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31.
D. Bruce Henschel 《Indoor air》1997,7(3):206-214
Abstract A computational sensitivity analysis was conducted to identify the conditions under which residential active soil depressurization (ASD) systems for indoor radon reduction might most likely exacerbate or create back-drafting of natural-draft combustion appliances. Parameters varied included: house size; normalized leakage area; exhaust rate of exhaust appliances other than the ASD system; and the amount of house air exhausted by the ASD system. Even with a reasonably conservative set of assumptions, it is predicted that ASD systems should not exacerbate or create back- drafting in most of the U.S. housing stock. Only at normalized leakage areas lower than 3 to 4 cm2 (@ 4 Pa) per m2 of floor area should ASD contribute to back-drafting, even in small houses at high ASD exhaust rates (compared to a mean of over 10 cm2/m2 determined from data on over 12,000 U.S. houses). But on the other hand, even with a more forgiving set of assumptions, it is predicted that ASD systems could contribute to back-drafting in some fraction of the housing stock – houses tighter than about 1 to 2 cm2/m2– even in large houses at minimal ASD exhaust rates. It is not possible to use parameters such as house size or ASD system flow rate to estimate reliably the risk that an ASD system might contribute to back-drafting in a given house. Spillage/back-draft testing would be needed for essentially all installations. 相似文献
32.
通过理论分析和文献综述,阐述了长期过量不合理开采地下流体是城市密集化高层建筑等地面沉降形成的原因,详细分析和简述了地面沉降给沿海地区带来的危害以及地面沉降的概况、发展趋势。最后,提出了"预防为主,防治结合"防治策略,如加强宣传、建立地面沉降观测网、地下水回灌、调整采水层等防治措施。 相似文献
33.
The costs and potential for several carbon mitigation options were analyzed for Tompkins County, NY, within several categories: terrestrial carbon sequestration, local power generation, transportation, and energy end-use efficiency. The total county emissions are about 340 Gg C/year, with current biomass sequestration rates of about 121 Gg C/year. The potential for mitigation with the options examined, assuming full market penetration, amounts to at least 234 Gg C/year (69%), with 100 Gg C/year (29%) at no net cost to the consumer. Effective carbon mitigation strategies for this county based on costs per mg carbon and maximum potential include reforestation of abandoned agricultural lands for terrestrial carbon sequestration, biomass production for residential heating and co-firing in coal power plants, changes in personal behavior related to transportation (e.g., carpooling or using public transportation), installation of numerous residential energy-efficient products and development of local wind power. The principal barriers to the implementation of these approaches are discussed and policies for overcoming these barriers are analyzed. 相似文献
34.
Olav Benestad Lars Brinck Lennart Emborg Bjarne Juul-Kristensen Alexander Kristiansen Niels I. Meyer Kysti Pulliaine Eivind Selvig Anssi Vaittinen 《Energy Policy》1993,21(12):1225-1236
The concept of a sustainable energy sector has received wide attention since the publication of the Brundtland Report in 1987. This paper analyses the possibilities of establishing by 2010 and 2030 an energy system in the Nordic countries which prevents the critical loads of NOx and SO2 respectively on the most vulnerable Nordic ecological systems being exceeded. In addition, the present concentration of CO2 in the atmosphere should not be significantly exceeded within a time horizon to around 2050. Different scenarios have been investigated in order to analyse the scope for attaining such a sustainable energy development within the limits of existing technologies and known potentials of renewable energy sources. Data on the technologies are available in a special catalogue. 相似文献
35.
Development of global electric generation and distribution systems will be central to mankind's economic and social well being. However, electricity is likely to be produced mainly from fossil fuel combustion for the foreseeable future. As a consequence, this global energy sector will contribute to growing carbon dioxide emissions, with a potential for climate alteration. Concern for potentially adverse climate effects has led to consideration of strategies for managing GHG emissions. With present technologies, extreme reduction strategies will be costly and may create significant stress on the projected world economic and energy systems. Technological options have been evaluated to a modest degree. These range from conventional emission control approaches to geo-engineering opportunities and biospheric carbon management. To be practical, these options need to be developed further and demonstrated to properly assess their operational characteristics. 相似文献
36.
