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排序方式: 共有252条查询结果,搜索用时 109 毫秒
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Singer N 《Science (New York, N.Y.)》1992,258(5079):32-33
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Coprinites dominicana gen.nov., spec.nov. (Coprinaceae) found in amber from the Dominican Republic is the earliest known gilled mushroom, the first fossil fleshy agaric determinable, and the only kiiown fossil "mushroom" (Agaricales) from the tropics. This find is of significance with respect to the evolutionary development of the Basidiomycetes. Because the appearance of this fossil is quite modern, it suggests that mushrooms as a group probably arose much earlier than the early to mid-Tertiary. 相似文献
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S F Singer 《Science (New York, N.Y.)》1969,166(902):270-271
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Hoar BR Carpenter TE Singer RS Gardner IA 《American journal of veterinary research》2003,64(5):520-529
OBJECTIVE: To create a stochastic model to quantify the risk that shipments of cattle from regions within the United States would contain animals seropositive for bluetongue virus and to determine shipment-level accuracy of serologic testing by use of a competitive ELISA (c-ELISA). SAMPLE POPULATION: 19,216 shipments containing 528,918 cattle and calves. PROCEDURE: Data were obtained on number of animals and state of origin of cattle in export shipments originating within the United States between January 1994 and March 2002. Probability distributions for size of export shipments were determined for all states within the United States, and distributions for agar gel immunodiffusion and c-ELISA accuracy (sensitivity and specificity) were determined from expert opinion and review of the literature. The model simulated selection of a shipment and then determined the probability that a threshold number or percentage of cattle within that shipment would have a positive c-ELISA result. Shipment-level sensitivity, specificity, positive-predictive value, and negative-predictive value were calculated. RESULTS: Substantial differences were evident in the regional probability of a shipment being declared positive, with shipments from northeastern states having the lowest probability and shipments from southwestern states having the highest probability. The c-ELISA had variable predictive values at the shipment level, depending on the threshold used and the prevalence of antibody-positive cattle within the region. CONCLUSIONS AND CLINICAL RELEVANCE: Results from this study will aid importers in making scientifically based decisions regarding risk of importing antibody-positive cattle. 相似文献
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Moore DA Atwill ER Kirk JH Brahmbhatt D Herrera Alonso L Hou L Singer MD Miller TD 《Journal of the American Veterinary Medical Association》2003,223(6):839-845
OBJECTIVE: To evaluate the effect of daily oral administration of decoquinate to neonatal calves experimentally challenged with various numbers of Cryptosporidium parvum oocysts. DESIGN: Clinical trial. ANIMALS: 75 calves. PROCEDURE: Calves were purchased from a commercial dairy during a 5-week period. Calves were housed in individual hutches and fed milk replacer with or without decoquinate (2 mg/kg [0.9 mg/lb per day]). Calves were randomly assigned to treatment and 1 of 5 challenge groups (0, 50, 100, 1000, or 10,000 C. parvum oocysts in 60 mL of saline [0.9% NaCl] solution administered p.o. on the day after arrival). Calves were maintained in the study for as long as 28 days. Calves were clinically assessed for diarrhea and dehydration. Fecal samples were submitted for oocyst enumeration 3 times each week. RESULTS: Treatment did not affect number of days to first watery feces (diarrhea), number of days to first oocyst shedding, or duration of diarrhea or oocyst shedding. Duration of oocyst shedding was significantly associated with challenge dose of oocysts administered to calves and number of days to first oocyst shedding. Duration of diarrhea and number of days to first oocyst shedding were significantly associated with week of arrival and number of days to first watery diarrhea. CONCLUSIONS AND CLINICAL RELEVANCE: Daily treatment with decoquinate at the dosage used in this study did not affect oocyst shedding or clinical signs associated with cryptosporidiosis. However, there was an indication that if the number of oocysts calves received could be reduced, then the duration of oocyst shedding and, hence, environmental loading of C. parvum oocysts could be reduced. 相似文献
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REASONS FOR PERFORMING STUDY: Serious injuries to horses and riders in horse trials (HT) and three-day events (3DE) are usually associated with falls of horses, which invariably involve falls of the riders. Many potential causes for these falls have been discussed. OBJECTIVES: The aim of this case-control study was to investigate the risk factors for horse falls on the cross-country phase of horse trials and three-day events. METHODS: Using retrospective data, significant risk factors identified with unvariable analysis (P value <0.2) were entered into a multivariable logistic regression model. Significant risk factors (P value <0.05) were included in the final model. RESULTS: It was revealed that a number of course, obstacle and rider variables were significantly and independently associated with the risk of falling. Falling was associated with obstacles sited downhill (Odds ratio [OR] 8.41) and with obstacles with ditches in front (OR = 5.77). CONCLUSIONS: The relationship between course variables and the risk of falling was characterised and showed a significantly increased risk with increasing numbers of jumps on the course and for jumping efforts later in the course. In contrast, after allowing for the total number of obstacles on the course, an increase in the total number of jumping efforts appeared to have a protective effect. A later cross-country start time was associated with a decreased risk of a horse fall. Amateur event riders were approximately 20 times more likely to fall than professional riders. POTENTIAL CLINICAL RELEVANCE: This study has identified a number of risk factors associated with horse falls and highlights areas that can be altered to improve safety in cross-country competitions. 相似文献
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REASONS FOR PERFORMING STUDY: Wounds to the plantar aspect of the tarsus present a diagnostic and treatment challenge. This study was undertaken to describe specific features of traumatic wounds involving the calcaneal bursa, with a view to determining which clinical examination findings and diagnostic tests results could provide reliable indicators of prognosis. OBJECTIVES: To report clinical presentation, diagnostic findings, treatment and outcome of 24 cases of septic calcaneal bursitis; and to determine the importance of the involvement of specific anatomical structures in relation to the prognosis for survival and return to athletic function. METHODS: Records of 24 horses that had suffered traumatic wounds involving the calcaneal bursae were reviewed and divided into 3 groups, based on the bursa involved and presence or absence of involvement of the tuber calcanei. Clinical, diagnostic imaging and surgical findings were recorded for each case. Differences between groups and outcome were examined for significance with Chi-squared, Fisher's Exact or Kruskal-Wallis tests, as appropriate. RESULTS: Wounds involving only the subcutaneous bursa had an excellent prognosis for survival. Seventy-five percent of horses with wounds involving the intertendinous calcaneal bursa survived. Involvement of the tuber calcanei presented a fair to guarded prognosis, with only 44% of horses with involvement of this structure surviving. CONCLUSIONS: In contrast to other studies of septic synovial structures, the time between initial injury and referral did not affect the outcome. Correct identification of invasion of the calcaneal bursa(e) and/or tuber calcanei in wounds to the plantar aspect of the tarsus allows for more accurate pronostication. Damage to the tuber calcanei presents a poorer prognosis than for cases that involve only the soft tissue structures in the region. POTENTIAL RELEVANCE: This study demonstrates the importance of correct anatomical identification of structures involved in wounds in the region of the calcaneal bursa. The use of radiography, ultrasonography and synoviocentesis are essential in these cases to provide the most appropriate treatment for the horse and accurate prognosis for the owner. 相似文献
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A four-year-old gelding was lame owing to a chronic septic common digital extensor tendon and sheath. The horse had been treated by open surgical lavage but the sepsis had recurred after three months. Physical, ultrasonographic, cytological and histological examinations confirmed chronic septic tenosynovitis and tendonitis. The entire intrathecal component of the common digital extensor tendon was resected under general anaesthesia and the synovial lining of the sheath was ablated. Postoperatively the horse regained good limb function and became sound. 相似文献