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排序方式: 共有65条查询结果,搜索用时 46 毫秒
1.
Jürgen Tomiuk Lutz Bachmann Michael Leipoldt Jörg U. Ganzhorn Reiner Ries Michaela Weis & Volker Loeschcke 《Conservation biology》1997,11(2):491-497
The genetic polymorphism of natural populations of Lepilemur mustelinus ruficaudatus was studied by protein electrophoresis. We sampled blood from 72 individuals from four populations separated by geographic or anthropogenic barriers from southwestern Madagascar. Six out of 22 enzyme loci showed genetic variation with a degree of polymorphism of 0.273. The expected and observed degree of genetic heterozygosity over all loci is similar to that of other primates (He = 0.058, Ho = 0.036). The F-statistics revealed that the four subpopulations were similar with respect to gene structure (FST = 0.065, p = 0.016), but the genotypic structures within subpopulations were inconsistent with random mating. For the total of the four subpopulations the proportion of heterozygous individuals was significantly smaller than expected under random mating (FIS = 0.373, FIT = 0.414, p < 0.01). These results correspond closely to what is expected considering the low migration ability of individuals of L. m ruficaudatus leading to small and rather isolated inbred populations. 相似文献
2.
Julia Metag Michaela Maier Tobias Füchslin Laurits Bromme Mike S. Schäfer 《Environmental Communication: A Journal of Nature and Culture》2018,12(8):1077-1094
ABSTRACTCitizens’ attitudes toward science are related to their use of science-related information from various sources. Evidence is scarce regarding citizens’ individual media repertoires for staying informed about science as segmentation studies so far have primarily focused on scientific attitudes. In this paper, we explore audience segments regarding their science-related information behavior and whether such segments are comparable or vary between two countries with similar information environments. Based on two surveys in Switzerland and Germany, we identify national audience segments that differ in their science-related information repertoires, and analyze their sociodemographic characteristics and science-related attitudes. In both countries, we find very comparable information user segments ranging from those who inform themselves frequently about science (“Active Seekers”/“Science Consumers”) to those who hardly get in contact with any information about science and research (“Non-Users”). Those segments which get in contact with information about science frequently show generally more positive attitudes. 相似文献
3.
Michaela Zeiner Iva Juranović Cindrić Ivanka Lovrenčić Mikelić Gordana Medunić Štefica Kampić Nenad Tomašić Gerhard Stingeder 《Environmental monitoring and assessment》2013,185(1):223-229
Concentrations of Ag, Al, Ba, Cd, Co, Cr, Cu, Fe, K, Mn, Na, Ni, Pb, Sr, and Zn—isolated by sequential extraction steps from apple orchard soil—were analyzed by inductively coupled plasma-atomic emission spectroscopy and compared to the total amount of metal in soil determined by XRF. The extractable amount of each metal was calculated by the extraction yields of the four steps. The LODs of the different elements in all extracts ware below 3 μg/L except for Ba (steps 1 and 2), Cu (step 1), Fe (all steps), K (steps 1–3), Mn (step 2), Na (steps 1–3), Ni (step 1), Pb (steps 1 and 4), and Zn (steps 1 and 2). The highest LOD (>10 μg/L) was found for Fe, K, and Na (step 1). The recovery of all metals after four sequential extraction steps was 90–112%. The repeatability (<1.1%), the intermediate precision (<5.3%), the day-to-day reproducibility (<6.2%), and the overall uncertainty of measurement (approximately 4–8.5%) for all analyzed metals supports the choice of the method used. 相似文献
4.
Katia Vangelova Michel Israel Desimira Velkova Michaela Ivanova 《The Environmentalist》2007,27(4):551-555
The aim of this paper is to study the effect of electromagnetic radiation (EMR) on the excretion rates of stress hormones
of medical staff in physiotherapy. The excretion rates of stress hormones cortisol, adrenaline and noradrenaline were followed
during morning shift in 15 female physiotherapists using RIA kits and a spectrofluorimetric method. The mean number of treatments
with EMR emitting devices per month and the emission of each device was assessed. A control group of nurses, matched by age,
sex and work task was used. The psychosocial factors were evaluated and no differences between the two groups was found. Calculations
of the individual EMR exposure show levels above the ICNIRP guidelines. Significantly higher excretion rates of cortisol,
adrenaline and noradrenaline among the studied physiotherapists in comparison with the control group of nurses were found.
In conclusion, our data showed that EMR influenced the excretion rates of stress hormones of medical staff in physiotherapy. 相似文献
5.
An Analysis of the Effects of Land Use and Land Cover on Flood Losses along the Gulf of Mexico Coast from 1999 to 2009 下载免费PDF全文
Samuel D. Brody Wesley E. Highfield Russell Blessing 《Journal of the American Water Resources Association》2015,51(6):1556-1567
Major coastal flooding events over the last decade have led decision makers in the United States to favor structural engineering solutions as a means to protect vulnerable coastal communities from the adverse impacts of future storms. While a resistance‐based approach to flood mitigation involving large‐scale construction works may be a central component of a regional flood risk reduction strategy, it is equally important to consider the role of land use and land cover (LULC) patterns in protecting communities from floods. To date, little observational research has been conducted to quantify the effects of various LULC configurations on the amount of property damage occurring across coastal regions over time. In response, we statistically examine the impacts of LULC on observed flood damage across 2,692 watersheds bordering the Gulf of Mexico. Specifically, we analyze statistical linear regression models to isolate the influence of multiple LULC categories on over 372,000 insured flood losses claimed under the National Flood Insurance Program per year from 2001 to 2008. Results indicate that percent increase in palustrine wetlands is the equivalent to, on average, a $13,975 reduction in insured flood losses per year, per watershed. These and other results provide important insights to policy makers on how protecting specific types of LULC can help reduce adverse impacts to local communities. 相似文献
6.
