全文获取类型
收费全文 | 1402篇 |
免费 | 137篇 |
国内免费 | 138篇 |
出版年
2024年 | 5篇 |
2023年 | 26篇 |
2022年 | 19篇 |
2021年 | 25篇 |
2020年 | 57篇 |
2019年 | 60篇 |
2018年 | 69篇 |
2017年 | 84篇 |
2016年 | 58篇 |
2015年 | 85篇 |
2014年 | 73篇 |
2013年 | 110篇 |
2012年 | 48篇 |
2011年 | 58篇 |
2010年 | 46篇 |
2009年 | 71篇 |
2008年 | 79篇 |
2007年 | 85篇 |
2006年 | 81篇 |
2005年 | 79篇 |
2004年 | 56篇 |
2003年 | 34篇 |
2002年 | 47篇 |
2001年 | 34篇 |
2000年 | 34篇 |
1999年 | 31篇 |
1998年 | 27篇 |
1997年 | 24篇 |
1996年 | 20篇 |
1995年 | 17篇 |
1994年 | 17篇 |
1993年 | 13篇 |
1992年 | 21篇 |
1991年 | 8篇 |
1990年 | 11篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有1677条查询结果,搜索用时 15 毫秒
101.
Kentaro?HayashiEmail author Masanori?Okazaki Norihiro?Itsubo Atsushi?Inaba 《The International Journal of Life Cycle Assessment》2004,9(1):13-22
Background Acidification is one of the important impact categories for life cycle impact assessment. Although its characterization has
progressed during this decade through the employment of midpoint approaches, only limited studies of endpoint approaches have
been performed. Objective. This study aimed at developing damage function of acidification for terrestrial ecosystems in Japan.
Damage function expresses a quantitative relationship between the inventory and endpoint damage.
Methods The geographical boundary was limited in Japan both for emission and impact. In this study, sulfur dioxide (SO2), nitrogen monoxide (NO), nitrogen dioxide (NO2) (NO and NO2 collectively mean NOx), hydrogen chloride (HC1), and ammonia (NH3) were considered as major causative substances of acidification. Net primary production (NPP) of existing vegetation was
adopted as an impact indicator of terrestrial ecosystems. The aluminum toxicity was adopted as the major factor of effect
on terrestrial ecosystems due to acidification. The leachate concentration of monomeric inorganic aluminum ions was selected
to express the plant toxicity of aluminum.
Results and Discussion The results of damage function gave utilizable factors both for a midpoint approach and an endpoint approach; Atmospheric
Deposition Factor (ADF) and Damage Factor (DF) applicable to the former and the latter, respectively. The ADF indicates an
increase of H+ deposition per unit area to an additional emission of causative sustance. The additional emission corresponds to some alternatives
in industry, not the baseline emission. The DF indicates the total NPP damage in all of Japan due to the additional emission
of causative substances. The derived NPP damage is on the order of one millionth of the NPP itself. HC1 and NH3 showed larger
ADFs and DFs than that of SO2 and NOx. The reason was ascribed to the relatively large source-receptor relationships (SRR) of HC1 and NH3. However, since the method applied to determine the SRR of HC1 and NH3 has larger uncertainties than that of SO2 and NOx, attention is needed to handle the difference.
Conclusion The damage function easily defines the concrete NPP damage due to an additional emission. The impact indica tor, NPP, also
has an advantage in its mass unit that is directly summable through the entire impact categories. Expansion of endpoints,
such as in aquatic ecosystems, material degradation, human health, and biodiversity aspects of terrestrial ecosystems, is
an important subject for future work. Further, uncertain analyses for major parameters will provide helpful information on
the reliability of damage function. 相似文献
102.
Ten microsatellite loci were used to investigate the impact of human activity on the spatial and temporal genetic structure of Vitellaria paradoxa (Sapotaceae), a parkland tree species in agroforestry systems in southern Mali. Two stands (forest and fallow) and three cohorts (adults, juveniles and natural regeneration) in each stand were studied to: (i) compare their levels of genetic diversity (gene diversity, HE; allelic richness, Rs; and inbreeding, FIS); (ii) assess their genetic differentiation (FST); and (iii) compare their levels of spatial genetic structuring. Gene diversity parameters did not vary substantially among stands or cohorts, and tests for bottleneck events were nonsignificant. The inbreeding coefficients were not significantly different from zero in most cases (FIS = -0.025 in forest and 0.045 in fallow), suggesting that the species is probably outbreeding. There was a weak decrease in F(IS) with age, suggesting inbreeding depression. Differentiation of stands within each cohort was weak (FST = 0.026, 0.0005, 0.010 for adults, juveniles and regeneration, respectively), suggesting extensive gene flow. Cohorts within each stand were little differentiated (FST = -0.001 and 0.001 in forest and fallow, respectively). The spatial genetic structure was more pronounced in fallow than in forest where adults showed no spatial structuring. In conclusion, despite the huge influence of human activity on the life cycle of Vitellaria paradoxa growing in parkland systems, the impact on the pattern of genetic variation at microsatellite loci appears rather limited, possibly due to the buffering effect of extensive gene flow between unmanaged and managed populations. 相似文献
103.
