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Condensed tannins can be found in various parts of many plants. Unlike lignin there has been little study of their fate as they enter the soil organic matter pool and their influence on nutrient cycling, especially through their protein-binding properties. We extracted and characterized tannin-rich fractions from humus collected in 1998 from a black spruce [Picea mariana (Mill.) Britton et al.] forest in Canada where a previous study (1995) showed high levels (3.8% by weight) of condensed tannins. A reference tannin purified from black spruce needles was characterized by solution 13C nuclear magnetic resonance (NMR) as a pure procyanidin with mainly cis stereochemistry and an average chain length of four to five units. The colorimetric proanthocyanidin (PA) assay, standardized against the black spruce tannin, showed that both extracted humus fractions had higher tannin contents than the original humus (2.84% and 11.17% vs. 0.08%), and accounted for 32% of humus tannin content. Consistent with the results from the chemical assay, the aqueous fraction showed higher tannin signals in the 13C cross-polarization and magic-angle spinning (CPMAS) NMR spectrum than the emulsified one. As both tannin-rich humus fractions were depleted in N and high in structures derived from lignin and cutin, they did not have properties consistent with recaldtrant tannin-protein complexes proposed as a mechanism for N sequestration in humus. Further studies are needed to establish if tannin-protein structures in humus can be detected or isolated, or if tannins contribute to forest management problems observed in these ecosystems by binding to and slowing down the activity of soil enzymes. 相似文献
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Jan M. Pestka Florian Barvencik Frank T. Beil Robert P. Marshall Eilin Jopp Arndt F. Schilling Andreas Bauerochse Mamoun Fansa Klaus Püschel Michael Amling 《Die Naturwissenschaften》2010,97(4):393-402
Although numerous bodies were deposited in Western European bogs in the past centuries, few were found and underwent archeological
analysis. No studies comparing skeletal structure and mineralization of bog bodies from different ages have been performed
to this day. Therefore, the aim of this study was to analyze and compare skeletal features and specifics of the human remains
of three bog bodies from the Iron and Middle Ages found in Northern European peat bogs. Demineralization due to the acidic
environment in peat bogs was comparably pronounced in all three bodies. Still, the macroscopic state of skeletal preservation
was excellent. In addition to contact radiography, we used peripheral quantitative computed tomography to measure cortical
bone mineral density. The conservation of skeletal three-dimensional microstructural elements was assessed by high-resolution
microcomputed tomography analysis. These techniques revealed severe differences in bone mineral density and enabled us to
determine handedness in all three bodies. Additionally, unique skeletal features like intravital bone lesions, immobilization
osteoporosis, and Harris lines were found. A deformity of the left femoral head was observed which had the typical appearance
of an advanced stage of Legg–Calve–Perthes disease. This study gives detailed insight into the skeletal microstructure and
microarchitecture of 800- to 2,700-year-old bog bodies. Skeletal analysis enables us to draw conclusions not only concerning
changes in the acidic environment of the bog, but also serves as a diagnostic tool to unravel life circumstances and diseases
suffered by humans in the Iron and Middle Ages. 相似文献
268.
Environmental implications of urbanization and lifestyle change in China: Ecological and Water Footprints 总被引:2,自引:0,他引:2
Klaus Hubacek Dabo Guan John Barrett Thomas Wiedmann 《Journal of Cleaner Production》2009,17(14):1241-1248
Since the open door policy in 1978 China has undergone enormous economic and social changes making China to be one of the largest economies and consumers of resources in the world. The pronounced differences in income and lifestyles especially between urban and rural China were also part of China's economic rebirth.This paper explores current trajectories and scenarios for urbanization and lifestyle changes and other important socio-economic trends in China. The implications of these changes are analysed for Beijing in particular and then compared to China for the year 2020. These changes by 2020 are modelled using input–output analysis in combination with the Ecological Footprint and Water Footprint. 相似文献
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Genetic variability among males is a necessary precondition for the evolution of female choice based on indirect genetic benefits.
In addition to mutations and host–parasite cycles, migration of locally adapted individuals offers an explanation for the
maintenance of genetic variability. In a previous study, conducting a reciprocal transplant experiment on a grasshopper, Chorthippus biguttulus, we found that environmental conditions significantly influenced not only body condition but also an important trait of male
calling song, the amplitude of song. Although not significant, all other analysed physical and courtship song traits and attractiveness
were superior in native than in transferred males. Thus, we concluded that local adaptation has a slight but consistent influence
on a range of traits in our study populations, including male acoustic attractiveness. In our present study, we scanned male
grasshoppers from the same two populations for amplification fragment length polymorphism (AFLP) loci connected with acoustic
attractiveness to conspecific females. We found greater differences in allele frequencies between the two populations, for
some loci, than are expected from a balance between drift and gene flow. These loci are potentially connected with locally
adapted traits. We examined whether these alleles show the proposed genotype environment interaction by having different associations
with attractiveness in the two populations. One locus was significantly related to sexual attractiveness; however, this was
independent of the males’ population affiliation. Future research on the evolution of female choice will benefit from knowledge
of the underlying genetic architecture of male traits under intraspecific sexual selection, and the ‘population genomics’
approach can be a powerful tool for revealing this structure. 相似文献
270.
Amine scrubbing is the most developed technology for carbon dioxide (CO2) capture. Degradation of amine solvents due to the presence of high levels of oxygen and other impurities in flue gas causes increasing costs and deterioration in long term performance, and therefore purification of the solvents is needed to overcome these problems. This review presents the reclaiming of amine solvents used for post combustion CO2 capture (PCC). Thermal reclaiming, ion exchange, and electrodialysis, although principally developed for sour gas sweetening, have also been tested for CO2 capture from flue gas. The three technologies all have their strengths and weaknesses, and further development is needed to reduce energy usage and costs. An expected future trend for amine reclamation is to focus on process integration of the current reclaiming technologies into the PCC process in order to drive down costs. 相似文献