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排序方式: 共有158条查询结果,搜索用时 0 毫秒
1.
Leiv M. Mortensen 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):157-163
Abstract Seedlings of nine different conifers were exposed to 355 and 730 μmol mol-1 CO2, or low (> 15 nmol mol?1) and elevated 03 concentration (70 nmol mol?1) for 81–116 days. The experiments were conducted in growth chambers placed in a greenhouse. Increased CO2 concentration enhanced the mean relative growth rate (RGR) and total plant dry weight by 4 and 33% in Larix leptolepis, by 4 and 38% in Larix sibirica, by 7 and 47% in Picea glauca and by 3 and 16% in Picea sitchensis, respectively. The growth rates and dry weights of Pimis contorta, Pinus mugo and Pseudotsuga menziesii were not significantly affected. Carbon dioxide enrichment enhanced RGR of two provenances of Picea abies by 4 and 6%, respectively, while a third provenance was unaffected. In Pimis sylvestris, only the RGR of one of three provenances was stimulated by CO2 enrichment (4%). After two growth seasons CO2 enrichment enhanced RGR and total plant dry weight by 11 and 35% in Picea abies and by 12 and 36% in Pinus sylvestris, respectively. Elevated CO2 decreased the shoot:root ratio in Larix leptolepis, and decreased the needlerstem ratio in Picea glauca, but increased it in Pseudotsuga menziesii. Elevated O3 significantly decreased the plant dry weight in Picea sitchensis, Pseudotsuga menziesii and in one of three provenances of Pinus sylvestris, while the other species and provenances were unaffected. Increased O3 concentration increased the shoot:root dry weight ratio in one of three Picea abies provenances, in all three Pinus sylvestris provenances and in Pinus contorta. The needle:stem ratio was enhanced by O3 in seven of the nine species. The O3 exposure caused chlorosis of needles in all species except Pseudotsuga menziesii. 相似文献
2.
Two experiments comprising a total of 80 Danish Landrace pigs in the period 20–90 kg live-weight were carried out to study the effect of dietary levels and ratios of Ca and P on serum values of Ca, inorg. P, and alkaline phosphatase and on the development of degenerative arthritis and atrophic rhinitis.In both experiments each kg feed (Table 1) was supplemented with 600 i. u. vitamin D3 and 80 p. p. m. Zn.In the first experiment the Ca:P ratio was 1.2 and the amount of Ca increased from 0.48 % to 1.20 % without influencing daily gain, feed conversion, carcass performance (Table 2) or frequency of atrophic rhinitis (Table 3). The Ca:P ratio in scapula was 2.15. Only when the diet was supplemented with 1.20 % Ga and 1.00 % P the bone quality was histomorphologically adequate (Figs. 1–4).In the second experiment various Ca:P ratios (ranging from 0.1 to 3.0) were compared with the recommended level and ratio of 0.72 % Ga and 0.60 % P. Performance of pigs on the normal level was better than for the other pigs (Table 4). Clinically, various degrees of leg-weakness and -deformation occurred, most pronounced in the high Ca — low P group. Very little lameness and no convulsions were observed. Marked hypocalcemia was not found. Unilateral high Ca intake increased serum Ca significantly, and serum alkaline phosphatase slightly, and decreased serum P (Figs. 5–7). Advanced pericytic osteolysis, poor mineralization and generalized osteodystrophia fibrosa were found in the low Ca groups (Figs. 8–13). The groups showed no differences in frequency of atrophic rhinitis (Table 5), and rickets was not observed.The incidence of degenerative joint lesions was not increased in pigs on the unfavourable Ca:P ratios, and depended apparently more on litters than on diets. 相似文献
3.
