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排序方式： 共有94条查询结果，搜索用时 31 毫秒
21.
Grzegorz Żurek 《Genetic Resources and Crop Evolution》1999,46(5):485-490
Qualitative and quantitative changes in populations of meadow fescue (Festuca pratensis Huds.) after seed storage under different conditions were estimated. Phenotypic characters of plants grown from seeds stored for 54 months under two different storage conditions were compared. The germination of most of the seed accessions stored under favourable conditions remained at the initial level while storage under unfavourable conditions resulted in a decrease of the initial germination percentage as well as in an increase in the number of plants showing chlorophyll aberrations. There is great variability among the accessions resulting from storage under unfavourable conditions. In case of a few accessions a decrease in germination below 35% resulted in chlorophyll aberrations, faster flowering, shorter inflorescence and reduced viability of pollen grains. 相似文献
22.
Christian Hoffmann Irena Savric Grzegorz Jozefaciuk Mieczyslaw Hajnos Zofia Soko&#x;owska Manfred Renger Bernd Marschner 《植物养料与土壤学杂志》2002,165(1):67-71
Heavy metal polluted soils from a recent and a former sewage farm were studied in a 2.5 years‐column experiment under various irrigation regimes and/or liming treatment. The copper (Cu), zinc (Zn), lead (Pb), and cadmium (Cd) concentrations in the soil and the leaching of these elements were studied. The amounts of the metals leached differed markedly between both soils, however, the effect of various irrigation treatments was less pronounced. The heavy metal content in the soil solid phase depended on the organic carbon content, however these dependencies differed for both soils as well as for particular metals. In lower soil horizons, the amount of heavy metals bound by unit mass of organic carbon was constant. It was assumed that the same amount of the heavy metals can be bound by the unit mass of the DOC. Under this assumption the amount of the DOC in the former sewage farm soil was in general too small to carry all heavy metals leached. Therefore leaching of their cationic forms has been postulated. The amount of the DOC in the present sewage farm soil could carry more heavy metals than these being leached. Therefore, an undersaturation of the DOC in heavy metals could occur in this soil.<?show $6#> 相似文献
23.
Samples of six Polish and three Korean soils were acidified and alkalized with elevated concentrations of hydrochloric acid or sodium hydroxide from 0.001 to 1 mol dm—3. The pore system of the studied soils was investigated using mercury intrusion (”︁macropores”) and water vapor adsorption (”︁mesopores”) experiments. The characteristics of the pores and their surfaces were very sensitive against acid and alkaline treatments. The macropore volume and radii increased in general with increasing of the concentrations of the treatment solutions. The macropore surface of all the clay rich soils exhibited a fractal behavior. The ranges of fractal scaling differed for particular soils. Macropore surface fractal dimensions changed under both treatments. For a given soil, the macropore fractal dimensions changed in the same direction under the effect of acid as under alkali. Both treatments decreased the mesopore volumes of Polish and increased the mesopore volumes of Korean soils. However, this was not true for two of Korean soils after extreme alkali treatments. In general, the average mesopore radius increased under lower treatments concentrations and decreased under higher concentrations. The mesopores were also fractal. The range of their fractal scaling was different for the Polish and Korean soils and roughly the same within each group. The fractal dimension of the mesopores decreased after acid treatment showing a smoothing of the material porous surface. Alkaline treatment affected the mesopore fractal dimension to a lower extent. A slight rise of the mesopore fractal dimension was noted in most cases.<?show $6#> 相似文献
24.
Ali Serhan Tarkan Gordon H. Copp Grzegorz Zięba Michael J. Godard Julien Cucherousset 《水产资源保护:海洋与淡水生态系统》2009,19(7):797-805
- 1. The crucian carp Carassius carassius is a species of cyprinid fish native to south‐east England, but few studies exist on its growth and reproduction in England, and the species is threatened by introductions of its Asiatic congener, goldfish Carassius auratus. To increase knowledge of the crucian carp as a means of aiding its conservation, the present study assesses the growth (back‐calculated length at age, body condition) and reproduction (fecundity, egg size, length and age at maturity) of crucian carp in small ponds of Epping Forest (north‐east London, England).
- 2. Evaluation of growth and reproduction data with published data for populations from northern Europe (i.e. latitude ?50°) suggest that growth is very variable, even within the same area, and that data on reproductive indices, in particular length and age at maturity, are scarce. In England, the length at age trajectory of crucian carp living in sympatry with feral goldfish Carassius auratus did not differ significantly from allopatric crucian carp populations, but crucian carp body condition and relative fecundity (eggs per body weight) were highest, and mean age and standard length at maturity were lowest in sympatry with goldfish.
- 3. These data suggest that somatic growth and reproductive output may be maximized in crucian carp when confronted by coexistence with feral goldfish. However, the potential impact of goldfish introductions on crucian carp growth and reproduction requires further study, involving a much larger number of crucian carp populations, both in allopatry and sympatry with feral goldfish populations.
25.
The specific composition of bacterial flora in the intestines of O. sabulosus cannot be explained simply by antibiotic inhibition of contaminating microflora since the predominant types of bacteria present are unable to produce any bacteriolytic activity of lysozyme-like enzymes, bacteriocins or other antimicrobial molecules. The lack of microbial contaminators could rather result from the unfavourable biochemical niche in the midgut enzymes and little or no competition for the enteric bacteria group predominant in the millipede alimentary tract. In other words, the rapid colonization and overgrowth of the Ommatoiulus intestines eliminate adventitious bacteria, yeasts and moulds ingested with food. 相似文献
26.
