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排序方式: 共有971条查询结果,搜索用时 15 毫秒
891.
E. Menzel Max Schmidt R. Bünsow Gottwalt Christian Hirsch 《Die Naturwissenschaften》1962,49(14):335-336
892.
Anne-Marie Boulay Christian Bouchard Cecile Bulle Louise Deschênes Manuele Margni 《Mitigation and Adaptation Strategies for Global Change》2002,7(4):417-418
Subject Index
Subject Index 相似文献893.
The Science of Nature - 相似文献
894.
Christian Hoffmann 《Die Naturwissenschaften》1965,52(14):436-437
895.
Deep-sea hydrothermal vent ecosystems host both symbiotic and non-symbiotic invertebrates. The non-symbiotic vent fauna is
generally assumed to rely on free-living chemoautotrophic bacteria as their main food source but other sources such as detritus
have recently been suggested to be a part of the invertebrate diets. Little is known about how food availability influences
the distribution of vent organisms on a small scale. In addition, the feeding ecology and role of small, often numerically
dominant invertebrates, the meiofauna is poorly understood at vents. In this study, we used stable carbon and nitrogen isotopic
analysis to investigate the role of particulate detritus in the diets of macro- and meiobenthic invertebrates within three
vent assemblages at Axial Volcano, Juan de Fuca Ridge, and Northeast Pacific. Particulate organic matter of a detrital origin
became more important in the diet of invertebrates in assemblages typically associated with low-hydrothermal flow intensities.
Meiobenthic species occupied several different feeding guilds and trophic levels in the assemblages investigated. We conclude
that small-scale spatial variability in food sources is an important feature of vent food webs and that spatial patterns observed
here and elsewhere are shaped by variations in hydrothermal discharge. 相似文献
896.
897.
898.
Stem cells for regenerative medicine: advances in the engineering of tissues and organs 总被引:2,自引:0,他引:2
The adult bone marrow stroma contains a subset of nonhematopoietic cells referred to as mesenchymal stem or mesenchymal progenitor cells (MSC). These cells have the capacity to undergo extensive replication in an undifferentiated state ex vivo. In addition, MSC have the potential to develop either in vitro or in vivo into distinct mesenchymal tissues, including bone, cartilage, fat, tendon, muscle, and marrow stroma, which suggest these cells as an attractive cell source for tissue engineering approaches. The interest in modern biological technologies such as tissue engineering has dramatically increased since it is feasible to isolate living, healthy cells from the body, expand them under cell culture conditions, combine them with biocompatible carrier materials and retransplant them into patients. Therefore, tissue engineering gives the opportunity to generate living substitutes for tissues and organs, which may overcome the drawbacks of classical tissue reconstruction: lacking quality and quantity of autologous grafts, immunogenicity of allogenic grafts and loosening of alloplastic implants. Due to the prerequisite for tissue engineering to ensure a sufficient number of tissue specific cells without donor site morbidity, much attention has been drawn to multipotential progenitor cells such as embryonic stem cells, periosteal cells and mesenchymal stem cells. In this report we review the state of the art in tissue engineering with mesenchymal stem and mesenchymal progenitor cells with emphasis on bone and cartilage reconstruction. Furthermore, several issues of importance, especially with regard to the clinical application of mesenchymal stem cells, are discussed. 相似文献
899.
The luminescence inhibition test was applied to contaminated soils. Two different methods were used: The standard sediment elutriate test and the so-called “solid-phase test”. Cadmium sulfate, p-cresol and o-nitroanisole were used as model substances for the contamination of two different soils that show significant differences in grain size. While five of six elutriates acted toxically in the standard elutriate test, the solid-phase test detected only the heavy metal clearly. The interpretation of the solid-phase test results, unlike those of the standard sediment test, is problematic because of the high and varied ground inhibitions of the uncontaminated soils. This suggests that the rate of adsorption of the bacteria depends on the type of soil. An interpretation without an uncontaminated reference seems impossible. A good correlation between the portion of elutriated contaminants and the values of inhibition was only obtained by using the standard elutriate test. 相似文献
900.
Aline Ghanem Jacqueline Dubroca Véronique Chaplain Christian Mougin 《Environmental Chemistry Letters》2006,4(2):63-67
We studied the fate of sludge spiked with 14C-labelled diuron, glyphosate and nonylphenol applied to the soil by the way of contaminated sewage sludge in the soil-plant-water system. Here we show that the mineralization of the chemicals in mixture is reduced by 40–80% by comparison with a direct soil contamination. The persistence of the chemicals in soils is increased in the presence of sludge. We showed also that the chemicals present in the sludge are mobile and partly transferred to soil leachates and plant seedlings. These results allow postulating that these compounds may induce an ecotoxicological impact on the soil ecosystem. 相似文献