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排序方式: 共有179条查询结果,搜索用时 15 毫秒
71.
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Roberta Gentile Mike Dodd Mark Lieffering Shona C. Brock Phil W. Theobald Paul C. D. Newton 《Biology and Fertility of Soils》2012,48(3):357-362
Altered soil nutrient cycling under future climate scenarios may affect pasture production and fertilizer management. We conducted
a controlled-environment study to test the hypothesis that long-term exposure of pasture to enriched carbon dioxide (CO2) would lower soil nutrient availability. Perennial ryegrass was grown for 9 weeks under ambient and enriched (ambient + 120 ppm)
CO2 concentrations in soil collected from an 11.5-year free air CO2 enrichment experiment in a grazed pasture in New Zealand. Nitrogen (N) and phosphorus (P) fertilizers were applied in a full
factorial design at rates of 0, 12.5, 25 or 50 kg N ha−1 and 0, 17.5 or 35 kg P ha−1. Compared to ambient CO2, under enriched CO2 without P fertilizer, total plant biomass did not respond to N fertilizer, and tissue N/P ratio was increased indicating
that P was co-limiting. This limitation was alleviated with the lowest rate of P fertilizer (17.5 kg P ha−1). Plant biomass in both CO2 treatments increased with increasing N fertilizer when sufficient P was available. Greater inputs of P fertilizer may be
required to prevent yield suppression under enriched CO2 and to stimulate any response to N. 相似文献
73.
Chlorophyll concentrations in western wheatgrass, an important dominant species in the grasslands of the northern Great Plains of North America, exposed to controlled SO2 concentrations were examined. Concentrations of chlorophylls a and b were significantly decreased, without visible plant necrosis. Chlorophyll-a was more sensitive than chlorophyll-b. Sensitivity of chlorophylls to SO2 changed as the growing season progressed, indicating cumulative effects and interactions with normal senescence. 相似文献
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Dodd RY 《Science (New York, N.Y.)》1974,186(4169):1138-1140
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CC Pérez‐Marín FD Requena A Arando L Requena F Requena EI Agüera 《Reproduction in domestic animals》2018,53(2):534-544
The aim of this study was to determine the effects of various abiotic factors, such as light, physical stress (pipetting) and thermal shock, on the quality of fresh and cooled equine sperm. In experiment I, four sperm aliquots were subjected to different light exposures: (i) protected control samples (CTRL), (ii) exposed to UV light at 10 cm (UV10), (iii) exposed to UV light at 20 cm (UV20) and (iv) exposed to laboratory lighting (LAB). In experiment II, four semen aliquots were subjected to repeated pipetting for 0, 10, 20 and 30 times (CTRL, P10, P20 and P30, respectively). In experiment III, four semen aliquots at 15°C were subjected to thermal oscillations: (i) cooled control sperm at 15°C (CTRL), (ii) oscillations of 1.9°C/min to a temperature of 30°C (T30), (iii) oscillations of 1.4°C/min, with the temperature rapidly falling until reaching 1.3°C (T0R) and (iv) oscillations of 1.1°C/min, with the temperature slowly falling until reaching 4.2°C (T0S). The results revealed that after 30 min, UV10 and UV20 sperm samples showed significantly (p < .05) lower total and progressive motility values, sperm kinematic parameters and mitochondrial potential. After 45 min of exposure, differences were highly significant (p < .001). No significant differences (p > .05) were found for pipetting or thermal oscillations. The results suggest that, even if equine sperm samples are not handled in the laboratory under optimal conditions, fresh and cooled equine spermatozoa are able to resist the impact of various abiotic stimuli without any reduction in their quality. This study analyses the effect on normospermic samples, but future research could look at the tolerance that asthenozoospermic equine samples have to these abiotic influences. 相似文献
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Brian P. Grossbard DVM Catherine A. Loughin DVM Diplomate ACVS ACCT Leonard J. Marino MD FAAP Joseph Sackman Scott E. Umbaugh BSE MSEE PhD Patrick S. Solt BSEE MSCS Jakia Afruz BSAPECE MSAPECE Peter Leando PhD DSc DAc Martin L. Lesser PhD EMT‐CC Meredith Akerman MS 《Veterinary surgery : VS》2014,43(7):869-876
80.
Shari M. Greenberg Caryn E. Plummer Dodd Sledge Misa Komine Serena L. Craft Julia A. Conway 《Veterinary ophthalmology》2016,19(4):332-339
A 1‐day–old miniature horse filly was presented to the University of Florida Veterinary Ophthalmology service for evaluation of multiple ocular anomalies which were present from birth. Protruding from the right orbit was a large, fluctuant, red, dry and variably ulcerated mass. A globe could not be appreciated clinically in the left orbit. Ocular ultrasound of both orbits was performed. This revealed a lobular, hypo‐echoic structure filling the right orbit, with multiple hyperechoic septations; normal ocular structures were not identified. Ultrasound of the left orbit revealed a microphthalmic eye, with a well‐defined, hyperechoic structure in the vitreous that was thought to be the lens. Due to irreversible blindness, the foal was humanely euthanized. Histopathology and immunohistochemistry of the orbital contents revealed bilateral microphthalmos with cyst, a congenital defect rarely reported in the veterinary literature. 相似文献