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701.
Tracking habitat and resource use for the jumbo squid Dosidicus gigas: a stable isotope analysis in the Northern Humboldt Current System 总被引:1,自引:0,他引:1
Juan Argüelles Anne Lorrain Yves Cherel Michelle Graco Ricardo Tafur Ana Alegre Pepe Espinoza Anatolio Taipe Patricia Ayón Arnaud Bertrand 《Marine Biology》2012,159(9):2105-2116
To determine the habitat and resource use of Dosidicus gigas in the Northern Humboldt Current System, we analysed carbon and nitrogen stable isotopes of 234 individuals collected during 2008–2010. Large variations in mantle stable isotope ratios were recorded, with values ranging from −19.1 to −15.1 ‰ (δ13C) and from 7.4 to 20.5 ‰ (δ15N). Most of the variation was explained by latitude, followed by distance to shelf break for carbon and by squid size for nitrogen. Latitudinal variations with increasing values from north to south were also found in zooplankton samples and were related to changes in isotope baseline values probably due to oxygen minimum zones that occur off Peru. This similar latitudinal trend in both zooplankton and D. gigas samples reveals that D. gigas is a relatively resident species at the scale of its isotopic turnover rate (i.e. a few weeks), even if this is not necessarily the case at the scale of its life. A small but significant size effect on δ13C values suggests that jumbo squid perform offshore–onshore ontogenic migration, with juveniles distributed offshore. For nitrogen, the high inter-individual variability observed with mantle length indicates that D. gigas can prey on a high variety of resources at any stage of their life cycle. This large-scale study off the coast of Peru provides further evidence that D. gigas have the capability to explore a wide range of habitats and resources at any stage of their life. 相似文献
702.
Hudson Wallace Pereira Carvalho Ana P. L. Batista Peter Hammer Gustavo H. P. Luz Teodorico C. Ramalho 《Environmental Chemistry Letters》2010,8(4):343-348
Polysaccharide natural seed coat from the tree Magonia pubescens, in the form of hydrogel was used to remove metals in aqueous solution. Swelling tests indicate that seed coat presents hydrogel
behavior, with maximum water absorption of 292 g water/g. Adsorption experiments performed using Na+, Mg2+, K+, Ca2+, Cr3+, Fe3+ and Zn2+ demonstrated that the polysaccharide structure has a high capacity to extract these ions from the aqueous solution. Scanning
electron microscopy revealed significant morphological changes of the material before and after water contact. Differential
scanning calorimetry measurements indicate a signal shift of the water evaporation temperature in the material with adsorbed
zinc. X-ray photoelectron spectroscopy analysis combined with theoretical studies by the density functional theory and on
Hartree–Fock (HF) level evidence that the metallic ions were adsorbed through coordination with hydroxyl groups of polysaccharide.
In the case of Zn2+ the lowest HF energy was observed for the tetracoordination mode, where Zn2+ is coordinated by two hydroxyl groups and two water molecules. 相似文献
703.
The growth pattern of Loxechinus albus in southern Chile was studied using size-at-age data obtained by reading growth bands on the genital plates. The scatter
plots of sizes-at-age for samples collected in three different locations indicated that growth is linear between ages 2 and
10. Five different growth models, including linear, asymptotic and non-asymptotic functions, were fitted to the data, and
model selection was conducted based on the Akaike information criteria (AIC) and the Bayesian information criteria (BIC).
The AIC identified the Tanaka model as the most suitable for two of the three sites. However, the BIC led to the selection
of the linear model for all zones. Our results show that the growth pattern of L. albus is different from the predominantly asymptotic pattern that has been reported for other sea urchin species. 相似文献
704.
With the discovery of previously unreported populations of hemoglobin-possessing Ophiactis from the Texas coast in the Gulf of Mexico, an investigation into its population structure, including populations of O. simplex from the Pacific coast of California and O. rubropoda from the Atlantic coast of Florida, was undertaken using DNA sequence data from the mitochondrial COI gene. The reconstructed
haplotype network suggests that California populations contain the ancestral source of mtDNA variation, and there is no evidence
of recent introductions into Texas. Population genetic analyses reveal the California, Florida, and Texas Ophiactis populations to each be significantly differentiated from one another. Sequence divergence among the three areas is shallower
than would be predicted given biogeographic history. Texas and Florida populations are equally genetically diverged from California
populations as they are to one another, despite the greater potential for gene flow between these areas. The genetic distinctiveness
of the Texas populations and the concordance of this pattern with phylogeographic patterns in other brittle star systems indicate
an isolated and independent evolutionary history and we hypothesize that the three geographic regions included in this study
each serve as hypotheses of population-level lineages that remain to be tested with independent sources of data. 相似文献
705.
