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排序方式: 共有155条查询结果,搜索用时 459 毫秒
1.
Adams Alison B. Pontius Jennifer Galford Gillian Gudex-Cross David 《Landscape Ecology》2019,34(10):2401-2419
Landscape Ecology - Understanding how the Northern Forest landscape has changed and is likely to change, both in terms of forest extent and forest configuration, has important implications for... 相似文献
2.
Stergiadis S Leifert C Seal CJ Eyre MD Nielsen JH Larsen MK Slots T Steinshamn H Butler G 《Journal of agricultural and food chemistry》2012,60(29):7270-7281
There is increasing concern that the intensification of dairy production reduces the concentrations of nutritionally desirable compounds in milk. This study therefore compared important quality parameters (protein and fatty acid profiles; α-tocopherol and carotenoid concentrations) in milk from four dairy systems with contrasting production intensities (in terms of feeding regimens and milking systems). The concentrations of several nutritionally desirable compounds (β-lactoglobulin, omega-3 fatty acids, omega-3/omega-6 ratio, conjugated linoleic acid c9t11, and/or carotenoids) decreased with increasing feeding intensity (organic outdoor ≥ conventional outdoor ≥ conventional indoors). Milking system intensification (use of robotic milking parlors) had a more limited effect on milk composition, but increased mastitis incidence. Multivariate analyses indicated that differences in milk quality were mainly linked to contrasting feeding regimens and that milking system and breed choice also contributed to differences in milk composition between production systems. 相似文献
3.
Six pregnant mares were used to determine what level of water restriction causes physiological and/or behavioural changes indicative of stress. Nonlegume hay was fed ad libitum. During the first week of restriction, 5 l water/100 kg bwt was available, during the second week 4 l/100 kg bwt and, during the third week, 3 l/100 kg bwt. Ad libitum water intake was 6.9 l/100 kg bwt; at 3 l/100 kg bwt water intake was 42% of this. Daily hay intake fell significantly with increasing water restriction from 12.9 +/- 0.75 kg to 8.3 +/- 0.54 kg; bodyweight fell significantly for a total loss of 48.5 +/- 8.3 kg in 3 weeks. Daily blood samples were analysed; osmolality rose significantly with increasing water restriction from 282 +/- 0.7 mosmols/kg to 293.3 +/- 0.8 mosmols/kg bwt, but plasma protein and PCV did not change significantly. Cortisol concentrations fell from 8.1 ng/ml to 6.4 ng/ml over the 3 week period. Aldosterone fell from 211.3 +/- 74.2 pg/ml to 92.5 +/- 27.5 pg/ml at the end of the first week. The behaviour of 4 of the 6 mares was recorded 24 h/day for the duration of the study. The only significant difference was in time spent eating, which decreased with increasing water restriction from 46 +/- 3% to 30 +/- 3%. It is concluded that water restriction to 4 l/100 kg bwt dehydrates pregnant mares and may diminish their welfare, but is not life- or pregnancy-threatening. 相似文献
4.
5.
Molly K. Shepard Wesley L. Lee Randy B. Eggleston 《The Canadian veterinary journal. La revue veterinaire canadienne》2015,56(1):48-52
A 21-year-old Thoroughbred gelding with a history of equine pituitary pars intermedia dysfunction (PPID) presented with priapism of 2 days’ duration. The horse received a caudal morphine epidural and then underwent corpus cavernosum lavage and phallectomy under general anesthesia. The patient’s recovery featured multiple unsuccessful attempts to stand and his respiratory distress persisted for several hours until he acutely developed severe colic and was euthanized. Necropsy findings revealed a pituitary adenoma of the pars intermedia, bilateral adrenal cortical hyperplasia, and diaphragmatic herniation. This report suggests that horses with PPID may present a greater risk for diaphragmatic hernia under general anesthesia or during procedures placing stress on the diaphragm, including anesthetic recovery. 相似文献
6.
