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排序方式: 共有328条查询结果,搜索用时 78 毫秒
41.
Peng F Tao Q Wu X Dou H Spencer S Mang C Xu L Sun L Zhao Y Li H Zeng S Liu G Hao X 《Fitoterapia》2012,83(3):568-585
Twenty-nine phenolic compounds were isolated from the root bark of fresh (Yunnan) ginger and their structures fully characterized. Selected compounds were divided into structural categories and twelve compounds subjected to in-vitro assays including DPPH radical scavenging, xanthine-oxidase inhibition, monoamine oxidase inhibition, rat-brain homogenate lipid peroxidation, and rat pheochromocytoma PC12 cell and primary liver cell viability to determine their antioxidant and cytoprotective properties. Isolated compounds were also tested against nine human tumor cell lines to characterize anticancer potency. Several diarylheptanoids and epoxidic diarylheptanoids were effective DPPH radical scavengers and moderately effective at inhibiting xanthine oxidase. An enone–dione analog of 6-shogaol (compound 2) was isolated and identified to be most effective at protecting PC12 cells from H2O2-induced damage. Almost all tested compounds inhibited lipid peroxidation. Three compounds, 6-shogaol, 10-gingerol and an enone-diarylheptanoid analog of curcumin (compound 6) were identified to be cytotoxic in cell lines tested, with KB and HL60 cells most susceptible to 6-shogaol and the curcumin analog with IC50 < 10 μM. QSAR analysis revealed cytotoxicity was related to compound lipophilicity and chemical reactivity. In conclusion, we observed distinct compounds in fresh ginger to have biological activities relevant in diseases associated with reactive oxygen species. 相似文献
42.
Yanchong Huangfu Michael E. Essington Shawn A. Hawkins Forbes R. Walker John S. Schwartz Alice C. Layton 《Communications in Soil Science and Plant Analysis》2019,50(11):1358-1369
Determining the total elemental concentrations of soils requires a total dissolution method, in which hydrofluoric acid (HF) is commonly used. However, this method is tedious and risky due to the dangerous reagent HF. This study compared a single acid extraction technique using a nitric acid (HNO3) extraction method to total dissolution (HF + microwave assisted aqua regia) for evaluating the total elemental concentrations in soils and sediments. The two methods were used to analyze the elemental content of soils and sediments from the Oostanaula Creek and Pond Creek watersheds in East Tennessee. Twenty-one elements (Al, Ba, Ca, Co, Cr, Cu, Fe, K, La, Li, Mg, Mn, Nd, P, S, Si, Sr, Ti, V, Zn, and Zr) were subsequently measured using inductively coupled plasma optical emission spectrometry (ICP-OES). The extraction efficiency for HNO3 relative to the total was compared and discussed. In general, HNO3 can extract the elements in absorbed phases and those residing in non-silicate minerals. Six elements (Ba, Co, Fe, Ca, Mn, and P) generated significant correlations between total and HNO3 in both OC and PC watersheds. Finally, the elements were grouped according to the interrelationships of their total elemental concentrations based on the dendrogram plots, suggesting their geochemical association in soils and sediment forming minerals. 相似文献
43.
The force‐restore method originally developed to enable soil temperature predictions assumes that soil is uniform with depth (i.e. the vertical gradient of thermal diffusivity is zero in soil) and that thermal conduction is the only heat transfer mechanism necessary for prediction of soil temperature. These assumptions hamper the applicability of the force‐restore method to many natural soil conditions. The main objective of this study is to revise the force‐restore method by extending it to include the possibility of soil heterogeneity with depth (i.e. non‐zero vertical gradient of thermal diffusivity in soil) and to include the possible occurrence of convective heat transfer as well as conductive heat transfer in soil. Soil temperatures calculated by the current and the revised force‐restore methods for a shallow soil layer were compared with measured soil temperatures at a bare soil site in the China Loess Plateau from 22 to 26 July 2005. Results showed that the revised method improved on the current force‐restore method, which overestimated either the diurnal amplitude or the phase shift for the shallow soil layer. These results indicate that the revised force‐restore method is more applicable than the current force‐restore method for predicting soil temperatures in naturally occurring non‐uniform soil. The revised force‐restore method has potential application within many land‐atmosphere numerical models. 相似文献
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45.
Shawn‐Elizabeth Maloney Firdous A. Khan Tracy S. Chenier Mariana Diel de Amorim Michael Anthony Hayes Elizabeth L. Scholtz 《Reproduction in domestic animals》2019,54(3):473-479
Proteomic analysis of mare uterine flush fluid provides a minimally invasive technique for studying protein changes associated with the oestrous cycle. The aim of this study was to identify differentially abundant proteins in the uterine flush fluid of mares in oestrus and dioestrus. In this study, uterine flush fluid samples were collected from eight reproductively healthy mares in either oestrus (n = 5) or dioestrus (n = 3). Proteomic analysis was performed using liquid chromatography‐tandem mass spectrometry. Of 172 proteins identified, six proteins (immunoglobulin lambda‐like polypeptide 1, haemoglobin subunit alpha, alpha‐1B‐glycoprotein, serotransferrin, apolipoprotein A‐1, and haemoglobin subunit beta) were significantly more abundant in oestrus. These proteins may contribute to the endometrial defence system through roles in inflammation, immunity or antimicrobial activity. In other species, some of these proteins have been described as immunoglobulins, negative acute phase proteins or defence agents against micro‐organisms. During dioestrus, immunoglobulin alpha‐1 chain C region‐related, complement factor I, CD 109 antigen and uterocalin, were significantly more abundant. Research in other species suggests that these four proteins contribute to the immune response through proposed immunoregulatory characteristics, complement system involvement or roles in B cell–T cell interactions. In conclusion, ten differentially abundant proteins were identified in the uterine flush fluid of mares in oestrus and dioestrus. Targeted studies on these proteins could elucidate their role in uterine defence mechanisms during the oestrous cycle in the mare. 相似文献
46.
