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排序方式: 共有507条查询结果,搜索用时 18 毫秒
41.
42.
Salzmann CG Radaelli PG Hallbrucker A Mayer E Finney JL 《Science (New York, N.Y.)》2006,311(5768):1758-1761
Two hydrogen ordered phases of ice were prepared by cooling the hydrogen disordered ices V and XII under pressure. Previous attempts to unlock the geometrical frustration in hydrogen-bonded structures have focused on doping with potassium hydroxide and have had success in partially increasing the hydrogen ordering in hexagonal ice I (ice Ih). By doping ices V and XII with hydrochloric acid, we have prepared ice XIII and ice XIV, and we analyzed their structures by powder neutron diffraction. The use of hydrogen chloride to release geometrical frustration opens up the possibility of completing the phase diagram of ice. 相似文献
43.
Liu PT Stenger S Li H Wenzel L Tan BH Krutzik SR Ochoa MT Schauber J Wu K Meinken C Kamen DL Wagner M Bals R Steinmeyer A Zügel U Gallo RL Eisenberg D Hewison M Hollis BW Adams JS Bloom BR Modlin RL 《Science (New York, N.Y.)》2006,311(5768):1770-1773
In innate immune responses, activation of Toll-like receptors (TLRs) triggers direct antimicrobial activity against intracellular bacteria, which in murine, but not human, monocytes and macrophages is mediated principally by nitric oxide. We report here that TLR activation of human macrophages up-regulated expression of the vitamin D receptor and the vitamin D-1-hydroxylase genes, leading to induction of the antimicrobial peptide cathelicidin and killing of intracellular Mycobacterium tuberculosis. We also observed that sera from African-American individuals, known to have increased susceptibility to tuberculosis, had low 25-hydroxyvitamin D and were inefficient in supporting cathelicidin messenger RNA induction. These data support a link between TLRs and vitamin D-mediated innate immunity and suggest that differences in ability of human populations to produce vitamin D may contribute to susceptibility to microbial infection. 相似文献
44.
The objective of this study was to investigate the potential of various raw bean components as precursors of pyrogallol (1), hydroxyhydroquinone (2), catechol (3), 4-ethylcatechol (4), 4-methylcatechol (5), and 3-methylcatechol (6) under quasi "natural" roasting conditions by using the recently developed "in bean" model roast experiments. Freeze-dried, fully extracted bean shells were loaded with aqueous solutions of either single coffee compounds or fractions isolated from the raw bean solubles. After freeze-drying, these reconstituted beans were roasted, aqueous coffee brews were prepared, and the target phenols were quantified by means of a stable isotope dilution assay with LC-MS/MS detection. On the basis of the quantitative data, it can be concluded that upon coffee bean roasting, catechol (3) is primarily formed by degradation of caffeoylquinic acids from both the caffeic acid and the quinic acid moiety of the molecule, as well as from Maillard-type reactions from carbohydrates and amino acids. In contrast, pyrogallol (1) and hydroxyhydroquinone (2) are efficiently generated from carbohydrates and amino acids and, in addition, from free or chlorogenic acid bound quinic acid moieties. 4-Ethylcatechol (4) is exclusively generated upon thermal breakdown of caffeic acid moieties. 3-Methylcatechol (6) is formed primarily from the Maillard reactions and, to a minor extent, also from various phenolic precursors, whereas 4-methylcatechol (5) is produced in trace amounts only from all of the different precursors investigated. On the basis of this precursor study, reaction routes explaining the formation of the target phenols are proposed. 相似文献
45.
Kummer M Geyer H Imboden I Auer J Lischer C 《Veterinary journal (London, England : 1997)》2006,172(1):58-66
The understanding of the normal position of the third phalanx (P3) and the distal sesamoid bone in relation to the size and shape of the hoof capsule in sound horses is helpful in the diagnosis of equine foot lameness. Some measurements on radiographs used to define the position of the pedal bone within the hoof capsule are significantly influenced by hoof trimming and the height of the withers. In this study, the front hooves of 40 Warmblood horses were radiographed twice, eight weeks apart, both before and after their hooves were trimmed by an experienced farrier. Using the software programme Metron PX, 22 parameters on the lateromedial view and 16 parameters on the dorsopalmar view were measured and the effect of hoof trimming and height of the withers were calculated, respectively. Some of the hoof parameters showed mild positive correlation with the height of the withers. In 70% of the horses the left hoof capsule and P3 were significantly larger than the right. Hoof trimming had a remarkable influence on hoof conformation, especially for parameters in the toe region. Of all the measurements that describe the position of the third phalanx (P3) in relation to the hoof capsule, the distances between the distal tip of P3 to the solar surface of the foot, P3 to the tip of the toe and P3 to the point of break-over showed the greatest differences before and after trimming. The database of the present study can be used by farriers and veterinarians as a guideline for routine and corrective shoeing of Warmblood horses. 相似文献
46.
