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Geoff M Hilton Phil W Atkinson Gerard A.L Gray David W Gibbons 《Biological conservation》2003,111(1):79-89
Prior to 1995, the Montserrat oriole (Icterus oberi) was confined to ca. 30 km2 of hill forest on the Lesser Antillean island of Montserrat, but was not listed as globally threatened. Since then, the eruption of the Soufriere Hills volcano has destroyed more than half of the species’ range. Recent intensive monitoring has indicated that the species has also declined dramatically within the remaining intact forest, and is now critically threatened. Different monitoring and analytical methods indicate a decline of 8-52% p.a., and a remaining global population of ca. 100-400 pairs. This case study justifies the use of the restricted range criterion in designating threatened species. Despite intensive monitoring and the use of several analytical methods, it has proved surprisingly difficult to estimate the magnitude of the oriole’s decrease, or to control for potential artefacts in the census method. We discuss the reasons for this. The cause(s) of population decline in the intact forest are unclear, though two hypotheses appear plausible: a decrease in arthropod food, a result of volcanic ash fall, and an increase in nest predation as a result of increases in populations of opportunistic omnivores. 相似文献
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Phil Mount 《Agriculture and Human Values》2012,29(1):107-121
“Scaling-up” is the next hurdle facing the local food movement. In order to effect broader systemic impacts, local food systems
(LFS) will have to grow, and engage either more or larger consumers and producers. Encouraging the involvement of mid-sized
farms looks to be an elegant solution, by broadening the accessibility of local food while providing alternative revenue streams
for troubled family farms. Logistical, structural and regulatory barriers to increased scale in LFS are well known. Less is
understood about the way in which scale developments affect the perception and legitimacy of LFS. This value-added opportunity
begs the question: Is the value that adheres to local food scalable? Many familiar with local food discourse might suggest
that important pieces of added value within LFS are generated by the reconnection of producer and consumer, the direct exchange
through which this occurs, and the shared goals and values that provide the basis for reconnection. However, these assertions
are based on tenuous assumptions about how interactions within the direct exchange produce value, and how LFS are governed.
Examination shows that existing assumptions do not properly acknowledge the hybridity, diversity, and flexibility inherent
in LFS. A clear analysis of the potential of scale in LFS will depend on understanding both how value is determined within
LFS, and the processes through which these systems are governed. Such an analysis shows that, while scaled-up LFS will be
challenged to maintain legitimacy and an identity as “alternative”, the establishment of an open governance process—based
on a “negotiation of accommodations”—is likely to enhance their viability. 相似文献
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Summary The performance of transgenic varieties depends not only upon the stable and correctly-regulated expression of specific transgenes but also upon the agronomic potential of the background genotype. Ideally, transgenes should be introduced into agronomically-superior cultivars and transgenic varieties will become out-classed if their agronomic properties are not continually improved. It will often prove desirable to use conventional breeding techniques, as opposed to new cycles of transformation, to carry out this process of varietal improvement.Continuing advances in marker-assisted selection have made possible the selection and manipulation of an entire genetic background. This means that transgenes can be transferred to new and often untransformable varieties with relative ease. To carry out this process efficiently requires the correct choice of male and female parents, the use of appropriate marker-systems and the concentration of selection on the most appropriate generations.Efficient, phenotypically-neutral marker-systems have revolutionised the identification and manipulation of quantitative trait loci (QTLs). The loci which modify the expression of transgenes are a form of QTL. Desirable alleles at modifier QTLs can be transferred to new varieties along with the transgenes themselves, using marker-assisted breeding.The strategies for maker-assisted selection are becoming ever more sophisticated. A range of complementary marker systems allows the selection of desirable genotypes. In addition, the meiotic reassortment and recombination of chromosomes which produces new genotypes is becoming better understood. The most efficient plant breeding methods and the most powerful genetics will make optimal use of both markers and meiosis. 相似文献
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Keryn Paul Phil Polglase Peter Snowdon Tivi Theiveyanathan John Raison Tim Grove Stan Rance 《New Forests》2006,31(3):513-533
There is a need to calibrate models for carbon accounting in forest systems if they are to be applied for carbon trading and
off-set schemes. One such model, Full Carbon Accounting Model (FullCAM), calculates stem mass by taking annual inputs of tree
growth in stem volume and multiplying these by basic stem wood density. Stem mass is then multiplied by user-entered coefficients
to determine the mass of other tree components. Using datasets of Pinus radiata and Eucalyptus globulus that comprised of between 73 and 187 observations, we determined empirical relationships that can be used in FullCAM to relate
basic stem wood density to stand age, and masses of bark, foliage or branches to mass of stem wood for these two species.
All fitted relationships were highly significant (p < 0.001), explaining between 35 and 89% of the variance. These calibrations were then tested using three case studies where
data on volume yield curves and repeated measures of biomass of stand components were available: one of P. radiata and two of E. globulus. Although accumulation of biomass in foliage and branches were not well predicted by the model, sensitivity analysis showed
that this was relatively unimportant to total carbon storage because of the dominance of the stem, particularly once the stand
is older than 5 years. Indeed, FullCAM accounted for 99% of the variance in measured above-ground biomass at all three sites
because calibrations for the mass of stem was reasonably well constrained. Uncertainty analysis showed that despite the standard
errors of parameters used in relationships for basic density and biomass partitioning, and for estimates of carbon contents
of tree components, we can be 95% confident that sequestration of carbon in trees and debris of Pinus radiata and Eucalyptus globulus plantations are, on average, within 13% of that predicted by FullCAM.
Ensis is a joint venture between CSIRO FFP P/L and Scion Australasia P/L 相似文献
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The phenolic composition of pine bark from a variety of Pinus species was estimated by measuring Klason lignin, acid-soluble lignin, and a 1% NaOH extract. Polyphenol contents of hot
water extracts from pine bark were determined by the Folin-Ciocalteu assay and the vanillin-H2SO4 assay. Among the pine bark varieties investigated, Pinus radiata bark showed the highest polyphenol content and potent antioxidant activity. Pinus rigida bark was also a usable polyphenol-rich source, whereas Pinus densiflora bark had a low yield (5.1%) of hot water extract, although it showed potent antioxidant activity. Correlations between proanthocyanidin
content in pine bark and antioxidant activity were observed. The results suggested that proanthocyanidin was the crucial contributor
to potent antioxidant activity in pine bark.
The publication of this article was made possible by an Emachu Research Fund. The authors are grateful for the fund. 相似文献