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Ökophysiologische Untersuchungen an Pflanzen der Namib-Wüste   总被引:1,自引:0,他引:1  
The southern Namib desert has a vegetation cover of mainly succulent plants in which species of the Mesembryanthemaceae are predominant. Climatically this area is characterized by hot and dry days, and cool and humid nights with episodic rainfalls only in winter. In this environment a great number of species perform a crassulaceaen acid metabolism (CAM). The responses of these plants to water stress as well as the regulation of CAM in the natural habitat are described and discussed.  相似文献   
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In response to the increasingly complex social–ecological issues facing society, there is a growing trend to conduct environmental research in large collaborative programs. This approach is described as transdisciplinary research as it transcends formal disciplinary boundaries, explicitly acknowledges that many different perspectives are relevant to the resolution of complex problems, and actively involves the users of research. This poses challenges for the evaluation of “impact” as any evaluation process must take into consideration the different expectations, values, culture, language and reward structures of the main participating groups, the funders, researchers and end users. How can these participating groups learn about the progress of a transdisciplinary research program in a way that is purposeful and structured, continues through the life of the program, and includes explicit feedback mechanisms that facilitate adaptation during the course of the program? This paper presents a framework for co-reflecting on the accomplishment of transdisciplinary research programs. The framework incorporates the perspectives of funders, researchers and users, and recognizes that while they place different emphasis on measures of achievement such as efficiency, rigor and relevance, ultimate accomplishment in terms of translating knowledge into practice requires that the needs and expectations of all three groups are adequately addressed. What emerges from the framework is the importance of early investment in processes, behaviors and relationships that foster social learning and the co-production of the knowledge and understanding that are required to ensure relevance; while maintaining emphasis in the traditional areas of formally testing evidence and mentoring young researchers to ensure rigor and build confidence and capacity in transdisciplinary approaches.  相似文献   
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The impact of prenatal sonographic diagnosis of oesophageal and gastrointestinal obstructions has been analysed over a 10-year period. Three groups of patients were evaluated. The first group consisted of 46 newborns with abnormal prenatal sonogratns, 41 of which were confirmed to have intestinal obstruction postnatally. The second group consisted of 17 neonates with normal prenatal sonograms who had intestinal obstruction postnatally. The third group included 56 newborns who did not undergo a prenatal sonogram but who had intestinal obstruction confirmed at surgery. Polyhydramnios without the appearance of a stomach on ultrasound was diagnostic of pure oesophageal atresia. Polyhydramnios with intestinal dilation was diagnostic of intestinal obstruction. Although surgery was performed earlier in the infants diagnosed prenatally with ultrasound, mortality was no less than in the group that did not undergo a prenatal sonogram, probably because of the high incidence of associated anomalies.  相似文献   
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We report the preparation of poly(3,4-ethylene dioxythiophene) (PEDOT)-modified polyvinylidene fluoride electrospun fibers and their use as a novel adsorbent material for the removal of the anionic dye Methyl Orange (MO) from aqueous media. This novel adsorbent material can be used to selectively remove MO on a wide pH range (3.0–10.0), with a maximum capacity of 143.8 mg/g at pH 3.0. When used in a recirculating filtration system, the maximum absorption capacity was reached in a shorter time (20 min) than that observed for batch mode experiments (360 min). Based on the analyses of the kinetics and adsorption isotherm data, one can conclude that the predominant mechanism of interaction between the membrane and the dissolved dye molecules is electrostatic. Besides, considering the estimated values for the Gibbs energy, and entropy and enthalpy changes, it was established that the adsorption process is spontaneous and occurs in an endothermic manner. The good mechanical and environmental stability of these membranes allowed their use in at least 20 consecutive adsorption/desorption cycles, without significant loss of their characteristics. We suggest that the physical-chemical characteristics of PEDOT make these hybrid mats a promising adsorbent material for use in water remediation protocols and effluent treatment systems.  相似文献   
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