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2.
Report cards are an increasingly popular method for summarising and communicating relative environmental performance and ecosystem health, including in aquatic environments. They are usually underpinned by an Ecosystem Health Index (EHI) that combines various individual indicators to produce an overall ecosystem health “score”. As a result of public water quality concerns, an integrated means of monitoring and reporting on aquatic ecosystem health was needed for the Fitzroy Basin in central Queensland, Australia. The Fitzroy Partnership for River Health was formed to address this need, and developed an EHI and report card for the Basin using existing monitoring data collected from various third parties including regulated companies operations and government. At 142,000 square kilometres, the Fitzroy Basin is the largest catchment draining to the World Heritage Listed Great Barrier Reef. The Fitzroy Basin provides an example of how to deliver an effective aquatic ecosystem health reporting system in a large and complex river basin. We describe the methodology used to develop an adaptive EHI for the Fitzroy Basin that addresses variability, complexity and scale issues associated with reporting across large areas. As well, we report how to manage the design and reporting stages given limitations in data collection and scientific understanding. 相似文献
3.
Recent conservation efforts recognize that human needs cannot be ignored. One way to understand the social components of resource management is to evaluate stakeholder perspectives. Stakeholder perspectives are an important component of developing effective natural resource management plans, specifically in the developing world. However, most stakeholder research in Africa focuses on local communities in locales adjacent to protected areas. This research expands the stakeholder population by looking at university students’ perspectives regarding the Maasai Mara region of Kenya in relation to two complex and high profile issues: wildlife and grazing. Increased understanding of these topics in a diverse and urbanizing nation like Kenya can lead to better outcomes for conservation efforts. Using Photovoice, a qualitative research method, participants shared their perspective and built upon others’ ideas about wildlife and grazing. Results suggest that there was a wide array of perspective regarding wildlife and grazing. Economics played a large part in both wildlife and grazing perspectives. However, there was also concern for the aesthetic and cultural value of wildlife and grazing in Kenya, which is contrary to some previous findings. Due to the varying perspective and multiple stakeholder groups, research should continue to explore the social aspects of natural resource management regarding wildlife and grazing in the Maasai Mara region of Kenya. 相似文献
4.
Diel variation of phytoplankton functional groups in a subtropical reservoir in southern Brazil during an autumnal stratification period 总被引:1,自引:0,他引:1
A knowledge of diel variation and the vertical distribution of phytoplankton communities may contribute to a better understanding
of the driving factors of key species. Applying functional-group classification provides important information on the causes
of species selection in the pelagic community. The diel variation of phytoplankton functional groups was analysed during an
autumnal stratification period with the aim of understanding their changes in the vertical position related to light, mixing
regime and grazing pressure. Phytoplankton and zooplankton communities were sampled every 4 h during a 24-h period in a vertical
profile in a subtropical meso-eutrophic reservoir. Strong stratification during a 24-h cycle and a mixed clear epilimnion
with partial atelomixis marked the autumn season in the Faxinal reservoir, southern Brazil. The highest phytoplankton densities
and biomass were found during the second part of the day, a general pattern reported in the literature, and may be explained
by zooplankton dynamics. During the 24-h cycle, phytoplankton functional groups lacking a self-regulating capacity and those
able to regulate their vertical position were vertically segregated in the lake. The diel behaviour of both groups was driven
by the mixing regime (including atelomixis), light and zooplankton grazing pressure. 相似文献
5.
At what intensity the grazing should be practiced on the Qinghai-Tibetan Plateau in China is always confusing farmers, scientists and policy makers for a long time owing to its geographical exception. In order to develop a strategy for sustainable grazing management, we used the dominant Stipa purpurea as a model species to detect genetic diversity and fine spatial structure under different grazing intensities. Intra-population neutral genetic diversity in non-grazed population was significantly higher than three grazed populations; however, the highest value among grazed populations appeared in the moderately grazed population. A relatively low degree of genetic differentiation among populations by AMOVA analysis and a high level of gene flow existed among populations (Gst = 0.2649, Nm = 1.3875 〉 1). The genetic ‘patch’ size increased from 4 m to 16 m and subpopulation number within the S. purpurea populations ranged from 7 to 5 with increasing grazing intensity, therefore grazing will be beneficial to reduce the fragmentation and to increase the population-level adaptation. Though enclosure or no grazing is the best protection of plant germplasm like wind-pollination S. purpurea, moderate grazing is better strategy for grassland use on the Qinghai-Tibetan Plateau. 相似文献
6.
