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排序方式: 共有76条查询结果,搜索用时 15 毫秒
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Wilhelm Grzesiak Daniel Zaborski Piotr Sablik Agata ?ukiewicz Andrzej Dybus Iwona Szatkowska 《Computers and Electronics in Agriculture》2010,74(2):265-273
In the present study, the detection of cows with artificial insemination (AI) difficulties using selected statistical and machine learning methods is presented. Cows were divided into two classes: those that conceived after one or two services (“GOOD”) and those that required more than two services per conception (“POOR”). The best performance was exhibited by one of the artificial neural networks (ANN) and the multivariate adaptive regression spline (MARS) method (AIC, BIC, RMS and accuracy); whereas logistic regression (LR) and classification functions (CF) were of somewhat lower quality. The detection of cows with AI difficulties, performed on the basis of the test set comprising new instances, showed that the ANN and MARS were more precise in comparison with the statistical methods. Sensitivity and specificity were over 85% for the perceptron with two hidden layers (MLP2) and MARS and approximately 80% or lower for LR and CF. From among variables determining the AI category, the average calving interval and cow body condition index were the most important. Other significant variables were lactation number, pregnancy length, sex of calf from previous calving and cow age. The prognoses obtained using ANN and MARS can be used for the appropriate preparation of cows for AI. 相似文献
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This work investigated the effects of land cover and land-use change (LUC) on the ability of a soil to store carbon (C) and reduce carbon dioxide (CO2) emissions, in a Mediterranean area. Using a paired-site approach, we estimated the effect of land-cover change on the C stock from 1972 to 2008 in a natural reserve (Grotta di Santa Ninfa) in western Sicily. We selected 15 paired sites representative of five LUCs. We studied the effect of land use on soil organic C (SOC) content in bulk soil and in different particle-size fractions (2000-1000 μm, 1000-500 μm, 500-250 μm, 250-63 μm, 63-25 μm, and < 25 μm). Laboratory incubation of the soil samples was conducted to measure CO2 evolution in bulk soil collected at two different depths from each paired site. We found that the conversion of natural vegetation to orchards (vineyards and olive groves) resulted in SOC decreases ranging from 27% to 50%. The conversion from vineyards to arable land led to a 9% decrease in SOC, whereas the opposite caused a 105% gain. When arable land was replaced by Eucalyptus afforestation, a 40% increase in SOC was observed. SOC decline occurred mainly in coarser soil fractions, whereas the finest fractions were not influenced by land use. We calculated an overall SOC reduction of 63% in the study area, corresponding to a 58 Mg ha− 1 SOC loss in less than 30 years. Our results indicate that land-use conversion, vegetation type, and management practices that control the biogeochemical and physical properties of soil could help reduce CO2 emissions and sequester SOC. 相似文献
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Olejniczak T Boratyński F Białońska A 《Journal of agricultural and food chemistry》2011,59(11):6071-6081
Five optically active and sixteen racemic lactones (nine of them new) of bicyclo[4.3.0]nonane structure were synthesized. IC(50) values for the following phytopathogens were determined: Aspergillus ochraceus AM 456, Fusarium culmorum AM 282, Fusarium oxysporum AM 13, Fusarium tricinctum AM 16. Effect of compound structures, especially stereogenic centers, on fungistatic activity has been discussed. The highest fungistatic activity was observed for trans-7,8-dibromo-cis-3-oxabicyclo[4.3.0]nonan-2-one (3c), IC(50) = 30.1 μg/mL (0.10 μM/mL), and cis-7,8-epoxy-cis-3-oxabicyclo[4.3.0]nonan-2-one (3b), IC(50) = 72.2 μg/mL (0.47 μM/mL), toward F. oxysporum AM 13. 相似文献
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Wioleta Czelejewska Agata Zmijewska Mariusz Dziekonski Stanislaw Okrasa 《Reproduction in domestic animals》2020,55(5):604-612
In pigs, plasma prolactin concentration markedly changes during the oestrous cycle and the regulation of its secretion is very complex. The contribution of neurokinins in this process has not been sufficiently delineated. The aim of the study was to examine the effects of neurokinin A (NKA) on prolactin synthesis and secretion in cyclic gilts. The expression of NKA precursor (Ppta) and receptor (Tacr2) genes as well as NKA and TACR proteins content in the porcine pituitaries (days 2–3, 9–10, 12–13, 15–16 and 19–20 of the cycle) was determined. Furthermore, the in vitro influence of NKA on the expression of prolactin (Prl), dopamine receptor (D2r), TRH receptor (Trhr) genes and prolactin secretion by the porcine pituitary cells (days 9–10, 15–16 and 19–20 of the cycle) was assessed. The expression of Ppta and Tacr2 as well as NKA and TACR proteins in the pituitary tissue has been changing throughout the oestrous cycle. NKA affected in vitro the expression of studied genes and prolactin secretion depending on the stage of the cycle, dose of NKA and/or duration of the cell incubation. Altogether, the study indicates that NKA is engaged in the modulation of prolactin secretion in the pig during the oestrous cycle. 相似文献