A. Waldemar Wilczynski Manfred Renger G. Jozefaciuk M. Hajnos Z. Sokolowska 《植物养料与土壤学杂志》1993,156(3):235-238
Water vapor adsorption isotherms were used for estimation of (apparent) surface areas of samples of limed and unlimed plots of an acidic sandy forest soil. Samples were taken at two microrelief (ridge and furrow) positions from five subsequent 10 cm layers. Values of surface area and CEC correlated linearly with organic matter content but only for four bottom layers. Surface areas and CEC values calculated per the unit mass of organic carbon were higher in upper layers than in lower layers for control samples. For limed samples an opposite trend was observed. The estimated average (apparent) charge densities of organic matter showed a better correlation with humic to fulvic acids ratio. Values of surface charge densities for every investigated profile increased with depth and they were lower in limed than in unlimed profiles. 相似文献
27.
Song Yi-Gang Walas Łukasz Pietras Marcin Sâm Hoàng Văn Yousefzadeh Hamed Ok Tolga Farzaliyev Vahid Worobiec Grzegorz Worobiec Elżbieta Stachowicz-Rybka Renata Boratyński Adam Boratyńska Krystyna Kozlowski Gregor Jasińska Anna K. 《European Journal of Forest Research》2021,140(6):1323-1339
European Journal of Forest Research - Pterocarya fraxinifolia, native to the southern Caucasus and adjacent areas, has been widely introduced in Europe. In this study, we investigate the following:... 相似文献
28.
Michał Brzozowski Grzegorz Kowalewski Witold Szczuciński Lech Kaczmarek Mariusz Pełechaty 《水产资源保护:海洋与淡水生态系统》2021,31(10):2673-2689
- In a time of rapid environmental changes, identification of the effects of climate warming on charophytes (Characeae, Charophyta) will enable the optimization of conservation measures, especially for extremely rare species. Lychnothamnus barbatus is one of the rarest charophytes worldwide, which has decreased in the number of occupied sites over the last century. However, the recolonization of former sites has been observed in recent years (e.g. Lake Kuźnickie, Poland). The study aimed to analyse the effects of climatic changes and human pressure on the L. barbatus population.
- Three 30 cm sediment cores were collected from minimum, average, and maximum depths of L. barbatus occurrence to determine the past vegetation composition. Sediment cores were dated using the radioisotopes lead-210, caesium-137, and carbon-14. A spatial analysis of the lake catchment changes during the last 120 years was also conducted.
- The study demonstrated L. barbatus presence in Lake Kuźnickie at the beginning of the 16th century. However, a sharp increase in the proportion of this species in the vegetation community occurred in the 19th century and during climate warming at the end of the Little Ice Age. Factors that significantly influenced the present occurrence of the L. barbatus population included improvement in water quality and the oospore bank deposited in the bottom sediments.
- This study is the first palaeoreconstruction in a modern lake dominated by L. barbatus. Based on the history of L. barbatus in Lake Kuźnickie after the end of the Little Ice Age, the positive effect of climate warming on the contemporary recovery of this charophyte is postulated.
- The reaction of L. barbatus to climate warming appears to differ from commonly accepted scenarios for aquatic macrophytes because its recovery in the past and at present coincided with increases in air temperature. This research indicated the appropriate management and conservation practices for lakes with L. barbatus populations.
29.
Grzegorz Wo?niakowski El?bieta Samorek-Salamonowicz Wojciech Kozdruń 《Acta veterinaria Scandinavica》2011,53(1):10
Background
Twenty-nine Marek''s disease virus (MDV) strains were isolated during a 3 year period (2007-2010) from vaccinated and infected chicken flocks in Poland. These strains had caused severe clinical symptoms and lesions. In spite of proper vaccination with mono- or bivalent vaccines against Marek''s disease (MD), the chickens developed symptoms of MD with paralysis.Because of this we decided to investigate possible changes and mutations in the field strains that could potentially increase their virulence. We supposed that such mutations may have been caused by recombination with retroviruses of poultry - especially reticuloendotheliosis virus (REV).Methods
In order to detect the possible reasons of recent changes in virulence of MDV strains, polymerase chain reaction (PCR) analyses for meq oncogene and for long-terminal repeat (LTR) region of REV were conducted. The obtained PCR products were sequenced and compared with other MDV and REV strains isolated worldwide and accessible in the GeneBank database.Results
Sequencing of the meq oncogene showed a 68 basepair insertion and frame shift within 12 of 24 field strains. Interestingly, the analyses also showed 0.78, 0.8, 0.82, 1.6 kb and other random LTR-REV insertions into the MDV genome in 28 of 29 of strains. These genetic inserts were present after passage in chicken embryo kidney cells suggesting LTR integration into a non-functional region of the MDV genome.Conclusion
The results indicate the presence of a recombination between MDV and REV under field conditions in Polish chicken farms. The genetic changes within the MDV genome may influence the virus replication and its features in vivo. However, there is no evidence that meq alteration and REV insertions are related to the strains'' virulence. 相似文献30.
Grzegorz Buczkowski 《Pest management science》2023,79(10):4004-4010