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排序方式: 共有181条查询结果,搜索用时 31 毫秒
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Andrew C. Smith Verena Pfahler Federica Tamburini Martin S. A. Blackwell Steven J. Granger 《植物养料与土壤学杂志》2021,184(1):25-34
Understanding the phosphate oxygen isotope (δ18O‐PO4) composition of bedrock phosphate sources is becoming ever more important, especially in areas of soil research which use this isotope signature as a proxy for biological cycling of phosphorus (P). For many of these studies, obtaining a sample of the source bedrock or applied mineral fertiliser for isotope analysis is impossible; meaning there is now a demand for a comprehensive characterisation of global bedrock δ18O‐PO4 to support this work. Here we compile δ18O‐PO4 data from a wide range of global bedrocks, including 56 new values produced as part of this study and a comprehensive overview of those within the previously existing literature. We present δ18O‐PO4 data from the range of major phosphatic lithologies alongside as much metadata for the samples as could be gathered. Much of the data comes from bedrocks of marine sedimentary origin (< 1 Ma = > +22‰, > 540 Ma = ≈ +12‰), but we also present data from bedrocks associated with guano (range: +19.5 to +15‰) and igneous deposits (range: +12 to –0.8‰), both of which have distinct δ18O‐PO4 signatures due to their formation mechanisms. We show that where repeat measurements of the same formation have been undertaken, regardless of method or exact sample location, there is an average within formation error of ± 1.25‰. This is important, as is constitutes a reasonable level of uncertainty for phosphorus cycling studies which need to estimate bedrock δ18O‐PO4 composition based on the literature. In combination, this data set presents 284 δ18O‐PO4 values from 56 countries; a comprehensive starting point for researchers interested in understanding bedrock end member δ18O‐PO4. 相似文献
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Eleonora Binatti Gianni Zoccatelli Francesca Zanoni Giulia Don Federica Mainente Roberto Chignola 《Marine drugs》2021,19(3)
Radiation-induced fibrosis is a serious long-lasting side effect of radiation therapy. Central to this condition is the role of macrophages that, activated by radiation-induced reactive oxygen species and tissue cell damage, produce pro-inflammatory cytokines, such as transforming growth factor beta (TGF). This, in turn, recruits fibroblasts at the site of the lesion that initiates fibrosis. We investigated whether astaxanthin, an antioxidant molecule extracted from marine and freshwater organisms, could help control macrophage activation. To this purpose, we encapsulated food-grade astaxanthin from Haematococcus pluvialis into micrometer-sized whey protein particles to specifically target macrophages that can uptake material within this size range by phagocytosis. The data show that astaxanthin-loaded microparticles are resistant to radiation, are well-tolerated by J774A.1 macrophages, induce in these cells a significant reduction of intracellular reactive oxygen species and inhibit the release of active TGF as evaluated in a bioassay with transformed MFB-F11 fibroblasts. Micro-encapsulation of bioactive molecules is a promising strategy to specifically target phagocytic cells and modulate their own functions. 相似文献
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In Europe, rural landscapes are characterized by the presence of hedgerows and networks. In recent decades changes in agricultural systems, due in particular to the intensification of agricultural practices, have caused a transformation of hedgerows and networks, thereby reducing their qualities and changing their ecological and social functions. Yet, no global framework to analyze and design hedgerows and networks is available. Our paper is a step forward in combining the ecological and social dimension of hedgerows and hedgerow networks for both analytical and planning purposes. We propose to use a landscape grammar for deciphering the structural and functional aspects of hedgerow units and networks and to formalize rules for design and management based on scientific evidence. In the case of hedgerows, landscape grammar consists of letters, or single units of trees and shrubs of different species and their different shapes related to management practices. Appropriate or meaningful combinations of letters create words and sentences, hence forming hedgerow networks. In order to test the suitability of the grammar for reading or understanding and consequently writing or planning hedgerows in different landscapes, two study areas were chosen: Pleine-Fougères in Brittany (France) and Pianura Padana in Piedmont (Italy). The basic units, the aggregated units and the network were analyzed respectively as the letters, the words and the syntax of our landscape grammar. This metaphor provides an analytical framework for understanding hedgerows, from the individual tree to the landscape. Our model anticipates the concerns of both researchers and policymakers throughout the hedgerow network planning process. 相似文献
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Serum creatine kinase isoenzymes and macroenzymes in dogs with different neurologic diseases
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Morandi F Mattoon JS Lakritz J Turk JR Wisner ER 《American journal of veterinary research》2003,64(7):935-944
OBJECTIVE: To develop protocols for helical computed tomography (CT) and axial high-resolution CT (HRCT) of lungs and correlate densitometric CT values with morphometric and histologic data for normal pulmonary tissue in dogs. ANIMALS: 8 healthy adult dogs. PROCEDURE: 2 dogs were used to establish a protocol for helical CT and HRCT of lungs. Six dogs were used to acquire densitometric CT data regarding normal lungs. After the dogs were euthanatized, their lungs were fixed and sampled for morphometric and histologic evaluation. Four CT acquisitions were compared by means of paired t tests. RESULTS: For normal lung tissue of dogs, mean densitometric CT value obtained during helical CT scans reconstructed in a sharp algorithm was -846 Hounsfield units. Values obtained via helical CT or HRCT acquisitions and reconstructed with sharp or standard algorithms did not differ significantly. Morphometric analysis was used to determine the proportion of lung parenchymal (82%) and non-parenchymal tissue (18%). Alveolar size, estimated by mean linear intercept, was approximately 172 microm, and alveolar surface area-to-volume ratio was 0.024 to 0.026 microm(-1). Histologic evaluation confirmed the presence of normal lung tissue. CONCLUSIONS AND CLINICAL RELEVANCE: Correlation of densitometric CT data with morphometric and histologic findings and the establishment of helical CT and HRCT protocols were attained; clinical use of this information may facilitate investigation of pulmonary disease in dogs. Sharp helical CT acquisitions were preferred because of better lung parenchyma detail and rapid image acquisitions, compared with HRCT. 相似文献