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451.
Among recent lemmings (D. torquatus from the Yamal Peninsula and D. groenlandicus from Somerset, Bathurst, Melville, and Devon islands), there are populations with archaic sets of morphotypes characteristic of the end of the Late Pleistocene. In some parts of the species range, lemming morphotypes follow the pattern characteristic of the Holocene stage of their evolution. Lemmings with the best developed tooth system live in the Bering Sea sector of the Arctic (Wrangel Island, Chukotka and Alaska). The correspondence of the boundaries of the groups distinguished by odontological traits to the phylogeographic data on mitochondrial DNA (mtDNA) and chromosomal groups is discussed. 相似文献
452.
Vasil'eva I. A. Vasil'ev A. G. Lyubashevskii N. M. Chibiryak M. V. Zakharova E. Yu. Tarasov O. V. 《Russian Journal of Ecology》2003,34(6):405-412
Monitoring of A. uralensis populations in Kamenskii raion, Sverdlovsk oblast, in 1992–2002 and in Kaslinskii raion, Chelyabinsk oblast, in 2000–2001 revealed an increase in the proportion and diversity of minor morphogenetic aberrations and abnormalities in the structure of the cranium along the axis of the Eastern Ural Radioactive Trace (EURT). The samples from the southern and northern parts of the EURT (contaminated with 90Sr to 500 and 4 Ci/km2, respectively) were characterized by directed deviations from the control with respect to the frequencies of phenes of nonmetric cranial traits and an increase in the level of their fluctuating asymmetry in young females, which is indicative of epigenetic rearrangements in populations living in a radioactive environment. 相似文献
453.
Aspects of the population dynamics ofMacrocystis integrifolia Bory were determined from harvested wild populations over a 26-month period and cultivated plants over a 40-month period. Mean wild plant size varied from 0.1 wet kg and two fronds in the winter to 3.1 wet kg and mine fronds in the summer. Plant recruitment probably occurred year-round with recruits making up 20 to 86% of the total population. Plant half-lives, estimated from population data, ranged from 1 to 3 months, with few plants exceedings 2 to 3 years in age. Standing crop ranged from 1.6 plants m-2 and 0.1 wet kg m-2 in winter to 8.3 plants m-2 and 8 wet kg m-2 in summer. 相似文献
454.
455.
M. Gueri E.S. Guerra L.E. Gonzalez N.A. Martinez A.V. Olivares E. Rosero C. de Ville de Goyet 《Disasters》1983,7(3):174-179
A retrospective study of the effects of the Tumaco earthquake of 1979 shows a smaller number of deaths and injuries than in earthquakes of similar magnitude that have occurred elsewhere, which is probably related to the type of building. Most of the deaths were caused by a tsunami. Proportionally the mortality was higher in the 0 to 4 age group. Among the injured, most of the lesions were minor. Morbidity was higher in the over 45 years age group, and lower among the "under-fives." There was an evident need for a simple "disaster medical record card." Coordination among the different relief agencies could have been better. 相似文献
456.
The effects of varying the concentration of phosphorus and potassium independently in the growing medium of pot-grown tomato plants on their subsequent susceptibility in normal medium to vascular wilt caused by Verticillium dahliae Kleb. were studied. The degree of host invasion was measured by estimating the chitin component of diseased tissue. Different levels of potassium had little effect on the degree of invasion of inoculated stems, but this was considerably enhanced in plants raised in the absence of phosphorus. Root inoculated plants were particularly resistant when raised in nutrients totally lacking in potassium, and very susceptible when raised in the absence of phosphorus. 相似文献
457.
Behavior of dialifor, dimethoate, and methidathion in artificially fortified grape juice processed into wine. 总被引:1,自引:0,他引:1
N S Kawar Y Iwata M E Düsch F A Gunther 《Journal of environmental science and health. Part. B》1979,14(5):505-513
Dialifor and methidathion were added to diluted "Zinfandel" grape concentrate at 25 ppm and dimethoate at 1.0 and 25 ppm prior to fermentation with Saccharomyces cerevisiae. The finished wine 56 days later contained 10% (2.5 ppm) of the dialifor, 46% (12 ppm) of the methidathion and 85% (21 and 0.98 ppm) of the dimethoate added to the grape must. Residues in wine stored at 24 degrees C dissipated by hydrolysis; half-lives in wine were 7 days for dialifor and methidathion and 30 days for dimethoate. Residues were unchanged in wine in frozen storage for one year. Analysis of seven commercial wines for dimethoate indicated less than 0.03 ppm dimethoate was present; identity could not be confirmed by thin-layer chromatography at this level. 相似文献
458.
459.
The southern pine beetle, Dendroctonus frontalis Zimmermann, is a major insect pest of pines in the southern U.S.A. A population dynamic model of D. frontalis within an infestation was developed. The model is based on the integration of several component submodels that describe individual life stage processes of the beetle. The inclusion of variable forest stand density and microclimate conditions results in a model response which closely follows actual field responses. A sensitivity analysis was performed to investigate effects of weather conditions and the importance of the spatial patterns within the forest. 相似文献
460.
A 105-d field experiment was conducted to determine the potential of the slow-release fertilizer, Osmocote (Scotts, Marysville, OH), to stimulate the indigenous microbial biodegradation of petroleum hydrocarbons in an oil-spiked beach sediment on an intertidal foreshore in Singapore. Triplicate microcosms containing 80 kg of weathered sediment, spiked with 5% (w/w) Arabian light crude oil and 1.2% (w/w) Osmocote pellets, were established, together with control microcosms minus Osmocote. Relative to the control, the presence of the Osmocote sustained a significantly higher level of nutrients (NH(4)(+)-N, NO(3)(-)-N, and PO(4)(3-)-P) in the sediment pore water over the duration of the experiment. The metabolic activity of the indigenous microbial biomass, as measured using an intracellular dehydrogenase enzyme assay, was also significantly enhanced over the duration of the experiment in amended sediments. The loss of total recoverable petroleum hydrocarbons (TRPH) and biodegradation of total n-alkanes (C(10)-C(33)), branched alkanes (pristane and phytane), as well as total target polycyclic aromatic hydrocarbons (PAHs) (two- to six-ring), in both the control and Osmocote-amended sediments, followed a first-order biodegradation model. The first-order loss rate of total recoverable petroleum hydrocarbons was 2.57 times greater than that of the control. The hopane-normalized rate constants for total n-alkane, branched alkane, and total target PAH biodegradation in the Osmocote-treated sediments were 3.95-, 5.50-, and 2.45-fold higher than the control, respectively. Overall, the presence of Osmocote was able to significantly enhance and accelerate the biodegradation of aliphatics and PAHs in oil-contaminated sediments under natural field conditions in an intertidal foreshore environment. 相似文献