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31.
Dynamic Pricing and the Direct-to-Customer Model in the Automotive Industry   总被引:3,自引:0,他引:3  
The Internet is changing the automotive industry as the traditional manufacturer and dealer structure faces increased threats from third party e-tailers. Dynamic pricing together with the Direct-to-Customer business model can be used by manufacturers to respond to these challenges. Indeed, by coordinating production and inventory decisions with dynamic pricing, the automotive industry can increase profits and improve supply chain performance. To illustrate these benefits, we discuss a strategy that incorporates pricing, production scheduling, and inventory control under production capacity limits in a multi-period horizon. We show that under concave revenue curves, a greedy algorithm provides the optimal solution, and we describe extensions to the model such as multiple products sharing production capacity. Using computational analysis, we quantify the profit potential and sales variability due to dynamic pricing, and we suggest that it is possible to achieve significant benefit with few price changes.Research supported in part by ONR Contracts N00014-90-J-1649 and N00014-95-1-0232, NSF Contracts DDM-9322828, DMI-9732795 and DMI-0085683, a research grant from the Natural Sciences and Research Council of Canada (NSERC) a grant from General Motors, and a grant from the eBusiness Center at MIT.  相似文献   
32.
Demand Control System (DCV) is designed to optimise the energy consumption with respect to the demand of outdoor air quantity based on the number of people indoors. However, if significant indoor pollutant sources exist, which is not a function of the number of people, the DCV may cause the indoor air quality to be unacceptable. This paper discusses a procedure of calibrating the building in respect of managing the indoor air quality. The objective is to set the minimum fresh air quantity which is a function of the indoor pollutant concentrations rather than metabolic carbon dioxide. Radon is used as an example because it is a common pollutant embedded in the building materials of high-rise buildings in Hong Kong. This paper also presents a year-round record of the indoor air quality in a typical high-rise building which is very useful for building indoor air quality (IAQ) design.  相似文献   
33.
Apolipoprotein E allele 4 (apoE epsilon 4) is a major risk factor for late-onset AD. Inheritance of this allele is associated with an earlier age of onset of dementia in individuals with AD. It is unknown whether other polymorphisms in the apoE gene may influence the effect of apoE epsilon 4 on AD. We screened portions of the promoter enhancer element and of the apoE receptor binding domain for other polymorphisms that could affect risk of AD. In particular, a C/G polymorphism at position +113 of the apoE mRNA in the apoE intron 1 enhancer element (IE1) has been recently identified. We found no other polymorphisms. We studied the relationship of the two alleles of the IE1 polymorphism with AD and found an apparent association between IE1 G and AD (n = 94; p = 0.0515). However, the IE1 G allele is also closely associated with apoE epsilon 4 (p < 0.0001). When the presence of apoE epsilon 4 is covaried, the association between the IE1 G allele and AD is no longer statistically significant (odds ratio = 1.29, 95% confidence interval: 0.44, 3.78). In contrast, epsilon 4 is still highly associated with AD when IE1 G is controlled for (odds ratio = 5.91, 95% confidence interval: 3.29, 10.63). Furthermore, there is no significant association between the age of onset of dementia and the inheritance of the G allele. We believe that the apparent association between IE1 G and AD is a consequence of the association between the epsilon 4 and IE1 G alleles.  相似文献   
34.
In this study, we report the first ever large-scale environmental validation of a microbial reporter-based test to measure arsenic concentrations in natural water resources. A bioluminescence-producing arsenic-inducible bacterium based on Escherichia coli was used as the reporter organism. Specific protocols were developed with the goal to avoid the negative influence of iron in groundwater on arsenic availability to the bioreporter cells. A total of 194 groundwater samples were collected in the Red River and Mekong River Delta regions of Vietnam and were analyzed both by atomic absorption spectroscopy (AAS) and by the arsenic bioreporter protocol. The bacterial cells performed well at and above arsenic concentrations in groundwater of 7 microg/L, with an almost linearly proportional increase of the bioluminescence signal between 10 and 100 microg As/L (r2 = 0.997). Comparisons between AAS and arsenic bioreporter determinations gave an overall average of 8.0% false negative and 2.4% false positive identifications for the bioreporter prediction at the WHO recommended acceptable arsenic concentration of 10 microg/L, which is far betterthan the performance of chemical field test kits. Because of the ease of the measurement protocol and the low application cost, the microbiological arsenic test has a great potential in large screening campaigns in Asia and in other areas suffering from arsenic pollution in groundwater resources.  相似文献   
35.
