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841.
842.
Frank Vöhringer 《Mitigation and Adaptation Strategies for Global Change》2004,9(3):217-240
Deforestation is currentlythe source of about 20% of anthropogenicCO2 emissions. Avoided deforestationhas, nonetheless, been ruled out as a CleanDevelopment Mechanism (CDM) category in theKyoto Protocol's first commitment period,because several methodological issues wereconsidered too difficult to resolve. Thispaper explores whether CDM issues such as(1) carbon quantification, (2)additionality and baseline setting, (3)leakage risks, (4) non-permanence risks,and (5) sustainable development can beadequately dealt with in large, diversifiedforest conservation projects. To this aim,it studies the case of the Costa RicanProtected Areas Project (PAP), anActivities Implemented Jointly (AIJ)project which was meant to consolidate thenational park system to avoiddeforestation, promote the growth ofsecondary forests and regenerate pastureson an area that, in total, covers 10% ofthe national territory. The case studyexamines how the issues mentioned abovehave been addressed in the project designand in the certification process. It isfound that baseline uncertainties are themajor problem in this case. Nonetheless,the case suggests the possibility toaddress CDM issues by specific requirementsfor project design and very conservativeand temporary crediting. Provided thatother case studies support this conclusion,eligibility of well-designed forestconservation projects under the CDM in thesecond commitment period may be worthconsidering, given the secondary benefitsof avoided deforestation. 相似文献
843.
Marina Préault Olivier Chastel Frank Cézilly Bruno Faivre 《Behavioral ecology and sociobiology》2005,58(5):497-505
In monogamous bird species, male parental investment may influence offspring fitness and females may gain advantages through mating with males providing extensive paternal care. However, paternal care is a benefit that can only be assessed indirectly because mate choice precedes paternal activities. Individual quality and age, both signalled by morphological characteristics, may reflect parental abilities. Because they may reflect individual foraging abilities, carotenoid-based colorations have been proposed to honestly signal parental quality. The blackbird (Turdus merula), a socially monogamous species, exhibits biparental care and males show bills that vary from pale yellow to orange due to carotenoid pigments. In this study, we investigated whether male bill colour and age are associated with parental ability. Our results suggest that males with more orange bills and older males are better fathers. Indeed, male visit rate increased with their bill colour index independently of age, and brood condition was higher for adult males, compared to yearlings, independently of bill colour. Overall, the number of fledglings produced was positively influenced by both the age of males and the colour intensity of their bills. Males with more orange bills and adults had a greater number of fledglings and these males also had higher levels of prolactin, a hormone known to promote parental care. This latter finding suggests that prolactin may be the link between carotenoid based colorations and the intensity of paternal effort. Thus, male bill colour seems to honestly reveal male physiological adjustment to paternal activities. 相似文献
844.
Patterns of microzooplankton growth in dilution experiments across a trophic gradient: Implications for herbivory studies 总被引:1,自引:0,他引:1
To investigate the growth and grazing patterns of microzooplankton (MZP) in environments of differing productivity, dilution
experiments measuring phytoplankton growth (μ) and grazing mortality (m) rates were performed using samples from contrasting
locations along the Texas coast. Samples were collected from estuaries, coastal lagoons and offshore Gulf of Mexico locations
in the spring and summer of 2001. MZP growth rates were determined in each dilution treatment. Although MZP biomass changed
over time in most dilution treatments, adjusting μ and m for the actual grazer gradient (represented by geometric mean MZP
biomass) did not cause a significant deviation from the nominal dilution gradient. Likewise, these adjustments did not yield
significant regressions where none existed before adjustment. The dynamics of MZP taxonomic groups (ciliates, dinoflagellates)
and size categories differed suggesting that in some cases internal predation may lead to trophic cascades. MZP biomass was
higher in productive coastal waters and included a larger proportion of dinoflagellates than in the oligotrophic, ciliate-dominated
waters of the Gulf of Mexico. The MZP biomass-to-chlorophyll a ratio was lowest in the hypereutrophic Nueces River, where MZP biomass significantly increased in all dilution treatments
(net growth rates up to 2 day−1) suggesting a strong top–down control. In the brown-tide dominated Upper Laguna Madre and the oligotrophic seagrass-dominated
Lower Laguna Madre MZP growth was decoupled from that of phytoplankton. At these sites, MZP were likely fueled by bacterial
carbon and mixotrophy, respectively. Observing the growth response of MZP in dilution experiments can provide insight into
trophic structure and efficiency of the microbial food web. 相似文献
845.
846.
Nest Predators and Fragmentation: a Review and Meta-Analysis 总被引:14,自引:0,他引:14
Anna D. Chalfoun ‡ Frank R. Thompson III † Mary J. Ratnaswamy§ 《Conservation biology》2002,16(2):306-318
847.
848.
849.
P.W. Frank 《Marine Biology》1975,31(2):181-192
At higher latitudes along the west coast of the USA the herbivorous intertidal snail Tegula funebralis (Adams, 1854) lives longer, grows more slowly, but attains a larger size than further south. To the north, age distributions are less predictable and often far from stationary. The differences, which have some generality, can be explained either by a primary temperature effect joined with increased hazards to planktonic larvae in the north, or else may result from a combination of interactions between intensity of predation, population density and food supply. Growth rates of transplanted individuals suggest a genetic basis for the latitudinal differences. 相似文献
850.