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排序方式: 共有396条查询结果,搜索用时 15 毫秒
1.
Georg Steinhauser Johannes H. Sterba Karin Poljanc Max Bichler Karl Buchtela 《Journal of trace elements in medicine and biology》2006,20(3):119-153
In this study, 18 partly commercially available samples of rock salt from Austria, Germany, Pakistan, Poland, Switzerland, and Ukraine were investigated with respect to their content of trace elements using instrumental neutron activation analysis. Elements detected were Al, Ba, Br, Ca, Ce, Cl, Co, Cr, Cs, Eu, Fe, Hf, La, Mn, Na, Rb, Sb, Sc, Sm, Sr, Ta, Tb, Th, and Zn, some of them only in individual cases. An estimation of the bioavailability of these trace elements was performed by dissolving an equivalent of the sodium chloride samples in diluted hydrochloric acid (simulating stomach acid), filtering off the insoluble components, and analyzing the evaporated filtrate. It could be shown that in most cases bioactive trace elements like Fe can be found in rock salt in the form of almost insoluble compounds and are therefore not significantly bioavailable, whereas thorium, for example, was partly bioavailable in two cases. A significant contribution to the recommended daily intake of metal trace elements by using rock salt for nutrition can be excluded. 相似文献
2.
S. R. Saif 《Plant and Soil》1987,97(1):25-35
Summary Growth and mineral uptake of twenty-four tropical forage legumes and grasses were compared under glasshouse conditions in a sterile low P oxisol, one part inoculated and the other not inoculated with mycorrhizal fungi. Shoot and root dry weights and total uptake of P, N, K, Ca, and Mg of all the test plants were significantly increased by mycorrhizal inoculation. Mycorrhizal inoculation, with few exceptions, decreased the root/shoot ratio. Non-mycorrhizal plants contained always lower quantities of mineral elements than mycorrhizal plants. Plant species showed differences in percentage mycorrhizal root length and there was no correlation between percentage mycorrhizal infection and plant growth parameters. A great variation in dependence on mycorrhiza was observed among forage species. Total uptake of all elements by non-mycorrhizal legumes and uptake of P, N and K by non-mycorrhizal grasses correlated inversely with mycorrhizal dependency. Mycorrhizal plants of all species used significantly greater quantities of soil P than the nonmycorrhizal plants. Utilization of soil P by non-mycorrhizal plants was correlated inversely with mycorrhizal dependency. 相似文献
3.
A. B. MacDiarmid 《Journal of experimental marine biology and ecology》1988,120(3):277-285
An experimental approach was adopted to clarify whether fertilisation in Jasus, a southern temperate genus of rock or spiny lobster (Decapoda: Palinuridae), occurs internally or externally. Female Jasus edwardsii, isolated from males until they moulted, to ensure that they were unmated, were randomly assigned to treatments in which internal fertilisation was physically prevented or to methodological controls. Examination of eggs attached to setae on the pleopods indicated that those from all females from all treatments had divided and were therefore fertilised. The only mechanism that explains these results is external fertilisation via a spermatophore deposited on the sternal plates of the female during copulation. Because of similar morphologies it is likely that in all Jasus species fertilisation occurs by this external mechanism. These experimental results are important in understanding the mating system of Jasus and in clarifying the phylogenetic relationships of this genus, and suggest that claims for internal fertilisation in related taxonomic groups warrant similar experimental testing before they are accepted. 相似文献
4.
A new species of poecilostomatoid copepod, Ostrincola humesi (Myicolidae), is described, based on specimens collected from the mantle cavity of the rock oyster, Saccostrea cucullata (Born), cultured in the Gulf of Thailand. A close comparison was made between the new species and Ostrincola koe Tanaka with which the new species was previously confused. A key to the nine species of Ostrincola is provided. 相似文献
5.
6.
Within estuarine and coastal ecosystems globally, extensive habitat degradation and loss threaten critical ecosystem functions and necessitate widescale restoration efforts. There is abundant evidence that ecological processes and species interactions can vary with habitat characteristics, which has important implications for the design and implementation of restoration efforts aimed at enhancing specific ecosystem functions and services. We conducted an experiment examining how habitat characteristics (presence; edge vs. interior) influence the communities of resident fish and mobile invertebrates on restored oyster (Crassostrea virginica) reefs. Similar to previous studies, we found that restored reefs altered community composition and augmented total abundance and biomass relative to unstructured sand habitat. Community composition and biomass also differed between the edge and interior of individual reefs as a result of species-specific patterns over small spatial scales. These patterns were only weakly linked to oyster density, suggesting that other factors that vary between edge and interior (e.g. predator access or species interactions) are likely more important for community structure on oyster reefs. Fine-scale information on resident species' use of oyster reefs will help facilitate restoration by allowing decision makers to optimize the amount of edge versus interior habitat. To improve the prediction of faunal use and benefits from habitat restoration, we recommend investigations into the mechanisms shaping edge and interior preferences on oyster reefs. 相似文献
7.