The epaulette shark (Hemiscyllium ocellatum) and the grey carpet shark (Chiloscyllium punctatum) are commonly found in periodically hypoxic environments. The ecophysiological time available for these animals to safely
exploit these niches during different seasonal temperatures was examined. The time to loss of righting reflex (T
LRR) was examined in response to an open ended anoxic challenge at three seasonal temperatures (23, 25 and 27°C). Ventilation
rates were measured in an open ended anoxic challenge at 23°C and during 1.5 h of anoxia followed by 2 h of re-oxygenation
at 23 and 25°C. The mean T
LRR of epaulette and grey carpet sharks was inversely proportional to temperature. The T
LRR was similar between species at 23°C; however, grey carpet sharks had significantly reduced T
LRR at higher temperatures. During the standardised anoxic challenge, epaulette sharks entered into ventilatory depression significantly
earlier at 25°C. During re-oxygenation, epaulette sharks exposed to anoxia at 23°C had no significant increase in ventilation
rates. However, after anoxic challenge and re-oxygenation at 25°C, epaulette sharks showed a significant increase in ventilation
rates during re-oxygenation. Grey carpet sharks displayed no evidence of ventilatory depression during anoxia. However, during
re-oxygenation, grey carpet sharks had significantly elevated ventilation rates above pre-experimental levels and control
animals. These data demonstrate that the anoxia tolerance times of both species were temperature dependent, with a significant
reduction in the T
LRR occurring at higher temperatures. Epaulette sharks had a significantly greater T
LRR at higher temperatures than grey carpet sharks, which did not enter into a ventilatory depression. 相似文献
7.
The anatomy of the neck and forelimb of Chrysochloris asiatica is described and illustrated. The sequence of events during digging and modifications for fossorial action are described. Modifications include the appearance of a third bone in the forearm; the shortening and fusion of bones in the manus; enlarged processes on the scapula, humerus and ulna for greater muscle attachment; enlarged neck muscles and a dip in the spine in the cervical region to accommodate these and the enlarged shoulder muscles; an enlarged occiput for insertion of the powerful neck muscles; a greatly enlarged triceps and movement of the shoulder girdle to a position anterior to that normal in mammals. The possibility of the third forearm bone being the ossified tendon of a flexor muscle is discussed, without any conclusion being reached as to its true origin. 相似文献
8.
Igakura T Stinchcombe JC Goon PK Taylor GP Weber JN Griffiths GM Tanaka Y Osame M Bangham CR 《Science (New York, N.Y.)》2003,299(5613):1713-1716
Cell contact is required for efficient transmission of human T cell leukemia virus- type 1 (HTLV-I) between cells and between individuals, because naturally infected lymphocytes produce virtually no cell-free infectious HTLV-I particles. However, the mechanism of cell-to-cell spread of HTLV-I is not understood. We show here that cell contact rapidly induces polarization of the cytoskeleton of the infected cell to the cell-cell junction. HTLV-I core (Gag protein) complexes and the HTLV-I genome accumulate at the cell-cell junction and are then transferred to the uninfected cell. Other lymphotropic viruses, such as HIV-1, may similarly subvert normal T cell physiology to allow efficient propagation between cells. 相似文献
9.
A J Wong J M Ruppert J Eggleston S R Hamilton S B Baylin B Vogelstein 《Science (New York, N.Y.)》1986,233(4762):461-464
The relationship of the copy numbers of the c-myc and N-myc oncogenes to tumor formation and progression was studied in small cell carcinoma of the lung. When 96 neoplastic lesions from 45 patients were examined, these lesions could be grouped into three categories: high copy (tumors with greater than 3 copies of the N-myc or c-myc gene per haploid genome), middle copy (1.5 to 3 copies per genome), and normal copy. Fourteen of the patients had middle copy tumors, but this was almost always a result of chromosome duplication rather than the amplification of a small genetic locus. In contrast, five patients had high copy tumors, with the increased copy number in each case due to gene amplification. The amplification did not occur in a heterogeneous fashion within individual patients, since all metastatic lesions from patients with high copy lung tumors were also high copy, while none of 41 metastatic lesions from the other patients were high copy. These data suggest that gene amplification is an important step in neoplastic growth in a subset of patients with small cell carcinoma of the lung and that this genetic event occurs relatively early (before metastasis) in this subset. 相似文献
10.
Eggleston CM 《Science (New York, N.Y.)》2008,320(5873):184-185