S Naik N Bouladoux C Wilhelm MJ Molloy R Salcedo W Kastenmuller C Deming M Quinones L Koo S Conlan S Spencer JA Hall A Dzutsev H Kong DJ Campbell G Trinchieri JA Segre Y Belkaid 《Science (New York, N.Y.)》2012,337(6098):1115-1119
Intestinal commensal bacteria induce protective and regulatory responses that maintain host-microbial mutualism. However, the contribution of tissue-resident commensals to immunity and inflammation at other barrier sites has not been addressed. We found that in mice, the skin microbiota have an autonomous role in controlling the local inflammatory milieu and tuning resident T lymphocyte function. Protective immunity to a cutaneous pathogen was found to be critically dependent on the skin microbiota but not the gut microbiota. Furthermore, skin commensals tuned the function of local T cells in a manner dependent on signaling downstream of the interleukin-1 receptor. These findings underscore the importance of the microbiota as a distinctive feature of tissue compartmentalization, and provide insight into mechanisms of immune system regulation by resident commensal niches in health and disease. 相似文献
47.
Hijazin M Ulbegi-Mohyla H Alber J Lämmler C Hassan AA Timke M Kostrzewa M Prenger-Berninghoff E Weiss R Zschöck M 《Berliner und Münchener tier?rztliche Wochenschrift》2012,125(1-2):32-37
In the present study A. (T.) abortisuis isolated from pigs and bovines could be reliably identified by determination of phenotypic properties, genotypically by polymerase chain reaction with the help of A. (T.) abortisuis 16s-23S rDNA intergenic spacer region specific oligonucleotide primer and by Matrix-Assisted Laser Desorption Ionization-Time Of Flight mass spectrometry (MALDI-TOF MS). The latter appeared to be a promising tool for fast and cost effective identification of this species and might help to elucidate the role A. (T.) abortisuis plays in infections of pigs, bovines, possibly other animals or humans. 相似文献
48.
Müller T Freuling CM Gschwendner P Holzhofer E Mürke H Rüdiger H Schuster P Klöss D Staubach C Teske K Vos A 《Berliner und Münchener tier?rztliche Wochenschrift》2012,125(5-6):197-202
Large-scale oral vaccination of wildlife against rabies using aerial bait distribution has been successfully used to control terrestrial wildlife rabies in Europe and North America. A technical milestone to large-scale oral rabies vaccination campaigns in Europe was the development of fully-automated, computer-supported and cost-efficient technology for aerial distribution of baits like the SURVIS -system. Each bait released is recorded by the control unit through a sensor, with the exact location, time and date of release and subsequently the collected data can be evaluated, e.g. in GIS programmes. Thus, bait delivery systems like SURVIS are an important management tool for flight services and the responsible authorities for the optimization and evaluation of oral vaccination campaigns of wildlife against rabies or the control of other relevant wildlife diseases targeted by oral baits. 相似文献
49.
An agent-based approach to modeling impacts of agricultural policy on land use, biodiversity and ecosystem services 总被引:1,自引:1,他引:0
Mark Brady Christoph Sahrbacher Konrad Kellermann Kathrin Happe 《Landscape Ecology》2012,27(9):1363-1381
We present extensions to the agent-based agricultural policy simulator (AgriPoliS) model that make it possible to simulate the consequences of agricultural policy reform on farmers?? land use decisions and concomitant impacts on landscape mosaic, biodiversity and ecosystem services in a real agricultural region. An observed population of farms is modelled as a multi-agent system where individual farm-agent behaviour and their interactions??principally competition for land??are defined through an optimization framework with land use and landscape impacts resulting as emergent properties of the system. The model is calibrated to real data on the farms and the landscape to be studied. We illustrate the utility of the model by evaluating the potential impacts of three alternative frameworks for the European Union Common Agricultural Policy (CAP) on landscape values in two marginal agricultural regions. Mosaic value was found to be sensitive to the choice of policy scheme in one of the landscapes, whereas significant trade-offs were shown to occur in terms of species richness by habitat and species composition at the landscape scale in both regions. The relationship between food production and other ecosystem services was found to be multifaceted. Thus illustrating the difficulty of achieving landscape goals in a particular region with simple or general land management rules (such as the current rules attached to CAPs direct payments). Given the scarcity of funding for conservation, the level and conditions for allocating direct payments are, potentially, of great importance for preserving landscape values in marginal agricultural regions (subject to levels of other support). 相似文献
50.
This report presents the case of a 21-year-old Warmblood mare referred to the clinic with neurological dysfunctions and considerable signs of discomfort. A fracture of the caudal vertebral body of C2 with a very unusual radiographic appearance was diagnosed, and the mare was euthanized due to deterioration in neurological status. Histology revealed no evidence of neoplasia or pathological fracture. 相似文献