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Bamboo shoots are highly nutritious but difficult to preserve even under low temperature since they are sensitive to chilling. In the present research, bamboo shoots were exposed to UV-C light (4.1 kJ/m2) prior to 56 days storage at 1 C to evaluate the potential of UV-C treatment on alleviating chilling injury (CI) of bamboo shoots under cold storage. CI incidence and physiological and biochemical characteristics associated with CI were determined during storage. The results showed that UV-C treatment apparently inhibited the development of CI and resulted lower EI and MDA content than that of the control. Further investigation demonstrated that UV-C treatment increased activities of CAT, APX, GR and DPPH scavenging activity of bamboo shoots, which greatly contribute to alleviating CI. The increases in both O2 - production rate and H2O2 content of UV-C-treated bamboo shoots were significantly delayed, PAL activity was increased which contributed to enhancing accumulation of TP, and endogenous proline synthesis was promoted, which resulted from the increased activity of P5CS and decreased PDH activity. The results above suggest that the improved antioxidative defense system and enhanced proline accumulation is the underlying mechanism that UV-C treatment enhanced chilling tolerance in bamboo shoots.
The Songnen Plain in China has a typical type of soda saline-alkali soil that frequently shrinks and cracks under natural conditions, especially during water evaporation. This study aims to study the effects of salt contents on the cracking process of soda saline-alkali soils and to make a quantitative analysis between crack length and some primary salt parameters of soda saline-alkali soils. To achieve the objectives, 57 soil samples with different salinity levels were selected and a laboratory-controlled desiccation cracking test was then conducted. Next, correlation analysis was carried out between extracted crack lengths and salt parameters of all the specimens. The results showed that there are clear linear dependencies between crack length and salinity, Na⁺, Cl⁻, and electrical conductivity (EC), and that CO₃²⁻ is also quite linear with crack length. The fitting results conducted from the verification experiment showed that Na⁺ content, Cl⁻ content, EC, and total salinity showed high prediction performance (R²>0.91 and RPD>2.5); that the CO₃²⁻ content had quite reasonable accuracy (R²= 0.78 and RPD = 1.82) but with less stability and poor reliability; that the prediction accuracy for pH, however, was very poor, with R² and RPD only 0.42 and 1.06, respectively.
The investigation of mechanism of species coexistence promotes understanding of the mechanistic processes behind community ecology and ecosystem functions. Niche theory declares that species coexistence within a community must partition the resources of their environment. Two sympatric and morphologically similar bat species, Rhinolophus affinis and Rhinolophus pearsoni, provided a unique opportunity to test the causal mechanism of coexistence. Previous study showed that their coexistence was promoted not by the trophic and spatial niche differentiation but the relatively high abundance of prey resources, which was not in accord with the prediction of niche theory. Here, therefore, we reanalyzed the dietary composition by fecal analysis and surveyed the feeding time of both species. Our results showed that R. affinis and R. pearsoni hunt mainly mostly on Coleoptera and Lepidoptera, and there was a very high overlap (0.84) of trophic niche between the two species. However, significant difference in the duration of the activity period between both species was detected, which illustrated that temporal partitioning of prey resource use facilitated their coexistence. Additionally, our work highlighted the importance of integration of the traditional methods and next-generation sequencing methods for identifying dietary composition of carnivores, and suggested that ongoing studies of species coexistence must consider simultaneously multiple niche axes.
Based on basic equation and boundary layer theory of pneumodynamics, the thesis conducts numerical modeling and theoretical analysis on the last stage of turbine characteristics at a small volume flow by using FLUENT, gives an emphasized analysis on the position of first occurrence of backflow and its expansion direction and comes up with flow structure of the turbine flow field at last stage in the small volume flow condition. In connection with specific experiments, it puts forward the flow model of backflow occurring in the last stage field and the solution to the model. The flow field at last stage for a 100MW turbine in the small volume flow condition that is calculated by using the model is basically in conformity to the actual result
We studied the postnatal development of wing morphology and echolocation calls during flight in a free-ranging population of the big-footed bat, Myotis macrodactylus, using the mark-recapture methodology. Young bats were reluctant to move until 7 days of age and started fluttering at a mean age of 10 days. The wingspan and wing area of pups followed a linear pattern of growth until 22 days of age, by which time the young bats exhibited flapping flight, with mean growth rates of 0.62 mm/day and 3.15 mm2/day, for wingspan and area, respectively, after which growth rates decreased. Pups achieved sustained flight at 40 days of age. Of the three nonlinear growth models (logistic, Gompertz, and von Bertalanffy), the logistic equation provided the best fit to the empirical curves for wingspan and wing area. Neonates emitted long echolocation calls with multiple harmonics. The duration of calls decreased significantly between flutter (19 days) and flight (22 days) stages. The peak and start frequency of calls increased significantly over the 3-week period of development, but the terminal frequency did not change significantly over the development period.
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