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排序方式: 共有496条查询结果,搜索用时 15 毫秒
81.
Adriana Andrade Carvalho Daiane Finger Christiane Schinieder Machado Eduardo Morgado Schmidt Patrícia Marçal da Costa Ana Paula Negreiros Nunes Alves Thamires Maria Fontenele Morais Maria Goretti Rodrigues de Queiroz Sueli Pércio Quináia Marcos Roberto da Rosa Julio Murilo Trevas dos Santos Cláudia Pessoa Manoel Odorico de Moraes Letícia Veras Costa-Lotufo Alexandra Christine Helena Frankland Sawaya Marcos Nogueira Eberlin Yohandra Reyes Torres 《Food chemistry》2011
The present study aimed to evaluate in vivo and in vitro the antitumoural activity of a propolis extract obtained with edible vegetable oil and its fractions and also to investigate its chemical composition by LC–MS and LC–MS/MS. To evaluate the toxicological aspects related to the propolis extract treatment, hematological, biochemical, histopathological and morphological analyses of treated animals were performed. All propolis extracts showed an in vivo antitumour activity in the experimental model with a moderate toxicity effect at experimental exposure levels. The oil extract was as effective as the ethanolic extract at inhibiting tumour growth. In vitro assays showed that the whole oil extract produced better inhibition of tumour cells than its fractions. LC–MS and LC–MS/MS identified four phenolic acids and three flavonoids. The anticancer potential of the oil extract of propolis has been demonstrated and the edible vegetable oil was shown as an attractive alternative solvent to extract bioactive natural propolis components. 相似文献
82.
Christiane Queiroz Antonio Jorge Ribeiro da Silva Maria Lúcia Mendes Lopes Eliane Fialho Vera Lúcia Valente-Mesquita 《Food chemistry》2011
This study describes the extraction and characterisation of cashew apple polyphenol oxidase (PPO) and the effect of wounding on cashew apple phenolic acid composition, PPO activity and fruit browning. Purification factor was 59 at 95% (NH4)2SO4 saturation. For PPO activity, the optimal substrate was catechol and the optimum pH was 6.5. PPO Km and Vmax values were 18.8 mM and 13.6 U min−1 ml−1, respectively. Ascorbic acid, citric acid, sodium sulphite and sodium metabisulphite decreased PPO activity, while sodium chloride increased PPO activity. Wounding at 2 °C and 27 °C for 24 h increased PPO activity but storage at 40 °C reduced PPO activity. Gallic acid, protocatechuic acid and cinnamic acid (free and conjugate) were identified in cashew apple juice. Cutting and subsequent storage at 40 °C hydrolysed cinnamic acid. 5-Hydroxymethylfurfural content in cashew apple juice increased after injury and storage at higher temperatures, indicating non-enzymatic browning. 相似文献
83.
Anton Salomon Lilit Amirkhanyan Christiane Ullrich Mykhaylo Motylenko Olga Fabrichnaya Jens Kortus David Rafaja 《Journal of the European Ceramic Society》2018,38(16):5590-5600
Rutile coatings deposited on corundum substrates are considered as promising functional elements improving the efficiency of the filtration of oxide inclusions out of aluminium melts. This contribution describes the reactions between rutile and two kinds of the aluminium melts and discusses the consequences of these reactions for the filtration process. It was found that the contact of rutile coatings with molten aluminium leads to the formation of a corundum layer at the solid/liquid interface. The exposure of the rutile coatings to molten AlSi7Mg0.6 alloy produces an interface layer of MgTiO3. The interface layers possess defined orientation relationship to rutile which is characteristic for locally heteroepitaxial growth. The density functional theory calculations revealed that the TiO2/α-Al2O3 and TiO2/MgTiO3 interfaces with the orientation relationships observed experimentally have low interface energies. The mechanisms of the interface layer formation and the impact of these layers on the degradation of the rutile coatings are discussed. 相似文献
84.
Marcus Weyd Christian Pflieger Andy Vogel Hannes Richter Volker Prehn Christiane Günther Frank Splittgerber Alessa Gäbler Daniel Kaulbars Patrick Bräutigam Marcus Franke Samira Lambertz Julian Schlechtweg Ingolf Voigt 《化学,工程师,技术》2021,93(9):1432-1439
Reducing micropollutant pollution of water bodies is an important objective of water management and an integral part of environmental policy. Ceramic nanofiltration membranes were developed as multichannel membranes of increased membrane area and rotating disk filters. The membranes developed show retention of over 80 % for PEG 400. The membranes are currently being tested for the separation of micropollutants from wastewater contaminated with pharmaceuticals. With the help of a downstream oxidative process, the trace substances remaining in the permeate are degraded. 相似文献
85.
