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71.
A Chinese praying mantis, Tenodera sinensis, was observed feeding on a living red-spotted newt, Notophthalmus viridescens. Specimens of that newt’s population are known to contain high concentrations of tetrodotoxin (TTX), a specific blocker of voltage-gated sodium channels. After experimental oral administration of a TTX-solution (1 mg/ml) to adult specimens of four mantis species, all survived high TTX concentrations (up to 30.8 μg/g body mass) as revealed by analysis of their body extracts, but they are rapidly killed by intra-abdominal injection of 1 μg TTX. The toxin was found to be gradually excreted with faeces. As demonstrated by monoclonal antibody-based immunohistochemical technique, TTX does not penetrate the mid-gut membrane, since it was localized only in the gut lumen, but not in the epithelial cells. This prevents the toxin to reach its target, the sodium channels of the insect’s nervous system, and enables the mantids to feed on toxic prey without risking poisoning. 相似文献
72.
Marcellus M. Caldas Jason S. Bergtold Jeffrey M. Peterson Dietrich H. Earnhart 《Journal of Land Use Science》2016,11(5):579-594
Among the important alternatives for land conservation is the US Conservation Reserve Program (CRP) that celebrated its 30th anniversary in 2015. This paper explores how landowners decide on alternative land-use choices made available by the expiration of CRP contracts in Kansas. The study uses survey data and multinomial Logit models to predict land-use choices. Two models were tested. The first model does not incorporate variables concerning farmer perceptions and attitudes about land-use choices, while the second model does. The results show that CRP re-enrollment depends on factors, such as years of experience in cropping and percent of cropland irrigated. However, when perception variables are added, the models become more robust in explaining other land choice alternatives. The results suggest that as the perception of unfairness of more inflexible environmental policy rises, these farmers may be more likely to re-enroll their marginal land in the CRP program. 相似文献
73.
Edward F. Melvin Kimberly S. Dietrich Robert M. Suryan Shannon M. Fitzgerald 《Conservation biology》2019,33(4):842-852
Although bycatch of seabirds and other long-lived species is a critical conservation issue in world fisheries, case studies documenting significant reductions in the mortality of these low-productivity species in a fishery are rare. We studied progress toward seabird conservation in the Alaskan longline fisheries, one of the largest and most diverse demersal fisheries. We generated annual seabird bycatch rates in 4 target fisheries and all fisheries combined from 23 years of fisheries observer data. We used 0-inflated negative binomial models to evaluate variables influencing seabird bycatch per unit effort (BPUE) in 2 target fisheries. Following adoption of streamer lines, at first voluntarily and then mandatorily, seabird BPUE was reduced by 77–90%, preventing mortality of thousands of birds per year. Despite this, BPUE increased significantly in 2 of 4 target fisheries since streamer lines were adopted. Although night setting yielded significant reductions (74–97%) in seabird BPUE and significant increases (7–11%) in fish catch per unit effort over daytime setting, nighttime setting increased the BPUE of Northern Fulmar (Fulmarus glacialis) by 40% and nontarget fish species by 5–17%. Thus, best practices to prevent seabird mortalities in longline fisheries varied by species assemblage and fishery. Our results inform global efforts toward fisheries bycatch reduction by illustrating that successful conservation requires fishery-specific solutions, strong industry support, constant vigilance in analysis and reporting observer data, and ongoing outreach to fleets, especially to vessels with anomalously high BPUE. 相似文献
74.
With special filter materials it is possible to eliminate the heavy metals lead, copper and nickel and arsenic from water by sorption resp. chemical bounding. After a reaction time of 24 hours the reduction rates were between 97% and >99,9%. 相似文献
75.
It has been confirmed that the NOx-concentration in air is highest over industrial areas and that it decreases by more than 75%, parallel to traffic density, over urban areas as related to forested areas. A significant correlation excists between NO2-concentration and the parameters of “traffic density,” followed by “road density” and “number of inhabitants/km2” in urban areas. No positive correlation was found with the number of “registered cars” and the parameters of “land use”. In forested areas, the traffic density correlated with the NO2-concentration, but the correlation was not significant. The other parameters had no positive correlation with NO2-concentration. In forest, urban- and industrial-areas, the NOx-concentration in the air had a fairly constant ratio to traffic density. 相似文献
76.
Manuela Baumgarten Christian Huber Patrick Büker Hans-Peter Dietrich Christian Heerdt Rainer Matyssek 《Environmental pollution (Barking, Essex : 1987)》2009,157(7):2091-2107
Exposure and flux-based indices of O3 risk were compared, at 19 forest locations across Bavaria in southern Germany from 2002 to 2005; leaf symptoms on mature beech trees found at these locations were also examined for O3 injury. O3 flux modelling was performed using continuously recorded O3 concentrations in combination with meteorological and soil moisture data collected from Level II forest sites. O3 measurements at nearby rural open-field sites proved appropriate as surrogates in cases where O3 data were lacking at forest sites (with altitude-dependent average differences of about 10% between O3 concentrations). Operational thresholds of biomass loss for both O3 indices were exceeded at the majority of the forest locations, suggesting similar risk under long-term average climate conditions. However, exposure-based indices estimated higher O3 risk during dry years as compared to the flux-based approach. In comparison, minor O3-like leaf injury symptoms were detected only at a few of the forest sites investigated. Relationships between flux-based risk thresholds and tree response need to be established for mature forest stands for validation of predicted growth reductions under the prevailing O3 regimes. 相似文献
77.
78.
79.
Dietrich Neumann 《Die Naturwissenschaften》1995,82(7):310-320
Physiological clocks have been selected in various eukaryotic organisms in relation to daily, tidal, lunar and annual cycles of the environment. Insect species are appropriate experimental objects for the analysis of biological timing mechanisms and their evolutionary adaptation to the local environment. The most complex periodic environment occurs in the interface between the land and the sea, i.e., in the range of spring and neap tides. By the combination of ’circadian‘ and ’circalunar‘ clocks and their reliably perceptible ’zeitgeber‘ conditions, a few marine insects can temporally program their development to distinct tidal situations that occur only on distinct lunar days and at a distinct time of day every 14–15 days. 相似文献
80.
Dietrich Burkhardt 《Die Naturwissenschaften》1982,69(4):153-157
The problem of UV vision in vertebrates is briefly discussed in its historical context. For example, UV vision has been demonstrated in some birds by several authors. Hence the reflectances of plumage, petals of bird-pollinated flowers and of berries in the near UV may play an important rôle within the visual environment of birds. Some data obtained by means of UV photography are presented, and it is shown, that the waxlayer of glaucous fruits is highly reflective in the UV. 相似文献