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排序方式: 共有150条查询结果,搜索用时 15 毫秒
1.
Andrea Mariela Araya-Sibaja Valdir Soldi Carlos Eduardo Maduro Campos Simone Gonçalves Cardoso 《Drug development and industrial pharmacy》2015,41(5):851-858
Progesterone is a natural hormone steroid used in humans for several treatments and in livestock for artificial insemination, which exhibits two polymorphic forms at ambient conditions: form 1 and form 2. Form 2 is metastable and more soluble than form 1; however, it is not suitable to use as powder raw material because it transforms into form 1 by the effects of grinding. A polymorphic screening of progesterone based on polymer-induced heteronucleation method was performed as an alternative to prepare the metastable form. Polyvinyl alcohol, hydroxypropyl methylcellulose (HPMC), dextran, gelatin, polyisoprene (PI) and acrylonitrile-butadiene (NBR) copolymer were used. Crystals were prepared from 0.5, 10 and 40?mg/mL solutions in acetone at room temperature by solvent evaporation. The samples were characterized by X-ray powder diffraction, differential scanning calorimetry (DSC), scanning electron microcopy and attenuated total reflectance infrared Fourier transform spectroscopy. Form 1 was nucleated from 40?mg/mL solutions on the six polymers and from 10?mg/mL solutions on PI and NBR. The mixture of form 1 and form 2 was obtained from 10?mg/mL solution on HPMC, dextran and gelatin and from 0.5?mg/mL solution crystallizations. Therefore, the polymeric devices, which crystallized the metastable and more soluble polymorph (2) of progesterone, would be a promissory alternative for the pharmaceutical applications. 相似文献
2.
Mariela Hristova 《国际互联网参考资料服务季刊》2013,18(2):45-64
This study explores citation management usage patterns of undergraduate students, graduate students, and faculty. We analyze the temporal use of RefWorks with an eye toward informing reference services and instruction initiatives. The frequency and intensity of use allow us to glean an understanding of user groups on campus. While our findings for undergraduates and faculty conform to general assumptions, graduate students emerge as a group more similar to faculty than anticipated. Graduate students’ use of RefWorks is characterized by steady logins and large amounts of references; thus, suggesting that personalized instruction might benefit graduate students more than scheduled workshops. 相似文献
3.
Mariela Cerrada René-Vinicio Sánchez Fannia Pacheco Diego Cabrera Grover Zurita Chuan Li 《Applied Intelligence》2016,44(3):687-703
Feature selection is an important aspect under study in machine learning based diagnosis, that aims to remove irrelevant features for reaching good performance in the diagnostic systems. The behaviour of diagnostic models could be sensitive with regard to the amount of features, and significant features can represent the problem better than the entire set. Consequently, algorithms to identify these features are valuable contributions. This work deals with the feature selection problem through attribute clustering. The proposed algorithm is inspired by existing approaches, where the relative dependency between attributes is used to calculate dissimilarity values. The centroids of the created clusters are selected as representative attributes. The selection algorithm uses a random process for proposing centroid candidates, in this way, the inherent exploration in random search is included. A hierarchical procedure is proposed for implementing this algorithm. In each level of the hierarchy, the entire set of available attributes is split in disjoint sets and the selection process is applied on each subset. Once the significant attributes are proposed for each subset, a new set of available attributes is created and the selection process runs again in the next level. The hierarchical implementation aims to refine the search space in each level on a reduced set of selected attributes, while the computational time-consumption is improved also. The approach is tested with real data collected from a test bed, results show that the diagnosis precision by using a Random Forest based classifier is over 98 % with only 12 % of the attributes from the available set. 相似文献
4.
Luiz Antonio Joia Mariela Fontenelle Sily de Assis 《Information Systems Management》2019,36(3):228-242
ABSTRACTIn this paper, we use the Delphi method to identify the main motivations that have led IT professionals to intend to move to another area. We found that the pursuit of career growth and the quest for acquiring new experiences and abilities have a marked impact on the IT professional turnaway intention. Moreover, female IT professionals and IT professionals oriented by the career advancement paradigm have a higher propensity to abandon the IT area. 相似文献
5.
Giuseppe Di Battista Erlebach T. Hall A. Patrignani M. Pizzonia M. Schank T. 《Networking, IEEE/ACM Transactions on》2007,15(2):267-280
We investigate the problem of computing the types of the relationships between Internet Autonomous Systems. We refer to the model introduced by Gao [IEEE/ACM Transactions on Networking, 9(6):733-645, 2001] and Subramanian (IEEE Infocom, 2002) that bases the discovery of such relationships on the analysis of the AS paths extracted from the BGP routing tables. We characterize the time complexity of the above problem, showing both NP-completeness results and efficient algorithms for solving specific cases. Motivated by the hardness of the general problem, we propose approximation algorithms and heuristics based on a novel paradigm and show their effectiveness against publicly available data sets. The experiments provide evidence that our algorithms perform significantly better than state-of-the-art heuristics 相似文献
6.
