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121.
The Eurasian beaver (Castor fiber) has a greater impact on local ecosystems than other herbivores, and the affected area exceeds the range of its presence. Its activity may change or create new habitats by modifying the availability of the biotic and abiotic resources available not only to beavers, but also to other groups of animals. Our aim was to study how beaver activity affects the benthos composition in a small river and in a beaver pond. The way in which beavers function in the case of small rivers has received little attention. The study showed a lower density of benthos above the dam (beaver pond - 1467 ind./m2) compared to the river (3147 ind./m2). Below the dam, the diversity of Trichoptera and Coleoptera was greater, while Diptera were more abundant in the beaver pond. Betidae were a constant component in the benthos assemblages and were most abundant in the beaver pond. Collectors-gatherers and predators were the most numerous in the beaver pond. Decreasing percentages of collectors-gatherers were observed with an increased abundance of collectors-filterers and shredders in the river. All of the ratio values except the P/T FFG (Predators to total of all other groups) were lower in the beaver pond compared to the river. The % EPT (Ephemeroptera Plecoptera and Trichoptera) was also greater in the beaver pond. Small differences in the physicochemical properties of the water and organic matter content in the bottom sediments were found both above and below the beaver dam. 相似文献
122.
The existence of a two-host life-cycle in ophiotaeniid proteocephalideans was tested experimentally using Ophiotaenia europaea as a model. Three species of reptiles, Natrix natrix, Natrix tessellata and Lacerta viridis, were fed with experimentally infected copepods containing a large number of infective plerocercoids I. A few plerocercoids, most of which were dead, corresponding morphologically to the plerocercoid II developmental stage of O. europaea, were found encysted in the intestinal wall of N. natrix (8 days p.i.), N. tessellata (5 and 150 days p.i.) and L. viridis (40 days p.i.), while no plerocercoids or adult worms were recovered from their intestines. The results indicate that the infective plerocercoid I of O. europaea cannot undergo further development when ingested directly by the final host (a reptile), and that environmental temperature stimuli cannot initiate a reverse plerocercoid migration to the gut followed by strobilization. 相似文献
123.
Andrzej Małobęcki Thomas Marcussen Jerzy Bohdanowicz Grzegorz Migdałek Aneta Słomka Elżbieta Kuta 《Botanical journal of the Linnean Society. Linnean Society of London》2016,182(1):180-194
Viola uliginosa is an endangered species throughout its range in Central Europe. Based on an unusual combination of morphological characters, including a reported lack of cleistogamous (CL) flowers, it was previously placed in the monotypic subsection Repentes, section Viola. Available individual phylogenetic analyses identify V. uliginosa as a lineage deeply embedded in section Viola, but hitherto its exact position was unknown. Here we confirm the occurrence of cleistogamy in V. uliginosa. Unlike other species of section Viola, V. uliginosa produced both chasmogamous and CL flowers at the same time, not at different times of the year (seasonal cleistogamy). The two flower types differed conspicuously in morphology and microstructure, especially in size and shape of the pistil and stamens as confirmed by scanning electron microscopy. Secondly, we resolved the phylogenetic position of V. uliginosa as a lineage deeply embedded in subsection Rostratae by means of a multigene multispecies coalescent analysis using *BEAST. In this analysis, V. mirabilis and V. uliginosa were successive sisters to the rest of subsection Rostratae and, because allopolyploids exist between V. mirabilis and the last one, subsection Rostratae needs to comprise all these taxa to be monophyletic. The evolution of key morphological traits is briefly discussed. 相似文献
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Tamara I. Balakhnina Vladimir V. Matichenkov Teresa Wlodarczyk Aneta Borkowska Magdalena Nosalewicz Irina R. Fomina 《Plant Growth Regulation》2012,67(1):35-43
Barley (Hordeum vulgare L.) was grown in pots with brown loess soil and highly soluble amorphous silicon dioxide as the source of monosilicic acid
to examine its influence on plant growth and adaptive potential under optimal soil watering and flooding. The adaptive potential
of plants was estimated by the concentration of the thiobarbituric acid reactive substances (TBARs) as well as superoxide
dismutase (SOD), guaiacol peroxidase (GPX) and ascorbate peroxidase (AsP) activities. Application of amorphous silica to the
soil increased the Si content in barley shoots and roots and stimulated their growth and biomass production under optimal
soil watering. Soil flooding suppressed the growth both of the (−Si)- and (+Si)-plants. The intensity of oxidative destruction
estimated by the concentration of TBARs was lower in the roots and leaves of the (+Si)-plants. Soil flooding induced SOD activity
in the roots and in the leaves of the (−Si;+flooding) and (+Si;+flooding)-plants, but no significant differences were observed
due to the Si treatment. GPX activity in the roots of (+Si)-plants was higher than in the (−Si)-ones under optimal soil watering,
but under soil flooding no differences between (+Si)- and (−Si)-treatments were observed. AsP activity was not influenced
by Si treatment neither under optimal soil watering nor under flooding. Thus, application of Si stimulates growth processes
of barley shoots and roots under optimal soil watering and decreases intensity of oxidative destruction under soil flooding
without significant changes in the activities of antioxidant enzymes. 相似文献
129.
Tadeusz Włostowski Alicja Krasowska Aneta Salińska Monika Włostowska 《Biological trace element research》2009,131(3):291-297
The objective of this study was to examine relations between body iron (Fe) status and cadmium (Cd) accumulation in a small
rodent, the bank vole, caught from the wild population in late autumn (November) and early spring (March). The concentrations
of Fe in the liver, kidneys, and duodenum in the bank voles from the spring were only 30%, 60%, and 70%, respectively, of
those found in the animals from the autumn. An analysis of hematocrit and hemoglobin content of blood showed no significant
effect of the season, suggesting that the animals from the spring were not anemic. The exposure to dietary Cd (10 μg/g) for
7 days resulted in 70% higher accumulation of Cd in the liver and kidneys of the spring than autumn bank voles, and the concentration
of Cd in the duodenum was 3.5 times higher in the spring animals, despite the fact that relative Cd intake was significantly
higher in the autumn bank voles. The data indicate that seasonal changes of body Fe status occurring in the wild bank voles
may influence tissue accumulation of Cd. 相似文献
130.
Weryszko-Chmielewska Elżbieta Sulborska-Różycka Aneta Sawidis Thomas 《Protoplasma》2022,259(6):1467-1476
Protoplasma - Chaenomeles japonica is an attractive ornamental shrub flowering in spring. It is also a valuable source of nectar and pollen for entomofauna. The study was carried out to investigate... 相似文献