In our recent studies on the effects of plasticizers on nail enamel films, we developed a high interest in a phenomenon that we named as 'internal flow'[1]. During the film forming process there is an area that develops beneath the film surface where the film components remain dynamic and mobile. The time frame during which the film maintains this status is directly related to the balance of the resins, plasticizers, polymers and solvents utilized. We found that the longer this 'internal flow' persists, the better the nail enamel wears. At Tevco, we have been able to control the rate at which the solvents and plasticizers flash off the substrate during the film forming process by regulating the interactions and the levels of film constituents. This 'time release' action is the foundation of our study. This study shows that the alkyl adipates are an integral component in controlling the film's internal flow through time release. As plasticizers, these materials, when in proper balance with other components, can create a film surface that is crack-and scuff-resistant. Finally, the substrate in this study is the human nail. The film we developed has to adhere and provide consistent performance over a wide range of temperatures, oil content and the surface abrasion of human nails. We have found that by utilizing adhesion promoters in conjunction with our optimized internal flow time release formula, our film meets all required criteria and generally outperforms conventional quick dry films. In conclusion, we have been able to optimize the film characteristics of conventional quick dry nail enamels. By controlling the internal flow of the film, we can enhance the performance criteria generally expected by consumers in nail enamels.  相似文献   
36.
Air-conditioned office buildings are one of the biggest energy consumers of electricity in developed cities in the subtropical climate regions. A good energy policy for the indoor environment should respond to both the needs of energy conservation and the needs for a desirable indoor healthy environment with a reduction in carbon dioxide (CO2) generation. This study evaluates energy implications and the corresponding CO2 generation of some indoor environmental policies for air-conditioned office buildings in the subtropical climate. In particular, the thermal energy consumption in an air-conditioned office building was evaluated by the heat gains through the building fabric, the transport of outdoor fresh air for ventilation, and the heat generated by the occupant and equipment in the space. With the Monte-Carlo sampling technique and the parameters from the existing office building stocks of Hong Kong, the energy consumption profiles of air-conditioned office buildings in Hong Kong were evaluated. Energy consumption profiles were simulated for certain indoor environmental quality (IEQ) policies on indoor air temperature and CO2 concentration settings in the offices, with other building parameters remaining unchanged. The impact assessment and the regression models described in this study may be useful for evaluation of energy performances of IEQ policies. They will also be useful for the promotion of energy-saving measures in air-conditioned office buildings in Hong Kong. This study presented a useful source of references for policymakers, building professionals and end users to quantify the energy and environmental impacts due to an IEQ policy for air-conditioned office buildings.  相似文献   
37.
Blood plays an important role in homeostatic regulation with each of its cellular components having important therapeutic and diagnostic uses. Therefore, separation and sorting of blood cells hasa been of a great interest to clinicians and researchers. However, while conventional methods of processing blood have been successful in generating relatively pure fractions, they are time consuming, labor intensive, and are not optimal for processing small volume blood samples. In recent years, microfluidics has garnered great interest from clinicians and researchers as a powerful technology for separating blood into different cell fractions. As microfluidics involves fluid manipulation at the microscale level, it has the potential for achieving high‐resolution separation and sorting of blood cells down to a single‐cell level, with an added benefit of integrating physical and biological methods for blood cell separation and analysis on the same single chip platform. This paper will first review the conventional methods of processing and sorting blood cells, followed by a discussion on how microfluidics is emerging as an efficient tool to rapidly change the field of blood cell sorting for blood‐based therapeutic and diagnostic applications.  相似文献   
38.
