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排序方式: 共有117条查询结果,搜索用时 31 毫秒
1.
An experiment was carried out to determine how the late application of nitrogen (N) fertilizer affects the use of pre‐anthesis carbon reserves during the grain‐filling period of pot‐grown wheat with no water shortage. Increasing doses (equivalent to 0, 140, and 180 kg N ha–1) of N fertilizer were applied, either in two amendments (stages GS20 and GS30) or in three amendments (stages GS20, GS30, and GS37, according to Zadoks scale). The management of fertilizer by combining an increased N rate with late N application was able to stimulate canopy development, to raise photosynthetic capacity and carbohydrate accumulation during the vegetative stages, and to increase grain yield. Based on the dynamics of carbohydrate accumulation in the ear, three phases were differentiated during the grain‐filling period, whose temporary pattern remained stable regardless of the fertilizer management. The net remobilization of carbohydrates started 12 d after anthesis from the leaves and 28 d after anthesis from roots and stems. The increase of the N dose with late N application allowed on one hand a lower use of the pre‐anthesis carbon reserves in favor of greater de novo photosynthesis during the grain‐filling period, and on the other hand greater relative contribution of the leaf and ear C reserves to remobilization towards the grain. Further splitting the dose increased only the relative contribution of ear C reserves. The stem contribution seemed to be independent of N applied whereas the root contribution tended to diminish with late N application.  相似文献   
2.
One hundred and six dogs (61 males and 45 females) were examined for Echinococcus granulosus infection in a farming cooperative in the central highlands of Peru during November 1998. Canine echinococcosis was diagnosed using direct microscopic examinations of purged feces following arecoline purging and a coproantigen-detection enzyme-linked immunosorbent assay (ELISA) for E. granulosus. Mean age was 2 years with a range of 3 months to 9 years. The overall prevalence of canine echinococcosis using the ELISA test was 79% (84/106). Seventy-four dogs were successfully purged with arecoline. The frequency of canine echinococcosis was 82 (61/74) and 34% (25/74) by the coproantigen ELISA test and arecoline purging, respectively. The sensitivity and specificity of the coproantigen ELISA test was 88 and 95%, respectively. We found this assay to be especially advantageous in remote geographical areas. In future control programs against echinococcosis in Peru and other areas where E. granulosus is endemic the coproantigen ELISA should be used for the surveillance of the dog population.  相似文献   
3.
The aim of this study was to develop an immunological method for the identification of sheep infected with Echinococcus granulosus which would allow the monitoring of animals imported into countries free from hydatidosis and as an aid to countries where control schemes for the disease are in operation. Three enzyme-linked immunosorbent assays (ELISAs) were developed and validated, using as antigen either a purified 8 kDa hydatid cyst fluid protein (8kDaELISA), a recombinant EG95 oncosphere protein (OncELISA) or a crude protoscolex preparation (ProtELISA). Sera used for the assay validations were obtained from 249 sheep infected either naturally or experimentally with E. granulosus and from 1012 non-infected sheep. The highest diagnostic sensitivity was obtained using the ProtELISA at 62.7 and 51.4%, depending on the cut-off. Assay sensitivities were lower for the 8kDaELISA and the OncELISA. Diagnostic specificities were high, ranging from 95.8 to 99.5%, depending on the ELISA type and cut-off level chosen. A few sera from 39 sheep infected with T. hydatigena and from 19 sheep infected with T. ovis were recorded as positive. Western immunoblot analysis revealed that the dominant antigenic components in the crude protoscolex antigen preparation were macromolecules of about 70-150 kDa, most likely representing polysaccharides. This study demonstrated that the ProtELISA was the most effective immunological method of those assessed for detection of infection with E. granulosus in sheep. Because of its limited diagnostic sensitivity of about 50-60%, it should be useful for the detection of the presence of infected sheep on a flock basis and cannot be used for reliable identification of individual animals infected with E. granulosus.  相似文献   
4.
  1. Marine protected areas (MPAs) are becoming a widely used tool for the conservation of biodiversity and for fishery management; however, most of these areas are designed without prior knowledge of the basic ecological aspects of the species that they are trying to protect.
  2. This study investigated the movement of two top predators: the Galapagos shark, Carcharhinus galapagensis, and the yellowtail amberjack, Seriola lalandi, in and around the Motu Motiro Hiva Marine Park (MMHMP) using MiniPAT satellite tags to determine the effectiveness of this MPA for the protection of these species.