Cardenas LM Cuttle SP Crabtree B Hopkins A Shepherd A Scholefield D del Prado A 《The Science of the total environment》2011,409(6):1104-1115
As much as 60% of the nitrate in water in England is thought to derive from agriculture. Legislation aims to improve water quality by limiting nitrate concentration in surface and groundwaters to 50 mg l−1. The UK Government responded to the requirements of the EC Nitrate Directive by delineating Nitrate Vulnerable Zones (NVZs) to cover 55% of England in 2002 and increased it to 70% in 2009. In this study we assessed the cost-effectiveness of measures for implementation in livestock systems to mitigate nitrate leaching in the UK. These estimates were prepared for a range of hypothetical farms representative of typical dairy, beef and sheep farms at different locations in England and Wales and for a list of mitigation measures identified to reduce leaching. The NGAUGE and NFixCycle models were used to estimate leaching from these systems. The costs of implementation of the mitigation measures were also assessed in order to evaluate the cost-effectiveness of these measures. In general, the most effective measures to reduce leaching for all systems were the ones that involved a reduction in stocking rates and grazing time, followed by those involving improvements in fertiliser and crop management. Only in the case of the dairy system was effectiveness affected by location of the farm. The costs for implementation in the sheep system were relatively low compared with beef and dairy systems. Implementation of some of the measures with high cost-effectiveness would need to be incentivised financially or with legislation due to the high costs involved. 相似文献
37.
The systematized study of urban morphology has led to the development of integrated tools based on the knowledge of the relation between physical density and urban form. These tools do help planners and decision makers; however, environmental data is rarely included in them.This paper presents the GWP-Chart, a method that combines urban planning tools with environmental data, obtained through the use of the life cycle assessment (LCA) results. In order to explain its use, three urban fabrics have been selected. According to their morphology and their ground space index (GSI) and public space ratio (PSR) values, the contribution of the sidewalk subsystem to the global impact per square meter of urban development can be quantified and communicated.The GWP-Chart is applicable to all types of urban fabrics and scales (street or square, island, fabric or district), as well as adaptable to any urban infrastructure or subsystem and can be extended to other environmental impacts. Its advantages lie in its accurateness, adaptability and ease of interpretation. 相似文献
38.
The cooling effect of green spaces as a contribution to the mitigation of urban heat: A case study in Lisbon 总被引:2,自引:0,他引:2
Green areas in the urban environment can contribute to the mitigation of the Urban Heat Island. In a context of climate change, with the expected increase in temperature, dryness and intensity of heat waves, green areas assume even higher importance as they can create a cooling effect that extends to the surrounding areas. This study analyses the thermal performance of a small green space (0.24 ha) and its influence in the surrounding atmospheric environment of a densely urbanised area in Lisbon. Measurements of weather parameters (temperature, relative humidity, wind speed, solar and infrared radiation) were carried out along a selected path, starting from inside the green area to surrounding streets with different orientations and solar exposure. It was found that the garden was cooler than the surrounding areas, either in the sun or in the shade. These differences were higher in hotter days and particularly related to the mean radiant temperature (Tmrt). The highest difference found was of 6.9 °C in relation to air temperature and 39.2 °C in relation to Tmrt; in both cases this difference occurred between the shaded site inside the garden and the sunny site in an E–W oriented street in the southern part of the studied area. Besides the local weather conditions, particularly the low wind speed, the sun exposure and the urban geometry are the potential factors that explain these differences. The cooling effect of green areas on the surrounding environment can be enhanced by additional measures related to the urban features of each city. 相似文献
39.
40.
组合预测模型在电力系统负荷预测中的应用研究 总被引:1,自引:0,他引:1
本文基于灰色预测模型、滑动平均模型和指数平滑模型这三种单一预测模型,采用方差-协方差策略,建立组合预测模型。然后结合老挝电力系统的概况,对老挝的全国年用电量进行预测和分析。结果表明,组合预测模型的预测精度明显高于各单一预测模型,即组合预测模型的相对误差小于各单一预测模型的相对误差,说明组合预测模型具有相当的适用性和优越性。 相似文献