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The heterosis of leaf photosynthesis was studied on the main characters included in the range from CO2 exchange rate (CER) to enzymatic activity using a remote cross F, rice. The CER was significantly higher than those of the parental strains, showing a 111 % heterosis effect on average; at the same time strong heterosis was observed for the leaf area production and growth. Also stomatal and mesophyll conductances increased in the F1 rice, which may contribute to the increase in CER. Chlorophyll content (Ch1), soluble protein content (SPC) and ribulose 1,5-bisphosphate (RuBP) carboxylase activity (RCA) were measured as the internal factors related to photosynthesis, and compared between the F1 , rice and the parents. For all these factors, the F1 rice showed low values compared to the parents. Positive heterosis was not expressed here. On the other hand, the specific activity of RCA (RCA/SPC) increased in the F1 , rice, showing a 120% heterosis effect. This may be regarded as one of the main causes for the increase in CER of the F1 , rice. High CER expressed as heterosis concurrently with large leaf area production is one of the important findings in our study, and this may suggest a high possibility of further improvement in biomass production or yield of rice by gathering the advantageous elements into a hybrid plant. 相似文献
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Gabriela Halik Andrzej ozicki Agata Koziorzbska Ewa Arkuszewska Kamila Puppel 《Journal of animal physiology and animal nutrition》2019,103(1):1-7
Forty Simmental cows were divided into four groups with 10 per group to investigate the effect of a transition diet supplemented with synthetic β‐carotene and natural carotenoid‐rich feed (pumpkin silage) on chemical composition of the colostrum. The control group (I) was fed grass and maize silage and supplemental concentrates, group II additionally received 400 mg/day/cow of synthetic β‐carotene, in group, III 40% DM of maize silage was replaced with pumpkin silage to increase β‐carotene intake by 400 mg in relation to group I, and in group IV 60% DM of maize silage was replaced with pumpkin silage without adjusting for β‐carotene. Colostrum was collected from the cows within 5 hr of calving to determine colostrum composition, the content of immunoglobulins and carotenoids, total antioxidant status (TAS), the content of some bioactive proteins and the composition of fatty acids. The study showed that the experimental diets had no effect on the gross composition of colostrum. The content of α‐carotene, β‐carotene and violaxanthin was significantly higher in group IV than in group I and that of lutein higher in group IV than in groups I and II. Total antioxidant status of colostrum in group IV was significantly higher than in group I. Groups III and IV were characterized by a higher concentration of immunoglobulin IgG in relation to group I. IgM level in groups II, III and IV was significantly higher than in group I and that in groups III and IV was also higher than in group II. The highest IgA concentration was observed in group IV and the lowest in group I. Lysozyme concentration was higher in group IV compared to groups I and II. The diets had no effect on the total content of SFA, MUFA and PUFA in colostrum. 相似文献
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Paulo Pereira Pranas Mierauskas Agata Novara 《Land Degradation \u0026amp; Development》2016,27(4):871-883
The aim of this work is to study Lithuanian stakeholders' perceptions of fire impacts in protected areas. For this study, the stakeholders consisted of foresters, ecologists and farmers. A clear understanding of the opinions of stakeholders about fire effects on environmental, social and economic aspects of Lithuanian protected areas will allow an assessment of the stakeholders' reaction to fire policy, including government measures towards fire prevention, suppression and application of prescribed fire to landscape management. The results showed that stakeholders in general think that fire is not a threat to Lithuania and to the ecological processes in the protected areas. However, they agree that fires have negative impacts on soil properties and fertility but are not to an irremediable or irrecoverable extent. Stakeholders disagree that fire has positive consequences for agricultural and cattle activities but agreed that vegetation recovers quickly. They do not see fire as a social and economic problem, do not agree that prescribed fire could be used to landscape management, and believe that mechanical thinning is a better management tool than prescribed fire. Stakeholders agree that fire does not have negative impacts on the biodiversity. These opinions depended on the age group of the respondent but especially on the respondent's professional occupation. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献