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1.
The effect of different percentages of two fly ashes, derived from the combustion of coals from Poland (PO) and South Africa (SA), on organic N mineralization and nitrification in two different soils, was investigated. Following the addition of 2, 5, and 10% (w/w) PO and SA, the N mineralization constant K 1 decreased in the soil low in organic matter content. The addition of the same percentages of the two fly ashes to the soil higher in organic matter content gave contrasting results. When nitrification was taken into account, the nitrification constant K2 increased, following the addition of 2, 5, and 10% (w/w) PO and SA to the two soils. The most noticeable exception was the addition of 10% SA to the soil low in organic matter content, where K 2 decreased.  相似文献   
2.
The widespread use of vinyl phosphate insecticides and their interaction with soil organic phosphorus mineralization by phosphatases necessitates investigating their relationships. All insecticides investigated (dichlorvos, tetrachlorvinphos, crotoxyphos and phosphamidon) are competitive inhibitors of alkaline phosphatase. The inhibition constants depend on the substituents on the vinyl group and on their electronic influence on P atom.  相似文献   
3.
Plastic particles in surface waters of the northwestern atlantic   总被引:1,自引:0,他引:1  
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4.
The influence of the addition of anthracene (1 μg anthracene g?1 soil) in N transformations following (15NH4)2SO4 fertilization (200 mg N g?1 soil) was investigated in wheat pots by quadrapole mass-spectrometry. The dry matter yield at harvesting (after 16 days) was not statistically affected (P=0.05) by anthracene addition. The total amount of N from the fertilizer taken up by wheat seedings in 16 days was 29 and 26.8% of the added N in the absence and in the presence of anthracene, respectively, but the difference was not significantly different at level P=0.05. In order to investigate more deeply the effect of anthracene on the N cycle in the soil-plant system, the first-order rate constants of N mineralization, N immobilization, nitrification and N plant uptake have been determined according to a 15N + 14N soil-plant model. The comparison of the constants showed that organic N mineralization, nitrification and plant uptake proceeded at the same rate, while a small different rate (P=0.05) was shown by N immobilization. In fact, the N immobilization constant increased from 0.14±0.012 to 0.21±0.014 day?1 as a consequence of anthracene addition.  相似文献   
5.
The aim of the present study was to evaluate the effect of high pre‐slaughter environmental temperature on meat (Longissimus lumborum muscle) quality traits of Italian autochthonous pigs Suino Nero Lucano (SNL). High pre‐slaughter environmental temperature influenced the meat quality of autochthonous pigs. In particular, the meat from SNL pigs exposed to heat stress (H) showed significantly lower pH values at 24 and 48 hr post mortem, haem iron content and redness (a*) value, and a significantly higher shear force, drip loss and lightness (L*) values, compared to meat from SNL pigs reared under comfortable environmental temperature (C). Moreover, H meat showed a significant reduction of vitamin A, vitamin E, creatine and carnosine content, compared to C meat. Despite this, no pale‐soft‐exudative pork was found in our study, and no significant difference was detected between two studied groups for intramuscular fat and protein content of meat. In addition, despite the meat from SNL pigs exposed to heat stress has suffered a qualitative decrease, it showed a good endogenous antioxidants content.  相似文献   
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Gill respiratory surface area and oxygen consumption during aquatic respiration were measured in the facultative air-breathing loricariid fish,Hypostomus plecostomus. The fish did not surface to breathe atmospheric air in normoxic water; air-breathing was evoked by environmental hypoxia (water oxygen tension=35±2, mmHg) and did not show size-related threshold differences for air breathing.During gradual hypoxia, without access to atmospheric, air,H. plecostomus was found to be an oxyregulator and showed a reduced range of water oxygen tension in which the oxygen consumption remained constant in smaller fish. The critical oxygen tensions were 55 and 33 mmHg at 25°C for fish of 14–30 g and 31–80g body weight, respectively.The gill respiratory surface area (total lamellae area) is reduced, however, the lamellar frequency per mm of gill filament is high which facilitates the gas exchange. Moreover, the increase of gill respiratory surface area (b=0.666) is higher than the increase in routine VO2 (b=0.338) showing a positive relationship between the gill respiratory surface area /VO2 ratio and body mass (b=0.328); this indicates that the fish have greater gill respiratory surface area per unit of routine VO2 as they grow.  相似文献   
10.
ABSTRACT Pectobacterium and Dickeya spp. are related broad-host-range entero-bacterial pathogens of angiosperms. A review of the literature shows that these genera each cause disease in species from at least 35% of angiosperm plant orders. The known host ranges of these pathogens partially overlap and, together, these two genera are pathogens of species from 50% of angiosperm plant orders. Notably, there are no reported hosts for either genus in the eudicots clade and no reported Dickeya hosts in the magnoliids or eurosids II clades, although Pectobacterium spp. are pathogens of at least one plant species in the magnoliids and at least one in each of the three eurosids II plant orders. In addition, Dickeya but not Pectobacterium spp. have been reported on a host in the rosids clade and, unlike Pectobacterium spp., have been reported on many Poales species. Natural disease among nonangiosperms has not been reported for either genus. Phylogenetic analyses of sequences concatenated from regions of seven housekeeping genes (acnA, gapA, icdA, mdh, mtlD, pgi, and proA) from representatives of these genera demonstrated that Dickeya spp. and the related tree pathogens, the genus Brenneria, are more diverse than Pectobacterium spp. and that the Pectobacterium strains can be divided into at least five distinct clades, three of which contain strains from multiple host plants.  相似文献   
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