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排序方式: 共有501条查询结果,搜索用时 15 毫秒
21.
M.B. SÁNCHEZ‐ILÁRDUYA C. SÁNCHEZ‐FERNÁNDEZ M. VILORIA‐BERNAL D.M. LÓPEZ‐MÁRQUEZ L.A. BERRUETA B. GALLO F. VICENTE 《Australian Journal of Grape and Wine Research》2012,18(2):203-214
Background and Aims: During wine ageing, a great variety of reactions take place, resulting in an immense variety of products whose structure sometimes remains unknown. The aim of this work is the study of different fragmentation patterns of flavanol‐anthocyanin derivatives formed along the wine ageing; these patterns are useful for elucidating the different structures of these compounds and other new related ones. Methods and Results: Several wines from the Protected Denomination of Origin Rioja have been studied by an analytical method that combines column chromatography and high‐performance liquid chromatography with diode array and mass and tandem mass spectrometric detections. Thirty‐five coloured flavanol‐anthocyanin compounds formed by direct reaction or by acetaldehyde‐mediated condensation have been identified. For direct reaction derivatives, two different fragmentation patterns (one of them not previously reported) have been observed depending on the position of flavanol in the coloured derivative. Several compounds have been identified in aged wines for the first time to the authors' knowledge, like (+)‐gallocatechin‐cyanidin‐3‐glucoside and (+)‐catechin‐cyanidin‐3‐glucoside Conclusions: The developed analytical procedure has allowed the identification of some compounds for the first time, and two different fragmentation patterns have been observed depending on the position of flavanol in the pigment. Significance of the Study: The establishment of different fragmentation patterns allows the structural elucidation of unknown compounds. 相似文献
22.
Pharmaceuticals, hormones, and other organic wastewater contaminants in U.S. streams, 1999-2000: a national reconnaissance 总被引:14,自引:0,他引:14
Kolpin DW Furlong ET Meyer MT Thurman EM Zaugg SD Barber LB Buxton HT 《Environmental science & technology》2002,36(6):1202-1211
To provide the first nationwide reconnaissance of the occurrence of pharmaceuticals, hormones, and other organic wastewater contaminants (OWCs) in water resources, the U.S. Geological Survey used five newly developed analytical methods to measure concentrations of 95 OWCs in water samples from a network of 139 streams across 30 states during 1999 and 2000. The selection of sampling sites was biased toward streams susceptible to contamination (i.e. downstream of intense urbanization and livestock production). OWCs were prevalent during this study, being found in 80% of the streams sampled. The compounds detected represent a wide range of residential, industrial, and agricultural origins and uses with 82 of the 95 OWCs being found during this study. The most frequently detected compounds were coprostanol (fecal steroid), cholesterol (plant and animal steroid), N,N-diethyltoluamide (insect repellant), caffeine (stimulant), triclosan (antimicrobial disinfectant), tri(2-chloroethyl)phosphate (fire retardant), and 4-nonylphenol (nonionic detergent metabolite). Measured concentrations for this study were generally low and rarely exceeded drinking-water guidelines, drinking-water health advisories, or aquatic-life criteria. Many compounds, however, do not have such guidelines established. The detection of multiple OWCs was common for this study, with a median of seven and as many as 38 OWCs being found in a given water sample. Little is known about the potential interactive effects (such as synergistic or antagonistic toxicity) that may occur from complex mixtures of OWCs in the environment. In addition, results of this study demonstrate the importance of obtaining data on metabolites to fully understand not only the fate and transport of OWCs in the hydrologic system but also their ultimate overall effect on human health and the environment. 相似文献
23.
RBF Network Methods for Face Detection and Attentional Frames 总被引:1,自引:1,他引:0
In this paper we introduce a set of adaptive vision techniques which could be used, for example, in video-conferencing applications. First, we present methods for finding faces and selecting attentional frames to focus visual processing. Second, we present methods for recognising individual gesture phases for camera control. Finally, we discuss how these techniques can be extended to virtual groups of multiple people interacting at multiple sites. 相似文献
24.
