全文获取类型
收费全文 | 268篇 |
免费 | 29篇 |
国内免费 | 55篇 |
出版年
2023年 | 39篇 |
2022年 | 8篇 |
2021年 | 8篇 |
2020年 | 16篇 |
2019年 | 24篇 |
2018年 | 15篇 |
2017年 | 11篇 |
2016年 | 8篇 |
2015年 | 12篇 |
2014年 | 8篇 |
2013年 | 18篇 |
2012年 | 12篇 |
2011年 | 19篇 |
2010年 | 10篇 |
2009年 | 14篇 |
2008年 | 4篇 |
2007年 | 16篇 |
2006年 | 7篇 |
2005年 | 7篇 |
2004年 | 11篇 |
2003年 | 11篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 8篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有352条查询结果,搜索用时 31 毫秒
331.
Gereon Müller 《Morphology》2007,17(1):1-38
It is shown that assuming instances of syncretism to be systematic in the unmarked case may significantly reduce the number
of possible inflection classes that can be generated on the basis of a given inventory of markers, without recourse to specific
constraints like Carstairs’ (Allomorphy in Inflection, Croom Helm 1987) Paradigm Economy Principle or Carstairs-McCarthy’s (Language 70:737–787, 1994) No Blur Principle. If there is always one radically underspecified (i.e., elsewhere) marker per morphological
domain, and if there is always one unique marker that is chosen in cases of marker competition, it turns out that there can
be at most 2
n
− 1 inflection classes for n markers, independently of the number of instantiations of the grammatical category that the markers have to distribute over.
The argument relies on the notion of marker deactivation combinations. 相似文献
332.
333.
Karan Bhuwalka Randolph E. Kirchain Elsa A. Olivetti Richard Roth 《Journal of Industrial Ecology》2023,27(1):141-154
Raw materials costs form an increasingly significant proportion of the total costs of renewable energy technologies that must be adopted at unprecedented rates to combat climate change. As the affordable deployment of these technologies grows vulnerable to materials price changes, effective strategies must be identified to mitigate the risk of higher input costs faced by manufacturers. To better understand potential threats to deployment, a market modeling approach was developed to quantify economic risk factors including material demand, substitutability, recycling, mining productivity, resource quality, and discovery. Results demonstrate that price changes are determined by interactions between demand growth, mining productivity, and resource quality. In the worst cases with high demand and low productivity, development of material substitutes and large recycling rates help reduce the prevalence of price risk from over 90% to under 10%. Investing in these strategies yields significant benefits for manufacturers and governments concerned about costs of materials critical to decarbonization and other advanced technologies. 相似文献
334.
Chemical recycling (CR) could support a circular approach for municipal solid waste (MSW) treatment. In promoting the recirculation of recyclable carbon-containing waste as secondary feedstock for chemical production, it could contribute to resource conservation, emissions reduction, and supply security. To evaluate CR's contribution to the transition from a linear to a circular carbon economy—and correspondingly to the achievement of environmental, economic, and social sustainability as indicated in the UN Sustainable Development Goals (UN-SDGs)—this study builds on extant literature of life cycle sustainability assessment (LCSA) to investigate consequential environmental, economic, and social CR impacts. Specifically, an integrated approach whereby process-based life cycle assessment, techno-economic analysis, and social indicators are linked in the framework of an agent-based model is developed to investigate sustainability consequences of CR via gasification of residual MSW in Germany. Results suggest that CR contributes to reducing climate change and to addressing terrestrial acidification and fossil resource scarcity. However, its deployment will be associated with significant system costs. Hence, to promote CR implementation, measures such as obliging direct waste incineration to trade CO2 certificates—provided that certificate prices increase sharply in the future—as well as implementing a recycling rate are found to be necessary to gap economic disadvantages. This study not only contributes to extending life cycle approaches for LCSA methodologically, it furthermore provides valuable insights into temporal and spatial interactions in waste management systems to inform science, industry, and politics about the sustainability impacts of CR on the achievement of the UN-SDGs. This article met the requirements for a gold-gold JIE data openness badge described at http://jie.click/badges . 相似文献
335.
