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171.
Using databases     
Through a relatively simple computer technique known as online searching, practitioners can use computers to "reach out" beyond their practice walls to expand their knowledge base. By bringing information sources closer to veterinarians, feelings of isolation, frustration, and ineptitude can be replaced with feelings of certainty, confidence, and knowledge. This article explores the equipment and the software needed, and by giving examples of a few of the veterinary databases, illustrates some techniques employed in signing up and signing on to the power of online searching.  相似文献   
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On a property in the Nelson District, blood and urine samples were taken from red deer (Cervus elaphus) from which low (<1:100) antibody titres to serovar copenhageni and suspected leptospiral abortions had previously been reported. A total of 27 hinds were sampled. Microscopic agglutination test (MAT) titres in sera ranging from 1:32 to 1:128 were found in six animals. Thirteen leptospiral isolations were made from nine of the 27 urine samples. Four of these were typed as copenhageni and nine as hardjo. Two cultures were prepared from each urine sample and hardjo and copenhageni were both isolated from single urine samples from two animals. None of the 27 deer had serum MAT titres at 1:32 or above to copenhageni.  相似文献   
174.
A large proportion of plant species has originated through allopolyploidy: interspecific hybridization followed by chromosome doubling. Heterozygosity remains fixed in allopolyploids because of nonsegregation of parental chromosomes. Two allotetraploid species of the fern genus Asplenium show allozyme polymorphisms at loci that are polymorphic in their diploid progenitors, indicating that each has originated more than once and implicating continued gene flow from diploids to tetraploids.  相似文献   
175.
Six distinctive types of fossiliferous marine deposits occur on the Galádpagos Islands that provide evidence for the age of emergence of the islands above sea level and hence a maximum age for the islands' terrestrial biota. These subtidal to supratidal deposits include (i) volcanic tuffs with fossils, (ii) limestones and sandstones interbedded with basalt, (iii) terrace deposits, (iv) beach rock, (v) supratidal talus deposits, and (vi) recently uplifted tidal and subtidal rocks and sand. With the exception of (vi), the deposits were previously assigned ages varying from Miocene to Pleistocene, but all are less than about 2 million years old. This age, together with independently determined geologic ages, indicate that the islands emerged from the sea relatively recently and that all evolution of the islands' unique terrestrial biota occurred within the past 3 to 4 million years.  相似文献   
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Practitioners commonly submit samples from dogs for partial thromboplastin time and prothrombin time determinations. Controversy exists as to the necessity for rapid separation of plasma and cells, and submission of the plasma on ice (or frozen). The purpose of this study was to address three questions. First, is it better to submit plasma or is whole blood satisfactory? Second, is it necessary to refrigerate the sample or is maintenance at room temperature (20° C) adequate? Third, does the sample have to arrive at the laboratory within a few hours of collection or can reliable partial thromboplastin time/prothrombin time determinations be made on samples up to 48 hours old?It has been shown by this study that reliable partial thromboplastin time and prothrombin time determinations can be carried out on canine plasma for up to 48 hours after collection regardless of whether or not the plasma is separated immediately; however the samples must be kept at 4°C. If the samples are maintained at room temperature, reliable prothrombin time determinations can be obtained for up to six hours after collection regardless of whether or not the plasma is separated immediately. Reliable partial thromboplastin time determinations can be made on plasma stored at 20°C for up to 24 hours after collection and possibly longer (up to 48 hours) if the plasma has been separated immediately.  相似文献   
179.
Ten out of eleven subcutaneous abscesses in cats harboured anaerobic bacteria. Seven of the ten abscesses contained a mixture of obligate anaerobes and facultative anaerobes or microaerophilic bacteria. All of the anaerobic isolates were sensitive to the antibiotic metronidazole, but were resistant to streptomycin. Three isolates from one abscess were resistant to penicillin and ampicillin. Clinical resolution of subcutaneous abscesses was poor when procaine penicillin was used alone as treatment.  相似文献   
180.
In this review, "productive efficiency" in dairy cows is defined as the yield of milk obtained in ratio to the nutritional costs associated with maintenance, milk synthesis and loss of body condition during lactation. Improvements in efficiency could occur as a result of changes in digestion and nutrient absorption, maintenance requirement, utilization of metabolizable energy for production or nutrient partitioning. Digestibility can be greatly enhanced by appropriate dietary manipulation. Likewise, it may be possible to reduce maintenance requirements and improve the efficiency with which metabolizable energy is used for milk synthesis by manipulation of the pattern of nutrients presented to tissues. However, these factors apparently do not respond to selection for increased milk yield, and little variation is observed among cows. In contrast, individual cows differ substantially in feed intake and in the partitioning of nutrients among body tissues. Techniques associated with genetic engineering and the early prediction of genetic merit have the potential to improve productive efficiency by manipulation of these processes. However, changes in nutrient partitioning and feed intake during lactation are coordinated by a complex network of controls that accommodate the nutrient requirements of each tissue while maintaining homeostatic balance. Future improvements in productive efficiency will therefore depend on our ability to understand the manner in which these controls operate.  相似文献   
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