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31.
Harry Olde Venterink Ignacy Kardel Wiktor Kotowski Wilma Peeters Martin J. Wassen 《Biogeochemistry》2009,93(3):235-252
To provide a reference for wetlands elsewhere we analysed soil nutrients and the vegetation of floodplains and fens in the
relatively undisturbed Biebrza-valley, Poland. Additionally, by studying sites along a water-table gradient, and by comparing
pairs of mown and unmown sites, we aimed with exploring long-term effects of drainage and annual hay-removal on nutrient availabilities
and vegetation response. In undrained fens and floodplains, N mineralization went slowly (0–30 kg N ha−1 year−1) but it increased strongly with decreasing water table (up to 120 kg N ha−1 year−1). Soil N, P and K pools were small in the undisturbed mires. Drainage had caused a shift from fen to meadow species and the
disappearance of bryophytes. Biomass of vascular plants increased with increasing N mineralization and soil P. Annual hay-removal
tended to have reduced N mineralization and soil K pools, but it had increased soil P. Moreover, N concentrations in vascular
plants were not affected, but P and K concentrations and therefore N:P and N:K ratios tended to be changed. Annual hay-removal
had induced a shift from P to K limitation in the severely drained fen, and from P to N limitation in the floodplain. The
low nutrient availabilities and productivity of the undisturbed Biebrza mires illustrate the vulnerability of such mires to
eutrophication in Poland and elsewhere. In nutrient-enriched areas, hay removal may prevent productivity increase of the vegetation,
but also may severely alter N:P:K stoichiometry, induce K-limitation at drained sites, and alter vegetation structure and
composition. 相似文献
32.
陕西省黄河湿地冬季鸟类群落初步研究 总被引:12,自引:2,他引:10
1998~2008年,采用直接计数法对陕西省黄河湿地冬季鸟类群落组成、鸟类物种多样性及数量变化进行了调查.在预先设置的5条调查样带中共记录到鸟类14目33科117种.观察结果表明,该地区鸟类多样性指数和均匀度指数分别为4.497和0.654.栖息地可分为人工渔塘、芦苇沼泽、滩涂湿地、农田和人工林5种类型.这些生境中鸟类组成及物种多样性差异均较大,其鸟类多样性指数分别为2.826、3.571、3.202、1.205、2.496,以芦苇沼泽中的鸟类多样性指数最高,滩涂湿地中鸟类数量最多,农田中鸟类优势度最高.通过对该地区鸟类群落组成及多样性分析研究以及黄河湿地冬季鸟类栖息地现状评价,为湿地鸟类资源的保护提供科学依据. 相似文献
33.
Steven J. Hall 《Human ecology: an interdisciplinary journal》2009,37(2):241-249
The influence of local actors and socioeconomic constraints on biological invasions is often ignored. Wetland plant harvesters
appeared to intentionally influence cattail (Typha domingensis) invasion around Lake Pátzcuaro, México, by altering their harvesting regimes, according to interviews with 44 expert respondents
and botanical surveys. The oldest and most experienced harvesters reported controlling Typha initially, sometimes through organized eradication efforts, in order to protect Schoenoplectus californicus, an economically and culturally valuable wetland plant. Later, outsiders commoditized Typha by introducing new weaving designs popular with tourists, while industrial products and new livelihood activities reduced
Schoenoplectus harvest. Harvesters from several communities began to promote Typha re-growth. Some harvesters, however, continued to combat Typha to maintain Schoenoplectus production, especially where supply was limited. Interviews suggested novel ecological cause–effect mechanisms and restoration
strategies; some local harvesting regimes could efficiently conserve rare plants. An understanding of local ecological knowledge
and incentives can inform invasive species control and conservation policy at a broader scale. 相似文献
34.