Management practices as antecedents of safety culture within the trucking industry: similarities and differences by hierarchical level 总被引:1,自引:0,他引:1
PROBLEM: A homogeneous perception of safety is important for the achievement of a strong safety culture; however, employees may differ in their safety perceptions, depending on their position and/or hierarchical level within the organization. Moreover, there is limited information on the antecedents of safety culture. This study examines how safety training, driver scheduling autonomy, opportunity for safety input, and management commitment to safety influence individuals' perceptions of safety culture. METHOD: Data for this study were drawn from 116 trucking firms, stratified by three safety performance levels. The data were collected from drivers (lowest hierarchical level), dispatchers (medium hierarchical level), and safety directors (highest hierarchical level), regarding their perceptions of their respective corporate safety cultures. Perceptions of safety culture were analyzed through a linear regression using dummy variables to differentiate among the three hierarchical groups. The resulting model allowed for examination of the specific antecedents of safety culture for the three employee groups and the extent to which the hierarchical groups were in agreement with each other. RESULTS: Driver fatigue training, driver opportunity for safety input, and top management commitment to safety were perceived to be integral determinants of safety culture in all three groups. IMPACT ON INDUSTRY: Trucking firms seeking to strengthen employees' perceptions of safety culture might begin by improving these safety management practices while appreciating that they may have a different impact depending on the employee's hierarchical position (e.g., drivers' perceptions of safety culture are more influenced by top management commitment and driver fatigue training). A fourth safety practice examined, driver scheduling autonomy, was not found to be instrumental in shaping safety culture for any of the three hierarchical levels. Consistent with previous research, implementation of stronger safety cultures should result in fewer accidents. 相似文献
706.
707.
Water quality levels and loads of nutrients transported by the Agüera stream (northern Spain) were studied for a year to assess
the self-purification capacity of this system. The main villages produce an increase of nutrient concentrations and a degradation
of water quality. Nevertheless, the high retention capacity, especially for phosphate, allows the stream to recover its previous
levels of quality after a short reach. The retention of nutrients depends on a complex combination of the flow level, hydrologic
stability and the development of periphytic communities. 相似文献
708.
Sabine Perch-Nielsen Ana Sesartic Matthias Stucki 《Environmental Science & Policy》2010,13(2):131-140
Greenhouse gas intensity is a ratio comparing the greenhouse gas (GHG) emissions of an activity or economic sector to the economic value it generates. In recent years, many countries have calculated the GHG intensity of their economic sectors as a basis for policy making. The GHG intensity of tourism, however, has not been determined since tourism is not measured as an economic sector in the national accounts. While for tourism-reliant countries it would be useful to know this quantity, a number of difficulties exist in its determination. In this study, we determine the GHG intensity of tourism's value added in Switzerland by means of a detailed bottom-up approach with the main methodological focus on how to achieve consistent system boundaries. For comparison, we calculate the tourism sector's GHG intensity for selected European countries using a simpler top-down approach. Our results show that the Swiss tourism sector is more than four times more GHG intensive than the Swiss economy on average. Of all tourism's sub-sectors, air transport stands out as the sector with by far largest emissions (80%) and highest GHG intensity. The results for other countries make similar, if not as pronounced, patterns apparent. We discuss the results and possible mitigation options against the background of the goal to prevent dangerous climate change. 相似文献
709.
Investigation at the scene of a crime begins with the search for clues. In the case of bloodstains, the most frequently used
reagents are luminol and reduced phenolphthalein (or phenolphthalin that is also known as the Kastle–Meyer colour test). The
limitations of these reagents have been studied and are well known. Household cleaning products have evolved with the times,
and new products with active oxygen are currently widely used, as they are considered to be highly efficient at removing all
kinds of stains on a wide range of surfaces. In this study, we investigated the possible effects of these new cleaning products
on latent bloodstains that may be left at a scene of a crime. To do so, various fabrics were stained with blood and then washed
using cleaning agents containing active oxygen. The results of reduced phenolphthalein, luminol and human haemoglobin tests
on the washed fabrics were negative. The conclusion is that these new products alter blood to such an extent that it can no
longer be detected by currently accepted methods employed in criminal investigations. This inability to locate bloodstains
means that highly important evidence (e.g. a DNA profile) may be lost. Consequently, it is important that investigators are
aware of this problem so as to compensate for it.
相似文献
Fernando Verdú (Corresponding author)Email: |
710.
Sofía Copello Ana I. Dogliotti Domingo A. Gagliardini Flavio Quintana 《Marine Biology》2011,158(6):1247-1257
The study of how and why marine animals distribute themselves at sea has important conservation and management implications
of the species and their habitats. We characterize the oceanographic and biological landscapes of the marine areas used by
breeding Southern Giant Petrels (Macronectes giganteus) at Patagonian colonies and explore inter-sexual and inter-colony differences. The at-sea movements of 16 adults (7 males
and 9 females) were studied by means of satellite telemetry techniques during 1999, 2000, 2002, and 2004 breeding seasons.
Southern Giant Petrels utilized an oceanographic scenario characterized by high productivity, warm sea surface temperature,
and shallow waters. The biological landscape was characterized by a high availability of squid and carrion nearby colonies.
Females spent more time in the shelf break and exploited deeper waters than males. In contrast, males spent more time in coastal
areas and they showed a higher spatial overlap with areas of high squid density than females. Such a prosperous foraging scenario
for both sexes may play a key role in the growth of the breeding population of Southern Giant Petrel Patagonian colonies. 相似文献