  3. The Galapagos sharks (n = 4) spent most of their tag deployment periods inside the MMHMP. However, high intraspecific variability was observed in their movement dynamics. Daily individual maximum movements ranged from 17 to 58 km and the maximum distance from Salas y Gómez Island, the only emergent island within the MMHMP, ranged from 31 to 139 km.
  4. The maximum linear distance travelled for a female juvenile Galapagos shark (152 cm total length) was 236 km, which is greater than the maximum distance previously documented for juveniles of this species (<50 km).
  5. For the yellowtail amberjack (n = 1), 91% of the satellite geolocations were within the MMHMP, with a maximum daily distance travelled of 6 km. The maximum distance travelled between points was 111 km and the maximum distance from Salas y Gómez Island was 62 km.
  6. All archival tagged fish spent most of their time at depths of <50 m and never left the epipelagic zone. Daytime versus night-time differences were pronounced in all individuals but showed high interindividual variability.
  7. This study provides a baseline on the movement of these two top predators in the MMHMP and provides valuable insights for the creation of MPAs in the region and elsewhere.
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5.
In this paper the authors analyze the two most important interrelated processes of social change in Italian agriculture: first the increasing productive specialization of family farming, both full and part-time, lending to the persistence of small farms but also to their growing integration and complementarity with other economic activities; and second the increasing heterogeneity of agricultural workers accompanied by the destructuring of their strong working-class identity, which had matured in the previous decades. This identity, however, also reflected a deep separation between agricultural laborers, their labor market and institutions, and the rest of the working class. The authors argue that these changes are progressively contributing to the full integration of agricultural social relations within an increasingly complex society. The analysis of these two processes in recent Italian experience shows that this trend towards integration differs totally from the hypothesis often advanced in the past according to which the integration of agriculture would occur through the development of green factories, more and more similar to large Fordist manufacturing plants. On the contrary, at least in present-day Italy, integration means increasing heterogeneity, also of organizational patterns in manufacturing, and growing inter-dependence.  相似文献   
6.
INTODUCTION: Anaesthesia in lambs undergoing experimental surgery may develop problems associated with age-related immune incompetency: a postoperative complication in a 3 week old Scottish blackface lamb after spinal surgery is presented. CASE HISTORY AND MANAGEMENT: Both lamb and ewe were in good condition. The ewe was vaccinated against Clostridium perfringens and Clostridium tetani 5 weeks pre-partum. There were no apparent problems with the lamb's intake of colostrum. Pre-anaesthetic medication was intramuscular medetomidine (10 μg kg(-1)). Anaesthesia was induced and maintained with sevoflurane in oxygen. Morphine (0.5 mg kg(-1)), meloxicam (0.6 mg kg(-1)) and ketamine (1 mg kg(-1) followed by 10 μg kg(-1) minute(-1)) were administered intravenously (IV) for perioperative analgesia. Atracurium (0.5 mg kg(-1) IV, followed by 0.17 mg kg(-1) injected when the first twitch of the four, train-of four count was palpated) was used to improve muscle relaxation. The lamb's trachea was intubated and the lungs mechanically ventilated to maintain normocapnia. Intrathecal morphine (0.2 mg kg(-1)), IV meloxicam (0.3 mg kg(-1)) and edrophonium (0.5 mg kg(-1)) were administered before recovery. Operative and initial recovery periods were unremarkable. Three hours after surgery the lamb became depressed. Tachycardia (180-250 beats minute(-1)), tachypnoea (30 breaths minute(-1)), poor peripheral perfusion and cold pelvic limb extremities were present mimicking severe pain, and/or hypovolaemic shock. Analgesics - morphine (total dose 1.3 mg kg(-1)) - and IV fluid therapy boluses - crystalloids (300 mL), colloids (120 mL) and fresh whole blood (60 mL) - failed to ameliorate clinical signs and so the lamb was euthanized 10 hours after surgery. Post-mortem findings supported a possible diagnosis of peracute Clostridium perfringens enterotoxaemia. CONCLUSION: Clostridium perfringens enterotoxaemia should be considered when clinical signs of severe pain and/or hypovolaemic shock fail to respond to analgesics and fluid resuscitation in lambs after major surgery.  相似文献   
7.