Joost G. Vogtländer Han C. Brezet Charles F. Hendriks 《The International Journal of Life Cycle Assessment》2001,6(6):344-355
‘Design for Recycling’ and dematerialization by enhancing the durability of products are major aspects of the quest for sustainable products. This article presents an LCA-based model for the integrated analyses of the product chain, its recycling systems, and its waste treatment systems at the ‘End of Life’ stage. The model is an extension of the EVR (Eco-costs/Value Ratio) model which has been published in this journal (Vogtländer et al. 2001), but can also be applied to other life cycle interpretation models, since the model as such is not restricted to the use of the eco-costs as a single indicator. The model has been developed to evaluate the design alternatives of complex products like buildings and cars. These products comprise several subsystems, each with its own special solution at the End of Life stage: Extending of the product life, object renovation, re-use of components, re-use of materials, useful application of waste materials, immobilization with and without useful applications, incineration with and without energy recovery, land fill. Since complex product systems always comprise a combination of these design alternatives, a methodology is given to calculate and allocate the eco-costs of the total system in order to select the best solution for sustainability. The methodology is characterized by:
- A main allocation model of the recycling flow based on physical relationships,
- a strict separation of the market value, the costs and the ecocosts in the system,
- a main allocation model for extension of lifetime based on ‘depreciation of eco-costs’, parallel to economic depreciation.
104.
There is a long tradition of artificially stocking lakes and rivers with fish in the hope to increase the quality and amount of fish that can be harvested. The animals used for stocking often originate in distant hatcheries or hatcheries that breed fish from remote regions. This stocking practice could have effects on the genetic integrity of resident populations. We have analysed here a case of the influence of stocking on Alpine populations of the Arctic charr (usually included into Salvelinus alpinus, but revised to Salvelinus umbla Kottelat 1997 ) within a unique geographical and historical setting. The Königssee in the Bavarian Alps (Berchtesgaden) was heavily stocked several times during the last century. However, a sample of the ancestral Königssee population still exists in the Grünsee, which lies close to Königssee, but 1000 m higher. To trace the influence of stocking in Königssee we have analysed more than 300 individuals from 10 lake populations, including the source populations of the fish used for stocking. From these we have sequenced a part of the mitochodrial control region and have typed them at six microsatellite loci. The differential distribution of haplotypes, as well as assignment tests, show that the influence of stocking on the genetic integrity of the Königssee population has been negligible. However, our data reveal that in another lake included in our study (Starnberger See), the ancestral population was apparently replaced completely by the populations used for stocking. The major difference between the lakes is the relative preservation of ecological integrity. Königssee was ecologically stable in the past, whereas Starnberger See was heavily polluted at one point, with charr approaching extinction. Interestingly, in a lake neighbouring Starnberger See, the Ammersee, which was also subject to strong pollution but not stocked, the ancestral population has recovered. Our data suggest that the practice of artificial stocking should be reconsidered, or at least monitored for effectiveness. 相似文献
105.
A continuous pollen record covering the last 28 kyr was obtained from core C106 collected in the Bay of Salerno in the southern
Tyrrhenian Basin, seven radiocarbon dates and the recognition of two tephra layers (Y3 and Pompeii Pumice) providing good
chronological constraints. The clear climatic signal given by the pollen spectra integrated by isotopic data, combined with
comparisons with other Mediterranean sites, allowed the Last Glacial, Late Glacial and Holocene periods to be distinguished
in the core. In particular, the Last Glacial period is characterised by large quantities of herbaceous and steppe elements
such as Artemisia. The beginning of the Late Glacial has been correlated with the first increase of deciduous Quercus and the reduction of steppe and herbaceous elements. The Younger Dryas event is recorded only by oxygen isotopes while the
vegetation does not seem to change, as in other Mediterranean sites. The Holocene corresponds to rich deciduous and evergreen
forests. The first features which could be interpreted as signs of human presence are represented by a few grains of Juglans, Castanea and cereal-type while intensive olive cultivation and deforestation seem to fall within the Middle Ages.
