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The viability of metapopulations in fragmented landscapes has become a central theme in conservation biology. Landscape fragmentation
is increasingly recognized as a dynamical process: in many situations, the quality of local habitats must be expected to undergo
continual changes. Here we assess the implications of such recurrent local disturbances for the equilibrium density of metapopulations.
Using a spatially explicit lattice model in which the considered metapopulation as well as the underlying landscape pattern
change dynamically, we show that equilibrium metapopulation density is maximized at intermediate frequencies of local landscape
disturbance. On both sides around this maximum, the metapopulation may go extinct. We show how the position and shape of the
intermediate viability maximum is responding to changes in the landscape’s overall habitat quality and the population’s propensity
for local extinction. We interpret our findings in terms of a dual effect of intensified landscape disturbances, which on
the one hand exterminate local populations and on the other hand enhance a metapopulation’s capacity for spreading between
habitat clusters. 相似文献
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Burcu Sancar Beşen Onur Balcı Cem Güneşoğlu Mehmet Orhan E. İnci Somuncuoğlu İ. İrem Tatlı 《Fibers and Polymers》2017,18(6):1079-1090
In this paper, it was aimed to obtain disposable medical textiles having antibacterial and wound healing properties, as well as biological adaption. For this purpose, the St. John’s Wort oil and flax seed oil were ozonated, and the oils were capsulated with arabic gum. The produced ozonated oils were characterized through FTIR and TGA analyses, as well as the properties of antibacterial, wound healing, and biological adaption were investigated. The produced microcapsules were examined via optical microscope and FTIR. The characterized microcapsules of the ozonated oils were applied to the textiles with padding method. After the applications, the fabrics were researched with SEM and FTIR analyses; in addition the antibacterial and wound healing properties and biological adaption of the textiles were also investigated. The results showed that the St. John’s Wort oil and flax seed oil were successfully ozonated and microcapsulated. The microcapsules of the oils could be applied to the fabric samples with the determined application recipe. The ozonated oils and the fabric samples applied microcapsules of the ozonated oils gained high antibacterial and wound healing property. In addition, the fabric samples were produced as having biological adaptation. 相似文献
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Branimir Jovančićević Mališa Antić Ivona Pavlović Miroslav Vrvić Vladimir Beškoski Alexander Kronimus Jan Schwarzbauer 《Water, air, and soil pollution》2008,190(1-4):299-307
This paper presents transformations of saturated hydrocarbons of petroleum type pollutants during ex situ bioremediation of soil on the pilot heap (halde), during a period of 6 months, within the grounds of Petroleum Refinery Pan?evo (Serbia). Samples for analysis were taken in time intervals of 2 weeks (P1–P12 samples). Organic substance was extracted by Soxhlet’s method and quantified. Isoprenoid aliphatics, in particular pristane and phytane, and polycyclic aliphatics of sterane and triterpane types in saturated hydrocarbon fractions were analysed by GC-MS (SIM method). Significant amounts of n-alkanes have not been detected. The MS-chromatogram revealed only marginal amounts of pristane and phytane in sample P1. Pristane and phytane occurred in sample P8, and in even higher quantities in the final sample P12. The proceeding bioremediation process was accompanied by the decrease of the relative amounts of pentacyclic terpanes of hopane type, compared to tri- and tetracyclic terpanes. In the initial sample P1 the distribution of steranes and hopanes follows a pattern, which is characteristic for crude oils. However, their identification by SIM method was not possible in samples P8 and P12 because of the reduced concentration. The observed changes in the alkane fractions’ compositions may be considered as atypical, referring to the fact that during oil biodegradation under natural conditions, decomposition of isoprenoids occurs much easier and faster than decomposition of polycyclic alkanes of tri-, tetra- and pentacyclic terpane, sterane and diasterane types, after the decomposition of n-alkanes has been almost completed. 相似文献
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Insect reproduction may be affected by a number of factors including seasonal changes in larval or adult nutrition. The effect
of season on the reproductive potential ofMonochamus galloprovincialis (Olivier) females reared inPinus sylvestris L. (Scots pine) logs was investigated by constructing fertility tables for each log that differed only in the season they
were cut. Population parameters were compared among three seasonal cohorts. The intrinsic rate of increase and most of the
associated population parameters of beetles that emerged from logs cut during spring were higher than for beetles emerged
from summer and autumn logs. Slight differences were found between summer and autumn cohorts. We suggest that seasonal differences
in the nutritional quality of logs caused differences inM. galloprovincialis survival and reproductive potential.
