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排序方式: 共有238条查询结果,搜索用时 18 毫秒
221.
Rodney Lacret Daniel Oves-Costales Cristina Gómez Caridad Díaz Mercedes de la Cruz Ignacio Pérez-Victoria Francisca Vicente Olga Genilloud Fernando Reyes 《Marine drugs》2015,13(1):128-140
A bioassay guided fractionation of the ethyl acetate extract from culture broths of the strain Streptomyces zhaozhouensis CA-185989 led to the isolation of three new polycyclic tetramic acid macrolactams (1–3) and four known compounds. All the new compounds were structurally related to the known Streptomyces metabolite ikarugamycin (4). Their structural elucidation was accomplished using a combination of electrospray-time of flight mass spectrometry (ESI-TOF MS) and 1D and 2D NMR analyses. Compounds 1–3 showed antifungal activity against Aspergillus fumigatus, Candida albicans and antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). 相似文献
222.
Kemachandra Ranatunga Rodney J. Keenan Stan D. Wullschleger Wilfred M. Post M. Lynn Tharp 《Forest Ecology and Management》2008
Understanding long-term changes in forest ecosystem carbon stocks under forest management practices such as timber harvesting is important for assessing the contribution of forests to the global carbon cycle. Harvesting effects are complicated by the amount, type, and condition of residue left on-site, the decomposition rate of this residue, the incorporation of residue into soil organic matter and the rate of new detritus input to the forest floor from regrowing vegetation. In an attempt to address these complexities, the forest succession model LINKAGES was used to assess the production of aboveground biomass, detritus, and soil carbon stocks in native Eucalyptus forests as influenced by five harvest management practices in New South Wales, Australia. The original decomposition sub-routines of LINKAGES were modified by adding components of the Rothamsted (RothC) soil organic matter turnover model. Simulation results using the new model were compared to data from long-term forest inventory plots. Good agreement was observed between simulated and measured above-ground biomass, but mixed results were obtained for basal area. Harvesting operations examined included removing trees for quota sawlogs (QSL, DBH >80 cm), integrated sawlogs (ISL, DBH >20 cm) and whole-tree harvesting in integrated sawlogs (WTH). We also examined the impact of different cutting cycles (20, 50 or 80 years) and intensities (removing 20, 50 or 80 m3). Generally medium and high intensities of shorter cutting cycles in sawlog harvesting systems produced considerably higher soil carbon values compared to no harvesting. On average, soil carbon was 2–9% lower in whole-tree harvest simulations whereas in sawlog harvest simulations soil carbon was 5–17% higher than in no harvesting. 相似文献
223.
Padilla Francisco M. de Souza Romina Peña-Fleitas M. Teresa Grasso Rafael Gallardo Marisa Thompson Rodney B. 《Precision Agriculture》2019,20(6):1087-1106
Precision Agriculture - Optical sensors are a promising approach for assessing nitrogen (N) status of vegetable crops. However, their potential may be undermined if time of day influences... 相似文献
224.
Colin Filer Rodney J. Keenan Bryant J. Allen John R. Mcalpine 《Annals of Forest Science》2009,66(8):813-813
225.
Gregory S. Starrak DVM Clifford R. Berry DVM Rodney L. Page DVM MS Jeffrey L. Johnson MS Donald E. Thrall DVM PhD 《Veterinary radiology & ultrasound》1997,38(6):411-418
A retrospective study was undertaken wherein the medical records and thoracic radiographs of 270 dogs with lymphosarcoma were reviewed to determine the type and frequency of thoracic radiographic changes. Statistical evaluation of the relationship between radiographic, clinical and immunologic factors and the primary remission duration and survival times was performed using univariate and multivariate analysis. One hundred ninety-two dogs (71 %) had some type of thoracic radiographicabnormality, including 80 dogs (29.6%) with pulmonary infiltrates and 164 dogs (64.4%) with thoracic lymphadenomegaly. Only T-cell phenotype (p = 0.0056 for survival, p = 0.0045 for remission) and the presence of cranial mediastinal lymphadenomegaly (p = 0.0005 for survival, p = 0.0129 for remission) were identified as having a significant negative correlation to both primary remission and survival duration by multivariate analysis. 相似文献
226.
Alan S. Hammer Marcia A. Carothers Cheryl L. Harris Deborah A. O'Keefe Rodney D. Ayl Janet L. Peterson Karen A. Shank C. Guillermo Couto 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1994,8(3):240-243
An inexpensive combination chemotherapy protocol containing cyclophosphamide, dactinomycin, and 5-fluorouracil was evaluated in dogs with carcinomas. Fifteen dogs were entered in this study, and there were 1 complete response and 2 partial responses among 12 evaluable dogs. However, 6 of 15 dogs (40%) developed neurotoxicity. The neurotoxicity of this protocol was compared with a previous 5-fluorouracil-containing protocol and found to be significantly higher. Due to the unacceptably high rate of neurotoxicity, this protocol cannot be recommended for use in dogs with cancer. 相似文献
227.
