共查询到20条相似文献,搜索用时 15 毫秒
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The authors describe electromyographic electrodes (EMG electrodes) for recording the activity of several muscles in chronic experiments on cats. An EMG electrode is a loop made of a silver wire 200 micron in diameter and 1.5-2 cm long, to which a flexible copper wire insulated with teflon 300 micron in diameter is soldered. The soldering site is insulated with biologically indifferent material. The EMG electrodes turned out fairly good in numerous experiments. 相似文献
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Jassey VE Gilbert D Binet P Toussaint ML Chiapusio G 《Canadian journal of microbiology》2011,57(3):226-235
Microbial communities living in Sphagnum are known to constitute early indicators of ecosystem disturbances, but little is known about their response (including their trophic relationships) to climate change. A microcosm experiment was designed to test the effects of a temperature gradient (15, 20, and 25°C) on microbial communities including different trophic groups (primary producers, decomposers, and unicellular predators) in Sphagnum segments (0-3 cm and 3-6 cm of the capitulum). Relationships between microbial communities and abiotic factors (pH, conductivity, temperature, and polyphenols) were also studied. The density and the biomass of testate amoebae in Sphagnum upper segments increased and their community structure changed in heated treatments. The biomass of testate amoebae was linked to the biomass of bacteria and to the total biomass of other groups added and, thus, suggests that indirect effects on the food web structure occurred. Redundancy analysis revealed that microbial assemblages differed strongly in Sphagnum upper segments along a temperature gradient in relation to abiotic factors. The sensitivity of these assemblages made them interesting indicators of climate change. Phenolic compounds represented an important explicative factor in microbial assemblages and outlined the potential direct and (or) indirect effects of phenolics on microbial communities. 相似文献
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Immigration and local competition in herbaceous plant communities: a three-year seed-sowing experiment 总被引:8,自引:0,他引:8
Understanding the relative roles of local and regional processes in determining local species diversity is now of strong relevance in basic ecology. To address this question, we have tested the influence of immigration on species diversity dynamics in a three-year experiment using herbaceous plant communities. We manipulated the intensity of seed rain (i.e., immigration) and the relative contribution of each species to the seed rain. For each of three levels of intensity of immigration (seed rain), we considered three cases, in which immigration was either negatively correlated, positively correlated, or uncorrelated with local competitive ability. Our experiment illustrates how both immigration and local competition contribute to explaining species diversity in herbaceous plant communities. Communities were more diverse when they received more seeds and when immigration was inversely correlated or uncorrelated with local competitive ability. Only species of intermediate or low competitive ability responded positively to the seed-addition treatment. Community-level functional properties were not strongly modified by immigration: immigration treatments did not differ in total above-ground biomass and plant cover, soil surface occupation was higher at high immigration intensities. A comparison of our results with theoretical models of plant community structure suggests that the mechanisms underlying the species dynamics in our communities were probably a mixture of colonization-extinction and competitive weighted lottery. 相似文献