Experiments in laboratory stream channels compared the behaviour of Deleatidium mayfly nymphs in the absence of fish with that in the presence of either native common river galaxias (Galaxias vulgaris Stokell) or introduced brown trout (Salmo trutta L.). Galaxias present similar predation risks to prey during day and night but are more active at night. Whereas, trout present a higher predation risk during the day. Deleatidium maintained a fixed nocturnal drift periodicity that is characteristic of streams containing visually feeding fish regardless of the nature of the predation regime presented in the laboratory. However, the number on the substratum surface, and therefore able to graze algae, was lower when fish were present than when they were absent. The number was lower during the day in the presence of trout, when they present the highest predation risk, and lower during the night compared to the day in trials with galaxias when galaxias activity disturbs Deleatidium from the substratum. Increases in the probability of Deleatidium leaving a patch, reductions in the proportion of mayflies on high quality patches and reductions in the distance travelled from refuge also reflected variations in the predation regime. Similar differences in positioning were observed under the same predation regimes in in situ channels in the Shag River and these were associated with differences in algal biomass. Algal ash-free dry mass (AFDM) and chlorophyll a (chl a) were higher on the tops of cobbles when fish were present. Fish also affected the biomass and the distribution of algae on cobbles as AFDM and chl a were higher on the sides of cobbles from channels with trout compared to those with galaxias. Changes in grazing behaviour, caused by predator avoidance, are likely to have been responsible for differences in algal biomass because no significant differences were detected between treatments in the biomass of Deleatidium or of total invertebrates. 相似文献
7.
Feeding strategies of copepods were studied during a dinoflagellate-dominated bloom in the North Sea in August 2001. The aim of this study was to evaluate the importance of mesozooplankton grazing as a biological loss factor of harmful algal blooms under natural conditions. Therefore, ingestion, egestion and egg production experiments were performed with the most abundant copepod species Calanus helgolandicus, Temora longicornis and Acartia sp. feeding on the natural phytoplankton community. Dinophysis norvegica and Ceratium furca were the most abundant dinoflagellate species at the time of the experiments. Grazing experiments as well as examination of fecal pellet content revealed C. helgolandicus fed efficiently on D. norvegica. Ingestion rates up to 47 cells female−1 h−1 were measured and a large proportion of the C. helgolandicus fecal pellets contained intact D. norvegica cells. Dinophysis cells were rarely seen in fecal pellets produced by T. longicornis, and never observed in pellets produced by Acartia sp. The ingestion rate of C. furca, which was the dominating Ceratium species, mimicked that of D. norvegica. C. helgolandicus grazed significantly on C. furca (16 cells female−1 h−1), while the ingestion rate of T. longicornis was low and Acartia sp. was not able to graze on C. furca. Egg production experiments revealed that 92% of the C. helgolandicus females produced eggs. The specific egg production rate and the proportion of females producing eggs among T. longicornis were low. This field experiment clearly shows that some copepod species feed efficiently on D. norvegica and C. furca under natural conditions, which may affect the bloom development of these dinoflagellates. 相似文献
8.