http://www.phytoparasitica.org posting March 16, 2008. 相似文献
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Magdalena Bełdowska Aleksandra Zgrundo Justyna Kobos 《Water, air, and soil pollution》2018,229(5):168
Mercury is a neurotoxin, its main source in the human organism being fish and seafood. The first level in the marine food web is formed of planktonic and benthic photosynthetic microorganisms, which form a biofilm on the surface of the hard bottom (epilithon) or plants (epiphyton). They are carriers of nutritional as well as toxic substances and pass these on to subsequent levels of the trophic web. Their biomass is often dominated by diatoms. This was the basis for the presented study into Hg accumulation in epilithic, epiphytic and planktonic diatoms, which was carried out in 2012–2013 in the coastal zone of the Puck Lagoon and the Gulf of Gdańsk (southern Baltic). In this coastal area, both micro- and macroorganisms develop particularly intensively. The collected results indicate an increase in Hg concentration in the biofilm during the warm season which, with the lengthening of the vegetative period due to global warming in recent years, is of great significance. As a consequence, the annual mercury load entering the trophic web is larger in comparison with a year in which there is a long, cold winter. An important parameter influencing the accumulation of Hg was the function of those organisms from the biofilm-forming communities. In this case, the highest concentrations of Hg were measured in organisms forming high-profile guilds. 相似文献
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Zusammenfassung Es wurde der Einfluss unterschiedlicher Düngergaben auf den Gehalt an Zitronens?ure in Knollen der Sorte ‘Radka’ geprüft,
wobei die Probennahmen in den Phasen Vollblüte, im Abblühen und der Reife erfolgten.
In reifen Knollen wurde ein relativ hoher Gehalt an Zitronens?ure bei einer Düngung von 120 kg N, 355 kg Ca und 30 kg Mg ha
festgestellt. ?hnliche Ergebnisse wurden auch bei der Variante ohne Magnesium gefunden. Relativ hohe Gehalte an Zitronens?ure
zeigte die Variante mit 60 kg Mg und 120 kg N ha-ohne Kalzium.
Stark verminderte Gehalte an Zitronens?ure in reifen Knollen wurden dagegen bei den Varianten gefunden, die kein Calzium oder
Magnesium erhalten hatten. 相似文献
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The effect of supplementing sheep with rapeseed and linseed oils on the activity of pancreatic digestive enzymes 下载免费PDF全文
Barbara Kowalik Małgorzata P. Majewska Renata Miltko Grzegorz Bełżecki 《Journal of animal physiology and animal nutrition》2018,102(5):1194-1198
The aim of this study was to compare the effect of rapeseed and linseed oils added to the diet on pancreatic enzyme activities in sheep. The experiment was conducted on six adult sheep with a catheter introduced into the common bile–pancreatic duct and a T‐cannula into the duodenum. The animals were divided into three groups, two sheep in each. A twice‐replicated 3 × 3 Latin square was used in the experimental design. The sheep were fed meadow hay and the concentrate alone or the same ration supplemented with rapeseed or linseed oils at a dose of 5% of the basal diet. After adaptation period, a mixture of pancreatic and bile juice was collected for three consecutive days. The secretion of bile–pancreatic juice showed an increasing trend in sheep fed rapeseed and linseed oils (69.5 and 68.5 ml/hr respectively) in comparison with control ones (59.8 ml/hr). Lipase and trypsin activities were significantly increased when sheep were fed diets with rapeseed or linseed oils (175 and 21.6 or 179 and 23.2 U/L respectively) in comparison with those fed control diet (128 and 13.1 U/L respectively). It was concluded that oil as a dietary supplement can mainly modify the secretion of bile–pancreatic juice and enzymatic activity of the pancreas and also might affect animal production. 相似文献
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Mehmet Be?ir Akpinar Semsettin Sahin Atilla Ilhan 《Pesticide biochemistry and physiology》2005,82(3):233-239
Rotenone, an insecticide, causes toxicity through inhibition of mitochondrial electron transport chain at complex I and oxidative injury to the tissues. The aim of the present study was to determine in vivo effects of rotenone on myocardium and cardio-protective effects of caffeic acid phenethyl ester (CAPE), an antioxidant agent, against rotenone toxicity in rats. The rats were divided into three groups: untreated control, rotenone (2.5 mg/kg/day for 60 days, i.p.) and rotenone + CAPE groups. CAPE was administrated i.p. 10 μmol/kg/day for 62 days started two days before first dose rotenone injection. The malondialdehyde, nitric oxide levels and xanthine oxidase activity of rotenone group was significantly higher than control and rotenone + CAPE groups (p < 0.05). However, catalase activity in the rotenone group was decreased in comparison with the other groups (p < 0.05). The superoxide dismutase activity of rotenone group was insignificantly decreased compared to the others. In conclusion, rotenone caused lipid peroxidation in myocardial tissue and CAPE treatment prevented this rotenone-induced lipid peroxidation in rats. CAPE might be a cardio-protective agent against myocardial toxicities. 相似文献