The paper contains results concerning the vitality of fir stands in the West Carpathian and Sudeten mountains and fir regeneration in most common forest communities. The primary causes of fir area decrease in forest of the Swietokrzyskie, Sudeten and Carpathian mountains are also given. 相似文献
Journal of Pest Science - Flower strips can play an important role in agro-ecosystems by supporting populations of pests’ natural enemies, thereby enhancing biological control. However, few... 相似文献
Selected potato (Solanum tuberosum L.) genotypes were grown in the field from May to September during 1984 and 1985, to study their growth and gas exchange responses in a warm climate. The parameters measured were leaf area index (LAI), canopy photosynthesis on ground area basis (CPn-Ga), stomatal conductance, dry matter partitioning and yield. The LAI ranged from 1.40 for Dakchip to 6.60 for Pungo during August 1984. The LAI also differed significantly among the potato genotypes for the three samplings during 1985. Atlantic, Chipbelle and DTO-33 showed no decline in their LAI up to 73 days after planting (DAP), indicating a better heat-stress tolerance response than the other genotypes. During both years, CPn-Ga differed significantly among the genotypes and Pungo had higher CPn-Ga than all the other genotypes. Mean CPn-Ga rates were 1.72 and 4.34 g CO2 m?2hr?1 during 1984 and 1985, respectively. Mean adaxial and abaxial stomatal conductances were 0.86 and 1.46 cm sec?1, during 1984, and stomatal conductances were similar for both years. Stomatal conductance did not appear to limit gas exchange in potato leaves. Dry matter partitioning to tubers ranged from 8.9% for Pungo to 55.5% for Atlantic 67 DAP during 1984. At final harvest, July 19, 1985, dry matter partitioning to tubers varied from 47.5% for Pungo to 69.9% for Chipbelle. The tuber yield ranged from 9.6 to 27.8 MT/ha. This study indicated that Atlantic and La Chipper have potential for growing in a warm climate. 相似文献
1. Pharmacokinetics of acetylsalicylic acid (ASA) and sodium salicylate (SS) were assessed following single intravenous (i.v.) and oral administration at doses of 50 mg/kg body weight to chickens and turkeys. Plasma drug concentrations were determined using high-performance liquid chromatography with ultraviolet detection and pharmacokinetic variables were calculated using a non-compartmental model.
2. The mean residence time (MRT) of salicylate (SA) after i.v. administration of SS was 6.08 ± 0.59 and 3.32 ± 0.27 h and after oral administration was 6.95 ± 0.72 and 4.55 ± 0.71 h in chickens and turkeys, respectively. The elimination half-life (T1/2 e) was shorter in turkeys compared with chickens. The value of body clearance (ClB) was higher in turkeys than in chickens, but the apparent volume of distribution (Vss) was similarly low in both species. The bioavailability of SS was complete and the maximal plasma concentration of SA (Cmax) after oral administration was 96.93 ± 8.06 and 91.76 ± 9.64 µg/ml, respectively, in chickens and turkeys.
3. The MRT of ASA after iv administration was 0.24 ± 0.08 and 0.24 ± 0.02 h and after oral administration was 0.78 ± 0.25 and 0.59 ± 0.13 h, respectively, in chickens and turkeys. In both species, T1/2 e was very short, ClB and Vss were similar and markedly higher than those of salicylate. The bioavailability of unchanged ASA was low and Cmax after oral administration was 6.9 ± 3.6 µg/ml in chickens and 8.6 ± 1.3 µg/ml in turkeys. 相似文献
Journal of Pest Science - The South American tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), has invaded most Afro-Eurasian countries and is threatening worldwide tomato... 相似文献
Tree structural diversity is assessed by modelling stand diameter at breast height (DBH) distribution. The aim of this study
was to verify the suitability of a mixture of two- and three-component Weibull and gamma models for describing irregular and
multimodal DBH distributions. Investigations were carried out in natural Abies alba Mill. and Fagus sylvatica L. stands, representing the growing-up stage, in the Świętokrzyski National Park (Central Poland) and in the Pieniny National
Park (Southern Poland). Sample plots (0.25–0.5 ha in area) were selected from a database used for forest dynamics analysis.
The parameters of the mixture model were estimated using maximum likelihood estimation (MLE) and a combination of an expectation–maximisation
(EM) algorithm with a Newton-type (NT) method. The multistart method (MM) of choosing initial values was used. The DBH distributions
in mixed Abies–Fagus forests of complex structure were accurately approximated by two- and three-component mixture models. The root mean square
error (RMSE) values varied from 3.4515 to 7.6682 for the Weibull mixture and from 3.6457 to 7.1419 for the gamma mixture.
The results indicated that the mixture Weibull and gamma models were, in general, equally suitable for modelling irregular
and multimodal DBH distributions. Finite mixture models may be used to characterise tree structural diversity, especially
in uneven-aged stands of complex structure. 相似文献
Left-handed DNA is shown to exist and elicit a biological response in Escherichia coli. A plasmid encoding the gene for a temperature-sensitive Eco RI methylase (MEco RI) was cotransformed with different plasmids containing inserts that had varying capacities to form left-handed helices or cruciforms with a target Eco RI site in the center or at the ends of the inserts. Inhibition of methylation in vivo was found for the stable inserts with the longest left-handed (presumably Z) helices. In vitro methylation with the purified MEco RI agreed with the results in vivo. Supercoil-induced changes in the structure of the primary helix in vitro provided confirmation that left-handed helices were responsible for this behavior. The presence in vivo of left-handed inserts elicits specific deletions and plasmid incompatibilities in certain instances. 相似文献