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381.
Population structure of humpback whales in the western and central South Pacific Ocean as determined by vocal exchange among populations
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Ellen C. Garland Anne W. Goldizen Matthew S. Lilley Melinda L. Rekdahl Claire Garrigue Rochelle Constantine Nan Daeschler Hauser M. Michael Poole Jooke Robbins Michael J. Noad 《Conservation biology》2015,29(4):1198-1207
For cetaceans, population structure is traditionally determined by molecular genetics or photographically identified individuals. Acoustic data, however, has provided information on movement and population structure with less effort and cost than traditional methods in an array of taxa. Male humpback whales (Megaptera novaeangliae) produce a continually evolving vocal sexual display, or song, that is similar among all males in a population. The rapid cultural transmission (the transfer of information or behavior between conspecifics through social learning) of different versions of this display between distinct but interconnected populations in the western and central South Pacific region presents a unique way to investigate population structure based on the movement dynamics of a song (acoustic) display. Using 11 years of data, we investigated an acoustically based population structure for the region by comparing stereotyped song sequences among populations and years. We used the Levenshtein distance technique to group previously defined populations into (vocally based) clusters based on the overall similarity of their song display in space and time. We identified the following distinct vocal clusters: western cluster, 1 population off eastern Australia; central cluster, populations around New Caledonia, Tonga, and American Samoa; and eastern region, either a single cluster or 2 clusters, one around the Cook Islands and the other off French Polynesia. These results are consistent with the hypothesis that each breeding aggregation represents a distinct population (each occupied a single, terminal node) in a metapopulation, similar to the current understanding of population structure based on genetic and photo‐identification studies. However, the central vocal cluster had higher levels of song‐sharing among populations than the other clusters, indicating that levels of vocal connectivity varied within the region. Our results demonstrate the utility and value of using culturally transmitted vocal patterns as a way of defining connectivity to infer population structure. We suggest vocal patterns be incorporated by the International Whaling Commission in conjunction with traditional methods in the assessment of structure. 相似文献
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384.
The quahog Mercenaria mercenaria has been introduced repeatedly to the Pacific coast of North America, but only one population is known to have become established.
In the 1970s, the population of M. mercenaria at Colorado Lagoon, in Los Angeles County, California (33o46′16″N, 118o08′05″W), was estimated at more than 300,000 individuals. To determine the current status of this non-indigenous species (NIS),
in 2009, we sampled 57 intertidal and 20 shallow subtidal plots, identifying and quantifying collected bivalves. No quahogs
were found among the 2,490 living bivalves in our plots, though two were found intertidally outside of our plots. The M. mercenaria population has thus collapsed since 1980, but the native community has not recovered. Six of the fourteen living bivalve
species we encountered were NIS; three are new records for the location, including the clam Venerupis philippinarum, which made up 87.6% of collected individuals. Though M. mercenaria is likely on its way to extinction on the US Pacific coast, the bivalve assemblage at this location remains heavily dominated
by NIS. 相似文献
385.
Su Y Hung H Stern G Sverko E Lao R Barresi E Rosenberg B Fellin P Li H Xiao H 《Journal of environmental monitoring : JEM》2011,13(11):3111-3118
Initiated in 1992, air monitoring of organic pollutants in the Canadian Arctic provided spatial and temporal trends in support of Canada's participation in the Stockholm Convention of Persistent Organic Pollutants. The specific analytical laboratory charged with this task was changed in 2002 while field sampling protocols remained unchanged. Three rounds of intensive comparison studies were conducted in 2004, 2005, and 2008 to assess data comparability between the two laboratories. Analysis was compared for organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in standards, blind samples of mixed standards and extracts of real air samples. Good measurement accuracy was achieved for both laboratories when standards were analyzed. Variation of measurement accuracy over time was found for some OCPs and PCBs in standards on a random and non-systematic manner. Relatively low accuracy in analyzing blind samples was likely related to the process of sample purification. Inter-laboratory measurement differences for standards (<30%) and samples (<70%) were generally less than or comparable to those reported in a previous inter-laboratory study with 21 participating laboratories. Regression analysis showed inconsistent data comparability between the two laboratories during the initial stages of the study. These inter-laboratory differences can complicate abilities to discern long-term trends of pollutants in a given sampling site. It is advisable to maintain long-term measurements with minimal changes in sample analysis. 相似文献
386.
