total bed inventory and particle size used. 相似文献
4.
5.
Quantification of secondary structure prediction improvement using multiple alignments 总被引:9,自引:0,他引:9
Levin Jonathan M.; Pascarella Stefano; Argos Patrick; Garnier Jean 《Protein engineering, design & selection : PEDS》1993,6(8):849-854
The use of multiple sequence alignments for secondary structurepredictions is analysed. Seven different protein families, containingonly sequences of known structure, were considered to providea range of alignment and prediction conditions. Using alignmentsobtained by spatial superposition of main chain atoms in knowntertiary protein structures allowed a mean of 8% in secondarystructure prediction accuracy, when compared to those obtainedfrom the individual sequences. Substitution of these alignmentsby those determined directly from an automated sequence alignmentalgorithm showed variations in the prediction accuracy whichcorrelated with the quality of the multiple alignments and distanceof the primary sequence. Secondary structure predictions canbe reliably improved using alignments from an automatic alignmentprocedure with a mean increase of 6.87percnt;, giving an overallprediction accuracy of 68.5%, if there is a minimum of 25% sequenceidentity between all sequences in a family. 相似文献
6.
目前离子膜电解槽的发展方向为复极、自然循环、高电流密度、低电耗,伍德诺拉公司BM2.7-Ⅲ型槽、美国西方化学公司ExL^B-65槽、日本氯工程公司BiTAC-858槽即具有这些先进性能。对这3种槽进行了介绍与对比。 相似文献
7.
A new synthesis of poly(amido-amine)s from bis (secondary amine)s and acryloyl chloride has been studied, leading to polymers in which the amido- and amino-groups are randomly arranged along the macromolecular chain. A poly(amido-amine) based on piperazine, chosen as the mother compound, has been fully characterized by 13C n.m.r. as well as by identification and quantitative evaluation of its hydrolysis products. 相似文献
8.
Walter J. Jakubas Bernard C. Wentworth William H. Karasov 《Journal of chemical ecology》1993,19(10):2353-2377
Various plant secondary metabolites related to cinnamic acid are of interest because of their repellency to birds and their occurrence in ecologically important food items. Coniferyl benzoate (CB), a phenylpropanoid ester that occurs in quaking aspen (Populus tremuloides) is of particular ecological interest because of its effect on ruffed grouse (Bonasa umbellus) feeding behavior and its possible influence on the population dynamics of this bird. During detoxification processes, CB and other analogous compounds are metabolized into by-products, such as ferulic acid (FA), that can cause anti-reproductive effects. We tested whether consumption of CB produces antire-productive effects similar to FA using male and female Japanese quail (Coturnix coturnix) as avian models for ruffed grouse. The parameters we investigated included: the production, morphology, and development of eggs; reproductive characteristics influenced by estrogen; serum prolactin levels; and male reproductive behavior. Dietary CB did not produce antireproductive effects similar to FA at intake levels that Japanese quail and ruffed grouse would freely consume. Consumption of CB by Japanese quail significantly reduced egg production and body mass but did not affect male reproductive performance. Coniferyl benzoate's effect on egg production may be explained by lower energy acquisition and retention rather than endocrine changes per se. Contrary to previous reports, it is unlikely that FA, or similar compounds act directly as estrogen mimics or antagonists. Although, CB did reduce egg production in quail, it is unlikely that it would affect egg production in wild ruffed grouse. Detoxification costs and the effects of CB on nutrient utilization may explain why ruffed grouse avoid high dietary levels of CB. 相似文献
9.
Fluid flow in coupled free and porous domain, particularly when the porous medium is heterogeneous, is encountered in many hydro-environmental conditions, e.g., leakage from underground pipe, combined groundwater lake-subsurface interactions. One of the most difficult problems in the study of coupled flow behaviour has been the development of a universally applicable modelling scheme for combining the flow regimes. This is because the free/porous interfacial properties (e.g., shear-stress; velocity slip) that govern the coupled flow behaviour are difficult to determine experimentally under hydro-environmental conditions. On the other hand, the implications of various forms of heterogeneity in the porous media properties can be very different on the fluid-flow behaviour. Difficulties may also arise in direct coupling of the model equations that govern the fluid flow in the individual regions (e.g., Navier-Stokes for free-flow region and the Darcy's equation for the porous flow region). Consequently, models of coupled free and porous flow for hydro-environmental conditions are not very well developed at the moment. While there are some indications that fluids in coupled free and porous domains may circulate (i.e., development of flow cells), there is a lack of appropriate 3D analysis on how heterogeneities in porous media may affect such flow patterns. In this paper, we aim to analyse how porous media heterogeneity affects the dynamics of flow circulation in the porous side of a coupled free and porous domain. For this purpose, we analyse flow patterns in several model domains made up of two porous layers with differing permeabilities. The governing model equations are discretised and solved using the standard finite volume method on a staggered cell-centred mesh. The temporal discretisation is done using the explicit method. An in-house graphical user interface (GUI) has been created specifically to aid in the visualisation of otherwise complex flow patterns. The GUI contains many post-processing options and provides a comprehensive tool for the analysis of hydrodynamics and contaminant motion (not discussed in this paper) in coupled free and porous flow domains. This GUI is described in this paper briefly. The effects of altering the aspect ratio (i.e., multi-scale) of the domain on the coupled flow pattern have also been discussed. 相似文献
10.
介绍了锦化化工(集团)有限责任公司提高二次精制盐水质量的成功经验,讨论了过滤系统中碳素烧结管间距、一次盐水的质量及其游离氯含量、人为操作失误和助体给料量等五大因素对二次精制盐水质量的影响,并采取了相应的措施,如调整合适的碳素烧结管间距、改走砂滤器、更换过滤器碳素管等。介绍了二次精制盐水精制系统树脂塔精制盐水的操作要素,诸如控制盐水流量最高为68m3/h、温度在(60±5)℃、pH值在9左右,控制树脂塔的压差、树脂填充量、树脂性能、仪表阀的检查情况等,从而生产出高质量的二次精制盐水,保证了离子膜电解槽的平稳、高效运行。 相似文献