Wetlands and global climate change: the role of wetland restoration in a changing world 总被引:11,自引:0,他引:11
Kevin L. Erwin 《Wetlands Ecology and Management》2009,17(1):71-84
Global climate change is recognized as a threat to species survival and the health of natural systems. Scientists worldwide are looking at the ecological and hydrological impacts resulting from climate change. Climate change will make future efforts to restore and manage wetlands more complex. Wetland systems are vulnerable to changes in quantity and quality of their water supply, and it is expected that climate change will have a pronounced effect on wetlands through alterations in hydrological regimes with great global variability. Wetland habitat responses to climate change and the implications for restoration will be realized differently on a regional and mega-watershed level, making it important to recognize that specific restoration and management plans will require examination by habitat. Floodplains, mangroves, seagrasses, saltmarshes, arctic wetlands, peatlands, freshwater marshes and forests are very diverse habitats, with different stressors and hence different management and restoration techniques are needed. The Sundarban (Bangladesh and India), Mekong river delta (Vietnam), and southern Ontario (Canada) are examples of major wetland complexes where the effects of climate change are evolving in different ways. Thus, successful long term restoration and management of these systems will hinge on how we choose to respond to the effects of climate change. How will we choose priorities for restoration and research? Will enough water be available to rehabilitate currently damaged, water-starved wetland ecosystems? This is a policy paper originally produced at the request of the Ramsar Convention on Wetlands and incorporates opinion, interpretation and scientific-based arguments. 相似文献
35.
Water levels were recorded weekly from six natural vernal pools and 10 created vernal pools at two forested wetland complexes
in central Ohio. Vernal pool median water depth and duration of inundation were significantly greater at the created vernal
pools than at the natural vernal pools (α = 0.05, P < 0.05). The average period of inundation for created pools was 309 ± 32 days, compared with 250 ± 16 days for natural pools.
The created pools produced a range of inundation times, from 163 to 365 days in length, with three pools permanently inundated. 相似文献
36.
Wetland mitigation and compensation: Canadian experience 总被引:3,自引:0,他引:3
Since Canada’s accession to the Ramsar Convention on Wetlands in 1981, the nation’s commitment to wetland conservation and
management has increased significantly. This includes the adoption of one of the World’s first national wetland conservation
policies by the Government of Canada, and the adoption of complementary policy and legislative initiatives by most of the
13 provincial and territorial jurisdictions. Numerous habitat ‘no net loss’ and environmental assessment policies, regulations
and guidelines for incorporating mitigation processes into development decisions affecting wetland resources are used throughout
Canada. The governments of Canada and six provinces have so far adopted wetland mitigation measures. These are in addition
to comprehensive wetland fish and wildlife habitat initiatives, such as the species and habitat joint ventures delivered in
Canada through the North American Waterfowl Management Plan by all jurisdictions and numerous non-government partners. This
paper examines the current policies, regulations and programs, as well as past implementation experience with wetland mitigation
and compensation in Canada. 相似文献
37.
John J. Mack 《Wetlands Ecology and Management》2009,17(2):117-130
Most plant-based indices of biotic integrity (IBIs) developed for wetlands have focused on emergent wetlands. A Vegetation
Index of Biotic Integrity (VIBI-Forest) was developed for forested wetlands in the four large ecoregions of the Ohio. Assessing
the effect of human disturbance on the ecological condition of wetland forests is complicated by several factors. First, forest
canopies can remain largely intact even after significant degradation of the herb and shrub stratum. Second, increases in
total diversity may not be good. In forested wetlands, a major artifact of disturbance is the addition of non-wetland or wetland
native or adventive plant species adapted to full sun conditions to their floras. Initial versions of the VIBI-Forest metrics
were very sensitive to disturbance-induced increases in diversity. Correcting this problem required modifying or replacing
metrics so that only forest dependent species were included in metric calculations. The final VIBI-Forest included metrics
which evaluated each forest stratum including the ground layer (% bryophyte), herb layer (shade or seed-less vascular plant
species), shrub layer (subcanopy importance value (IV), relative density of young trees), canopy (canopy IV), and composite
metrics for all vertical strata (Floristic Quality Assessment Index score, % hydrophytes, % sensitive, % tolerant). Assessing
wetland forest condition is further complicated by the fact that some successional communities after canopy death or destruction
(shrub swamp, marsh, wet meadow) may have intrinsic value as wetland community types. The solution is not to attempt to derive
a one-size-fits-all assessment method but to derive separate protocols for other successional phases that are of value or
interest. 相似文献
38.
