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991.
Biogas production is mainly based on the anaerobic digestion of cereals silages and maize silage is the most utilized. Regarding biogas production, the most important portion of the plant is the ear. The corn ear, due to high starch content, is characterized by a higher biogas production compared to the silage of the whole plant.In this paper, we present the results of experimental field tests carried out in Northern Italy that aim to evaluate the anaerobic methane potential (BMP) of different portions of ensiled maize hybrids. The BMP production is evaluated considering the possibility of harvesting and ensiling: the whole plant; the plant cut at 75 cm of height; the ear only; the plant without the ear. For the different solutions, the results are reported as specific BMP and as average biogas production achievable per hectare. The methane production by harvesting and ensiling the whole plant (10,212 and 10,605 m3 ha−1, for maize class 600 and 700, respectively) is higher than the ones achievable by the other plant portions (7961 and 7707 m3 ha−1, from the ear; 9523 and 9784 m3 ha−1, from the plant cut at 75 cm; 3328 and 3554 m3 ha−1, from the plant without the ear, for maize class 600 and 700, respectively). The harvest of the whole plant, although it is the most productive solution, could not be the best solution under an economic and environmental point of view. Harvesting only the ear can be interesting considering the new Italian subsidy framework and for the biogas plants fed by biomass transported over long distances. 相似文献
992.
The use of forest biomass for energy production is growing in Europe and biomass energy plants market is constantly increasing. However, there is the need to define the environmental sustainability issues dealing with the emerging renewable energy scenario. In particular, the polluting emissions (i.e. PMx, NOx and ozone) caused by the biomass combustion heavily impact on the air quality. In this context, the elemental characterization of the wood and the element allocation in the different tree organs, can provide important information about the quality of the derived wood fuels and give hints about the choice of the most appropriate combustion technique and/or the right wood fuel for a given combustion technique. Moreover, since elements have different concentrations in the different plant tissues, the preventive knowledge of the elements allocation can lead to the identification of the best harvesting strategy aimed at producing wood fuel with the lowest possible ash forming elements and environmental impact.This work focuses on the allocation in three tree compartments (foliage, branches and stem) of five important macroelements (K, Mg, Ca, N and P) in Norway spruce (Picea abies), and points out the possible effects of different harvesting strategies and tree age on the quality of the wood fuels. Results suggest that the Stem Only Harvesting is preferable to Whole Tree Harvesting system in terms of prevention of mineral content loss, as well as is preferable to avoid forest biomass from young trees because of the poorer fuel quality of the wood chips. 相似文献
993.
This study estimates the potential physical amounts and financial costs of post-harvest forest residue biomass supply in Canada. The analyses incorporate the locations of harvest activities in Canada, the geographical variation of forest productivity patterns and the costs associated with the extraction and transportation of residue feedstock to bioenergy facilities. We estimated the availability of harvest residues within the extent of industrial forest management operations in Canadian forests. Our analyses focused on the extraction of biomass from roadside harvest residues that involve four major cost components: pre-piling and aggregation, loading, chipping and transportation. The estimates of residue extraction costs also included representation of basic ecological sustainability and technical accessibility constraints. Annual supply of harvestable residual biomass with these ecological sustainability constraints were estimated to be approximately 19.2–23.3 Tg*year−1 and 16.5–20.0 Tg*year−1 in scenarios that included both ecological and technical accessibility limitations. These estimates appear to be less than other similar studies, due to the higher level of spatial details on inventories and ecological and operational constraints in our analyses. The amount of residual biomass available in baseline scenarios at a supply cost of $60 ODT−1 and $80 ODT−1 were 1.08 and 1.38 Tg year−1 and 7.82 and 10.14 Tg year−1 respectively. Decreasing residue extraction costs by 35% increased the amount of residues available at a $60 ODT−1 and $80 ODT−1 supply price by ∼5.5–5.7 and ∼1.5–1.6 times respectively. The assessment methodology is generic and could be extended to examine residue supplies for specialized biomass markets such as lignocellulosic ethanol production. 相似文献
994.