Amber D. Goguen Shawn J. Riley John F. Organ Brent A. Rudolph 《Human Dimensions of Wildlife》2018,23(3):197-212
An increased societal focus on wildlife as food and recent policy deliberations regarding legal markets for wild-harvested meat are encouraging wildlife managers and researchers to examine the amount, use, and distribution of meat yielded through recreational hunting. We used responses to questions on the Michigan Deer Harvest Study to estimate the maximum yield of edible venison and assess hunters’ sharing behaviors. We estimated 11,402–14,473 metric tons of edible venison were procured during the 2013 hunting season. Of hunters who harvested a deer, 85% shared their venison. Hunters who shared did so with an average of 5.6 people (SD = 4.5). Sharing occurred most frequently within tight social networks: members of hunters’ households (69%), relatives (52%), and friends, neighbors, or coworkers (50%). In the absence of legal markets, venison is distributed widely by hunters and greatly amplifies the number of people benefiting from hunting. Nonetheless, we also identified the potential breadth of exposure to disease or contaminants from wild-harvested meat. 相似文献
47.
Impact of rewilding,species introductions and climate change on the structure and function of the Yukon boreal forest ecosystem
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Rudy BOONSTRA Stan BOUTIN Thomas S. JUNG Charles J. KREBS Shawn TAYLOR 《Integrative zoology》2018,13(2):123-138
Community and ecosystem changes are happening in the pristine boreal forest ecosystem of the Yukon for 2 reasons. First, climate change is affecting the abiotic environment (temperature, rainfall and growing season) and driving changes in plant productivity and predator–prey interactions. Second, simultaneously change is occurring because of mammal species reintroductions and rewilding. The key ecological question is the impact these faunal changes will have on trophic dynamics. Primary productivity in the boreal forest is increasing because of climatic warming, but plant species composition is unlikely to change significantly during the next 50–100 years. The 9–10‐year population cycle of snowshoe hares will persist but could be reduced in amplitude if winter weather increases predator hunting efficiency. Small rodents have increased in abundance because of increased vegetation growth. Arctic ground squirrels have disappeared from the forest because of increased predator hunting efficiency associated with shrub growth. Reintroductions have occurred for 2 reasons: human reintroductions of large ungulates and natural recolonization of mammals and birds extending their geographic ranges. The deliberate rewilding of wood bison (Bison bison) and elk (Cervus canadensis) has changed the trophic structure of this boreal ecosystem very little. The natural range expansion of mountain lions (Puma concolor), mule deer (Odocoileus hemionus) and American marten (Martes americana) should have few ecosystem effects. Understanding potential changes will require long‐term monitoring studies and experiments on a scale we rarely deem possible. Ecosystems affected by climate change, species reintroductions and human alteration of habitats cannot remain stable and changes will be critically dependent on food web interactions. 相似文献
48.
We investigated the potential role of feral pigs and wild deer as FMD reservoirs with a susceptible-latent-infected-recovered geographic-automata model, using spatially referenced data from southern Texas, USA. An uncontrolled FMD outbreak initiated in feral pigs and in wild deer might infect up to 698 (90% prediction interval 181, 1387) and 1557 (823, 2118) cattle and affect an area of 166 km(2) (53, 306) and 455 km(2) (301, 588), respectively. The predicted spread of FMD virus infection was influenced by assumptions we made regarding the number of incursion sites and the number of neighborhood interactions between herds. Our approach explicitly incorporates the spatial relationships between domesticated and non-domesticated animal populations, providing a new framework to explore the impacts, costs, and strategies for the control of foreign animal diseases with a potential wildlife reservoir. 相似文献
49.
David R. Horton 《Integrated Pest Management Reviews》1999,4(1):1-20
Pear psylla, Cacopsylla pyricola (Foerster) (Homoptera: Psyllidae), is one of the key insect pests in North American pear production. In some growing areas, more than 50% of dollars spent to control arthropod pests in commercial pear are directed specifically at controlling this species. Control measures require accurate and timely information about dispersal, onset of egg-laying in spring, densities in the orchard, and age composition of the population. To meet these ends, a number of sampling methods have been developed to monitor pear psylla, the most common being (for pest management purposes) visual inspection of spurs and foliage for nymphs and eggs, and use of beat trays to monitor adults. Action thresholds have been developed for counts obtained with either method. However, threshold estimates are fairly narrowly defined, referring to a somewhat limited group of pear cultivars, type of injury to be prevented, and pest management program being used. Further refinement has been difficult because of an incomplete understanding of psylla's spatial distribution, seasonal changes in spatial distribution, and unknown or seasonally changing action thresholds. Beat trays and visual inspection of foliage have also been used to monitor pear psylla in various types of research projects, including studies of dispersal and biological control. Other sampling tools used in research include sticky traps, suction traps, and water pan traps. Density estimates obtained by these different sampling methods tend be positively correlated, albeit with high levels of unexplained variation. For counts obtained by sticky traps, much of the unexplained variation can be attributed to flight activity of the insect, which is known to depend (at a minimum) on sex, morphotype, reproductive status, time of year, time of day, leaf fall, and weather. Thus, if sticky traps are to be used in a pest management program for pear psylla, it must be recognized that counts on traps will include both density and (potentially large) behavioral components. I conclude this review with suggestions about the type of research that would improve monitoring techniques for this pest and assist eventually in developing a more effective control program. 相似文献
50.