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排序方式: 共有1664条查询结果,搜索用时 31 毫秒
1.
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Janitha A. Liyanage David M. Taylor David R. Williams 《Chemical Speciation and Bioavailability》2013,25(2):73-75
ABSTRACTA method has been developed for impregnating alginate-based wound dressings with trace elements required for wound healing and for quantifying the transfer from these dressing to wound fluid (for which a substitute—blood serum—was used in these experiments). Under ideal conditions, up to 85% can be carried across from the tow to the wound fluid. 相似文献
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NICOLAS RAY 《Molecular ecology resources》2005,5(1):177-180
pathmatrix is a tool used to compute matrices of effective geographical distances among samples using a least‐cost path algorithm. This program is dedicated to the study of the role of the environment on the spatial genetic structure of populations. Punctual locations (e.g. individuals) or zones encompassing sample data points (e.g. demes) are used in conjunction with a species‐specific friction map representing the cost of movement through the landscape. Matrices of effective distances can then be exported to population genetic software to test, for example, for isolation by distance. pathmatrix is an extension to the geographical information system (GIS) software arcview 3.x. 相似文献
5.
L. Brzsnyi 《Biometrical journal. Biometrische Zeitschrift》1981,23(3):283-295
The paper deals with the analysis of 2 × 2 table measures and describes several new possibilities for applying them. An estimate is given for HELLMICH's asymmetric K-measure and a possible extension of the contingency concept in a special 2×2 case is presented. The concept introduced and the recommended computer application of the 2×2 table measures is supported by new results obtained for the relationship between jaw joint pains and noises examined earlier by F. SCHMID and C. ZSCHEGE. With a larger number of observations the opportunity arises for a deeper analysis of this dental problem using path analysis. The plan of evaluation and the conncetion between the variables examined is illustrated by a path-diagram. The association tables determined on the basis of the (C) values introduced during the examination of jaw joint disturbances using association analysis draw attention to the special role of the left side of mastication. The paper raises ideas for further generalisations and indicates where further research is needed. 相似文献
6.
Johan R. Michaux† Joëlle Goüy De Bellocq‡ Maurizio SarৠSerge Morand‡ 《Global Ecology and Biogeography》2002,11(5):427-436
Insular mammalian populations living in areas of small size are often characterized by a drastic change in body mass compared to related continental populations or species. Generally, small mammals (less than 100 g) evolve into giant forms while large mammals (up to 100 g) evolve into dwarf forms. These changes, coupled with changes in other life, behavioural, physiological or demographic traits are referred to generally as the insular syndrome. We tested in this study the relative contribution of three factors — area of island, numbers of competitor species and number of predator species — to changes in body size of the woodmouse (Apodemus sylvaticus) in the Western Mediterranean Sea. Our results, based on a comparative analysis using the phylogenetic independent contrasts method, indicate that the increase in body size is related both to the decrease of island size and to the lower number of predator species. A decrease of competitor species does not seem to have an important effect. 相似文献
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H. Daniel 《Biological trace element research》1987,13(1):301-318
Because of the large μ mass compared to the electron mass, the muonic X-rays have energies very suitable for standard γ-ray
spectroscopy (Ge detectors), so every element is easily recognized. By selecting the primary μ energies appropriately any
part of the specimen, also well inside, can be nondestructively investigated. On the other hand, surface layers may be analyzed.
Accuracies of quantitative analyses are 1% of the atomic abundance of the element in question in favorite cases. Results on
applications in nuclear medicine and surface physics are presented, and ways of improving the muon flux density are discussed. 相似文献
9.
P. lanceolata andP. major were grown in culture solutions with nitrate or ammonium as the nitrogen source. Dry matter accumulation in the shoot was
faster with nitrate than with ammonium, whilst that of the roots was not affected by the nitrogen source. As a consequence,
the shoot-to-root ratio was lower with ammonium than with nitrate. InP. lanceolata, dry matter percentage of shoot and root tissue was lower with nitrate nutrition, suggesting better elongation growth than
with ammonium. However, in shoot tissue ofP. major the opposite was found. The rate of root respiration declined with time, and this was almost completely due to a declining
activity of the alternative path, which amounted to about 30–60% of total root respiration. Respiration via the cytochrome
path was for a part of time slightly increased by ammonium, whereas the activity of the alternative path was strongly enhanced.
The concentration of ethanol-soluble carbohydrates (SC) in the roots of both species was higher when nitrate was used, but
no difference in the concentration of starch was found. When the plants were transferred from one nitrogen source to the other,
many parameters, including the concentration of nitrate and chloride, and the shoot to root ratio, adjusted to the new situation
in both species.
Grassland Species Research Group, Publication no. 116. 相似文献
10.
Abstract Species of Trillium have a disjunct distribution occurring in both North America and eastern Asia. In North America all 36 species are diploid. The 11 species of eastern Asia, however, include only a single diploid with all the other species being polyploids. Why do different patterns of speciation develop in North America and in eastern Asia? The breeding systems of populations in the North American T. erectum, T. grandiflorum and T. ovatum , and in Asian T. kamtschaticum were investigated by estimating the inbreeding coefficient from cold-induced banding patterns which reveal homozygotes and heterozygotes. From the analyses of the inbreeding coefficients, T. erectum, T. grandiflorum and the Pacific coastal species, T. ovatum are predominantly inbreeding species. T. ovatum populations from the Rocky Mountain region are outbreeders. However the Japanese species, T. kamtschaticum has a mixture of outbreeding and inbreeding among populations. The development of polyploid systems in Asia is possibly the result of the diversity of the breeding systems among the populations. The shift from outbreeding to inbreeding appears to be an important key step in the occurrence of poliploids by hybridization between the different species. 相似文献