Patterns of ash (Fraxinus excelsior L.) colonization in mountain grasslands:
the importance of management practices 总被引:2,自引:2,他引:0
Woody colonization of grasslands is often associated with changes in abiotic or biotic conditions or a combination of both. Widely used as fodder and litter in the past traditional agro-pastoral system, ash (Fraxinus excelsior L.) has now become a colonizing species of mountain grasslands in the French Pyrenees. Its present distribution is dependent on past human activities and it is locally controlled by propagule pressure and abiotic conditions. However, even when all favourable conditions are met, all the potentially colonizable grasslands are not invaded. We hypothesize that management practices should play a crucial role in the control of ash colonization. From empirical field surveys we have compared the botanical composition of a set of grasslands (present and former) differing in management practices and level of ash colonization. We have displayed a kind of successional gradient positively linked to both ash cover and height but not to the age of trees. We have tested the relationships between ash presence in grassland and management types i.e. cutting and/or grazing, management intensity and some grassland communities’ features i.e. total and local specific richness and species heterogeneity. Mixed use (cutting and grazing) is negatively linked to ash presence in grassland whereas grazing alone positively. Mixed use and high grazing intensity are directly preventing ash seedlings establishment, when low grazing intensity is allowing ash seedlings establishment indirectly through herbaceous vegetation neglected by livestock. Our results show the existence of a limit between grasslands with and without established ashes corresponding to a threshold in the intensity of use. Under this threshold, when ash is established, the colonization process seems to become irreversible. Ash possesses the ability of compensatory growth and therefore under a high grazing intensity develops a subterranean vegetative reproduction. However the question remains at which stage of seedling development and grazing intensity these strategies could occur. 相似文献
9.
Tolerance to grazing is a plant trait that can be adaptive in systems where plants are subjected to a diversity of herbivore attack types. To test the tolerance ability of the clonal sedge Carex bigelowii, which is food plant to several herbivores in alpine and arctic areas, and the potential fitness costs of this tolerance, replicated units of genets were subjected to three levels of damage throughout three consecutive seasons. The three levels of treatment were no damage, light damage and heavy damage, and the damage was conducted by tearing off all plant material at 3 and 0 cm above-ground respectively. The genets had no tolerance under damage in terms of sexual reproduction. In terms of clonal reproduction the genets showed tolerance under light damage but not under heavy damage. However, no fitness cost was found for this tolerance ability, i.e. genets had higher reproduction and growth under no damage. The average ramet weight had a similar decrease under both a low and high damage treatment. Changed partitioning of biomass between plant parts and reduced concentration of total non-structural carbohydrates (TNC) in storage organs are possible mechanisms for the ability to uphold clonal reproduction in response to damage. There were no significant indications that tolerance ability or its fitness cost differed between genets. Our results suggest that when subjected to heavy damage genets will only reproduce vegetatively. Consequently, it seems C. bigelowii has evolved to allocate resources to the survival of an already successful genet rather than to a potential new genet of unknown success. 相似文献
10.
Question: How is tundra vegetation related to climatic, soil chemical, geological variables and grazing across a very large section of the Eurasian arctic area? We were particularly interested in broad‐scale vegetation‐environment relationships and how well do the patterns conform to climate‐vegetation schemes. Material and Methods: We sampled vegetation in 1132 plots from 16 sites from different parts of the Eurasian tundra. Clustering and ordination techniques were used for analysing compositional patterns. Vegetation‐environment relationships were analysed by fitting of environmental vectors and smooth surfaces onto non‐metric multidimensional scaling scattergrams. Results: Dominant vegetation differentiation was associated with a complex set of environmental variables. A general trend differentiated cold and continental areas from relatively warm and weakly continental areas, and several soil chemical and physical variables were associated with this broad‐scaled differentiation. Especially soil chemical variables related to soil acidity (pH, Ca) showed linear relationships with the dominant vegetation gradient. This was closely related to increasing cryoperturbation, decreasing precipitation and cooler conditions. Remarkable differences among relatively adjacent sites suggest that local factors such as geological properties and lemming grazing may strongly drive vegetation differentiation. Conclusions: Vegetation differentiation in tundra areas conforms to a major ecocline underlain by a complex set of environmental gradients, where precipitation, thermal conditions and soil chemical and physical processes are coupled. However, local factors such as bedrock conditions and lemming grazing may cause marked deviations from the general climate‐vegetation models. Overall, soil chemical factors (pH, Ca) turned out to have linear relationship with the broad‐scale differentiation of arctic vegetation. 相似文献