李科锋 《建设机械技术与管理》2006,19(8):42-44
第八届国际公路水运交通技术与设备展览会(CHINA TRANSPO 2006)将于2006年9月26-29日在北京全国农业展览馆举行。截至目前.参展企业已近300家,包括徐工、柳工、三一重工、中联重科、西筑等筑路机械厂家.中海油、壳牌等道路材料生产企业.中国重型汽车集团、宇通客车、厦门金龙等商用车辆制造企业,尤其引人注目的是,本届展会有十余家省市交通厅局单位设台参展,这是历年来同类展会中不多见的。据悉,目前预订的展位面积已达38000平方米,一场交通行业的国际展览盛宴正在徐徐拉开帷幕。 相似文献
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26.
Microsporidia, as a group, cause a wide range of infections, though two species of microsporidia in particular, Enterocytozoon bieneusi and Encephalitozoon intestinalis, are associated with gastrointestinal disease in humans. To date, the mode of transmission and environmental occurrence of microsporidia have not been elucidated due to lack of sensitive and specific screening methods. The present study was undertaken with recently developed methods to screen several significant water sources. Water concentrates were subjected to community DNA extraction followed by microsporidium-specific PCR amplification, PCR sequencing, and database homology comparison. A total of 14 water concentrates were screened; 7 of these contained human-pathogenic microsporidia. The presence of Encephalitozoon intestinalis was confirmed in tertiary sewage effluent, surface water, and groundwater; the presence of Enterocytozoon bieneusi was confirmed in surface water; and the presence of Vittaforma corneae was confirmed in tertiary effluent. Thus, this study represents the first confirmation, to the species level, of human-pathogenic microsporidia in water, indicating that these human-pathogenic microsporidia may be waterborne pathogens. 相似文献
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29.
IL Gerner JC N?rregaard OA Jensen JU Prause 《Canadian Metallurgical Quarterly》1998,160(25):3728-3731
The clinicopathological characteristics of 343 naevi of the conjunctiva were studied. A significant increase in the number of naevi excised per year was observed. This may have been caused by an increased exposure to actinic rays. An approximately even distribution was found between the three main locations: caruncle, limbal area and eye ball. Intrastromal naevi were excised at a higher median age than compound naevi, and the lowest median age at excision was for junction naevi, which is in accordance with the known histopathological nature of naevi. Recurrence occurred in nine patients (2.7%), and one had transformed into a malignant melanoma. Eight of the recurring naevi were located in the limbal area. Eight of the nine patients were women, suggesting hormonal factors as a possible cause. Recommendations for the handling of conjunctival naevi are given, based on the present findings and on previous reports. 相似文献
30.
The characteristics are described of an antibody (designated L6) which has virtually absolute specificity for heptadecapeptide gastrin. This antibody binds G17, but does not bind peptide fragments or molecular forms of gastrin comprising G17 with either amino acid deletions, or additions, at the carboxyl- and amino-terminals. In serum from patients with Zollinger-Ellison syndrome the only form of gastrin revealed by L6 was compatible with G17, and there was good agreement between estimated G17 concentrations in serum analyzed by gel filtration and by direct radioimmunoassay using L6. Using L6 in conjunction with antibodies specific for carboxyl- and amino-terminals of G17 it has been possible to measure concentrations of different forms of gastrin in serum of normal subjects after a meal in greater detail than previously possible. After a light meal consisting of eggs, toast, and Oxo, serum concentrations of G17 measured by L6 increased to a peak 20 min after feeding (delta gastrin, 19 pmoles per liter; n = 17). In contrast, concentration of G34 peaked at 50 min (delta gastrin, 27 pmoles per liter). Small amounts of amino-terminal fragments of G17 were present throughout the digestive period. Applying the known ratio of biological potencies of G34 and G17 for stimulation of acid secretion in man, it is estimated that G17 accounts for about 75% of the biological activity in blood after a meal, even though G34 is present in higher molar concentrations. 相似文献