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61.
Hubert J. Morel-Seytoux 《Journal of the American Water Resources Association》1981,17(6):1012-1022
ABSTRACT: The purpose of this paper is to show through the use of numerical examples that modern infiltration theory can be used in everyday hydrologic practice. The actual use of four methods of calculation of infiltration rates and of excess rainfall rates is demonstrated for the case when simultaneous data of rainfall and stream flow are available for a watershed. The four methods are: (1) the well known Π-index method, (2) the traditional Horton's infiltration capacity formula, (3) the less traditional Green and Ampt infiltration capacity formula, and (4) a ponding time approach. It is recommended that hydrologists become at least familiar with the numerical procedures involved in the ponding time and postponding infiltration approach. This approach, though not flawless, should be preferred to the other three methods if use of the other three is at all considered. 相似文献
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Werner Brack Rolf Altenburger Falk Dorusch Andreas Hubert Monika Möder Peter Morgenstern Susanne Moschütz Sibylle Mothes Kristin Schirmer Rainer Wennrich Klaus -Dieter Wenzel Gerrit Schüürmann 《Environmental Sciences Europe》2002,14(4):213-220
In August 2002, highly contaminated areas in the region of Bitterfeld, e.g. the floodplain of the creek Spittelwasser, as well as the adjacent regions of Jeßnitz and Raguhn, were submerged by the river Mulde. An input of mobilized contaminated sediments in residential areas was the matter of concern. The objective of the present study was to estimate the pollutants load on the basis of chemical and biological data and identify the sources of pollutants. Deposited sludge and flood water samples were assessed on the basis of biological and chemical analyses and in comparison with administrative reference values. The pollution of the investigated sites was rather heterogeneous. At several sites, tolerance limits of the German Klärschlammverordnung or the Bundesbodenschutzverordnung were clearly exceeded, e.g. for Pb, As and HCH. Organic extracts exhibited significant effects in several biotests. This may be relevant with respect to direct particle uptake via ingestion or respiration. Pollution patterns for heavy metals as well as for organic pollutants differed significantly from the pattern found in the Spittelwasser flood plain before the inundation, which is in contrast to the initial hypothesis of a possible transport of contaminated Spittelwasser sediments into residential areas. Interestingly, a correlation of chemical load and the overall biological effect could be shown. From the viewpoint of the precautionary principle, the identification of the compounds exerting toxic effects and of the respective pollutant sources would be desirable. 相似文献
65.
Rosemary?StrasserEmail author Hubert?Schwabl 《Behavioral ecology and sociobiology》2004,56(5):491-497
Vertebrate eggs contain maternal steroid hormones in their yolks; and in avian species the concentration of these steroids vary within and among clutches. The organizational actions of these variable doses of maternal steroids in the avian egg, analogous to those regulating the development of sexually dimorphic traits, are little explored. In this study, we examined the organizational effects of yolk testosterone in the house sparrow,
Passer domesticus, a sexually dichromatic passerine bird in which males are characterized by the presence of a throat patch or badge of black feathers that varies in size among males. We injected a physiological dose of testosterone or vehicle into eggs in the field, removed nestlings, and hand-raised them in the laboratory. At 5 months of age, we investigated treatment effects on plumage and behavior. Males that hatched from testosterone-injected eggs developed a larger badge than males that hatched from vehicle-injected (control) eggs. However, testosterone did not induce the expression of a badge in females. In staged dyadic encounters, both males and females hatched from testosterone-injected eggs were more successful at obtaining and defending a food source than individuals of the same sex hatched from control eggs. The results suggest that variable concentrations of maternal testosterone in the eggs of the house sparrow organize the expression of a plumage trait in males and behavior in both sexes.Communicated by J. Graves 相似文献
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67.
A positive surge results from a sudden change in flow that increases the depth. It is the unsteady flow analogy of the stationary
hydraulic jump and a geophysical application is the tidal bore. Positive surges are commonly studied using the method of characteristics
and the Saint-Venant equations. The article presents the results from new experimental investigations conducted in a large
rectangular channel. Detailed unsteady velocity measurements were performed with a high temporal resolution using acoustic
Doppler velocimetry and non-intrusive free-surface measurement devices. Several experiments were conducted with the same initial
discharge (Q = 0.060 m3/s) and six different gate openings after closure resulting in both non-breaking undular and breaking bores. The analysis
of undular surges revealed wave amplitude attenuation with increasing distance of surge propagation were in agreement with
Ippen and Kulin theory. Also, undular wave period and wave length data were relatively close to the values predicted by the
wave dispersion theory for gravity waves in intermediate water depths. 相似文献
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69.
Current knowledge in tidal bores and their environmental,ecological and cultural impacts 总被引:3,自引:3,他引:0
Hubert Chanson 《Environmental Fluid Mechanics》2011,11(1):77-98
A tidal bore is a series of waves propagating upstream as the tidal flow turns to rising. It forms during the spring tide
conditions when the tidal range exceeds 5–6 m and the flood tide is confined to a narrow funnelled estuary with low freshwater
levels. A tidal bore is associated with a massive mixing of the estuarine waters that stirs the organic matter and creates
some rich fishing grounds. Its occurrence is essential to many ecological processes and the survival of unique eco-systems.
The tidal bore is also an integral part of the cultural heritage in many regions: the Qiantang River bore in China, the Severn
River bore in UK, the Dordogne River in France. In this contribution, the environmental, ecological and cultural impacts of
tidal bores are reviewed, explained and discussed. 相似文献
70.
Hubert Chanson 《Environmental Fluid Mechanics》2011,11(4):385-404
A tidal bore may occur in a macro-tidal estuary when the tidal range exceeds 4.5–6 m and the estuary bathymetry amplifies
the tidal wave. Its upstream propagation induces a strong mixing of the estuarine waters. The propagation of undular tidal
bores was investigated herein to study the effect of bridge piers on the bore propagation and characteristics. Both the tidal
bore profile and the turbulence generated by the bore were recorded. The free-surface undulation profiles exhibited a quasi-periodic
shape, and the potential energy of the undulations represented up to 30% of the potential energy of the tidal bore. The presence
of the channel constriction had a major impact on the free-surface properties. The undular tidal bore lost nearly one third
of its potential energy per surface area as it propagated through the channel constriction. The detailed instantaneous velocity
measurements showed a marked effect of the tidal bore passage suggesting the upstream advection of energetic events and vorticity
“clouds” behind the bore front in both channel configurations: prismatic and with constriction. The turbulence patches were
linked to some secondary motions and the proposed mechanisms were consistent with some field observations in the Daly River
tidal bore. The findings emphasise the strong mixing induced by the tidal bore processes, and the impact of bridge structures
on the phenomenon. 相似文献