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31.
Understanding departure decisions of migratory birds and the environmental factors affecting them is important for predicting their distribution, abundance, and arrival times to breeding and wintering areas. In the past, methodological difficulties to obtain fine-scale bird departure and meteorological data have limited testing the multi-scale effects of meteorology on bird departure during migration. We investigated departure timing of European bee-eaters (Merops apiaster) staging in southern Israel, identified their departure flight mode (flapping or soaring) using radio telemetry, and measured local meteorological conditions to study if bird departure was affected by these. Departure timing was examined using a timescale analysis design. The conditions before, during, and after the time of departure were compared using timescales of 24 h, 6 h, 1 h, and 10 min and in relation to bird flight mode. At the between-days timescale, barometric pressure at departure time was significantly lower compared with 2–1 day earlier, whereas temperature at departure was significantly higher compared with 3–2 days earlier. Temperature at departure was also higher compared with 6 h and 3–2 h earlier. Tailwind assistance had no significant effect at any timescale. Soaring birds departed at significantly higher temperature compared with flapping birds. We suggest that bee-eater departure is tuned to the infrequent passage of warm atmospheric depressions at the between-days timescale and with an increasing temperature trend within these days enabling the birds to use energetically cheap soaring flight. We thus suggest that energetic considerations dictate the departure decisions of migrating European bee-eaters.  相似文献   
32.
Ecosystem responses to physical or chemical stress may vary from changes in single organisms to alteration of the structure and function of the ecosystem. These responses to stress cannol be predicted exactly. Ecosystems repeatedly exposed to physical and/or chemical stress can be used to study the separate and combined environmental effects of stress. Such studies also allow the development of procedures to select test systems for the analysis of stress in ecosystems. A preliminary field survey of six military training sites at Fort Riley, Kansas, USA, was conducted to identify and verify ecological test systems for evaluating ecosystem responses to physical and/or chemical stress. Comparisons of these data with data collected concurrently from Konza Prairie Research Natural Area reference sites showed that soil microarthropods, some species of macroarthropods, small mammals, and native earthworm species were negatively affected by stress. In contrast, plant species diversity, plant foliage biomass, soil mycorrhizae, and many soil characteristics were within the boundaries of nominal variations observed on “pristine” Konza Prairie. Introduced European earthworms appeared to be positively affected by training activities. This study provided a test of systematic procedures to support impact analysis, ecological toxicology, and ecosystem risk assessments. This is paper IX in D. J. Schaeffer's “Environmental Audit” series.  相似文献   
33.
Journal of Polymers and the Environment - Limonene represents a possible candidate for the synthesis of polymers from renewable sources. However, because of some structural characteristics, the...  相似文献   
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35.
Hatching asynchrony of nestling birds leads to weight asymmetries, which in turn affect the nestlings’ relative success when competing for feedings brought to the nest. We present a game theoretic model that predicts how weight asymmetry influences the nestlings’ energy on securing feedings, thus determining the caloric value remaining for weight gain as well as the distribution of feedings obtained. The model has a unique Evolutionary Stable Strategy (ESS) profile, in which nestlings in more asymmetric nests exhibit less aggression and hence achieve larger weight gain per feeding. The impetus for this model was data from a long-term study of Arabian babblers (Turdoides squamiceps) that showed a surprising negative correlation between the number of feedings that a nest received and the overall weight gain in the nest. This finding is, however, entirely consistent with our model—in more symmetric nests, the individuals fight more and are consequently hungrier and beg for additional food, are fed more, but still gain less weight due to the higher energetic costs of fighting. The model provides a fundamental explanation also for related findings in other species, in which chicks in asynchronous broods were found to be heavier than those from synchronous broods. In addition, it supports the sibling rivalry hypothesis by which brood asynchrony may diminish aggressive interactions among nestlings, leading to more efficient use of resources.  相似文献   
36.
Environmental evaluation of subdivision site developments   总被引:5,自引:0,他引:5  
An environmental evaluation was performed at 16 subdivision sites within four communities in east-central Michigan. The primary objective was to evaluate the fit between environmental ordinances and the physical/environmental conditions to which they were applied. An environmental response index was developed with indicators to assess water, soil, slope, development density, roads, vegetation, and ecology. Water-related indicators achieved the highest scores, while soil-related indicators scored the poorest, with generally poor performance across all indicators. The poor performance indicates there are problems in the ability of environmental ordinances developed at broader jurisdictional scales (e.g., the state) to address the existing environmental conditions at smaller geographic scales (subdivisions within communities). Two key problems include the lack of scientific specificity in the broader state-level ordinances and the lack of local expertise and/or resources to monitor the environment.  相似文献   
37.
OBJECTIVE: The objective of the study was to determine which vehicle factors are significantly related to pelvic injury in side impact collisions. Identification of relevant parameters could aid in the reduction of these injuries. METHOD: Side impact crashes from the CIREN database were separated into those in which the occupant sustained a pelvic fracture and those in which no pelvic fracture occurred, although all occupants had serious injuries. A multibody MADYMO model was created of a USDOT SINCAP (U.S. Department of Transportation Side Impact New Car Assessment Program) test of a vehicle with a large center console. RESULTS: From a study of 113 side impact crashes in the ciren database, nearside occupants with pelvic fractures (n = 78) had (i) more door intrusion (mean, 37 vs. 32 cm, p = 0.02) than those who had serious injuries, but not pelvic fractures (ii) a greater likelihood that the lower border of the door intruded more than the upper part (40% vs. 18%, p < 0.025); and (iii) a greater likelihood that their vehicle had a center console (47 vs. 17%, p < 0.005). Other parameters such as occupant age, weight, gender, vehicle weight, and struck vehicle speed change were not significantly different. MADYMO modeling showed that with a center console, an initial positive pelvic acceleration occurred at about 30 msec, followed at about 45 msec by a second acceleration peak in the opposite direction. Reducing console stiffness reduced the second acceleration but not the initial peak. Allowing the seat to translate laterally when contacted by the door reduced the initial pelvic acceleration by 50% and eliminated the second acceleration peak. CONCLUSIONS: Redesigning the center console using less stiff materials and allowing some lateral translation of the seat could aid in reducing pelvic injuries in side impact collisions.  相似文献   
38.
Objective: To evaluate the influence of forward-facing child restraint systems’ (FFCRSs) side impact structure, such as side wings, on the head kinematics and response of a restrained, far- or center-seated 3-year-old anthropomorphic test device (ATD) in oblique sled tests.

