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排序方式： 共有119条查询结果，搜索用时 15 毫秒
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Deborah S. Greco Rod A.W. Rosychuk Gregory K. Ogilvie Lynn M. Harpold Camilla H. Van Liew 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1998,12(1):7-10
Thirty adult, client-owned dogs were diagnosed with hypothyroidism based on history, physical examination findings, hematologic and biochemical abnormalities, thyrotropin (TSH) response testing, endogenous canine thyrotropin (cTSH) concentration, or both, and total serum thryoxine concentration. All dogs received levothyroxine (L-thyroxine) at an initial dose of 22 μg/kg PO sid in either a tablet (13 dogs) or chewable form (17 dogs). Energy expenditure of each dog during apparent rest was estimated with an open-flow indirect calorimetry system by determining the rates of carbon dioxide production and oxygen consumption. Energy expenditure of apparent rest (EE) was lower in untreated hypothyroid dogs compared with reference values for EE. After treatment with L-thyroxine, EE of the hypothyroid dogs was significantly ( P < .05) higher than pretreatment values. 相似文献
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Camilla Wikstrm 《Forest Pathology》1975,5(6):349-356
In contrast to the woodrotting fungi which can only attack Populus tremula after felling, Phellinus tremulae successfully invades the central part of the living tree. Possible causes for this difference were investigated. It was found that sterile wood samples were decomposed more rapidly by saprophytic fungi than by parasitic fungi. With both types of fungi, heartwood was more resistant to decay than sapwood. It is postulated that living sapwood inhibits infection by most woodrotting fungi, but that P. tremulae can successfully overcome this barrier. This postulate cannot be confirmed by experiments using sterilized wood samples. 相似文献
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Isolation and determination of alpha-dicarbonyl compounds by RP-HPLC-DAD in green and roasted coffee
Daglia M Papetti A Aceti C Sordelli B Spini V Gazzani G 《Journal of agricultural and food chemistry》2007,55(22):8877-8882
Glyoxal, methylglyoxal, and diacetyl formed as Maillard reaction products in heat-treated food were determined in coffee extracts (coffee brews) obtained from green beans and beans with different degrees of roast. The compounds have been reported to be mutagenic in vitro and genotoxic in experimental animals in a number of papers. More recently, alpha-dicarbonyl compounds have been implicated in the glycation process. Our data show that small amounts of glyoxal and methylglyoxal occur naturally in green coffee beans. Their concentrations increase in the early phases of the roasting process and then decline. Conversely, diacetyl is not found in green beans and forms later in the roasting process. Therefore, light and medium roasted coffees had the highest glyoxal and methylglyoxal content, whereas dark roasted coffee contained smaller amounts of glyoxal, methylglyoxal, and diacetyl. For the determination of coffee alpha-dicarbonyl compounds, a reversed-phase high performance liquid chromatography with a diode array detector (RP-HPLC-DAD) method was devised that involved the elimination of interfering compounds, such as chlorogenic acids, by solid phase extraction (SPE) and their derivatization with 1,2-diaminobenzene to give quinoxaline derivatives. Checks of SPE and derivatization conditions to verify recovery and yield, respectively, resulted in rates of 100%. The results of the validation procedure showed that the proposed method is selective, precise, accurate, and sensitive. 相似文献
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Maxine P. Piggott Samuel C. Banks Ben T. Broadhurst Christopher J. Fulton Mark Lintermans 《水产资源保护:海洋与淡水生态系统》2021,31(1):173-184
- Detecting rare species is often a necessity for conservation and management, yet challenging for many field survey methods. Environmental DNA (eDNA) is a highly promising solution that has been shown to outperform many established survey methods.
- Macquarie perch (Macquaria australasica) is an endangered native species that has declined significantly in range and abundance. Detection of M. australasica was compared with an abundant alien fish species (Oncorhynchus mykiss) using eDNA and three conventional survey methods: gill nets, electrofishing and fyke nets.
- eDNA occupancy estimates for both fish species were compared using four different models to investigate what effect these differences have on false positives and false negatives for the rare and common fish species. These models used unadjusted eDNA detections in water samples, eDNA detections that have been screened using a limit of detection method to remove potential false positives, eDNA data supplemented with a second survey method, or eDNA data augmented with sequencing of positive polymerase chain reaction replicates.
- eDNA surveying as a single detection method was found to be more efficient and sensitive compared with each capture method separately and combined. Occupancy estimates for the common and rare species did not vary significantly between the four site occupancy-detection models, suggesting that supplementary data may not have as much effect on occupancy estimates compared with other approaches such as temporal or spatial sampling.
