首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   49篇
  免费   3篇
基础科学   2篇
  3篇
综合类   5篇
水产渔业   5篇
畜牧兽医   35篇
植物保护   2篇
  2023年   1篇
  2020年   2篇
  2018年   1篇
  2017年   1篇
  2015年   1篇
  2014年   2篇
  2013年   1篇
  2012年   2篇
  2011年   2篇
  2010年   2篇
  2009年   5篇
  2008年   5篇
  2007年   2篇
  2006年   1篇
  2005年   2篇
  2004年   2篇
  2003年   2篇
  2001年   1篇
  2000年   2篇
  1998年   2篇
  1996年   3篇
  1992年   3篇
  1991年   1篇
  1989年   2篇
  1987年   1篇
  1986年   1篇
  1985年   2篇
排序方式: 共有52条查询结果,搜索用时 31 毫秒
1.
Abstract  The effects of an extreme flash flood on the native fish assemblages across a Mediterranean catchment in Southwest Portugal were investigated. The fish community structure and habitat were surveyed at 10 sites pre- and post-flood. Overall species richness and rank abundances changed little after the flood, despite there being a consistent decline in the abundance of small cyprinids. Pre- and post-flood habitat correlates of abundance changed for at least some species, and variability in assemblage structure was associated with flood, depth and pH. These results indicate that extreme floods occurring early in the wet season may have little disruptive effects on the overall structure of native fish assemblages in Mediterranean streams, although may at least partially influence population dynamics for some species. Habitat quality and complexity are likely to play a role in mediating species responses to flooding.  相似文献   
2.
The objective of this study was to examine the effect of donor breed on pronuclear‐stage embryo yield to be used for DNA microinjection in a transgenesis goat program. Twelve Canindé and twelve Saanen goats were heat synchronized using a progestagen‐cloprostenol treatment. Forty‐eight hours before the sponge removal, superovulation was induced with a total administration of 4.4 mg/kg bodyweight NIH‐FSH‐P1, given twice daily in decreasing doses over 3 days. In addition, goats received 100 μg of GnRH and they were hand‐mated at 36 and 48 h after progestagen removal. Embryo recovery was performed by oviduct flushing at 72 h after sponge removal. Embryos were microinjected with a DNA construct and noticeable swelling of the nuclei was the criterion for successful microinjection. The total diameter, cytoplasm diameter, zona pellucida thickness and pronuclei diameter were measured for each microinjected embryo. A higher (p < 0.05) percentage of fertilized ova was observed in Canindé (89.9%) than Saanen (36.2%) goats. In addition, Canindé donors produced a higher percentage of pronuclear embryos when compared with Saanen: 72.5% vs 20.6% (p < 0.05), respectively. Successful microinjection was verified in 96.7% and 73.3% of times in Canindé and Saanen embryos, respectively (p < 0.05). Significant differences were observed for all morphometric parameters except for cytoplasm diameter. In conclusion, under our study experimental conditions, Canindé were more efficient than Saanen goats concerning the pronuclear embryo yield and manipulation. The use of Canindé goats in transgenesis programs could be increase the interest in their breeding and could be contribute to saving them from extinction.  相似文献   
3.
4.
The gluteus medius muscles were removed from a four-year-old female Welsh pony and her nine-month-old fetus. The muscles were divided into sections which were histochemically examined to determine the variation in the distribution of fast-twitch-glycolytic (FG), fast-twitch oxidative glycolytic (FOG), and slow-twitch oxidative (SO) muscle fibers throughout the entire cross-section of the muscle. The fetal muscle had a larger percent of FOG fibers and smaller percent of SO fibers than the same muscle from the mare. Variation in the distribution of muscle fiber type within the fetal gluteus medius was found. This is the first study of fiber type variation in fetal equine muscle.  相似文献   
5.
Furosemide, which commonly is used as a prophylactic treatment for exercise-induced pulmonary hemorrhage in horses, may mediate hemodynamic changes during exercise by altering prostaglandin metabolism. To determine if furosemide's hemodynamic effects during exercise in horses could be reversed, cyclooxygenase inhibitors were administered with furosemide. Four treatments were administered 4 hours prior to treadmill exercise at 9 and 13 m/s. They included a control treatment (10 ml of 0.9% NaCl solution, IV), furosemide (1 mg/kg of body weight, IV) administered alone, and furosemide in combination with phenylbutazone (4 mg/kg, IV, q 12 h for 2 days) or with flunixin meglumine (1.1 mg/kg, IV, on the day of experiment). Five horses were randomly assigned to complete all treatments. Physiologic variables at rest prior to exercise were not influenced by treatments. Furosemide, administered alone, reduced mean right atrial pressure and mean pulmonary artery pressure during exercise. The combinations of furosemide and flunixin meglumine or furosemide and phenylbutazone, at both levels of exercise intensity, returned mean right atrial pressure and mean pulmonary artery pressure to the value of the control treatment. During rest and exercise, plasma lactate concentration, PCV, heart rate, mean carotid artery pressure, oxygen consumption, carbon dioxide elimination, and cardiac output were not altered by any of the treatments. At 5 minutes after exercise, the administration of furosemide, alone or with phenylbutazone, reduced mean right atrial pressure. Other measured variables were not significantly influenced by treatments during recovery from exercise. These results suggested that cyclooxygenase inhibition partially reverses the decrease in mean right atrial pressure or pulmonary artery pressure induced by furosemide during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
6.
