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21.
A phylogeny of the cucujoid family Boganiidae (Coleoptera) is inferred for the first time based on a parsimony analysis of 102 morphological characters (70 adult and 32 larval). The analysis resulted in a monophyletic Boganiidae divided into two main clades, Boganiinae and Paracucujinae, each supported by a series of synapomorphies. The Boganiinae genera recovered were Afroboganium Endrödy‐Younga & Crowson and Boganium Sen Gupta & Crowson, whereas Paracucujinae includes Paracucujus Sen Gupta & Crowson, Metacucujus Endrödy‐Younga & Crowson, Athertonium Crowson and the New Caledonian Dzumacium caledonicum gen.n. , sp.n. New specimen data and biological information for the Australian taxa are summarized with overviews on biogeography and comments on the fossil Jurassic Parandrexis Martynov (Parandrexidae). Two new species of Boganium, primarily from the Australian mallee are described: B. malleense sp.n. and B. medioflavum sp.n . Boganium malleense is recorded from flowers of Eucalyptus gracilis F. (Myrtaceae). Adults and larvae of Paracucujus rostratus Sen Gupta & Crowson are redescribed. Athertonium parvum Crowson is redescribed and Athertonium williamsi sp.n. is described from coastal New South Wales. Several host records for Athertonium are also presented.  相似文献   
22.
Wet forest ecosystems in temperate regions have been heavily drained and logged, often with significant negative consequences for biodiversity in these habitats. Our research focused on population maintenance mechanisms of a declining wet forest sedge Carex loliacea L. We studied germination under different light regimes and seedling survival under different vegetation densities using an in situ removal experiment. For successful germination, seeds of C. loliacea need light; germination in reduced light conditions is depressed. The seeds of C. loliacea are able to accumulate a seed bank and exhibit seasonal dormancy cycles. Survival of seedlings strongly depends on competition with other plant species. Our results imply that changes in habitat conditions (draining, forest cutting) affect the successful generative reproduction of C. loliacea primarily via a change in light conditions, which is a strong factor both at the stage of germination and seedling growth. However, adult plants are able to persist over a much broader range of habitat conditions without detectable vitality loss.  相似文献   
23.
RNA of Australia Antigen   总被引:6,自引:0,他引:6  
ALTHOUGH the exact nature of Australia (Au) antigen is not resolved, increasing evidence suggests that it is the causal agent of viral hepatitis. This supposition is based chiefly on the frequent occurrence of Au antigen in the sera of patients with viral hepatitis1–4 and on its virus-like appearance under the electron microscope5–7. Biochemical studies have shown that Au antigen consists largely of protein, with a minor lipid moiety8, 9. So far, however, no genetic material has been detected in the Au antigen and it has been suggested that the Au antigen might be “a unique infectious particle with little or no nucleic acid”10. We wish to present evidence, however, that RNA is an essential component of Au antigen.  相似文献   
24.
The main generic feature of the hyolithid genus Pterygotheca Novlk, 1891 - the fringe on the lateral edges and on the dorsal side of the conch - is interpreted here as a colony of a tabulate coral, Hyostragulum gen. n. This coral covered the living specimens of different hyolithid species in the Bohemian and Moravian Lower and Middle Devonian and occasionally also of nautiloids and gastropods. Because of this discovery it is necessary to withdraw the order Pterygothecida Syssoiev, 1968 and probably also the family Ptery-gothecidae Syssoiev, 1958. The genus Pterygotheca is questionable, but further study may prove its validity. The character of the epifaunal coral strongly supports the interpretation of a benthic life of hyolithids.  相似文献   
25.
Under elevated atmospheric CO2 concentrations, soil carbon (C) inputs are typically enhanced, suggesting larger soil C sequestration potential. However, soil C losses also increase and progressive nitrogen (N) limitation to plant growth may reduce the CO2 effect on soil C inputs with time. We compiled a data set from 131 manipulation experiments, and used meta‐analysis to test the hypotheses that: (1) elevated atmospheric CO2 stimulates soil C inputs more than C losses, resulting in increasing soil C stocks; and (2) that these responses are modulated by N. Our results confirm that elevated CO2 induces a C allocation shift towards below‐ground biomass compartments. However, the increased soil C inputs were offset by increased heterotrophic respiration (Rh), such that soil C content was not affected by elevated CO2. Soil N concentration strongly interacted with CO2 fumigation: the effect of elevated CO2 on fine root biomass and –production and on microbial activity increased with increasing soil N concentration, while the effect on soil C content decreased with increasing soil N concentration. These results suggest that both plant growth and microbial activity responses to elevated CO2 are modulated by N availability, and that it is essential to account for soil N concentration in C cycling analyses.  相似文献   
26.
27.
1. Saproxylic beetles (Coleoptera) have particular requirements for dead wood. Little is known about their larval development, especially within intermediate and late stages of dead wood decay. 2. We studied the natural foraging behaviour of three saproxylic beetles with morphologically similar (i.e. convergent) larvae and similar habitat requirements –Cucujus cinnaberinus Scopoli (Cucujidae), Pyrochroa coccinea L., and Schizotus pectinicornis L. (Pyrochroidae) – examining dietary components using visual gut content analysis. 3. There were few significant differences in diet among the study species, but there were significant differences for the different dietary components in individual species. Guts of all three species included more plant and fungal material than animal. We also observed that with increasing body size larvae foraged significantly less on fungal material. We observed significant differences among species and selection with respect to body size during the overwintering period. Larvae swallowed more animal and less fungal material with increasing body size. 4. The study species seem to be opportunistic foragers, varying their foraging capability according to seasonality and age. They probably generally foraged woody material infested by filamentous fungi (i.e. xylomycetophagy), swallowing other material that is in their way while foraging, including animal parts and small arthropods. 5. We found that morphologically similar larvae do not differ much in their foraging behaviour even when sharing the same habitat. Larval size seems to be a useful predictor for foraging behaviour of saproxylic beetles within the same guild. The study species are probably occasional predators with less ability to forage on other animals than previously suggested.  相似文献   
28.
ABSTRACT. Electrophysiological recordings from the tarsal D-sensilla of mature, 5–7-day-old female European cherry fruit fly ( Rhagoletis cerasi L.) revealed that a large proportion of sensilla showed no sensory activity in response to stimulation with the oviposition deterring pheromone ('ODP') or sucrose. In contrast, good recordings were obtained from almost all sensilla in freshly emerged, 1-day-old flies. Ageing, nutritional state and contamination were excluded as possible major factors influencing the responsiveness of the D-sensilla. The study of the variability in responsiveness of the sensilla of 1-day-old flies among different tarsomers, among tarsi of the same individual and among individuals, revealed that the major source of variability was among individuals.
Individual flies were also affected by the humidity in the holding cages: relative air humidity of less then 75% for 4–6 days was shown to reduce the number of D-sensilla giving recordings with a good signal-to-noise ratio. The D-sensilla on the most distal tarsomers were affected most by the reduced (30–55% r. h.) air humidity. Flies which had contact with plant leaves showed less reduction in responsiveness at low air humidity (40% r. h.) then flies without leaf contact.  相似文献   
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