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A. V. Trapeznikov P. I. Yushkov V. N. Nikolkin V. N. Trapeznikova M. Ya. Chebotina V. P. Guseva 《Russian Journal of Ecology》2007,38(1):27-33
Radioecological conditions have been estimated in Lake Chervyanoe located on the central axis of the Eastern Ural Radioactive Trace (EURT) about 100–110 km northeast of the Mayak Production Association. Data on the 90Sr and 137Cs contents in the main components of the lake, the distribution of these radionuclides over the profile of bottom sediments, and their amounts in the lake are presented. The experimental data have been used to construct mathematical models for estimating changes in the radionuclide concentrations and amounts in the water and bottom sediments of the lake over a long period after the nuclear accident, as well as the tritium content of the lake water in different periods of time. 相似文献
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G. Langhendries D. E. De Vos B. F. Sels I. Vankelecom P. A. Jacobs G. V. Baron 《Clean Products and Processes》1998,1(1):21-29
Liquid phase hydrocarbon oxidation is one of the principal routes towards industrial organic chemicals. However, low product
selectivity and associated by-product formation are major problems in several oxidation processes. As a result of the increasingly
stringent environmental regulations, the development of oxidation catalysts has been a major challenge in the last decade.
An overview of novel selective and clean oxidation catalysts and processes is presented.
Received: 27 July 1998 / Accepted: 8 September 1998 相似文献
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Madeleine Beekman Stephen J. Martin Falko Drijfhout Benjamin P. Oldroyd 《Behavioral ecology and sociobiology》2007,61(12):1847-1853
Anarchy, where honeybee workers produce males in the presence of a queen, is extremely rare in natural honeybee populations,
suggesting that there are colony-level costs associated with being anarchistic. Yet, no significant costs have yet been identified.
A possible reason for this may be that researchers have only focused on the behaviour of anarchistic workers, which have been
shown to perform worker-tasks as do wild-type workers. Possibly, therefore, costs associated with anarchy should be sought
in anarchistic queens and not workers. A potential cost could be a lower survival rate of eggs laid by anarchistic queens
perhaps because their egg-marking signal is not as clear as that of a wild-type queen. In this paper, we determined the removal
rate of eggs laid by anarchistic queens in standard worker-policing bioassays. Our results show that eggs laid by anarchistic
queens are removed at a higher rate than eggs laid by wild-type queens. This does not seem to be due to differences in hydrocarbons
found on the surface of eggs, as both egg types showed the same alkanes and alkenes in similar proportions. We postulate that
higher removal rates of queen-laid eggs due to recognition errors may be one reason that anarchy is rare in natural honeybee
populations. 相似文献
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Amir P. Nejadhashemi Joseph M. Sheridan Adel Shirmohammadi Hubert J. Montas 《Journal of the American Water Resources Association》2007,43(3):744-756
Abstract: Evaluating the relative amounts of water moving through the different components of the hydrological cycle is required for precise management and planning of water resources. An important aspect of this evaluation is the partitioning of streamflow into surface (quick flow) and base‐flow components. A prior study evaluated 40 different approaches for hydrograph‐partitioning on a field scale watershed in the Coastal Plain of the Southeastern United States and concluded that the Boughton’s method produced the most consistent and accurate results. However, its accuracy depends upon the proper estimation of: (1) the end of surface runoff, and (2) the fraction factor (α) that is function of many physical and hydrologic characteristics of a watershed. Proper identification of the end of surface runoff was accomplished by using a second derivative approach. Applying this approach to 12 years of separately measured surface and subsurface flow data from a field scale watershed (study area) proved to be accurate for 87% of the time. Estimation of the α value was accomplished in this study using two steps: (1) alpha was fitted to individual hydrographs: and, (2) a regression equation that determines these alpha values based on climatological factors (e.g., rainfall, evapotranspiration) was developed. Using these strategies improved the streamflow partitioning method’s performance significantly. 相似文献