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261.
Tests were conducted using 53-L dynamic chambers to determine airborne styrene emission rates over time from freshly copied paper. Copies were produced on a single photocopier using two toners manufactured for this copier but having different styrene contents. The resulting emission models were used to predict whether indoor styrene concentrations resulting from copied paper in a typical office might be significantly reduced by use of a low-emitting toner for a given copier. The styrene emissions were best represented by either a 3rd-order decay model or by a power law model having an exponent between 0.3 and 0.5 (R2 = 0.94-0.99). The two toners resulted in copied paper having significantly different styrene emissions (p < 0.01), with unit mass emissions over 1000 hr being nine times greater with the higher-emitting toner. But copied paper is predicted to produce peak indoor styrene concentrations in a typical office no more than 1% of the World Health Organization health-based guideline. Thus, for the toners considered here, indoor styrene exposures from copied paper appear to be too limited to provide incentive for switching to the lower-emitting toner. The ability to generalize these conclusions is limited by the fact that only one copier and two toners could be tested.  相似文献   
262.
The increase in solar ultraviolet radiation can have various direct and indirect effects on human health, like the incidence of ocular damage. Data of eye damage in residents of three suburban regions in Greece and in two groups of monks/nuns and fishermen are examined here. The statistics performed on these data provides new information about the plausible association between increased levels of solar ultraviolet radiation, air-pollution at ground level, and the development of ocular defects.  相似文献   
263.
Natural radionuclides have been proposed as a means of assessing the transport of ozone (O3) and aerosols in the troposphere. Beryllium-7 (7Be) is produced in the upper troposphere and lower stratosphere by the interaction of cosmogenic particles with atmospheric nitrogen and oxygen. 7Be has a 53.29-day half-life (478 keV gamma) and is known to attach to fine particles in the atmosphere once it is formed. It has been suggested that O3 from aloft can be transported into rural and urban regions during stratospheric-tropospheric folding events leading to increased background levels of O3 at the surface. 7Be can be used as a tracer of upper atmospheric air parcels and the O3 associated with them. Aerosol samples with a 2.5-microm cutoff were collected during 12-hr cycles (day/night) for a 30-day period at Deer Park, TX, near Houston, in August-September of 2000, and at Waddell, AZ, near Phoenix, in June-July of 2001. A comparison of 7Be levels with 12-hr O3 averages and maxima shows little correlation. Comparison of nighttime and daytime O3 levels indicate that during the day, when mixing is anticipated to be higher, the correlation of 7Be with O3 in Houston is approximately twice that observed at night. This is consistent with mixing and with the anticipated loss of O3 by reaction with nitric oxide (NO) and dry deposition. At best, 30% of the O3 variance can be explained by the correlation with 7Be for Houston, less than that for Phoenix where no significant correlation was seen. This result is consistent with the intercept values obtained for 7Be correlations with either O3 24-hr averages or O3 12-hr maxima and is also in the range of the low O3 levels (25 ppb) observed at Deer Park during a tropical storm event where the O3 is attributable primarily to background air masses. That is, maximum background O3 level contributions from stratospheric sources aloft are estimated to be in the range of 15-30 ppb in the Houston, TX, and Phoenix, AZ, area, and levels above these are because of local tropospheric photochemical production.  相似文献   
264.
Herring (Clupea harengus pallasi) spawning sites in Puget Sound, Washington overlap spatially and temporally with blooms of Alexandrium catenella, a toxic dinoflagellate species responsible for paralytic shellfish poisoning. Consequently, newly hatched herring larvae may be regularly exposed to the suite of dissolved paralytic shellfish toxins that are released into the water column from toxic cells during blooms. To date, virtually nothing is known about the impacts of these neurotoxins on early developmental stages of marine fish. In the present study, herring larvae at three ages, 0 days post hatch (dph), 4 dph, and 11 dph, were exposed to dissolved saxitoxin (STX) in 24-h and multi-day exposures. All larvae were examined for sensorimotor function (i.e. spontaneous swimming behavior and touch response). Significant reductions in spontaneous and touch-activated swimming behavior occurred within 1 h of exposure. EC50s at 1 h of exposure were 1,500, 840, and 700 μg STX equiv. l−1 for larvae introduced to STX at 0, 4, and 11 dph, respectively. This progressive age-specific increase in STX-induced paralysis suggests that older larvae were more sensitive to the toxin than younger larvae. Interestingly, herring larvae at all ages exhibited a significant degree of neurobehavioral recovery within 4–24 h of continuous exposure relative to the 1-h time point. This recovery of normal motor behaviors was not observed in previous studies with freshwater zebrafish (Danio rerio) larvae under the same continuous exposure conditions, suggesting that an adaptive detoxification or toxin sequestration mechanism may have evolved in some species of marine fish larvae. Our data reveal that (1) dissolved STX is bioavailable to marine finfish larvae, (2) the toxin is a paralytic agent with potencies that differ between developmental stages, and (3) STX-induced sensorimotor inhibition occurs rapidly but is transient in marine larvae. Collectively, these results suggest that dissolved algal toxins may have important sublethal effects on marine fish populations.  相似文献   
265.