- We conclude that eDNA outperforms the three established survey methods for both a rare and common freshwater fish species. Although there was no significant effect of augmenting eDNA survey methods with other survey data, additional data may improve confidence in detection, and provide confirmatory evidence for unexpected or new detections of a species.
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Joanna Day David Power Rosemary Gales John Bannister Maxine P. Piggott Kerstin Bilgmann Robert Harcourt Luciano B. Beheregaray Luciana M. Möller 《水产资源保护:海洋与淡水生态系统》2021,31(6):1452-1465
- Understanding the factors driving population structure in marine mammals is needed to evaluate the impacts of previous exploitation, current anthropogenic threats, conservation status, and success of population recovery efforts.
- Sperm whales are characterized by a worldwide distribution, low genetic diversity, complex patterns of social and genetic structure that differ significantly within and between ocean basins, and a long history of being commercially whaled. In Australia, sperm whales from the (International Whaling Commission assigned) southern hemisphere ‘Division 5’ stock were very heavily exploited by whaling.
- The present study assessed the potential effects of whaling on the genetic diversity of sperm whales in Australia and the population genetic structure of these whales within a global context. A combination of historical and contemporary sperm whale samples (n = 157) were analysed across six regions, from south-eastern Australia (‘Division 6’ stock in the Pacific Ocean) to south-western Australia (‘Division 5’ stock in the Indian Ocean).
- Sperm whales sampled from the ‘Division 5’ and ‘Division 6’ stocks belong to the same population based on nuclear and mitochondrial DNA (mtDNA) analyses. Four novel sperm whale mtDNA haplotypes were identified in animals from Australian waters. Levels of genetic diversity were low in Australian sperm whales but were similar to those previously reported for populations in the Indian and Pacific Oceans.
- Given the genetic distinctiveness of sperm whales in Australian waters from other regions in the Pacific and Indian Oceans, and the lack of recovery in population numbers, further scientific studies are needed to increase our understanding of population dynamics and the effectiveness of threat management strategies in this species.
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Characterization of commercial kava-kava herbal drug and herbal drug preparations by means of nuclear magnetic resonance spectroscopy 总被引：1，自引：0，他引：1
Bilia AR Bergonzi MC Lazari D Vincieri FF 《Journal of agricultural and food chemistry》2002,50(18):5016-5025
The efficiency of one- and two-dimensional NMR experiments in characterizing the content of the constituents of both herbal drugs and herbal drug preparations is demonstrated for kava-kava. These experiments directly detect active constituents represented by kavalactones in both a finely powdered herbal drug and a commercial extract. In addition, NMR spectroscopy can detect all other compounds present in the extract. As previously evidenced, NMR experiments can represent a generally applicable technique for rapid screening and are a complement to the classical analytical techniques such as high-performance thin-layer chromatography, high-performance liquid chromatography, capillary gas chromatography, and electrophoresis. These experiments can be considered a very simple and fast analytical method to obtain a fingerprint of the herbal drugs and their preparations, and to quantify the content of the active principles of the extract. 相似文献
9.
Fry FH Okarter N Baynton-Smith C Kershaw MJ Talbot NJ Jacob C 《Journal of agricultural and food chemistry》2005,53(3):574-580
Allicin, an active ingredient of garlic, possesses a range of antimicrobial properties. Unfortunately, certain properties of the compound, such as chemical instability and low miscibility with water, have hampered its practical use in the past. Here, we show that it is possible to use a binary system consisting of the plant enzyme alliinase and its substrate alliin to generate allicin, and hence antifungal activity, in situ. During application, the two inactive components generate compounds that inhibit growth and infection-related development of the rice blast fungus Magnaporthe grisea. It is therefore possible to "trigger" biological activity in a controlled, yet effective manner. Apart from circumventing many of the drawbacks of allicin, this binary system has additional important advantages, such as low toxicity of its individual components and selective activation. Importantly, alliinase is also able to use different substrates, therefore paving the way to a range of novel, binary antimicrobial systems with custom-made chemical and biochemical properties. 相似文献
10.
英国第一个气候周(Climate Week)组织者称,采取主动应对气候变化的行动(pro-climate action)会有助于企业和生意的发展。各行各业都在积极采取行动支持抑制气候变化的努力。气候周是一个新的机会来展示最得意的成绩。方式多样,可以是开会,发表新的研究成果或只是宣传更有利于环境的实用的经营之道。气候周也是企业在对未来有重要意义的问题上取得领先地位的良机。木业企业如何为抑制气候变化做贡 相似文献