Postharvest storage of beans (Phaseolus vulgaris L.) can alter the color, texture, flavor and time required for cooking. These alterations have been associated with the ‘hard‐to‐cook’ phenomenon (HTC) and a reduction in the quality of the grains. HTC has been linked to the genotype, environment and/or storage conditions of the grains, but very few studies have shown the interrelationship between these factors. Therefore, the objective of this study was to analyze the effect of two genotypes, Paraiso and Peruano, grown under the same phosphorus levels, on the development of HTC. These genotypes were evaluated for phytate, protein, tannin and phosphorus contents, hydration time and cooking time when stored for 45, 90 and 135 days, at 29 °C and 5 °C at a relative humidity of 75%. HTC was observed in Peruano after 135 days, which correlated with a reduction in the phytate content. Paraiso did not show HTC even though there was a reduction of tannins during the storage period. The lower storage temperature appeared to control HTC for both genotypes. Overall, the content of phytate can be an indicative factor for the cookability of fresh beans when the relationship between genotype and storage conditions has been determined. Copyright © 2007 Society of Chemical Industry  相似文献   
39.
Elemental composition and structural analysis are important considerations in evaluating osseous matrix formation in tissue-engineered bone constructs. Using X-ray spectroscopy techniques, such as the X-ray scanning analytical microscope (XSAM), enables the mapping of elements with simultaneous structural imaging. The aim of this study was to evaluate the feasibility of this microscopy technique to analyze tissue-engineered samples. Fused deposition modeling (FDM), a rapid prototyping technology, was used to fabricate 3-D scaffolds made of polycaprolactone (PCL)–hydroxylapatite (HA) (90/10 wt.%). The scaffolds had a regular architecture and the honeycomb-like pores were fully interconnected with a total matrix porosity of 70%. Biopsies of human calvarial corticocancellous bone were harvested and a primary explant system of the morcellized grafts was established within the PCL–HA constructs.

Tissue constructs were cultured in vitro for 3 weeks and then implanted into the back of Balb C nude mice. Grafts were explanted after 17 weeks and tissue formation was assessed via XSAM and CT scan and histology.

Outgrowth from osteoblasts from the bone chips started after 2 weeks in culture, with cells migrating radially into the composite constructs. Osteocalcin levels showed an increasing tendency during the 3-week culture period. After 17 weeks in vivo, areas of ectopic bone formation could be detected throughout the whole construct, compared to the control implants where only fibrous tissue formation was present. In the XSAM, calcium- and phosphorus-enriched bands presented a relatively even distribution with some dense spots. Quantitative elemental analysis revealed an average X-ray intensity of 131 cps for calcium in a mapped area of 2 mm2. Trichrome Goldner staining showed good vascularization as well as irregular osteoid formation and mineralization of the newly formed woven bone-like tissue.

In this study, we were able to show that the XSAM is a useful analytical technique which enabled us to trace elements simultaneously and provides structural image with mapping information in tissue-engineered samples.  相似文献   

40.
Edward L.K. Mui 《Carbon》2004,42(14):2789-2805
A review of the production of activated carbons from waste tyres is presented. The effects of various process parameters, particularly, temperature and heating rate, on the pyrolysis stage are reviewed. The influence of activating conditions, physical and chemical, nature of the activation chemicals, on the active carbon properties are discussed. Under certain process conditions several active carbons with BET surface areas over 1000 m2/g have been produced with extensive micropore volumes, over 40% of the total pore volume.A review is carried out of the reaction kinetic modeling applied to the pyrolysis of tyres and the chemical activation of tyres. The models cover one step and two step pyrolysis models, plus more recent models which are based on the actual chemical components such as natural rubber, SBR and other additives.  相似文献   
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