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31.
SUSAN M. BANDONI MARGARET MULVEY ERIC S. LOKER 《Biological journal of the Linnean Society. Linnean Society of London》1995,54(1):1-27
Freshwater snails in the genus Biomphalaria transmit Schistosoma mansoni in Africa, South America and the Caribbean region. Although considerable attention has been given to the identification of species, little is known of evolutionary relationships among the species. A phylogenetic analysis of 25 populations representing 11 species was performed on 25 enzyme loci examined using starch gel electrophoresis. A phylogenetic analysis of the individual populations produced 60 trees of equal length. The 60 trees have a consistency index value of 75.9% and a retention index value of 76.5%. The phylogenetic analysis provided strong support for the monophyly of Biomphalaria with either 14 or 15 synapomorphies uniting all of the species included and separating them from the outgroup, two species of Helisoma. Four nominal species represented by multiple populations formed monophyletic groups. Populations of B. sudanica, B. choanomphala, and B. alexandrina were interspersed. Ten arrangements were obtained for the populations of these three species. A variety of ingroup taxa were used to root the trees, and all provided support for the use of Helisoma species as an outgroup. In all of the trees obtained, the African species together formed a monophyletic group. In none of the trees obtained did the neotropical species form a monophyletic group. A constrained analysis requiring the monophyly of the neotropical species as well as the African species resulted in 90 trees just two steps longer than the shortest trees. Analysis of the species from either hemisphere alone resulted in decreased resolution, as measured by an increase in the number of trees obtained. This finding suggests that further comparisons of species from the two hemispheres will be of considerable value. Finally, two species which are resistant to infection with S. mansoni were included among the eleven studied. Neither of these species formed the sister group to all of the other species included, indicating that susceptibility is the plesiomorphic state, and that resistance is derived. Similarly, in none of the trees obtained did the two resistant species fall out as sister taxa, indicating that resistance arose independently twice. 相似文献
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Eighteen commercial cat litters were characterized for the following physical characteristics: water holding capacity, drying time, pH, cost, density, residual water, and particle size. Using sensory analysis, eight of the litters were evaluated for dustiness, clumpability and odor control before and after use and storage. The cat litters differed substantially in both physical and sensory properties. The crystal litters were noted for their small uniform size, high water holding capacity and clumpability. The recycled litter was most dusty and ammoniacal; whereas, the granule litter had an innately offensive odor. The alfalfa litter had superior odor control, but neither clumped nor dried well. The clay litters could be differentiated by pH, residual water, water holding capacity and could be classified as either perfumed and nonperfumed. Some of the perfumed litters became intensely perfumed when used and stored; whereas, the other perfumed litters behaved like the nonperfumed litters and became more offensive. 相似文献
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In indirect ELISA using protein A-horseradish peroxidase (HRP) as enzyme conjugate and 3,3′, 5,5′-tetramethylbenzidine (TMB) as substrate, extracts of roots of all cucumber, Chenopodium quinoa and Petunia hybrida plants previously inoculated with virus or buffer produced A450 values up to seven-fold greater than those for comparable shoots or for extracts of roots from undisturbed, uninoculated plants, irrespective of the virus antiserum used for detection. This effect was also produced in tests in which no HRP conjugate was used, indicating that root extracts from virus-infected or physically injured plants, but not healthy uninjured plants, contain high levels of a factor able to oxidise TMB. The HRP conjugate/TMB substrate version of ELISA is therefore not reliable for detecting viruses in root extracts of herbaceous plants. In contrast, non-specific reactions were not obtained with root extracts, and viruses were reliably detected, when protein A-alkaline phosphatase was used as conjugate and p-nitrophenyl phosphate as substrate. 相似文献
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