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排序方式: 共有283条查询结果,搜索用时 15 毫秒
1.
This paper describes an assay procedure for acyclovir quantification in human skin after in vitro transdermal transport experiments. The procedure employs warm distilled water for acyclovir (ACV) extraction and high-performance liquid chromatography (HPLC) as analytical method. The procedure has good reproducibility, sensitivity and specificity, resulting in a reliable method for biopharmaceutical studies of ACV distribution in skin tissue. The chromatographic conditions set up, using distilled water as mobile phase, makes the analytical procedure simple and easy to perform. 相似文献
2.
In Fifth Generation (5G) Heterogeneous Mobile Networks (HetNets), deploying dense small cell networks makes user association more challenging. The process of collecting cell load information from the User Equipments (UEs) and broadcasting the feedback message involves significant overhead and time complexity. Moreover, the UEs may not know the optimum cell to reselect, satisfying its data rate requirements. In order to overcome these drawbacks, in this paper, we propose to design an Hierarchical and Hybrid Cell Load Balancing (HHCLB) technique using Selective Handoff. In this technique, the UEs of each cell are grouped into clusters depending on their proximity distance. Each cluster contains a cluster controller (CC) which is in charge of determining the intra-cell load and redirecting the cell-reselection request of a UE. If the data rate of any UE in a cluster becomes less than its required rate, then the cell reselection process is performed. By simulation results, it is shown that load balancing can be done proactively (implicitly) by the CCs when the load is unbalanced or can be done on demand (explicitly) when a UE send a request for cell reselection. In the case of Macro cells, HHCLB attains 71% higher throughput for low load scenario and 59% higher throughput for high load scenario. Similarly, in the case of Femto cells, HHCLB attains 19% higher throughput for low load scenario and 27% higher throughput for high load scenario. 相似文献
3.
Fatos Xhafa Leonard Barolli Santi Caballé Raul Fernández 《The Journal of supercomputing》2010,53(1):45-65
With the fast development of IT technologies, virtual organizations are more and more present in the current collaborative
work and learning activity. For instance, many subjects in virtual distance learning are organized as online groups of students,
who use groupware tools to complete their learning tasks. In this paper, we address the efficient management of peer groups
in JXTA-based P2P systems as a key issue in many P2P applications that use peer group as a unit such as for remote execution
of tasks in parallel and distributed applications. From this perspective, we consider peer grouping as the basis in the development
of groupware tools in P2P systems. 相似文献
4.
Santi CaballéAuthor Vitae Thanasis DaradoumisAuthor VitaeFatos XhafaAuthor Vitae Angel JuanAuthor Vitae 《Computers in human behavior》2011,27(4):1372-1381
Learning and knowledge building have become critical competences for people in the knowledge society era. In this paper, we propose a sociolinguistic dialogue model for understanding how learning evolves and how cognitive process is constructed in on-line discussions. The knowledge extracted from this model is used to assess participation behavior, knowledge building and performance. The ultimate purpose is to provide effective feedback, evaluation and monitoring to the discussion process. Seven hundred students from the Open University of Catalonia in Spain participated in this study. Results showed that learning and knowledge building may be greatly enhanced by presenting selected knowledge to learners as for their particular skills exhibited during interaction. In addition, this valuable provision of information is used as a meta cognitive tool for tutors and moderators for monitoring and evaluating the discussion process more conveniently. This contribution presents our conceptual model for interaction management as well as key design guidelines and evaluation results. Implications of this study are remarked and further research directions are proposed. 相似文献
5.
Santi Chillemi Author VitaeMichele Barbi Author Vitae Angelo Di GarboAuthor Vitae 《Neurocomputing》2011,74(8):1159-1164
The transmission of excitatory inputs by a network of coupled pyramidal cells is investigated by means of numerical simulations. The pyramidal cell models are coupled by excitatory synapses and each one receives an excitatory pulse at a random time extracted from a Gaussian distribution. Moreover, each cell model is injected with a noisy current. It was found that the excitatory coupling promotes the transmission of the synaptic inputs on a time scale of a few ms. 相似文献
6.
7.
Release characteristics of four model drugs from drug-loaded electrospun cellulose acetate fiber mats 总被引:1,自引:0,他引:1
Ultra-fine fiber mats of cellulose acetate (CA; Mw ≈ 30?000 Da; degree of acetyl substitution ≈ 2.4) containing four different types of model drugs, i.e., naproxen (NAP), indomethacin (IND), ibuprofen (IBU), and sulindac (SUL), were successfully prepared by electrospinning from 16% w/v CA solutions in 2:1 v/v acetone/N,N-dimethylacetamide (DMAc). The amount of the drugs in the solutions was fixed at 20 wt.% based on the weight of CA powder. The morphology of the drug-loaded electrospun (e-spun) CA fiber mats was smooth, with the average diameters of these fibers ranging between 263 and 297 nm. No presence of the drug aggregates of any kind was observed on the surfaces of these fibers, suggesting that the drugs were encapsulated well within the fibers. After submersion in the acetate buffer solution at 37 °C for 24 h, the drug-loaded e-spun CA fiber mats swelled particularly well (i.e., 570-630%), while the corresponding solvent-cast film counterparts did not. The release characteristics of the model drugs from both the drug-loaded CA fiber mats and the drug-loaded as-cast CA films were carried out by the total immersion method in the acetate buffer solution at 37 °C. At any given immersion time point, the release of the drugs from the drug-loaded e-spun CA fiber mats was greater than that from the corresponding as-cast films. The maximum release of the drugs from both the drug-loaded fiber mats and films could be ranked as follows: NAP > IBU > IND > SUL. 相似文献
8.
The hepatitis A virus (HAV) and poliovirus 1 were added to estuarine water samples and their stability in maintenance medium was compared to that in water samples untreated and treated by heat and filtration. The inactivation curves show that the inactivating factor is biological in nature. 相似文献
9.
Anthocyanin composition and extractability in berry skin and wine of Vitis vinifera L. cv. Aglianico
Manfra M De Nisco M Bolognese A Nuzzo V Sofo A Scopa A Santi L Tenore GC Novellino E 《Journal of the science of food and agriculture》2011,91(15):2749-2755
BACKGROUND: The present article reports the anthocyanin content in the berry skin and wine of the Italian red grape cultivar Aglianico (clone VCR11 grafted onto 1103 Paulsen), one of the most ancient vines and famous for its deep‐red colour. Anthocyanins were extracted from frozen berry skin in an acidified methanol solution. The extraction mixtures, monitored for 120 h, were analysed by high‐performance liquid chromatography. RESULTS: The extraction from berry skin of delphinidin, petunidin and malvidin appeared to be a time‐independent process, whereas the concentration of peonidin increased linearly with time. Peonidin‐O‐acetyl‐glucoside was transferred from skin more slowly than petunidin‐O‐acetyl‐glucoside and malvidin‐O‐acetyl‐glucoside. The anthocyanin composition of the resulting wine showed that the total anthocyanin content was about one‐tenth of the corresponding berry skin content. The ratio acetyl/coumaroyl anthocyanins in the wine was sharply higher than the value in berry skin (0.85 and 0.10, respectively), indicating an enrichment of acetyl derivatives in the wine. CONCLUSION: Levels of single anthocyanins in wine were not always correlated with those detected in grapes, as they were affected by winemaking. The high values of some anthocyanins in Aglianico wine could ameliorate its quality, increasing the chromatic properties, aging stability and product acceptance. Copyright © 2011 Society of Chemical Industry 相似文献
10.