Anne-Laure Brochet Michel Gauthier-Clerc Raphaël Mathevet Arnaud Béchet Jean-Yves Mondain-Monval Alain Tamisier 《Biodiversity and Conservation》2009,18(7):1879-1894
Many wild species, like waterbirds, are exploited for their economic interests. At present, the annual western Palearctic
duck bag is at least 17 million birds. From a sustainable management perspective, wetland users and managers request predictions
of spatial distribution and abundance variations of these bird populations. The objective of this study was to analyze local
factors potentially influencing the diurnal distribution and population size of wintering ducks and coots, the main game species,
in Camargue (southern France). First, we showed that marshland surface area, salinity and hunting disturbance were the principal
variables explaining the duck and coot distribution. Secondly, we tested the hypothesis that hunting disturbance would reduce
the carrying capacity of the Camargue with two analyses: the effect of creating a protected area and the change of the hunting
closing date. This hypothesis was not validated. Our study therefore led us to reconsider the research orientations on the
carrying capacity in this wetland. The surface of protected day roosts seems presently sufficient in the Rhone delta. Consequently,
to increase the population size with the same level of hunting disturbance at the scale of the Camargue, alternative strategies
should be envisaged, such as the creation of nature reserves on nocturnal feeding ground or the creation of large management
units with limited disturbance. 相似文献
39.
What confines an annual plant to two separate zones along coastal topographic gradients? 总被引:1,自引:0,他引:1
We investigated the roles of flooding, salinity, and plant competition in creating a bimodal zonation pattern of the marsh
dominant annual plant, Suaeda salsa, along coastal topographic gradients on the Pacific coast of northern China. In two consecutive years, we manipulated salinity
and flooding, salinity, and competition for S. salsa seedlings that had been transplanted into the mudflat, the high marsh, and the upland, respectively. S. salsa plants that had been transplanted into the mudflat were completely eliminated in the non-elevated treatments whereas they
performed much better in the 10 cm elevated treatments, regardless of salinity treatments. Although the performance of S. salsa transplanted into the high marsh did not differ between the fresh (watered) and the salt (control) treatments, S. salsa seedling emergence in the high marsh was nearly completely inhibited in the salt treatments. In contrast, a large number
of S. salsa seedlings did emerge in the fresh treatments. S. salsa transplanted into the upland performed well when neighbors were removed, whereas it appeared to be strongly suppressed when
neighbors were present. These data indicated that flooding, salinity, and competition all played a role in determining the
zonation pattern of S. salsa. Furthermore, the importance of salinity was found to vary with life-history stage. Based on the results from these field
manipulative experiments, we suggest that the marsh plant zonation paradigm may hold true for plant distributions along landscape-scale
topographic gradients from mudflats to uplands in general. The relative importance of flooding, salinity, and competition,
however, may vary at different elevations within a site and between sites.
Handling editor: Pierluigi Viaroli 相似文献
40.
Palaeoclimatic signals and anthropogenic disturbances from the peatbog at Nagybárkány (North Hungary) 总被引:1,自引:1,他引:0
Gusztáv Jakab Péter Majkut Imola Juhász Sándor Gulyás Pál Sümegi Tünde Törőcsik 《Hydrobiologia》2009,631(1):87-106
Investigation of a small peatbog in northern Hungary provides a late Quaternary record of vegetation development effected
by climatic changes and anthropogenic disturbances. The aim of this study was to separate climatic signals from the development
of a continental eutrophic peatland with the use of plant macrofossil analysis. The development of water catchment is reconstructed
using pollen and geochemical analyses. The formation of the lakebed can be traced back to the Late Glacial. A higher water
level with oligotrophic conditions can be existed from the Late Glacial to middle Holocene, when the reed beds covered a small
area only. This was followed by a hiatus spanning ca. 4400 years, caused by peat cutting during the Imperial Age. The water
level decreased and the water quality was more eutrophic. A reed bed evolved around the lake. Terrestrialization started with
a bulrush floating mat phase at the close of the árpádian Age, ca. cal yr AD 1400. The initiation of the Sphagnum-bog underwent similar phases as in the other Hungarian peatbogs. Although remarkable anthropogenic disturbances can be reconstructed
in the development of the peatbog, some climatic effects and authogenic processes might be separated by palaeoecological analyses.
Guest editors: K. Buczkó, J. Korponai, J. Padisák & S. W. Starratt
Palaeolimnological Proxies as Tools of Environmental Reconstruction in Fresh Water 相似文献