Barbara V. Kasulaitis Callie W. Babbitt Andrew K. Krock 《Journal of Industrial Ecology》2019,23(1):119-132
The rapid technological evolution and adoption of consumer electronics highlights a growing need for adaptive methodologies to evaluate material consumption at the intersection of technological change and increasing consumption. While dematerialization and the circular economy (CE) have both been proposed to mitigate increasing material consumption, recent research has shown that these methods may be ineffective at achieving net material use reduction: When focused on specific products, these methods neglect the effects of complex interactions among and increasing consumption of consumer electronic products. The research presented here develops and applies a material flow analysis aimed at evaluating an entire “product ecosystem,” thereby including the effects of increasing consumption, product trade‐offs, and technological innovations. Results are then used to evaluate the potential efficacy of “natural” dematerialization (occurring as technology advances or smaller products substitute for larger ones) and CE (closing the loop between secondary material supply and primary material demand). Results show that material consumption by the ecosystem of electronics commonly used by U.S. households peaked in 2000. This consumption relies on increasingly diverse materials, including gold, cobalt, and indium, for whom secondary supply is still negligible, particularly given low recovery rates, often less than 1%. Potential circularity metrics of material “dilution,” “dispersion,” and “demand mismatch” are also evaluated, and indicate that CE approaches aimed at closing the loop on consumer electronic material still face several critical barriers particularly related to design and efficient recycling infrastructure. 相似文献
336.
337.
338.
African countries are today the major importers of the lowest grade of second-hand clothing (SHC). With the opening of global markets and the intense circulation of fast fashion in the Global North from the 1990s, the trade of SHC has exploded in the twenty-first century. The fast fashion business model, which fuels the SHC trade, has led to reduced quality of clothes, limited clothing lifetime, and accelerated discard of clothing, which end up as donations or become waste. The complexity of the international geographies of the SHC trade creates opacity and secrecy, maintaining inequalities and imbalances between Global North (GN) and South (GS), which continue a relationship of colonial dependence. This paper presents a critical look at SHC exchange in Kantamanto, the biggest SHC market in West Africa, situated within the central business district of Accra, Ghana. The paper scrutinizes the export of unwanted donated clothing, popularly known as “Obroni w'awu” (white man is dead), to Kantamanto. We use direct observation along with an interpretive research design through the analysis of photos taken from Kantamanto, and scholarly and gray literature. The paper documents local practices of reuse, exposing a duality: on the one hand, clothing's symbolic value that is lost in the GN is reconstituted in the GS through exchange and labor-creating local economies. On the other, the global trade of SHC has become synonymous with dumping, continuing a colonialist relationship between the GN and GS whereby the GN exports unwanted clothing to predominantly African countries’ landfills. 相似文献
339.
Summary
In situ acetylene reduction assays (ARA) were carried out over two growing seasons at 2550 m in the upper alpine zone of the Tyrolean Central Alps of Austria. For comparative purposes, some Fabaceae species introduced into the upper alpine zone from lower elevation (2000 m) were subjected to ARA. At the end of the growing season the potted plants were transferred to the laboratory where their acetylene reducing activities were measured again. In situ nitrogenase activity is very low. The highest values were found in association with Leucanthemopsis alpina and Veronica bellidioides (150 and 217 nmol ethylene 24 h-1 per pot respectively). Higher levels of activity were detected in pots transferred to the laboratory (maximum value 750 nmol ethylene 24 h-1 per pot; assay temperature about 12°C higher than in the field) and in the Fabaceae transferred to the upper alpine zone (14×103 nmol ethylene 24 h-1 per pot of Trifolium badium and T. pallescens). Maximum nitrogen input in the field is in the range of 8 mg m-2 a-1. Therefore, under natural circumstances biological nitrogen fixation contributes only very small amounts of nitrogen to this alpine vegetation system, the process being inhibited by low soil temperatures. Possible alternative sources and patterns of N acquisition are discussed in relation to the overall nitrogen economics of plants of the upper alpine zone. 相似文献
340.