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61.
Changes in butterfly distributions and species assemblages on a Neotropical mountain range in response to global warming and anthropogenic land use
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This study obtained baseline information for adult Odonata and assessed their conservation priorities and suitability as biological
indicators in S’Albufera Natural Park in Mallorca, Spain. At this site, human activities in and around the wetland have raised
concerns about their impact on the ecosystem. Investigations on adult diversity produced records of 14 species (four Zygoptera
and 10 Anisoptera) and included the first record of Erythromma viridulum for the park. Detrended Correspondence Analysis (DCA) ordination categorised study sites according to their geographical
locations in the park and showed clustering of the sites around particular species based on these locations. This pattern
might reflect the differences in brackishness in water supplied by different water sources. Canonical Correspondence Analysis
(CCA) indicated that some environmental factors were related to particular species. Water flow, vegetation, and depth and
size of a water body could discriminate stenotopic species from eurytopic species. Only a few species appeared to be tolerant
to the sites with high salinity and low oxygen concentration. The ordination results can be useful for establishing conservation
priorities with information of species diversity, abundance, distribution and flight period. Although, with the current limited
basic information, the use of Odonata species as biological indicators seems to be difficult, some clear relationships between
environmental factors and particular species indicate the great potential of using adult Odonata as biological indicators
in the park. 相似文献
66.
Claudet J Osenberg CW Benedetti-Cecchi L Domenici P García-Charton JA Pérez-Ruzafa A Badalamenti F Bayle-Sempere J Brito A Bulleri F Culioli JM Dimech M Falcón JM Guala I Milazzo M Sánchez-Meca J Somerfield PJ Stobart B Vandeperre F Valle C Planes S 《Ecology letters》2008,11(5):481-489
Marine reserves are widely used throughout the world to prevent overfishing and conserve biodiversity, but uncertainties remain about their optimal design. The effects of marine reserves are heterogeneous. Despite theoretical findings, empirical studies have previously found no effect of size on the effectiveness of marine reserves in protecting commercial fish stocks. Using 58 datasets from 19 European marine reserves, we show that reserve size and age do matter: Increasing the size of the no-take zone increases the density of commercial fishes within the reserve compared with outside; whereas the size of the buffer zone has the opposite effect. Moreover, positive effects of marine reserve on commercial fish species and species richness are linked to the time elapsed since the establishment of the protection scheme. The reserve size-dependency of the response to protection has strong implications for the spatial management of coastal areas because marine reserves are used for spatial zoning. 相似文献
67.
Lake Balaton (Hungary), one of the largest lakes in Europe, has undergone eutrophication and restoration during the last two decades. The first quantitative phytoplankton records date back to the 1930s, and since that time thousands of data have been published or accumulated in counting protocols or computer sheets. These data provide material for both scientific analyses (e.g. effects of global change) and applications (e.g. estimation of reference state for the Water Framework Directive). The ALMOBAL phytoplankton database was developed to provide computing support for these applications. It stores data in standardized forms, handles synonyms and allows analyses to be conducted on the basis of floral records, numbers or biomass. The analysis includes records of about 3000 phytoplankton samples taken during the past 60 years from two representative basins in Lake Balaton. This article represents the first attempt at historical reconstruction of the ecological status and compares it with changes in trophic state and current water quality. The results indicate that the phytoplankton biomass and community structure found in the early 1960s could be regarded as reference conditions. Statistical analyses support the view that late summer phytoplankton assemblages are the most sensitive indicators of trophic change, and clearly show the eutrophication of the lake that occurred from the mid-1970s to the mid-1990s and the restoration during the last decade. An additional advantage is that, since quality estimation is based on relative biomass, the method can be used to reconstruct water quality in cases when counting protocols are available, but some basic data for quantitative estimates are missing. 相似文献
68.
Klára Řeháková Eliška Zapomělová Ondřej Prášil Jana Veselá Hana Medová Aharon Oren 《Hydrobiologia》2009,636(1):77-88
There are several conflicting hypothesis that deal with the influence of flooding in the natural river–floodplain systems.
