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91.
92.
The influence of soil pH on denitrification: progress towards the understanding of this interaction over the last 50 years 总被引:7,自引:0,他引:7
Results from the pioneering research on the interactions between pH and denitrification in soil from the 1950s to the present are reviewed, the changing perceptions of this complex relationship are discussed, and the current status of the subject is assessed. Facets of this relationship that are analysed in detail include the direct or indirect influence of pH on overall denitrification rates in soils, changes in the composition of gaseous products that depend on pH, methods for measuring the process, the concept of an optimum pH for denitrification, and the adaptation of microbial denitrifying communities to acidic environments. The main conclusions to be drawn are as follows. Total gaseous emissions to the atmosphere (N2O, NO and N2) have repeatedly been shown to be less in acidic than in neutral or slightly alkaline soils. This may be attributable to smaller amounts of organic carbon and mineral nitrogen available to the denitrifying population under acid conditions rather than a direct effect of low pH on denitrification enzymes. Numerous laboratory and field studies have demonstrated that the ratio N2O:N2 is increased when the pH of soils is reduced. The relation between soil pH and potential denitrification as determined by various incubation methods remains unclear, results being influenced both by original conditions in soil samples and by unknown changes during incubation. The concept of an optimum pH for denitrification has been frequently proposed, but such a term has little or no meaning without reference to specific attributes of the process. 相似文献
93.
94.
G K Ogilvie R C Straw B E Powers M F Cooper S J Withrow 《Journal of the American Veterinary Medical Association》1991,199(5):613-616
The study reported here was undertaken to determine the nephrotoxicosis associated with the administration of cisplatin, an antineoplastic agent, to dogs when administered during 6-hour saline solution diuresis. Cisplatin (70 mg/m2 of body surface, IV, every 21 days) was given to 61 dogs with malignant neoplasia with a total of 185 doses in 1 (n = 9 dogs), 2 (n = 26 dogs), 3 (n = 4 dogs), 4 (n = 9 dogs), 5 (n = 2 dogs), and 6 (n = 11 dogs) treatments. The cisplatin was given over a 20-minute period after 0.9% NaCl solution (saline solution) was administered IV for 4 hours at a rate of 18.3 ml/kg of body weight/h. After the cisplatin infusion, saline solution diuresis was continued at the same rate for 2 hours. Before each treatment with cisplatin, dogs were evaluated with at least a physical examination, CBC, determination of serum urea nitrogen concentration, and in most cases, determination of serum creatinine concentration and urine specific gravity. Four of the 61 dogs (6.6%) developed clinically evident renal disease after 2 (1 dog), 3 (2 dogs), and 4 (1 dog) doses of cisplatin were administered. Three of the 4 dogs had preexisting disease of the urinary tract prior to the start of treatment. The survival time in dogs that developed renal disease (median, 145 days; range, 15 to 150 days) was similar to that of all dogs in this study (median, 154 days; range, 30 to 500 days), with 13 dogs still alive at the conclusion of the study.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
95.
The concentration of peripheral plasma progesterone was measured by a double isotope derivative assay in hens slaughtered at various stages during the ovulatory cycle. A peak value was obtained 2 to 6 h before ovulation and basal levels were reached at ovulation. No secondary peaks were observed during the cycle. Similar results were obtained using a protein‐binding assay on plasma from individual birds taken serially during the cycle. Birds which did not ovulate on a particular day showed no peak of progesterone. In two birds sampled at the beginning of a laying cycle, the progesterone peak was of longer duration. 相似文献
96.
A 4-year-old Scotch Collie bitch was presented for examination because of hyperthermia and anaemia. Haematological examination and bone marrow biopsy led to a diagnosis of myeloid neoplasia. At autopsy there was slight enlargement of the liver, spleen and some lymph nodes. Microscopic examination revealed extensive infiltration of these tissues by neoplastic myeloid cells. 相似文献
97.
A four-year-old entire male cocker spaniel was presented with a history of dyspnoea due to tracheal stenosis. As part of the clinical approach, a coagulation screening profile revealed moderately reduced levels of Factor VIII procoagulant activity (VIII: C), but elevated factor VHI-related antigen levels (VIIIR: Ag). A diagnosis of haemophilia A (classic haemophilia) was made and the tracheal stenosis attributed to a mediastinal haematoma. The dyspnoea was alleviated by the surgical insertion of a tracheostomy tube and the dog was treated with citrated whole blood and fresh-frozen canine plasma. Response to treatment was excellent and follow-up radiography three months later revealed resolution of the tracheal stenosis. 相似文献
98.
M J Cooper 《The Veterinary record》1986,119(25-26):634-635
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100.