《L'Anthropologie》2023,127(2):103132
As part of the research program “Archaeology of rock art in Mato Grosso: the Chapada dos Guimarães National Park (Cuiabá, Brazil)” placed under the coordination of Patrick Paillet and Veronica Wesolowski, an integrated and interdisciplinary approach to the territory still largely unpublished rock art of the Chapada dos Guimarães, has been undertaken since 2020 by combining strictly archaeological research (surveys, excavations and prospecting-inventories), rock art studies (analysis and graphic, photographic and photogrammetric recording of representations) and geological analyzes and, to define and characterize the structure of its ornamented landscapes. Our program is an extension of other projects carried out from 1983 to 2013 under the direction of Agueda Vilhena-Vialou, Denis Vialou and Levy Figuti in the region of the Cidade de Pedra near Rondonópolis and at Santa Elina in the Serra das Araras (Jangada). The region of the Chapada dos Guimarães National Park (PNCG) was the subject of exploration and partial studies between 2017 and 2019 under the direction of Caroline Bachelet within the framework of the program “Prehistory and Paleoenvironments in the Pantanal region (Mato Grosso, Brazil)”. The pursuit of archaeological research in the PNCG contributes to better defining the chronology and the dynamics of occupations at local and regional scales, to characterizing chrono-culturally the settlements and their variability in the region, extending from the Rio Vermelho in the south to the Rio Cuiabá in the north, and to understand the processes of settlement and/or mobility of past populations along the firm lands and especially the hydrographic systems that border the floodplains of the Pantanal and which constitute the main routes of population movement. 相似文献
8.
Spermatozoa of the American oyster Crassostrea virginica were frozen to ?196 °C in concentrated Hanks' salt solution (2.6×) containing 8% dimethyl sulfoxide. About 0.2 ml of spermatozoa that were stored in liquid nitrogen for 68 days fertilized 91% of 65,600 eggs compared to fresh spermatozoa, which fertilized 92% of approximately the same number of eggs from the same females. Larvae resulting from fertilization of fresh eggs with 39-day-old cryopreserved spermatozoa appeared normal after 11 days. 相似文献
9.
David M. Smyth Nicholas S. Horne Elli Ronayne Rachel V. Millar Patrick W. S. Joyce Maria Hayden‐Hughes Louise Kregting 《Restoration Ecology》2020,28(3):645-654
Ostrea edulis was once prolific throughout Europe and considered as the continent's native oyster. However, O. edulis currently exists in small fragmented assemblages where natural unaided recovery is rarely encountered. This research identified the small semi‐enclosed sea Lough of Strangford on the northeast coast of Northern Ireland as one of the few locations within Europe where the native oyster displayed gregarious natural rejuvenation. On close examination, four influential parameters appeared to assist in concentrated settlement; raised topographical cultch formations, shell coverage, the number of fecund in situ adults, and site protection. If these components were to be combined and managed as part of reintroduction and restoration initiatives, high‐density settlements and self‐sustaining populations may be possible. The research also identified that unregulated harvesting of intertidal O. edulis assemblages has the potential to seriously hinder natural recoveries. Indeed, the findings suggest that a review of policy in regards to intertidal hand gathering is necessary. However, naturally occurring high‐density settlements recorded during this research should be inspirational to all involved in the restoration of the native oyster. 相似文献
10.
Positive species interactions such as facilitation are important for enabling species to persist, especially in stressful conditions, and the nature and strength of facilitation varies along physical and biological gradients. Expansion of coastal infrastructure is creating hotspots of invasive species which can spillover into natural habitats, but the role of positive species interactions associated with biological invasions remains understudied. Theory suggests that stronger biotic pressure in natural habitats inhibits invasion success. In space-limited marine systems, sessile organisms can overcome this limiting resource by settling as an epibiont on a substrate organism – basibiont. Using a series of spatially extensive surveys, we explored the role of invasive and native basibionts in providing habitat for other invasive and native epibionts, and tested whether environmental context (i.e. if the receiving habitat was natural or artificial), altered ecological outcomes. Overall, provision of space by basibionts was more important for invasive epibionts than for native epibionts but was dependent on the environmental context. Invasive basibionts facilitated invasive epibionts in natural habitats, and appeared to be more important for native epibionts in artificial habitats respectively. Native basibionts facilitated invasive, but not native epibionts in both natural and artificial habitats. These results advance our understanding of facilitation and highlight the idiosyncratic nature of biofouling and epibiosis, and the potentially important influence of environmental context. The degree to which native habitat-forming species versus invasive habitat-forming species either do or do not facilitate other native or non-native species is a rich area for investigation. Experimental work is required to disentangle the processes underpinning these patterns. 相似文献