This study tested the hypothesis that feeding an identically formulated, low sugar and starch concentrate in three forms (5-mm extruded [E], 4-mm pellet [P], and 19-mm oval [O]) would affect consumption rate and glucose or insulin responses, or both. Horses received 1.8 kg treatment feed in a randomized, crossover design, with samples taken every 30 minutes for 6 hours for blood glucose and insulin response. Pearson's correlation compared consumption time, insulin and glucose peak, and time to peak insulin and glucose. The pellet (P) elicited a lower (P = .01) glucose concentration at 2.5 hours than O. The pellet also elicited a lower (P = .03) insulin concentration at 5.5 hours than E and O. There were no differences (P > .05) in area under the curve (AUC) insulin, peak insulin, and time to peak insulin for the three treatments. Average insulin concentration was lower (P = .01) for P versus O. There were no differences (P > .05) in average insulin between P and E, nor between O and E. There were no differences (P > .05) in AUC and peak glucose concentration. Time to peak glucose was longer (P = .04) for P versus E. Average glucose concentration was lower (P = .02) for P versus O. Consumption time was longer (P = .03) for O versus P. There was a positive correlation between consumption time and time to peak insulin (r = 0.46, P = .029). Further research on feeding practices, feed forms, and consumption times that affect glycemic response is necessary.  相似文献   
7.
Unconditional quantum teleportation   总被引:5,自引:0,他引:5  
Quantum teleportation of optical coherent states was demonstrated experimentally using squeezed-state entanglement. The quantum nature of the achieved teleportation was verified by the experimentally determined fidelity Fexp = 0.58 +/- 0.02, which describes the match between input and output states. A fidelity greater than 0.5 is not possible for coherent states without the use of entanglement. This is the first realization of unconditional quantum teleportation where every state entering the device is actually teleported.  相似文献   
8.
Objective— To report long-term outcome after arthroscopic removal of fragmentation of the extensor process of the distal phalanx in horses.
Study Design— Case series.
Animals— Adult horses (n=13).
Methods— Medical records (2003–2004) of horses that had arthroscopic debridement of fragmentation of the extensor process of the distal phalanx were reviewed. Inclusion criteria included: lameness localized to the foot, fragmentation of the extensor process of the distal phalanx debrided arthroscopically, and a follow-up period of ≥4 years.
Results— Of the 13 horses, lameness was resolved in 11 (85%) initially but distal interphalangeal joint pain recurred in 2 (15%) within 1 year of surgery. Three (23%) other horses were retired because of lameness at other sites during the follow-up period resulting in 46% (6/13) being not lame and in full work after 4 years. Substantial changes were identified at surgery in the contralateral joint of 7 horses, even when fragments were only present unilaterally.
Conclusions— Arthroscopic debridement of fragmentation of the extensor process of the forelimb distal phalanx has a good short-term prognosis for resolution of lameness and return to work but a more guarded prognosis for long-term soundness.
Clinical Relevance— These results allow for more accurate prognostication preoperatively and may support early debridement of fragmentation of the extensor process of the distal phalanx.  相似文献   
9.
10.
ObjectivesTo evaluate the cardiorespiratory and biochemical effects of ketamine-propofol (KP) or guaifenesin-ketamine-xylazine (GKX) anesthesia in donkeys.Study designProspective crossover trial.AnimalsEight healthy, standard donkeys, aged 10 ± 5 years and weighing 153 ± 23 kg.MethodsDonkeys were premedicated with 1.0 mg kg?1 of xylazine (IV) in both treatments. Eight donkeys were administered ketamine (1.5 mg kg?1) and propofol (0.5 mg kg?1) for induction, and anesthesia was maintained by constant rate infusion (CRI) of ketamine (0.05 mg kg?1 minute?1) and propofol (0.15 mg kg?1 minute?1) in the KP treatment. After 10 days, diazepam (0.05 mg kg?1) and ketamine (2.2 mg kg?1) were administered for induction, and anesthesia was maintained by a CRI (2.0 mL kg?1 hour?1) of ketamine (2.0 mg mL?1), xylazine (0.5 mg mL?1) and guaifenesin (50 mg mL?1) solution. Quality of anesthesia was assessed along with cardiorespiratory and biochemical measurements.ResultsAnesthetic induction took longer in GKX than in KP. The induction was considered good in 7/8 with KP and in 6/8 in GKX. Anesthetic recovery was classified as good in 7/8 animals in both treatments. Xylazine administration decreased heart rate (HR) in both treatments, but in KP the HR increased and was higher than GKX throughout the anesthetic period. Respiratory rate was higher in GKX than in KP. PaO2 decreased significantly in both groups during the anesthetic period. Glucose concentrations [GLU] increased and rectal temperature and PCV decreased in both treatments. Arterial lactate [LAC] increased at recovery compared with all time points in KP. [GLU] and calcium were higher in GKX than in KP at recovery.Conclusion and clinical relevanceThese protocols induced significant hypoxemia but no other cardiorespiratory or metabolic changes. These protocols could be used to maintain anesthesia in donkeys, however, they were not tested in animals undergoing surgery.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号