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排序方式: 共有208条查询结果,搜索用时 15 毫秒
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Lopes AA López SN Regasini LO Junior JM Ambrósio DL Kato MJ da Silva Bolzani V Cicarelli RM Furlan M 《Natural product research》2008,22(12):1040-1046
This study describes the antichagasic potential of five compounds isolated from leaves of Piper crassinervium (Piperaceae). Two prenylated benzoic acid derivatives, one prenylated hydroquinone and two flavanones, were evaluated. The in vitro trypanocidal activity was determined against epimastigote forms of Trypanosoma cruzi (Y strain), the etiologic agent of Chagas disease. The most active compound was the prenylated hydroquinone [1,4-dihydroxy-2-(3(0),7(0)-dimethyl-1(0)-oxo-2(0)-E,6(0)-octadienyl)benzene] with an IC(50) value of 6.10 microg mL(-1), which was in the same order of activity if compared with the positive control benznidazole (IC(50) = 1.60 microg mL(-1)). This is the first report of trypanocidal activity for prenylated hydroquinone and benzoic acid derivatives. 相似文献
94.
Costa Renyer A. Oliveira Kelson M. T. de Cássia Saraiva Nunomura Rita Junior Earle Silva A. Pinheiro Maria Lucia B. Costa Emmanoel V. Barison Andersson 《Structural chemistry》2018,29(1):299-314
Structural Chemistry - A theoretical and experimental DFT study of the vibrational, structural, and quantum properties of 9-methoxy-canthin-6-one (I) and... 相似文献
95.
Novel 3‐hydroxypropyl‐bonded phase by direct hydrosilylation of allyl alcohol on amorphous hydride silica 下载免费PDF全文
A novel 3‐hydroxypropyl (propanol)‐bonded silica phase has been prepared by hydrosilylation of allyl alcohol on a hydride silica intermediate, in the presence of platinum (0)‐divinyltetramethyldisiloxane (Karstedt's catalyst). The regio‐selectivity of this synthetic approach had been correctly predicted by previous reports involving octakis(dimethylsiloxy)octasilsesquioxane (Q8M8H) and hydrogen silsesquioxane (T8H8), as molecular analogs of hydride amorphous silica. Thus, C‐silylation predominated (~94%) over O‐silylation, and high surface coverages of propanol groups (5 ± 1 μmol/m2) were typically obtained in this work. The propanol‐bonded phase was characterized by spectroscopic (infrared (IR) and solid‐state NMR on silica microparticles), contact angle (on fused‐silica wafers) and CE (on fused‐silica tubes) techniques. CE studies of the migration behavior of pyridine, caffeine, Tris(2,2′‐bipyridine)Ru(II) chloride and lysozyme on propanol‐modified capillaries were carried out. The adsorption properties of these select silanol‐sensitive solutes were compared to those on the unmodified and hydride‐modified tubes. It was found that hydrolysis of the SiH species underlying the immobilized propanol moieties leads mainly to strong ion‐exchange‐based interactions with the basic solutes at pH 4, particularly with lysozyme. Interestingly, and in agreement with water contact angle and electroosmotic mobility figures, the silanol–probe interactions on the buffer‐exposed (hydrolyzed) hydride surface are quite different from those of the original unmodified tube. 相似文献
96.
Henrique Silvano Arruda Eric Keven Silva Nayara Macêdo Peixoto Araujo Gustavo Araujo Pereira Glaucia Maria Pastore Mario Roberto Marostica Junior 《Molecules (Basel, Switzerland)》2021,26(9)
Anthocyanins are naturally occurring phytochemicals that have attracted growing interest from consumers and the food industry due to their multiple biological properties and technological applications. Nevertheless, conventional extraction techniques based on thermal technologies can compromise both the recovery and stability of anthocyanins, reducing their global yield and/or limiting their application in food systems. The current review provides an overview of the main innovative processes (e.g., pulsed electric field, microwave, and ultrasound) used to recover anthocyanins from agri-food waste/by-products and the mechanisms involved in anthocyanin extraction and their impacts on the stability of these compounds. Moreover, trends and perspectives of anthocyanins’ applications in food systems, such as antioxidants, natural colorants, preservatives, and active and smart packaging components, are addressed. Challenges behind anthocyanin implementation in food systems are displayed and potential solutions to overcome these drawbacks are proposed. 相似文献
97.
de Lima Filho E.B. da Silva E.A.B. de Carvalho M.B. da Silva Junior W.S. Koiller J. 《IEEE transactions on circuits and systems. I, Regular papers》2005,52(12):2739-2753
In this paper, we use the multidimensional multiscale parser (MMP) algorithm, a recently developed universal lossy compression method, to compress data from electrocardiogram (ECG) signals. The MMP is based on approximate multiscale pattern matching , encoding segments of an input signal using expanded and contracted versions of patterns stored in a dictionary. The dictionary is updated using concatenated and displaced versions of previously encoded segments, therefore MMP builds its own dictionary while the input data is being encoded. The MMP can be easily adapted to compress signals of any number of dimensions, and has been successfully applied to compress two-dimensional (2-D) image data. The quasi-periodic nature of ECG signals makes them suitable for compression using recurrent patterns, like MMP does. However, in order for MMP to be able to efficiently compress ECG signals, several adaptations had to be performed, such as the use of a continuity criterion among segments and the adoption of a prune-join strategy for segmentation. The rate-distortion performance achieved was very good. We show simulation results were MMP performs as well as some of the best encoders in the literature, although at the expense of a high computational complexity. 相似文献
98.
Neto Ade B Bustamante MC Oliveira JH Granato AC Bellão C Badino AC Badino AC Barboza M Hokka CO 《Applied biochemistry and biotechnology》2012,166(1):208-221
A study was made for purification of cephamycin C from fermentation of Streptomyces clavuligerus. Initially, the culture broth was clarified by microfiltration and ultrafiltration, after which the resulting permeates were
subjected to nonspecific adsorption and ion-exchange chromatography on resin columns. The antibiotic activity was measured
by the biological method at each stage by assaying its activity against the Escherichia coli ESS, super sensitive to β-lactam antibiotic. The purification processes were assessed in relation to the variables affecting
each step. The purification efficiency by nonspecific adsorption was monitored by UV spectrophotometry, while the ion-exchange
adsorption fractions were assessed by NMR spectroscopy. Some of the fractions obtained during purification were also analyzed
by mass spectrometry (LC/MS and LC/MS/MS) to identify the cephamycin C molecule. These preliminary results proved the process
feasibility. 相似文献
99.
Luiz Carlos S. de Figueiredo‐Filho Vagner B. dos Santos Bruno Campos Janegitz Thiago Brito Guerreiro Orlando Fatibello‐Filho Ronaldo Censi Faria Luiz Humberto Marcolino‐Junior 《Electroanalysis》2010,22(11):1260-1266
A bismuth‐film electrode (BiFE) ex situ electrochemically deposited onto a copper substrate has been presented for paraquat determination. The bismuth film was electrochemically deposited at an applied potential of ?0.18 V vs. Ag/AgCl (3.0 M KCl) for 200 s. The analytical curve was linear in the paraquat concentration range from 6.6×10?7 M to 4.8×10?5 M with a limit of detection of 9.3×10?8 M. The method presented satisfactory results at a confidence level of 95% and the performance was evaluated in water samples. 相似文献
100.