Exposed limestone cliffs in central Europe harbor a highly divers flora with many rare and endangered species. During the
past few decades, there has been increasing recreational use of these cliffs, which has caused local environmental disturbances.
Successful restoration strategies hinge on identifying critical limitations. We examined the composition of aboveground forest
vegetation and density and species composition of seeds in the soil seed bank at the base of four limestone cliffs in mixed
deciduous forests that are intensively disturbed by human trampling and at four undisturbed cliffs in the Jura Mountains in
northwestern Switzerland. We found that long-term human trampling reduced total aboveground vegetation cover at the base of
cliffs and caused a significant shift in the plant-species composition. Compared with undisturbed cliffs, total seed density
was lower in disturbed cliffs. Human trampling also altered the species composition of seeds in the soil seed bank. Seeds
of unintentionally introduced, stress-tolerant, and ruderal species dominated the soil seed bank at the base of disturbed
cliffs. Our findings indicate that a restoration of degraded cliff bases from the existing soil seed bank would result in
a substantial change of the original unique plant composition. Active seed transfer, or seed flux from adjacent undisturbed
forest areas, is essential for restoration success. 相似文献
387.
Regular, self-organized spatial patterns in primary producers have been described in a wide range of ecosystems and are predicted to affect community production and resilience. Although consumers are abundant in most systems, the effect of trophic interactions on pattern formation in primary producers remains unstudied. We studied the effects of top-down control by herbivores on a self-organized landscape of regularly spaced, diatom-covered hummocks alternating with water-filled hollows on an intertidal mudflat in The Netherlands. Spatial patterns developed during spring but were followed by a rapid collapse in summer, leading to a flat landscape with low diatom densities and little variation in sediment bed level. This dramatic decline co-occurred with a gradual increase of benthic herbivores. A manipulative field experiment, where benthic herbivores were removed from the sediment, revealed that both diatom growth and hummock formation were inhibited by the activity of benthic herbivores. Our study provides clear evidence of top-down control of spatial self-organized patterns by benthic herbivores within a biological-geomorphic landscape. 相似文献
388.
Nestmate recognition in social insects: overcoming physiological constraints with collective decision making 总被引:1,自引:1,他引:0
Social insects rank among the most abundant and influential terrestrial organisms. The key to their success is their ability
to form tightly knit social groups that perform work cooperatively, and effectively exclude non-members from the colony. An
extensive body of research, both empirical and theoretical, has explored how optimal acceptance thresholds could evolve in
individuals, driven by the twin costs of inappropriately rejecting true nestmates and erroneously accepting individuals from
foreign colonies. Here, in contrast, we use agent-based modeling to show that strong nestmate recognition by individuals is
often unnecessary. Instead, highly effective nestmate recognition can arise as a colony-level property from a collective of
individually poor recognizers. Essentially, although an intruder can get by one defender when their odor cues are similar,
it is nearly impossible to get past many defenders if there is the slightest difference in cues. The results of our models
match observed rejection rates in studies of ants, wasps, and bees. We also show that previous research in support of the
optimal threshold theory approach to the problem of nestmate recognition can be alternatively viewed as evidence in favor
of the collective formation of a selectively permeable barrier that allows in nestmates (at a significant cost) while rejecting
non-nestmates. Finally, this work shows that nestmate recognition has a stronger task allocation component than previously
thought, as colonies can nearly always achieve perfect nestmate recognition if it is cost effective for them to do so at the
colony level. 相似文献
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390.
Ellen Hollands Steffensen Anne Skakkebæk Kasper Gadsbøll Olav Bjørn Petersen Thomas Westover Heather Strange The NIPT-SCA-map Study Group Ida Vogel 《黑龙江环境通报》2023,43(2):144-155