Methods: Sled tests were conducted utilizing an FFCRS with large side wings and with the side wings removed. The CRS were attached via LATCH on 2 different vehicle seat fixtures—a small SUV rear bench seat and minivan rear bucket seat—secured to the sled carriage at 20° from lateral. Four tests were conducted on each vehicle seat fixture, 2 for each FFCRS configuration. A Q3s dummy was positioned in FFCRS according to the CRS owner's manual and FMVSS 213 procedures. The tests were conducted using the proposed FMVSS 213 side impact pulse. Three-dimensional motion cameras collected head excursion data. Relevant data collected during testing included the ATD head excursions, head accelerations, LATCH belt loads, and neck loads.

Results: Results indicate that side wings have little influence on head excursions and ATD response. The median lateral head excursion was 435 mm with side wings and 443 mm without side wings. The primary differences in head response were observed between the 2 vehicle seat fixtures due to the vehicle seat head restraint design. The bench seat integrated head restraint forced a tether routing path over the head restraint. Due to the lateral crash forces, the tether moved laterally off the head restraint reducing tension and increasing head excursion (477 mm median). In contrast, when the tether was routed through the bucket seat's adjustable head restraint, it maintained a tight attachment and helped control head excursion (393 mm median).

Conclusion: This testing illustrated relevant side impact crash circumstances where side wings do not provide the desired head containment for a 3-year-old ATD seated far-side or center in FFCRS. The head appears to roll out of the FFCRS even in the presence of side wings, which may expose the occupant to potential head impact injuries. We postulate that in a center or far-side seating configuration, the absence of door structure immediately adjacent to the CRS facilitates the rotation and tipping of the FFCRS toward the impact side and the roll-out of the head around the side wing structure. Results suggest that other prevention measures, in the form of alternative side impact structure design, FFCRS vehicle attachment, or shared protection between the FFCRS and the vehicle, may be necessary to protect children in oblique side impact crashes.  相似文献   
39.
The importance of nestling location for obtaining food in open cup-nests   总被引:1,自引:0,他引:1  
Observations and experiments were carried out at 34 four-nestling nests of Arabian babblers (Turdoides squamiceps) and feeding events were analyzed according to hatching order and nestling location in the nest. Nestlings were fed in a negative correlation with hatching order. Nestling locations in relation to the provisioners were defined as Near, Far, Right, Left, and Center. Feeders fed closer nestlings more often than those further away, and straight ahead rather than sideways. In the open circular nest, the feeding adults' positions were unpredictable and equally distributed around the nest. Each peripheral position therefore served equally as Near, Far, Right and Left positions. The Center was independent of the arrival direction of the feeders and was advantageous relative to the peripheral positions. The importance of the central position was demonstrated by three experiments. (a) Food deprivation for 1 h caused the first-hatched nestling to occupy the center position and gain more feedings than its siblings. (b) Introduction of a Perspex barrier into the nest, thus eliminating the central position and preventing the nestlings from changing places, led to a loss of importance of hatching order and equal provisioning of the nestlings. (c) Fencing the nest so that entry was possible from only one permanent direction, resulted in the first-hatched nestling occupying the near position more often than its nestmates and obtaining 52% of the feedings provisioned to the whole brood. These findings imply that the architecture of the nest has an important role in food distribution among the nestlings, and contributes to reducing inequalities in the siblings' abilities to obtain food.  相似文献   
40.
This paper examines the factors shaping non-governmental organization (NGO) messaging decisions on how meat consumption should be altered in light of climate change. In particular, we sought to understand the relative absence of messages promoting meat-free diets and the decision of some NGOs to pair meat reduction messages with messages encouraging consumers to switch to meat from ruminant grass-fed animals. Interviews were conducted with 27 staff members from environmental, food-focused, and animal protection NGOs from the USA, Canada, and Sweden. While strategic considerations consistently led to the use of modest messages for meat reduction, NGO missions were also key to shaping the specifics of messaging goals. The relatively low personal comfort levels that some NGO staffers held toward meat-free diets also led to the use of more modest requests for meat reduction. Findings highlight the complex nature of the factors underlying the environmental communication messages of NGOs.  相似文献   
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