Guillaume Roussel Christiane Weber Xavier Briottet Xavier Ceamanos 《International journal of remote sensing》2018,39(5):1593-1614
For remote-sensing applications such as spectra classification or identification, atmospheric correction constitutes a very important pre-processing step, especially in complex urban environments where a lot of phenomenons alter the shape of the signal. The objective of this article is to compare the efficiency of two atmospheric correction algorithms, COCHISE (atmospheric COrrection Code for Hyperspectral Images of remote-sensing SEnsors) and an empirical method, on hyperspectral data and for classification applications. Classification is carried out on several simulated spaceborne data sets with different spatial resolutions (from 1.6 to 9.6 m). Four classifiers are considered in the study: a k-means, a Support Vector Machine (SVM), and a sun/shadow version of each of them, which processes sunlit and shadowed pixels separately. Results show that the most relevant atmospheric method for classification depends on the spatial resolution of the processed data set. Indeed, if the empirical method performs better on high-resolution data sets (up to 4%), its superiority fades out as the spatial resolution decreases, especially with the lower spatial resolution where COCHISE can be 10% more accurate than the empirical method. 相似文献
86.
87.
88.
Yong Men Hubert Gnaser Christiane Ziegler Ralf Zapf Volker Hessel Gunther Kolb 《Catalysis Letters》2005,105(1-2):35-40
Thermal desorption spectroscopy (TDS) under ultra high vacuum (UHV) condition has been used to investigate the desorption
characteristics of Cu/CeO2/γ-Al2O3 thin film catalysts coated onto the microchannel of a microreactor. TDS results demonstrate that surface desorption profiles
and chemical properties (acid–base and redox properties) are remarkably influenced by the catalyst composition, i.e. the loading
of copper and ceria. The enhanced basicity with the increase of ceria loading and the decrease of copper loading is evident
from the shifted desorption maximum of CO2 in TDS spectra. Three oxygen species, ranging from weakly bound oxygen desorbed at low temperature to the strongly held lattice
oxygen desorbed at high temperature, are easily discernible and clearly identified by O2 TDS spectra, depending on the catalyst compositions. The concomitant thermal desorption of O2, CO2, and H2O at low temperature indicates the unique chemical properties of copper/ceria catalyst with appropriate copper and ceria contents.
The observed low-temperature feature is ascribed to the role of porthole of copper/ceria interfacial area for several desorbed
species. The weakly bound oxygen species is attributed to the enhanced abundance of copper/ceria interfacial anionic vacancies
created by the intimate contact between copper and ceria entities and its impact on steam reforming of methanol (SRM) reaction
is tentatively discussed in terms of reverse oxygen spillover. 相似文献
89.
Characterization of C–S–H and C–A–S–H phases by electron microscopy imaging,diffraction, and energy dispersive X‐ray spectroscopy 下载免费PDF全文
Christiane Rößler Frank Steiniger Horst‐Michael Ludwig 《Journal of the American Ceramic Society》2017,100(4):1733-1742
Improving concrete sustainability by increasing durability requires a detailed knowledge about microstructural properties. Due to the nanoscale nature of hydrate phases that determine concrete properties, microstructural characterization remains a challenge. Analytical electron microscopy offers promising techniques to characterize cement hydrates. In this study, electron microscopy imaging, diffraction, and energy dispersive X‐ray spectroscopic information are combined in order to compare the structural properties of calcium silicate hydrate (C–S–H) and calcium aluminum silicate hydrate (C–A–S–H) phases. Results are shown for 28 days hydrated C–(A)–S–H of portland cement and cement containing ground granulated blast‐furnace slag (GGFBS). Electron diffraction patterns of single fibrous C–S–H and foil‐like C–A–S–H phases reveal a nanocrystalline structure. Also, it is shown by electron diffraction pattern that the crystal structures of C–S–H and C–A–S–H phases are similar. It is confirmed that the crystal structure of 14 Å tobermorite serves as good base for the structure of C–S–H. The electron diffraction patterns of fibrous C–S–H show streaks which indicate stacking faults, proofing that polymerization of silicate chains in C–S–H is limited. Here, we demonstrate for the first time that the dreierketten silicate chains contained in the C–S–H structure are oriented in parallel to the long axis of C–S–H fibers. This finding should be implemented in modeling of crystal growth of C–S–H. 相似文献
90.
城市增长是未来几个世纪备受关注的问题。为了保证城市可持续发展,有必要对城市的发展进行监控,但预测城市的发展趋势需要一些空间信息的支持、卫星图像能够提供可靠的信息用来评定城市增长的不同状态,而预测未来的建设区段则更加重要。本文构建了相互作用模型(interaction models),或者更精确地说叫潜力模型(potential model),以确定城市空间的扩展方向。该模型被运用于法国斯特拉斯堡地区的分析,采用了两张遥感数据影像,一张用于模型处理,一张用于检验结果。另外,模型还运用GIS技术以提高准确度,同时还考虑到了交通网络。 相似文献