Michal Hejcman Michaela Klaudisová Pavla Hejcmanová Vilém Pavlů Martina Jones 《Agriculture, ecosystems & environment》2009,129(1-3):91-96
Calamagrostis villosa has recently expanded in Nardus stricta-dominated sub-alpine grassland of the Giant Mountains (Krkono?e/Karkonosze, the Czech Republic). To investigate whether this expansion has been promoted by high nitrogen deposition or by the cessation of agricultural management, grassland plots dominated by C. villosa were manipulated with four treatments: control (Con), fertilised (Fer), cut (Cut) and cut–fertilised (Cut–Fer). NH4NO3 was used at the rate of 30 kg N ha?1 and fertilisation and cutting were performed once a year after data collection in late July between 2000 and 2006.Plant species composition (analysed by RDA) was significantly influenced by cutting but not by fertilisation. Cutting reduced the cover, biomass, sward height and tiller density of C. villosa. Seedlings of N. stricta and panicles of C. villosa were recorded only in plots with cutting management.To investigate the effect of treatments on the spread of C. villosa, grassland sods dominated by N. stricta were transplanted into the experimental plots. Six years later, the density and cover of C. villosa spreading into the N. stricta sods were highest in Fer treatment.C. villosa was recognised as a defoliation-sensitive species and this sensitivity cannot be overcome by an increase in N supply. Recent expansion of C. villosa in the sub-alpine grassland can by explained by a long-term succession after the cessation of agricultural management and an increase in the N availability in recent decades. 相似文献
7.
Martina Duft Michaela Tillmann Ulrike Schulte-Oehlmann Bernd Markert Jörg Oehlmann 《Environmental Sciences Europe》2002,14(1):12-17
Currently, only few organismic biotest systems are available for the assessment of effects on reproduction, which consider an exposure toward whole sediments. A well-suited test organism is the parthenogenetic mudsnailPotamopyrgus antipodarum. This ovoviviparous prosobranch snail lives in the upper layers of freshwater and brackish sediments. The number of (unshelled) embryos turned out to be a very sensitive parameter for the indication of sediment components affecting reproduction. Additionally, this endpoint allows to signal possible estrogenic sediment compounds. With this 28-day bioassay, laboratory tests on the effects of various chemicals onP. antipodarum were performed, e.g. triphenyltin and bisphenol A, in relevant environmental concentration ranges. Furthermore, the suitability of our test system for the investigation of complex and multiple level ranged contaminations was examined by means of various natural sediments from the Neiße and Odra rivers. 相似文献
8.
9.
Blessing Masasi Saleh Taghvaeian Prasanna H. Gowda Jason Warren Gary Marek 《Journal of the American Water Resources Association》2019,55(4):976-993
Use of models to simulate crop production has become important in optimizing irrigation management in arid and semiarid regions. However, applicability and performance of these models differ across regions, due to differences in environmental and management factors. The AquaCrop model was used to simulate soil water content (SWC), evapotranspiration (ET), and yield for grain sorghum under different irrigation regimes and dryland conditions at two sites in Central and Southern High Plains. Prediction error (Pe), estimated as the difference between simulated and measured divided by measured, for SWC ranged from ?17% to 4% in fully irrigated, ?3% to ?10% in limited irrigated, and ?16% to 25% in dryland treatments. The Pe within ±4%, ?5%, and ?17% to 24% were attained for seasonal ET under fully irrigated, limited irrigated, and dryland conditions, respectively. Pe values for grain yield were within those previously reported and ranged from ?10% to 12%, ?12% to 7%, and 9% to 17% for fully irrigated, limited irrigated and dryland conditions, respectively. Overall performance of the AquaCrop model showed it could be used as an effective tool for evaluating the impacts of variable crop and irrigation managements on the production of grain sorghum in the study area. Finally, the application of the model in the study area revealed planting date has a significant impact on sorghum yield and irrigation requirements, but the impact of planting density was negligible. Editor's note : This paper is part of the featured series on Optimizing Ogallala Aquifer Water Use to Sustain Food Systems. See the February 2019 issue for the introduction and background to the series. 相似文献
10.
The leachability of some metals (Al, As, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Ti, Zn) from fly ashes was studied in the presence of ethylenediamine tetraacetic acid (EDTA) and naturally occurring complexing agents-humic acids (HAs). Secondary complex-forming equilibria taking place in the leachates increase significantly the leached amounts of most metals. Kinetic experiments showed that almost the whole "available" amounts of metals are leached from fly ash within a time period of several hours (mostly within 20 h), with exceptions of matrix constituents (typically aluminium), which are released more slowly. 相似文献