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91.
König HJ Sghaier M Schuler J Abdeladhim M Helming K Tonneau JP Ounalli N Imbernon J Morris J Wiggering H 《Environmental management》2012,50(1):153-165
Environmental threats and progressive degradation of natural resources are considered critical impediments to sustainable development. This paper reports on a participatory impact assessment of alternative soil and water conservation (SWC) scenarios in the Oum Zessar watershed, Tunisia. The first objective was to assess the impact of three SWC scenarios on key social, economic and environmental land use functions. The second objective was to test and evaluate the applicability of the 'Framework for Participatory Impact Assessment (FoPIA)' for assessing scenario impacts in the context of a developing country, in this case Tunisia. The assessed scenarios included: the originally planned SWC policy implementation at 85 % coverage of arable land of the watershed, the current implementation (70 %), and a hypothetical expansion of SWC measures to the entire watershed (100 %). Our results suggest that implementation of the SWC policy at 100 % coverage of arable land achieves the maximum socioeconomic benefit. However, if stakeholders' preferences regarding land use functions are taken into account, and considering the fact that the implementation of SWC measures also implies some negative changes to traditional landscapes and the natural system, SWC implementation at 85 % coverage of arable land might be preferable. The FoPIA approved to be a useful tool for conducting a holistic sustainability impact assessment of SWC scenarios and for studying the most intriguing sustainability problems while providing possible recommendations towards sustainable development. We conclude that participatory impact assessment contributes to an enhanced regional understanding of key linkages between policy effects and sustainable development, which provides the foundation for improved policy decision making. 相似文献
92.
This project was designed to establish baseline aquatic biological community structure and physical habitat conditions in select wadeable streams within the California Central Valley. A secondary objective was to evaluate possible water quality differences between site types and seasons. Two agricultural and two urban streams were monitored in spring and fall for two consecutive years beginning in the fall of 2002. Bioassessment sampling was conducted according to modified US EPA methods. The study included physical habitat assessment, water and sediment chemical analysis and characterization of the benthic macroinvertebrate community at each site. Water samples were analyzed for selected organophosphate insecticides, pyrethroid insecticides and herbicides, while sediment samples were analyzed for pyrethroids only. All sites had substantial physical habitat and water quality impairments, and the absence of pollution intolerant macroinvertebrates and dominance of pollution tolerant macroinvertebrates were indications of biological impairment. Due to the limited amount of water quality and pesticide data collected, it was not possible to definitively demonstrate any cause and effect relationships between BMI community structure and water quality or pesticide concentrations. Though most physical habitat parameters were similar and EPA physical habitat scores revealed on no significant differences between urban and agricultural sites (P? = ?0.290), a significant difference was seen in substrate embeddedness (P? = ?0.020). Dominant taxon found at all sites were chironomids, amphipods, and oligochaetes. Benthic macroinvertebrate metrics were significantly different between both types of sites (P? = ?0.001) and seasons (P? = ?0.014). Chironomidae taxon and those of the functional feeding group scrapers were greater at urban sites, while those of the functional feeding group filterers were greater at agricultural sites. In addition, the metric groups Chironomidae, filterers, and predators were found in greater numbers in the spring than the fall. 相似文献
93.
Environmental Fluid Mechanics - The water waves resulting from the collapse of a dam are important unsteady free surface flows in civil and environmental engineering. Considering the basic case of... 相似文献
94.
A positive surge is a unsteady open channel flow resulting from the rapid rise of the free-surface. The phenomenon may be
observed in water supply canals and channels as well as in some estuaries during spring tidal conditions. The formation and
development of positive surges can be predicted using the method of characteristics and shallow water equations. The paper
is the second part of a study presenting 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. A comparison
between main features of the undular surges with literature theories demonstrated that the experimental data were mostly in
agreement with Andersen’s theory. The analysis of unsteady flow field including Reynolds stresses confirmed and extended previous
findings about positive surge hydrodynamics. 相似文献
95.
96.
Katarzyna Wojczulanis-Jakubas Dariusz Jakubas Julien Foucher Joanna Dziarska-Pałac Hubert Dugué 《Die Naturwissenschaften》2013,100(11):1095-1098
Relatively little attention has been paid to sex differences in the migration of birds in autumn. We studied the autumn migration strategy of molecularly sexed males and females in the globally threatened aquatic warbler Acrocephalus paludicola. We captured 176 birds at a stopover site in the Loire estuary at Donges, France. The median date for the passage of adults was 8 days earlier in males than females, although the timing of migration in first-year males and females was similar. This indicates that males, who are without parental duties, can start their migration earlier than females and first-year birds. Adults were significantly heavier than immature birds but did not have higher fat scores. In both age categories, more males (two to three times more) were captured. However, various factors (including tape-luring) can affect observed sex ratio. 相似文献
97.
98.
Turbulence and turbulent flux events in a small estuary 总被引:2,自引:0,他引:2
Relatively little systematic research has been conducted on the turbulence characteristics of small estuaries. In the present
study, detailed measurements were conducted in a small subtropical estuary with a focus on turbulent flux events. Acoustic
Doppler velocimeters were installed in the mid-estuary at fixed locations and sampled simultaneously and continuously for
50 h. A turbulent flux event analysis was performed for the entire data sets extending the technique of Narasimha et al. (Phil
Trans R Soc Ser A 365:841–858, 2007) to the unsteady open channel flow motion and to turbulent sub-events. Turbulent bursting
events were defined in terms of the instantaneous turbulent flux. The data showed close results for all ADV units. The very-large
majority of turbulent events lasted between 0.04 and 0.3 s with an average of 1 to 4 turbulent events observed per second.
A number of turbulent bursting events consisted of consecutive turbulent sub-events, with between 1 and 3 sub-events per main
event on average. For all ADV systems, the number of events, event duration and event amplitude showed some tidal trends,
with basic differences between high- and low-water periods. A comparison between the present estuary data and the atmospheric
boundary layer results of Narasimha et al. (Phil Trans R Soc Ser A 365:841–858, 2007) showed a number of similarities and
demonstrated the significance of turbulent events in environmental flows. A burstiness index of 0.85 was found for the present
data. 相似文献
99.
Hubert Trzaska 《The Environmentalist》2005,25(2-4):181-185
Summary The paper discusses several aspects of the practical application of the SAR. It is shown that the unit is an ideal solution
for basic research and laboratory experiments. SAR is directly nonmeasurable unit. Although methods and devices based upon
indirect SAR measurements may widen our knowledge about EM energy distribution and absorption within a body. It is shown that
for practical applications the temperature SAR measurement methods are not sensitive enough while methods based upon E(H) measurement are less accurate than traditional approaches. As a result of assumption SAR = 4 W/kg as a basic restriction
the present protection standards are illogical and nonrealiazable. A return to traditional units (E, H, S) in the standards
and surveying metrology is suggested. 相似文献
100.