Received October 10, 2001 / Accepted June 20, 2002
Correspondence to: Elda Russo Ermolli 相似文献
106.
Stuart?RossEmail author David?Evans Michael?Webber 《The International Journal of Life Cycle Assessment》2002,7(1):47-52
In recent years many workers have examined the implications of various sources of uncertainty for the reliability of Life
Cycle Assessment (LCA). Indeed, the International Standardization Organization (ISO) has recognised the relevance of this
work by including several cautionary statements in the ISO 14040 series of standards. However, in practice, there is a risk
that the significance of these uncertainties for the results of an LCA could be overlooked as practitioners strive to complete
studies on time and within budget. This paper presents the findings of a survey of LCA studies we made to determine the extent
to which the problem of uncertainty had been dealt with in practice. This survey revealed that the significance of the limitations
on the reliability of LCA results given in the standards has not been fully appreciated by practitioners. We conclude that
the standards need to be revised to ensure that LCA studies include at least a qualitative discussion on all relevant aspects
of uncertainty. 相似文献
107.
Valérie?Benoit Patrick?RousseauxEmail author 《The International Journal of Life Cycle Assessment》2003,8(2):74-82
Background and Objectives Multiple Criteria Decision Aid (MCDA) methods may be employed in a great number of fields. Life Cycle Assessment (LCA) is
a specific method among the MCDA Methods. A stage of MCDA methods to be respected in LCA is the comparative evaluation of
the environmental impacts. This stage is the most difficult to implement because it is a question of estimating the global
environmental impact of the life cycles studied. To achieve this purpose, it is necessary to model the environmental impacts
and to apply a Multicriteria Analysis (MCA) method. The problem is to choose the most suitable among the available MCA methods.
The objective of this paper is to help the LCA practitioner to make this choice.
Methodology The MCA methods are compared according to their non-compensatory degree, their sensitivity to thresholds, their practicability
and their workability.
Results and Conclusion The protocol presented in this paper allows to choose the most appropriate MCA method for a given LCA according to the four
previous criteria. This choice will depend on the priorities of the decision maker with concern to the comparison criteria. 相似文献
108.
109.
Bruno Notarnicola Gjalt Huppes Nico W. van den Berg 《The International Journal of Life Cycle Assessment》1998,3(5):289-300
LCA aims to help direct decisions in an environmentally sustainable direction. It indicates the environmental effects of choices
and evaluates these against this background. Approaches to evaluation in LCA differ substantially, related to the way of modelling
environmental effects and to the way these effects are combined into an overall judgement on alternative options. Several
approaches are now operational, which are linked to different paradigms in decision making. It is shown that the choice of
paradigm is quite decisive on the outcome of the analysis. Also within similar paradigms, different methods now operational
may lead to different outcomes. These latter differences may be alleviated more easily than those related to paradigmatic
choices, as they are partly a matter of refinement, and they partly result from legitimate differences in subjective priorities.
The more basic paradigmatic differences can hardly be bridged. The practical relevancy of the subject is proven by applying
different operational methods to one case, showing widely differing outcomes. The paradigm behind evaluating environmental
effects is either values based, directly or through policy decisions, or economics based, as individual preferences measured
in the monetary terms of willingness-to-pay. Accordingly, the different methods are “policy-oriented” or “monetary”. It may
be doubted if the differences between these can be overcome in standardisation. 相似文献
110.
David A.B. Stewart 《Journal of Insect Conservation》1998,2(3-4):263-276
In most locust or grasshopper control programmes, the proximate aim is to suppress grasshopper numbers. However, in the semi-arid Karoo, South Africa, only the brown locust (Locustana pardalina) has significant pest status. Non-target grasshoppers form a conspicuous and important part of the Karoo ecosystem, many being endemic. Grasshopper diversity was monitored in treated and untreated plots (0.25 ha) to establish the impact of spraying. Grasshopper abundance was significantly reduced one day after treatment. Vagile species recovered by immigration from the surrounding areas following the breakdown of chemical residues. Endemic apterous bushhoppers with low vagility recovered the following season after rainfall triggered hatching. Grasshopper numbers hatching in treated plots were significantly lower than in untreated plots the following summer season because of a reduction in the number of individuals in the preceding generation. However, species composition was similar to untreated plots and this reduction is unlikely to have significant, long-term biological effects in such small treated areas (0.25 ha being usual for hopper band control). The rate of recovery of grasshoppers, particularly bushhoppers, was linked to rainfall indicating that the timing of control relative to rainfall is important. Grasshopper assemblages are potentially useful indicators of the effect of chemical locust control in the Karoo. 相似文献