The objective of this paper is to identify strategies to improve the resilience of interagency communication between relief organizations and the community when dealing with an emergency. This research draws from frameworks including information theory, organization design, and how the private sector has learned and evolved from the challenges of information flow to provide guidance to disaster relief agencies. During times of emergency, private organizations as well as public authorities must coordinate in real time to create an effective response. When coordination is absent, failure results, as was seen after Hurricane Katrina and the Haiti Earthquake. Using data that the authors collected immediately after these disasters, two case studies of systemic failure are presented to extract lessons that might be used to improve communication resilience through coordination between parties in humanitarian relief operations. Recent emergency response trends are identified, and the paper argues that the persistence of response failures is not surprising, in part because response organizations normally operate independently, and their operations evolve at different rates. As a result, the organizational interfaces that enable rapid integration during a disaster naturally degrade and may be weak or absent. Integrating the literature on information processing theory and organization design with the data from the two case studies, the paper proposes that increasing the resilience of disaster response systems can be achieved by (1) improving the interoperability and information flow across organizational boundaries; (2) increasing the synergies between organizations on adapting new technology such as social media for the coordination of structured and unstructured data for use in decision-making, and (3) increasing the flexibility of relief organizations to use external resources from areas not affected by disasters on an opportunistic basis. The paper concludes by discussing resilience enhancing solutions including boundary spanning investments and argues that effective emergency response does not result from sporadic or intermittent efforts but rather requires sustained investment, continuous monitoring, and data collection.  相似文献   
266.
267.
We employed our inhalation methodology to examine whether biomarkers of inflammation and oxidative stress would be produced in mice following inhalation of aerosols containing carbonaceous particles or the vapor of pesticides prevalent during the first Gulf War. Exposure to two putative Gulf War Illness toxins, fine airborne particles and the pesticide malathion, increased biomarkers of inflammation and oxidative stress in Friend virus B (FVB) female mice. Mice inhaling particles 24 h before had increased lung lavage and plasma Leukotriene B4 (LTB4) (a biomarker of inflammation) and PGF (a biomarker of oxidative stress) levels, lung lavage protein and lung lavage lactic dehydrogenase (LDH) levels. These changes were a function of particle density and exposure time. Compared to particle inhalation, mice inhaling malathion 24 h before had small increase in plasma LTB4 and PGF levels but no increase in lung lavage LTB4, lung lavage protein, lung lavage LDH, and lung lavage alveolar macrophage (AM) levels compared to unexposed control mice. AM from particle-exposed mice contained phagocytosed particles, while AM from malathion-exposed mice showed no abnormalities. Our results indicate that inhaling particles or malathion can alter inflammatory and oxidative biomarkers in mice and raise the possibility that these toxins may have altered inflammation and oxidative stress biomarkers in Gulf War-exposed individuals.  相似文献   
268.
Exposure to the nonsteroidal anti-inflammatory drug (NSAID) diclofenac resulted in the near extinction of three species of Gyps vultures on the Indian subcontinent. Other NSAIDs present in the environment, including flunixin, may pose a similar risk. In the course of a study to determine the feasibility of detecting NSAIDs in keratinous matrices (i.e., hair, nails and feathers) using GC-MS, wool opportunistically collected from a sheep treated with flunixin was analysed for residues. Flunixin was detected qualitatively in external wool wash and extract samples. While residues of veterinary agents and pesticides have previously been found in sheep’s wool, our preliminary investigation provides the first instance of an NSAID being detected in this matrix. Here we provide the sample preparation methods and GC-MS parameters used to enable further refinement as part of ongoing conservation and consumer quality control measures.  相似文献   
269.
ABSTRACT: This research examines the sensitivity and vulnerability of community water systems (CWSs) to weather and climate in the Pennsylvania portion of the Susquehanna River Basin. Three key findings emerge from a survey of 506 CWS managers. First, CWSs are sensitive to extreme weather and climate, but that sensitivity is determined more by type of system than system size. CWSs that rely partly or wholly on surface water face more disruptions than do groundwater systems. Larger systems have more problems with flooding, and size is not a significant determinant of outages from storms or disruptions from droughts. Second, CWS managers are unsure about global warming. Few managers dismiss global warming; most think global warming could be a problem but are unwilling to consider it in their planning activities until greater scientific certainty exists. Third, the nature of the CWS, its sensitivity to weather and climate, and projected risks from weather and climate are insignificant determinants of how managers plan. Experienced, full-time managers are more likely to consider future weather and climate scenarios in their planning, while inexperienced and part-time managers are less likely to do so. Implications of these findings include support for efforts to move away from surface water, for clear communication of climate change information, and for the hiring and retention of full-time professional CWS managers.  相似文献   
270.
A multitrophic outdoor mesocosm system was used to mimic a wetland ecosystem and to investigate the effects of glyphosate and two herbicide mixtures on wetland microbial communities. The glyphosate concentration used was 1000 times the environmentally relevant concentration (ERC). One herbicide mixture consisted of six auxin-type herbicides (2,4-D, MCPA, clopyralid, dicamba, dichlorprop, mecoprop), each at 1000 times the ERC. The second mixture was comprised of eight herbicides, including the six auxin-type herbicides as well as bromoxynil and glyphosate. For this mixture, a dose-response approach was used to treat mesocosms with the ERCs of each herbicide as the base concentration. Algal biomass and production and bacterial production and numbers for pelagic and attached communities were measured at different times over a 22-d period. The experimental results indicate that the eight-herbicide mixture, even at low concentrations, produced negative effects on microbial communities. Glyphosate on its own suppressed algal biomass and production for the duration of the study in pelagic and biofilm communities. Algal biomass and production, although initially depressed in the auxin-type herbicide treatment, were stimulated from Day 9 until experiment end. Due to their similar modes of action, the effects of this herbicide mixture appear to be a result of concentration addition. Such negative effects, however, were brief, and microbial communities recovered from herbicide exposure. Based on evidence presented in this study, it appears that glyphosate has a higher potential to inhibit primary production and chlorophyll content in pelagic and attached wetland algal communities than the auxin-type herbicide mixture.  相似文献   
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