In this work we report the results of a combined biochemical and electrochemical study aimed to analyze both the growth of biofilms of Pseudomonas fluorescens on copper samples and its possible role in the instability of the metal/electrolyte interface.DNA and RNA were quantified along the time for biofilms grown on copper and glass to estimate both the growth of the bacterial population and its metabolic state (through the RNA/DNA ratio). The expression and specific activity of catalase were also determined to gain insight into their possible role in corrosion acceleration. The electrochemical behavior of the biofilm/copper interface was monitored by Linear Polarization Resistance (Rp) and electrochemical impedance spectroscopy (EIS) along the experiments.Results showed a longer lag phase for biofilms developing on copper that included a period of high metabolic activity (as measured by the RNA/DNA ratio) without biomass growth. Biological activity introduced a new time constant at intermediate frequencies in EIS spectra whose capacitive behavior increased with the biofilm development. The increment in this biofilm-related signal was accompanied by a strong limitation to charge transfer through a diffusion controlled process probably due to oxygen exhaustion by cells respiration, while the resistance of the interface decreased presumably due to oxide dissolution by local acidification under the colonies. In addition, catalase activity was found to be high in mature copper-tolerant biofilms, which differentially express a catalase isoform not present in biofilms growing on glass. 相似文献
7.
Gabriel P. Silva Juliana Correa Cristiana Bentes Sergio Guedes Mariela Gabioux 《International journal of parallel programming》2014,42(2):265-286
This paper presents the Netuno supercomputer, a large-scale cluster installed at Federal University of Rio de Janeiro in Brazil. A detailed performance evaluation of Netuno is presented, depicting its computational and I/O performance, as well as the results for two real-world applications. Since building a high- performance cluster for running a wide range of applications is a non-trivial task, some lessons learned from assembling and operating this cluster, such as the excellent performance of the OpenMPI library, and the relevance of employing an efficient parallel file system over the traditional NFS system, can be useful knowledge to support the design of new systems. Currently, Netuno is being heavily used to run large scale simulations in the areas of ocean modeling, meteorology, engineering, physics, and geophysics. 相似文献
8.
Rosalba Lanciotti Francesca Patrignani Luciana Iucci Maria Elisabetta Guerzoni Giovanna Suzzi Nicoletta Belletti Fausto Gardini 《Food chemistry》2007,104(2):693-701
The aim of this work was to evaluate the biogenic amine (BA) content during the ripening of both bovine and ovine cheeses obtained using milk subjected to a homogenization treatment at 100 MPa before cheese-making. The data obtained were compared with those from cheeses produced by the same milks without any treatment or thermized. The results showed that both microbial ecology and BA concentrations of cheeses during ripening were significantly influenced by the type of milk used for cheese-making and by the treatment applied to the raw materials. In particular, the microbial counts found in Caciotta indicated that the high pressure homogenization (HPH) of milk significantly reduced the presence of the yeasts, Micrococcaceae and lactobacilli at the end of ripening. On the other hand, the HPH treatment of milk favoured the proliferation of yeasts in ovine cheese. Moreover, the ovine cheeses were characterized by a remarkably higher accumulation of BA than bovine cheeses. However, the HPH treatment of milk was able to drastically reduce the biogenic amine concentrations in both cheese typologies at the end of ripening. 相似文献
9.
Iucci L Patrignani F Belletti N Ndagijimana M Elisabetta Guerzoni M Gardini F Lanciotti R 《Meat science》2007,75(4):669-675
The aim was to study the effects of Debaryomyces hansenii and Yarrowia lipolytica strains, used with lactic acid starter cultures (Lactobacillus plantarum), in the manufacture of dried fermented sausages in order to understand their effects on volatile profile, biogenic amine content and sensory properties. The experimental data showed that every yeast strain produced a specific profile of volatile metabolic products. The yeasts also gave sausages with distinctive sensory properties. The degree of mincing also influenced these properties, but none of these factors had significant influence upon the accumulation of biogenic amines. 相似文献
10.
Benítez B Archile A Rangel L Bracho M Hernández M Márquez E 《Archivos latinoamericanos de nutrición》2002,52(3):307-312
The purpose of this research was to evaluate the nutritional quality and acceptability of a meat product formulated with mechanically deboned poultry meat (40%), bovine plasma (40%) and bovine red cells (3%) as major ingredients. Proteins, fat, humidity and ash were determined by AOAC procedure, iron and calcium by Atomic Absorption Spectrometry and essential amino acids by HPLC. Biological evaluation was performed using digestibility and PER procedures. To evaluate the acceptability (flavor, color and odor) of the product were used 277 children. Results indicated that 100 g of the formulated meat product contain 10.7 g of proteins, 4.4 g of fat, 68.6 g of humidity, 2.9 g of ash, 4.9 mg of iron, 46.6 mg of calcium. Essential amino acids are above the FAO requirements for a highly nutritional protein digestibility (92.4%) and PER (2.18). Acceptability was 91.3% for flavor, 81.2% for color and 92.4% for odor. The high nutritional quality and acceptability along with the low cost make this meat product suitable for government social programs. 相似文献