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371.
Experience affects mating behavior, but does not impact parental reproductive allocation in a lizard
Daniel A. Warner Clint D. Kelly Matthew B. Lovern 《Behavioral ecology and sociobiology》2013,67(6):973-983
Investment into reproduction is influenced by multiple factors and varies substantially between males and females. Theory predicts that males should adjust their ejaculate size or quality in response to variation in female experience or phenotypic quality. In addition, sperm investment by males may also be influenced by their own status and experience. Although such adjustments of male ejaculate size can impact reproductive success (via fertilization success), fitness returns from male sperm investment may be influenced (either limited or facilitated) by the level of maternal investment. To test this hypothesis, we conducted an experiment that simultaneously evaluated the effect of paternal and maternal experience (which incorporates mating status, age, body size, and other related variables) on paternal sperm investment and maternal reproductive allocation in the lizard Anolis sagrei. During staged mating trials, experienced males were more likely to copulate with females, but these individuals were less likely to transfer sperm during mating than were naïve individuals. Maternal experience had no impact on these mating behaviors. In contrast to expectations, experience and phenotypic quality (of both sexes) had no impact on male ejaculate size or quality (proportion of live sperm) or on maternal reproductive investment (in terms of egg size and yolk steroids). These findings were intriguing given the mating system and past evidence for differential maternal investment in relation to sire quality in A. sagrei. The results found in this study highlight the complexity of reproductive investment patterns, and we urge caution when applying general conclusions across populations or taxa. 相似文献
372.
Kelly M. Sennatt Nira L. Salant Carl E. Renshaw Francis J. Magilligan 《Journal of the American Water Resources Association》2006,42(6):1671-1682
Abstract: Five commonly used methods for measuring embeddedness the — degree to which fine particles surround coarse substrate on the surface of the streambed — are assessed and used to evaluate the sedimentation pattern resulting from impoundment on tributaries of the Connecticut River. Results show that the U.S. Environmental Protection Agency (USEPA) method best reflects the sediment regime on these rivers. On the Ompompanoosuc River, regulated by a run-of-the-river/flood control dam, embeddedness increases significantly directly downstream of the dam. On the unregulated White River, no downstream trends in embeddedness are observed. The USEPA results on the Ompompanoosuc River reflect the movement of a local decrease in embeddedness, interpreted as a moving region of scour, with a calculated transport rate of approximately 5 to 25 m/day. Observed transport rates are similar to previously measured sediment transport rates and consistent with results from a multifraction sediment transport model. Application of the USEPA method to an additional regulated tributary demonstrates the effects of dam management on embeddedness. Flow regulation with high sediment trapping efficiency results in a decrease in embeddedness downstream of the dam. Results provide insight into the utility of available methods for evaluating the effects of management practice on streambed composition. 相似文献
373.
Non-host organisms affect transmission processes in two common trematode parasites of rocky shores 总被引:1,自引:0,他引:1
Katrin Prinz Thomas C. Kelly Ruth M. O’Riordan Sarah C. Culloty 《Marine Biology》2009,156(11):2303-2311
The transmission of free-living trematode stages is mediated by various environmental factors, of which the presence of ambient
organisms within the host space is a potential major determinant. In two laboratory mesocosm experiments, we investigated
the influence of four intertidal rocky shore species on transmission success of cercariae of the digenean trematodes Echinostephilla
patellae (encysting in the tissue of blue mussels Mytilus edulis) and Parorchis
acanthus (encysting on mussel shells). Encystment success of both parasite species was significantly lower in the presence of test
organisms when compared to controls. Observations revealed that barnacles Austrominius
modestus actively filtered cercariae, whereas the larvae were obstructed by the seaweeds Corallina
officinalis and Fucus
serratus. Anemones Actinia
equina both physically disturbed and consumed cercariae. In a further laboratory experiment, grazing gastropods (Littorina
littorea, Patella
vulgata, and Gibbula
umbilicalis) were found to significantly reduce the numbers of P. acanthus metacercariae in artificially prepared dishes by ingestion of cysts. Our results suggest that non-host organisms may play
a key role in regulating the transmission of free-living trematode stages in rocky shore ecosystems, which is especially important
with regard to the relative diversity and density of species in these habitats. The findings also emphasize the need to include
parasites into marine food webs, since cercariae seem to be consumed by certain organisms to a considerable extent and could
possibly represent an important energy source. 相似文献
374.
Brian A. Kelly 《补救:环境净化治理成本、技术与工艺杂志》1997,7(4):95-103
The U. S. Nuclear Regulatory Commission has established a Working Group to evaluate methods for improving control of devices containing radioactivity in industry. These devices include radiography equipment and moisture/density gauges. The Working Group was the result of a number of incidents in which these devices were inadvertently shipped to scrap dealers and steel recycling facilities. The resulting release of radioactivity when the devices were processed has cost millions of dollars to clean up. This article discusses the Working Group's conclusions and the potential impact of these conclusions on the remediation industry. It also makes recommendations for both current and prospective owners of devices containing radioactivity on how to prepare for regulatory changes likely to occur as a result of the Working Group's conclusions. 相似文献
375.