Tarnow I Kristensen AT Texel H Olsen LH Pedersen HD 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2003,17(5):680-686
With aggregometry, increased platelet activity has been reported in Cavalier King Charles Spaniels (CKCS) without mitral regurgitation (MR). In contrast, dogs with MR have been found to have decreased platelet activity. The purpose of this study was to test an easy bedside test of platelet function (the Platelet Function Analyzer [PFA-100]) to see if it could detect an increase in platelet activity in CKCS without MR and a decrease in platelet activity in CKCS with MR. This study included 101 clinically healthy dogs > 1 year of age: 15 control dogs of different breeds and 86 CKCS. None of the dogs received medication or had a history of bleeding. The PFA-100 evaluates platelet function in anticoagulated whole blood under high shear stress. Results are given as closure times (CT): the time it takes before a platelet plug occludes a hole in a membrane coated by agonists. The CT with collagen and adenosine-diphosphate as agonists was similar in control dogs (median 62 seconds; interquartile interval 55-66 seconds) and CKCS with no or minimal MR (55; 52-64 seconds). The CT was higher in CKCS with mild MR (regurgitant jet occupying 15-50% of the left atrial area) (75; 60-84 seconds; P = .0007) and in CKCS with moderate to severe MR (jet > 50%) (87: 66-102 seconds; P < .0001). CKCS with mild, moderate, and severe, clinically inapparent MR have decreased platelet function. The previous finding of increased platelet reactivity in nonthrombocytopenic CKCS without MR could not be reproduced with the PFA-100 device. 相似文献
4.
Jason E. Anton Kristine L. Vernon Dale E. Kelley John R. Gibbons Glen Birrenkott Chris J. Mortensen 《Journal of Equine Veterinary Science》2014
Our previous research has demonstrated moderate exercise can be detrimental to early pregnancy in the mare, but little work has examined exercise after pregnancy has been detected. We exercised mares (n = 8) 6 days a week for 45 min from Day 16 until Day 80 of gestation. Color Doppler ultrasonography was used to evaluate embryonic vesicle size, fetal length, and uterine blood flow. Blood was sampled every other day to analyze cortisol and progesterone concentrations. Results indicated that exercising pregnant mares (n = 4) led to greater (P < .01) cortisol concentrations 30 min after the exercise period. No overall treatment effect could be detected in progesterone concentrations; however, following Day 60 of gestation, progesterone concentrations were lower (P < .05) in exercised mares. Additionally, progesterone concentrations peaked earlier in exercised mares at Day 52 of gestation compared to peak levels at Day 68 of gestation for control mares. No significant effects were detected in embryonic vesicle size. Fetal length tended (P = .06) to be longer in the conceptus of exercised mares. Uterine blood flow did not differ between groups but increased as pregnancy progressed (P < .001) in both groups. All mares in this study went on to deliver healthy foals and suffered no difficulties during parturition. These results indicated that moderate exercise was not detrimental to mare pregnancy. 相似文献
5.
Seedlings of Betula pubescens Ehrh. (mountain birch) and Phleum pratense L. (timothy) were grown for 42 days under full light or 50% shade in the field at 12°C, and at comparable photosynthetic active radiation (PAR) levels in a greenhouse at 18°C. Plants from the four pretreatments were exposed to 78 nmol mol-1 (ppb) O3 (8 h day-1) under two temperatures (15 and 25°C), two relative air humidities (50 and 80% RH) or two CO2 相似文献
6.
Evidence of long distance airborne transmission of Aujeszky's disease (pseudorabies) virus 总被引:4,自引:0,他引:4
L S Christensen J Mousing S Mortensen K J Soerensen S B Strandbygaard C A Henriksen J B Andersen 《The Veterinary record》1990,127(19):471-474
Aujeszky's disease has been the subject of an eradication campaign in Denmark since 1980. A detailed knowledge of the virus strains present in the country was provided by restriction fragment analyses of older clinical isolates, and of isolates from all the virologically confirmed outbreaks since 1985. The introduction of foreign strains into southern border areas was demonstrated during the winters of 1984/85, 1986/87 and 1987/88. An epizootic during the winter of 1987/88 was shown to correlate with an unusual predominance of southerly winds. Both conventional and specific pathogen free herds became infected. A herd level case-control analysis of the outbreaks during the winter of 1987/88 revealed that there was a positive correlation between the risk of infection and the size of the herd. The observations support the hypothesis of airborne transmission of the disease. 相似文献
7.