According to the Flood Pulse Concept, the flood pulses are not considered to be a disturbance, while some recent studies have
proven that floods can be a disturbance factor of phytoplankton development. In order to test whether flooding acts as a disturbance
factor in the shallow Danubian floodplain lake (Lake Sakadaš), phytoplankton dynamics was investigated during two different
hydrological years—extremely dry (2003) without flooding and usually flooded (2004). A total of 18 phytoplankton functional
groups were established. The sequence of phytoplankton seasonality can be summarized P/D → E (W1, W2) → C/P (only in potamophase) → S2/H1/SN/S1 → W1/W2 → P/D. The canonical correspondence analysis (CCA) demonstrated that the water level was a significant environmental
variable in 2004. Due to the higher total biomass of Bacillariophyceae established under potamophase conditions, floodings
in the early spring seem to be a stimulating factor for phytoplankton development. On the other hand, the flood pulses in
May and June had dilution effects on nutrients, so that a significantly lower phytoplankton biomass was established indicating
that flooding pulses can be regarded as a disturbance event. Such conditions supported diatom development (D, P, C species)
and prolonged its dominance in the total phytoplankton biomass. A long-lasting Cyanoprokaryota bloom (various filamentous
species—S1, S2, SN and H1 representatives) with very high biomass characterized the limnophase (dry conditions) in summer and autumn of both
years. In-lake variables (lake morphology, internal loadings of nutrients from sediments, light conditions) seem to be important
for the appearance of Cyanoprokaryota bloom. The equilibrium phase was found during the Cyanoprokaryota bloom only in the
extremely dry year. This study showed that depending on the time scale occurrence, flood pulses can be a stimulating or a
disturbance factor for phytoplankton development in Lake Sakadaš.
Handling editor: J. Padisak 相似文献
69.
1. Although the biomass of freshwater macrophytes consumed by invertebrate herbivores (excluding crayfish) is usually low, there is growing evidence that invertebrates do exert a structuring effect on macrophyte communities. To explain this, we postulated that the effect of invertebrates may be concentrated on macrophytes during their regenerative phase.
2. We tested this hypothesis by means of a mesocosm-based experiment, in which we investigated the effects of different densities of pond snails [ Lymnaea stagnalis (L.)] on macrophytes regenerating from the natural sediment propagule bank.
3. After 2 months, a diverse macrophyte community had established in the absence of snails, mainly from sexual propagules. Under moderate snail grazing (4 individuals m−2 ), the ultimate biomass of macrophytes was similar, but its species composition differed dramatically. Only a few unpalatable taxa, such as Ceratophyllum demersum and Nymphaeaceae, persisted. Moreover, the relative success of macrophytes regenerating from vegetative rather than sexual propagules improved. Under higher snail grazing (20 m−2 ), all macrophytes disappeared before the end of the experiment.
4. These results confirm that snails at natural densities can have a strong effect on the ultimate structure of macrophyte communities by selectively consuming some species at a juvenile stage. Therefore, the regenerative phase can be seen as a window of opportunity for invertebrate grazers, which can have a qualitative effect on communities that is disproportionate to the biomass consumed. 相似文献
2. We tested this hypothesis by means of a mesocosm-based experiment, in which we investigated the effects of different densities of pond snails [ Lymnaea stagnalis (L.)] on macrophytes regenerating from the natural sediment propagule bank.
3. After 2 months, a diverse macrophyte community had established in the absence of snails, mainly from sexual propagules. Under moderate snail grazing (4 individuals m
4. These results confirm that snails at natural densities can have a strong effect on the ultimate structure of macrophyte communities by selectively consuming some species at a juvenile stage. Therefore, the regenerative phase can be seen as a window of opportunity for invertebrate grazers, which can have a qualitative effect on communities that is disproportionate to the biomass consumed. 相似文献
70.
Aim To investigate the potential impacts of climate change on stream fish assemblages in terms of species and biological trait diversity, composition and similarity. Location One‐thousand one‐hundred and ten stream sections in France. Methods We predicted the future potential distribution of 35 common stream fish species facing changes in temperature and precipitation regime. Seven different species distribution models were applied and a consensus forecast was produced to limit uncertainty between single‐models. The potential impacts of climate change on fish assemblages were assessed using both species and biological trait approaches. We then addressed the spatial distribution of potential impacts along the upstream–downstream gradient. Results Overall, climate change was predicted to result in an increase in species and trait diversity. Species and trait composition of the fish assemblages were also projected to be highly modified. Changes in assemblages’ diversity and composition differed strongly along the upstream–downstream gradient, with upstream and midstream assemblages more modified than downstream assemblages. We also predicted a global increase in species and trait similarity between pairwise assemblages indicating a future species and trait homogenization of fish assemblages. Nevertheless, we found that upstream assemblages would differentiate, whereas midstream and downstream assemblages would homogenize. Our results suggested that colonization could be the main driver of the predicted homogenization, while local extinctions could result in assemblage differentiation. Main conclusions This study demonstrated that climate change could lead to contrasted impacts on fish assemblage structure and diversity depending on the position along the upstream–downstream gradient. These results could have important implications in terms of ecosystem monitoring as they could be useful in establishing areas that would need conservation prioritization. 相似文献