A review of soil acidity problems with regards to causes, extent and management in Ghana shows that the extent of soil acidity has changed within a period of 2–3 decades. In the 1970s' soil acidity was a major problem in the Western region and the lowlands. Oxisols and Ultisols are common soils found in this area. However, anthropogenic causes have augmented natural causes resulting in more low pH soils. Soil acidity has therefore become a serious problem throughout the country. Anthropogenic causes identified include general agronomic practices such as tillage, use of mineral fertilizers and continuous cultivation. Rates of 1–2 t ha−1 lime on ultisols and oxisols in Ghana are more than adequate to meet the calcium demands and sufficient to neutralize residual acidity of any nitrogen fertilizer. Addition of organic amendments on low pH soils was also found to be beneficial and resulted in increased yields. The adoption of the "sawah" technology for lowland rice production has also resulted in improved water management, increased nutrient availability and significant increases in rice yields.  相似文献   
8.
An SPME-GC/ion trap method was exploited to determine the chromatogram of volatile compounds of organic olive oils of southern Italian regions. The method is based on the assay of the terminal species of the "lipoxygenase pathway", which are present in the volatile fraction of the sampled compounds. Ethyl isobutanoate was used as internal standard in either the EI or CI ionization mode. The absolute concentration values of each analyte were evaluated through good-to-excellent calibration curves. Case studies on oils obtained from different cultivars or harvesting times are presented. The quantitative data for each compound were subjected to principal component analysis to characterize the different cultivars of this work.  相似文献   
9.
Objective-To investigate the effect of intraoperative extradural morphine administration on postoperative analgesia in dogs undergoing thoracolumbar spinal surgery to treat disk extrusion. Design-Prospective clinical trial. Animals-26 client-owned dogs undergoing thoracolumbar spinal surgery. Procedures-Animals were randomly allocated to receive morphine (0.1 mg/kg [0.045 mg/lb], extradurally) or no treatment (control group). Following preanesthetic medication with methadone (0.25 mg/kg [0.11 mg/lb], IM), anesthesia was induced with propofol and maintained with isoflurane or sevoflurane in oxygen. Lidocaine and fentanyl were administered during surgery in both groups at fixed rates. In the morphine administration group, morphine was splashed over the dura mater immediately prior to wound closure. Postoperative analgesia was assessed for 48 hours by assessors unaware of group allocation, and methadone was administered as rescue analgesic. Demographic characteristics, urinary output, days of hospitalization, and perioperative use of analgesics were compared via a Mann-Whitney U test. Results-Demographic data were similar between groups. In the morphine administration group, 2 of 13 dogs required postoperative methadone, and in the control group, methadone was administered to 11 of 13 dogs. The total number of doses of methadone administered in the 48 hours after surgery was 28 in the control group and 3 in the morphine administration group. No adverse effects were recorded in any group. Conclusions and Clinical Relevance-Intraoperative extradural morphine administration was effective in reducing postoperative analgesic requirement. Dogs undergoing thoracolumbar spinal surgery benefited from topical administration of preservative-free morphine administered directly on the dura mater as part of analgesic management.  相似文献   
10.
Babesiosis is an emerging tick-borne disease of animals and humans caused by intraerythrocytic protozoa of the genera Babesia and Theileria. In France canine babesiosis has a high prevalence with Babesia canis thought to be the main aetiological agent of the disease. Babesia vogeli has already been reported to occur in Europe and in other countries around the Mediterranean Sea. The tick Rhipicephalus sanguineus, the main known vector of B. vogeli, occurs in southern France. However, only one case of a B. vogeli infected dog has been reported to date in France. To gain further insight into the prevalence of Babesia and Theileria infections in dogs and ticks of the R. sanguineus complex, a study was conducted in a veterinary practice in the south of France from January to September 2010. Twelve bloods from dogs and 36 R. sanguineus ticks were analyzed using PCR and sequencing. For the analysis of ticks, a new primer was designed to specifically amplify the B. vogeli 18S rRNA gene. Four dogs (33.3%) and 8 ticks (22.2%) were found to be infected with B. vogeli. This approach has thus revealed for the first time a cluster of cases of canine babesiosis caused by B. vogeli in France and highlights the need to systematically screen for pathogens potentially responsible for canine babesiosis at the species level using suitable molecular tools.  相似文献   
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