We determined the usefulness of tapered element oscillating microbalances (TEOMs) for researchers and engineers involved with measuring diesel particulate mass. Two different test facilities were used for generating diesel particulates and comparing the TEOM to the commonly used U.S. Environmental Protection Agency (EPA) manual filter method. The EPA method is very labor-intensive and requires long periods of time to complete. The TEOM is an attractive approach because it has the potential to reduce the amount of time and labor required in diesel testing, as well as to provide real-time particulate-mass data that are not obtainable with the EPA method. It was found that the TEOM was a precise and easy-to-operate instrument that could measure the mass concentration (MC) of diesel particulate emissions in real time. Although the TEOM diesel particulate MC measurements were highly correlated with the manual filter measurements, the two techniques were not equivalent because the TEOM consistently reported MC results that were 20-25% lower than those obtained using the manual filter technique. In conclusion, the TEOM can be used to increase test-cell throughput and to measure transient values of diesel particulate emissions at sites performing diesel-engine testing. However, unless EPA is able to certify the TEOM as an equivalent method, it cannot replace the manual filter method for diesel certification work. 相似文献
376.
Denson Kelly McLain 《Behavioral ecology and sociobiology》1991,29(2):121-126
Summary Males and females of the seed bug, Neacoryphus bicrucis Say, were individually numbered in the field in southeastern Georgia (USA) and census taken daily for 6 weeks. Variation in male mating efficiency (ME = no. copulations/no. sightings) exceeded that in females and was significantly greater than that generated by a null model. Lifetime copulatory success, estimated as the product of ME and longevity, ranged from 0 to 41, with ME accounting for over 88% of the variation. Lifetime reproductive success (LRS), estimated as the product of ME, longevity, and clutch size, ranged from 0 to 898. Among males copulating at least once, ME accounted for over 40% of the variation in LRS, while longevity alone or in combination with clutch size accounted for 21% and 46%, respectively, of the variation in LRS. Failure of some males (26%) to copulate contributed 38% of the total variation in LRS. Thus, among males surviving to adulthood, sexual selection pressure arising from variation in ME is approximately as strong a force for phenotypic change as is natural selection pressure arising from variation in longevity. 相似文献
377.
Charles Kelly 《Disasters》1998,22(2):144-156
Since the first issue in 1977, Disasters has been one of the pre-eminent refereed journals on the study and reporting of disasters. This article reviews 703 articles and reports in the journal through 1996 to provide a snapshot of the nature of the journal throughout 20 years of publication. The results indicate the most common contributions: first, were research articles by authors from the North Atlantic; second, most often dealt with natural disaster relief or impact; and third, most frequently focused on Africa. These generalisations, however, do not reflect attention paid to food-related and political disasters and greatly understate the broad diversity of material presented in the journal. To improve the topical and geographic coverage of Disasters probably requires a proactive effort to close gaps in the journal's coverage of disasters. 相似文献
378.
379.
Effect of the hard clam Mercenaria mercenaria on benthic fluxes of inorganic nutrients and gases 总被引:2,自引:0,他引:2
The effect of the hard clam Mercenaria mercenaria (L.) on the exchange of dissolved nutrients (silicate, phosphate, ammonium, nitrate+nitrite) and gases (oxygen, carbon dioxide) across the sediment-water interface was examined in 1983 and 1984 using experimental mesocosms (13 m3), designed to simulate a shallow coastal ecosystem, that allow for reciprocal biogeochemical interactions between water column (5 m) and bottom sediments (30 cm deep). Benthic, fluxes, measured during a spring-summer warming period, were compared for mesocosms maintained either with added M. mercenaria (16 per m2, treatment) or without M. mercenaria (control) as a component of the benthic community. Fluxes were within the range observed for the (control) community in situ in mid-Narragansett Bay and exhibited the pattern of increasing flux with increasing temperature observed in nature. For dissolved inorganic (DIN=ammonia+nitrate+nitrite), analytical problems allowed comparison of fluxes only at the higher temperatures (17° to 22°C); average DIN fluxes were 57% higher in mesocosms with clams. Fluxes of other nutrients and gases were modelled as exponential functions of temperature (9° to 22°C) using a linear regression of the natural logarithm of flux upon temperature in both treatment and control situations. Differences between regression slopes and intercepts for conditions with and without clams were assessed by analysis of covariance. Slopes of the linearized temperature-flux relationships were not significantly different between treatments for any flux measured, suggesting that presence of the clams did not alter the basic relationship of flux and temperature normally observed with this community. For oxygen consumption and silicate production, the regression intercepts were significantly higher in the clam treatment, suggesting that the level of flux was generally elevated in the presence of M. mercenaria by about 20% (oxygen) and 86% (silicate) at any given temperature. Data for carbon dioxide and phosphate showed similar trends to oxygen and silicate, but the variance in fluxes was larger and regression intercepts for the two treatments were not significantly different. 相似文献
380.
Effective conservation of endangered species often is hampered by inadequate knowledge of demography. We extracted information on survival and fecundity from an 18-month, live-trapping study of Dipodomys stephensi , and from this we developed an age-structured demographic model to assess population viability. Adult Stephens' kangaroo rats persisted longer than juveniles, and adult females persisted longer than adult males. Disappearance rates were high in the first months after initial capture. Thereafter, the fraction of animals persisting decreased slowly and in an approximately linear fashion on a semilogarithmic scale, suggesting age-independent mortality factors such as predation. Juvenile persistence did not differ substantially between two years of strikingly different rainfall. Onset of breeding followed the start of winter rains. Length of the breeding season, average number of litters per female, and the fraction of first-year females breeding were much greater in the year of higher rainfall. We propose a birth-pulse demographic model for D. stephensi that distinguishes juvenile and adult age classes. Temporal environmental variation can be modeled adequately with a constant survivorship schedule and variable fecundity determined by yearly precipitation. Several issues should be resolved, however, before conservation decisions are based on the model. Better estimates of juvenile survivorship are critical, the quantitative relationship between precipitation and fecundity must be determined, and the potential for density dependence and source-sink population dynamics must be evaluated. 相似文献