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171.
Walt SM 《Science (New York, N.Y.)》1986,232(4753):1014-1015
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Tannenbaum GS 《Science (New York, N.Y.)》1986,232(4755):1272-1273
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L S Rivkin 《Veterinary Clinics of North America: Small Animal Practice》1986,16(4):647-668
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
179.
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
180.
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