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排序方式: 共有82条查询结果,搜索用时 19 毫秒
1.
Prediction of the shoot production of heather under grazing in the uplands of Great Britain 总被引:1,自引:0,他引:1
S. C. F. PALMER 《Grass and Forage Science》1997,52(4):408-424
An empirical model for the annual shoot production of heather Calluna vulgaris in the absence of grazing in the uplands of Great Britain is presented. Production is modelled as a function of the growth phase of the heather and weather conditions during the summer growing season and the previous winter.
The effects of grazing, principally by sheep, on changes in heather cover after burning are reviewed. A simple model of annual cover change is proposed, and fitted to data from dry and wet heaths in Scotland.
A model of the influence of grazing on annual heather shoot production is developed for dry heath.
The models indicate that previously published estimates of the utilization levels that heather can tolerate without a reduction in shoot production may be too high. For pioneer and early building heather, estimated threshold utilization levels are 16% in summer and 24% in autumn. Furthermore, it is suggested that any level of utilization will reduce the rate of increase of heather ground cover after burning. 相似文献
The effects of grazing, principally by sheep, on changes in heather cover after burning are reviewed. A simple model of annual cover change is proposed, and fitted to data from dry and wet heaths in Scotland.
A model of the influence of grazing on annual heather shoot production is developed for dry heath.
The models indicate that previously published estimates of the utilization levels that heather can tolerate without a reduction in shoot production may be too high. For pioneer and early building heather, estimated threshold utilization levels are 16% in summer and 24% in autumn. Furthermore, it is suggested that any level of utilization will reduce the rate of increase of heather ground cover after burning. 相似文献
2.
During the summer of 1962, levels of radioactivity in over 700 people at four villages above the Arctic Circle in Alaska were measured with a transportable whole-body counter. The averages for body burden of cesium-137 were much higher than the average for people in the rest of the United States. The people of the interior village of Anaktuvuk Pass had the highest average burden of cesium-137, which was 421 nanocuries; the maximum burden was 790 nanocuries. 相似文献
3.
D. L. HOLMBERG DVM MVSC DiplomateACVs N. C. PALMER DVM PhD D. VANPELT DVM A. R. WILLAN PhD 《Veterinary surgery : VS》1990,19(5):323-327
Thoracolumbar disc fenestration was performed in eight canine cadavers. A hole was cut in the anulus fibrosus with a scalpel in four dogs, and with a high speed drill and burr in four dogs. A curette was used to remove as much of the nucleus pulposus as possible. Sixty-five percent of the nucleus pulposus was removed with the power-assisted technique and 41% was removed by manual fenestration. Manual and power-assisted disc fenestration were performed on alternate intervertebral discs from T11-12 to L5-6 in four dogs. Six months after surgery, results of high-detail radiographic and histologic evaluation of the vertebral bodies and discs showed minimal difference in the sequelae of the two techniques. A retrospective medical records analysis and follow-up of 60 clinical cases treated with prophylactic, power-assisted disc fenestration failed to identify any cases with postoperative recurrence of neurologic deficits. Ten percent of the dogs had periodic back pain of unknown etiology, without other signs of intervertebral disc disease. The findings of this study indicate that power-assisted disc fenestration permits more complete evacuation of the nucleus than manual fenestration, causes no more postoperative complications, and results in a low recurrence rate of neurologic deficits. 相似文献
4.
SCOTT E. PALMER VMD 《Veterinary surgery : VS》1983,12(1):54-57
A sagittal fracture of the third carpal bone of a Standardbred racehorse was repaired with lag screw fixation. Healing of the fracture was uncomplicated, and the horse made a successful return to racing. It was concluded that selected sagittal fractures of the third carpal bone may be treated successfully with lag screw fixation. Criteria for selection of cases include fragment size and orientation of the fracture plane. 相似文献
5.
SUSAN R. YANOFF DVM MS DONALD A. HULSE DVM Dipiomate ACVS ROSS H. PALMER DVM MS Dipiomate ACVS MICHAEL R. HERRON DVM MS Dipiomate ACVS 《Veterinary surgery : VS》1992,21(6):480-487
Distraction osteogenesis was used to treat five dogs with limb deformities or limb shortening. The affected bones underwent osteotomy, and modified external fixators were attached. Complications included pin loosening, implant breakage, and soft-tissue contracture. Adequate limb length was attained in all cases, but clinical results varied from poor to excellent. Two dogs were not lame after the procedure, two dogs had improved function but were still lame, and one dog had complications necessitating amputation. 相似文献
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SUMMARY As part of a program to eradicate virulent footrot from Western Australia, 2745 isolates of Dichelobacter nodosus were isolated from 5263 specimens from 1883 submissions. The virulence of each isolate was assessed using protease thermostability and isoenzyme zymogram. We describe changes to the materials and methods required to handle these specimens and to reduce the interval between submission and report to 8 days. 相似文献
9.
Ovine Listeriosis in south coastal Western Australia 总被引:1,自引:0,他引:1
10.
Juliana DF Barbosa Viviane B Silva Péricles B Alves Giuseppe Gumina Roseli LC Santos Damião P Sousa Sócrates CH Cavalcanti 《Pest management science》2012,68(11):1478-1483
BACKGROUND: Dengue fever is a severe public health problem for several countries. In order to find effective larvicides to aid control programs, the structure‐activity relationships of eugenol derivatives against Aedes aegypti (Diptera: Culicidae) larvae were evaluated. Additionally, the composition and larvicidal activity of Syzygium aromaticum essential oil was assessed. RESULTS: Four compounds representing 99.05% of S. aromaticum essential oil have been identified. The essential oil was active against Ae. aegypti larvae (LC50 = 62.3 and 77.0 ppm, field‐collected and Rockefeller larvae respectively). The larvicidal activity of eugenol, the major compound of the essential oil, was further evaluated (LC50 = 93.3 and 71.9 ppm, field‐collected and Rockefeller larvae respectively). The larvicidal activity and structure‐activity relationships of synthetic derivatives of eugenol were also assessed. The larvicidal activity of the derivatives varied between 62.3 and 1614.9 ppm. Oxidation of eugenol allylic bond to a primary alcohol and removal of the phenolic proton resulted in decreased potency. However, oxidation of the same double bond in 1‐benzoate‐2‐methoxy‐4‐(2‐propen‐1‐yl)‐phenol resulted in increased potency. CONCLUSION: Structural characteristics were identified that may contribute to the understanding of the larvicidal activity of phenylpropanoids. The present approach may help future work in the search for larvicidal compounds. Copyright © 2012 Society of Chemical Industry 相似文献