A. Fangmeier L. De Temmerman L. Mortensen K. Kemp J. Burke R. Mitchell M. van Oijen H. -J. Weigel 《European Journal of Agronomy》1999,10(3-4):215-229
Nutrient element concentrations and grain quality were assessed in spring wheat grown under elevated CO2 concentrations and contrasting levels of tropospheric ozone at different nitrogen supply rates at several European sites. Carbon dioxide enrichment proved to affect nutrient concentrations in a complex manner. In green leaves, all elements (with exception of phosphorus and iron) decreased. In contrast, effects on the element composition of grains were restricted to reductions in nitrogen, calcium, sulphur and iron. Ozone exposure resulted in no significant effects on nutrient element concentrations in different tissues in the overall analysis. The nitrogen demand of green tissues was reduced due to CO2 enrichment as shown by reductions in the critical leaf nitrogen concentration and also enhanced nitrogen use efficiency. Reductions in the content of ribulose-bisphosphate carboxylase/oxygenase and repression of the photorespiratory pathway and reduced nitrogen allocation to enzymes driving the photosynthetic carbon oxidation cycle were chiefly responsible for this effect. Thus, nitrogen acquisition by the crop did not match carbon acquisition under CO2 enrichment. Since crop nitrogen uptake from the soil was already completed at anthesis, nitrogen allocated to the grain after anthesis originated from vegetative pools—causing grain nitrogen concentrations to decrease under CO2 enrichment (on average by 15% when CO2 concentrations increased from 360 to 680 μmol mol−1). Correspondingly, grain quality was reduced by CO2 enrichment. The Zeleny value, Hagberg value and dry/wet gluten content decreased significantly with increasing [CO2]. Despite the beneficial impact of CO2 enrichment on growth and yield of C3 cereal crops, declines in flour quality due to reduced nitrogen content are likely in a future, [CO2]-rich world. 相似文献
8.
The contribution of animal slurry to the supply of S to plants was studied. The total-S content of cattle and pig slurry was significantly correlated to DM and nitrogen content and was composed of sulfide, sulfate and C-bonded S. During 42 weeks of storage sulfate concentrations decreased and sulfide and C-bonded S concentrations increased. In a pot experiment plant-availability of S in slurry was found to be low, 5 to 7% of total-S. 相似文献
9.
Terracciano A Abdel-Khalek AM Adám N Adamovová L Ahn CK Ahn HN Alansari BM Alcalay L Allik J Angleitner A Avia MD Ayearst LE Barbaranelli C Beer A Borg-Cunen MA Bratko D Brunner-Sciarra M Budzinski L Camart N Dahourou D De Fruyt F de Lima MP del Pilar GE Diener E Falzon R Fernando K Ficková E Fischer R Flores-Mendoza C Ghayur MA Gülgöz S Hagberg B Halberstadt J Halim MS Hrebícková M Humrichouse J Jensen HH Jocic DD Jónsson FH Khoury B Klinkosz W Knezević G Lauri MA Leibovich N Martin TA 《Science (New York, N.Y.)》2005,310(5745):96-100
Most people hold beliefs about personality characteristics typical of members of their own and others' cultures. These perceptions of national character may be generalizations from personal experience, stereotypes with a "kernel of truth," or inaccurate stereotypes. We obtained national character ratings of 3989 people from 49 cultures and compared them with the average personality scores of culture members assessed by observer ratings and self-reports. National character ratings were reliable but did not converge with assessed traits. Perceptions of national character thus appear to be unfounded stereotypes that may serve the function of maintaining a national identity. 相似文献
10.
Walker MK Farkas DF Anderson SR Meunier-Goddik L 《Journal of agricultural and food chemistry》2004,52(26):8230-8235
High-pressure processing (HPP) was utilized to induce unfolding of beta-lactoglobulin (beta-LG). beta-Lactoglobulin solutions at concentrations of 0.5 mg/mL, in pH 7.5 phosphate buffer, were pressure treated at 510 MPa for 10 min at either 8 or 24 degrees C. The secondary structure, as determined by circular dichroism (CD), of beta-LG processed at 8 degrees C appeared to be unchanged, whereas beta-LG processed at 24 degrees C lost alpha-helix structure. Tertiary structures for beta-LG, as determined by near-UV CD, intrinsic protein fluorescence spectroscopy, hydrophobic fluorescent probe binding, and thiol group reactivity, were changed following processing at either temperature. The largest changes to tertiary structure were observed for the samples processed at 24 degrees C. Model solutions containing the pressure-treated beta-LG showed significant decreases in surface tension at liquid-air interfaces with values of 54.00 and 51.69 mN/m for the samples treated at 24 and 8 degrees C, respectively. In comparison, the surface tension for model solutions containing the untreated control was 60.60 mN/m. Changes in protein structure during frozen and freeze-dried storage were also monitored, and some renaturation was observed for both storage conditions. Significantly, the sample pressure-treated at 8 degrees C continued to display the lowest surface tension. 相似文献