Entrican G Wattegedera S Rocchi M Fleming DC Kelly RW Wathne G Magdalenic V Howie SE 《Veterinary immunology and immunopathology》2004,100(3-4):179-186
Chlamydia/Chlamydophila are a family of intracellular gram-negative bacteria that infect their hosts primarily via mucosal epithelia. Chronic disease associated with bacterial persistence, inflammation and tissue damage are common sequelae of infection with these organisms. Human epithelial cell lines respond to infection by releasing pro-inflammatory cytokines and chemokines such as interleukin (IL)-6 and IL-8, and upregulating the expression of mRNA encoding Iκ-B, the endogenous inhibitor of NF-κB. However, Iκ-B is not upregulated in response to bacterial lipopolysaccharide (LPS). The failure of epithelial cells to respond to LPS is associated with the absence of surface expression of CD14. Identification of the components of Chlamydia/Chlamydophila that can induce pro-inflammatory mediators coupled with the mechanisms by which epithelial cells detect infection and respond accordingly will advance the development of preventative strategies. 相似文献
228.
Liptak JM Dernell WS Straw RC Rizzo SA Lafferty MH Withrow SJ 《Journal of the American Animal Hospital Association》2004,40(6):461-467
Twelve dogs were diagnosed with osteosarcoma of the proximal radius or distal humerus from 1990 to 2002, representing 1.0% of all dogs diagnosed with appendicular osteosarcoma. The median body weight (29.8 kg) was significantly less than that of dogs with appendicular osteosarcoma at other sites. Ten dogs were treated with amputation and chemotherapy. These dogs had a metastatic rate of 60%, a median metastasis-free interval of 356 days, and a median survival time of 824 days. There were no significant differences in metastasis-free interval or survival time between dogs with osteosarcoma of the proximal radius or distal humerus and dogs with appendicular osteosarcoma at other sites. 相似文献
229.
Sanders SG Bagley RS Gavin PR Konzik RL Cantor GH 《Journal of the American Veterinary Medical Association》2002,221(5):659-61, 643-4
A 9-year-old spayed female Golden Retriever was examined because of progressive hind limb lameness. Magnetic resonance imaging of the thoracic and lumbar portions of the vertebral column revealed a focal, contrast-enhancing, intramedullary spinal cord mass. The history, signalment, and magnetic resonance findings were suggestive of spinal cord neoplasia. A hemilaminectomy, durotomy, and longitudinal myelotomy were performed, and a 1 X 1-cm mass that contained numerous blood vessels was removed with blunt dissection. Results of histologic examination and immunohistochemical staining of the mass suggested that it was a hamartoma. The dog improved after surgery, with no evidence of a recurrence of clinical signs 14 months after surgery. Vascular malformations of the CNS in dogs include hamartomas, hemangiomas, angiomas, hemangioblastomas, meningocerebral hemangiomatosis, and arteriovenous malformations. A hamartoma is a non-neoplastic overgrowth of cells or an improper proportion of cells that are normally in the involved tissue. Although magnetic resonance imaging may be helpful in determining the extent of the lesion in dogs with vascular malforrmations, it cannot be used to distinguish neoplastic from non-neoplastic formations. Excision may result in a good outcome for dogs with an intramedullary spinal cord hamartoma. 相似文献
230.
Floyd D Wilson Scott D Fitzgerald Matti Kiupel Rodney L Walker Corey B Williams Donna J Todd 《Journal of zoo and wildlife medicine》2007,38(2):329-332
A 14-yr-old male Nile lechwe (Kobus megaceros) from the Jackson Zoo (Mississippi, USA) had chronic weight loss that was associated with elevated serum alkaline phosphatase levels. Approximately 4 yr after the first clinical signs of weight loss, the animal fractured its left rear femur and was subsequently euthanized; on the same day necropsy was performed. The liver was grossly enlarged and contained a smooth-surfaced nodular mass that occupied the majority of the right lobe of the liver. The mass had a liver-like appearance exhibiting a tan-red coloration but having a soft consistency. A single, approximately 0.6 cm, round, slightly elevated discrete red nodule was present in the left anterior lung. Microscopically, the hepatic mass and pulmonary nodule diffusely consisted of irregular cords of cells exhibiting hepatoid features, but containing no evidence of normal portal bile duct or portal triad development. To our knowledge, this is the first report in the scientific literature of a naturally occurring case of hepatocellular carcinoma in a Nile lechwe or in any antelope species. 相似文献