《Energy Policy》2013
This article investigates possible evolution pathways for the transport sector during the 21st century, globally and in Europe, under a climate change control scenario. We attempt to shed light on the question how the transport sector should best be decarbonized. We perform our study with the global bottom-up energy systems model TIAM-ECN, a version of the TIAM model that is broadly used for the purpose of developing energy technology and climate policy scenarios, which we adapted for analyzing in particular the transport sector. Given the global aggregated perspective of TIAM-ECN, that in its current version yields at every point in time a single CO2 price for different forms of energy use across geographic regions and economic sectors, it generates a decarbonization process that for the transport sector occurs later in time than for the power sector. This merely reflects that emission reductions are generally cheaper for electricity production than for transportation, and that it is thus cost-minimizing to spend limited financial resources available for CO2 emissions abatement in the power sector first. In our scenarios the use of hydrogen in internal combustion engines and fuel cells, rather than electricity as energy carrier and batteries to store it, gradually becomes the dominant transport technology. This outcome is in agreement with some recent publications but is at loggerheads with the current popularity of the electric car. Based on sensitivity analysis we conclude that even if the establishment of a hydrogen infrastructure proves about an order of magnitude more costly than modeled in our base case, electricity based transportation only broadly emerges if simultaneously also the costs of electric cars go down by at least 40% with respect to our reference costs. One of the explanations for why the electric car is today, by e.g. entrepreneurs, often considered the supposed winner amongst multiple future transportation options is that the decision horizon of many analysts is no more than a few decades, instead of a full century. Electric cars fit better the current infrastructure than hydrogen fueled vehicles, so that from a short time perspective (covering the next decade or two) investments are not optimally spent by establishing an extensive hydrogen distribution network. Hence the path-dependency created by the present existence of a vast power transmission and distribution network can make electricity the most efficient choice for transportation, but only if the time frame considered is short. Electric transportation generally proves the more expensive alternative in our long-term perspective, except when electric car costs are assumed to drop substantially. 相似文献
995.
The objective of this study was to analyse the economic profitability of producing energy-grass fuels on marginal agricultural land in Sweden. Small and irregular-shaped fields, fields with less fertile soils, headlands and border strips were included, all located in four different regions representing different cultivation conditions. The grasses studied were reed canary grass (RCG) and ley, which were to be used as a solid fuel and biogas substrate, respectively. The economic profitability of these grasses was compared with the profitability of fallow land and the cultivation of winter wheat and spring barley. The results showed that all the alternatives studied, except winter wheat in southern Sweden, had a negative economic net gain (no subsidies included). Generally, the economic losses were greatest for small and irregular-shaped fields. Fallow had a higher economic competitiveness than RCG and ley for all marginal field categories and locations. RCG used as a solid fuel in boilers generally had a higher competitiveness than ley for biogas. However, when ley was used fresh without storage, its competitiveness improved considerably. Taking the direct payment subsidies and the economic value of reduced nutrient leakage into account, the economic net gain improved considerably. Nevertheless, fallow land still had a somewhat higher net gain than RCG for all field categories. Further cost reductions and higher revenues, including possible agro-environmental economic compensation, are required if RCG and ley are to be able to compete with fallow land. 相似文献
996.
As two of the most important instruments for dealing with the issues of energy supply security, strategic petroleum reserves (SPRs) and oil import tariffs have been proven effective in developed countries. While China is currently building up its strategic oil reserves to ensure energy security, it is of great importance to investigate China's optimal oil stockpiling policies while taking into account the possibility of imposing an import tariff or quota, which can also be used for alleviating the energy insecurity of an oil-importing country. Employing a dynamic programming framework, this paper examines the optimal SPR policies and oil import tariffs or quotas for China and the interactions between the two instruments under different scenarios for the world oil market. The results show that the combination of optimal tariffs and SPR policies can substantially reduce the expected oil insecurity cost for China; the effect is larger when the probability that a disruption will continue is higher. 相似文献
997.
《Energy Policy》2014
Evidence suggests that state control of wind facility siting decisions fosters new project development more effectively than local control, yet the literature suggests that affected citizens tend to be more fairly represented in local siting processes. We argue that successful renewable energy policy must satisfy both the need for new project development and the obligation to procedural justice. To suggest how it can do so, we analyze existing state- and county-level siting processes in Washington state, finding that both fall short on measures of procedural justice. To overcome this limitation and address the tension between procedural justice and project development, we then propose a collaborative governance approach to wind facility siting, in which state governments retain ultimate authority over permitting decisions but encourage and support local-level deliberations as the primary means of making those decisions. Such an approach, we argue, would be more just, facilitate wind development by addressing community concerns constructively and result in better projects through the input of diverse stakeholders. 相似文献
998.
The purpose of this paper is to investigate both environmental effects and cost effects of using less specified contracts regarding bus sizes in public bus transports. The process of choosing the best bid in the public procurement of bus transports is easier if the demands of the qualifications are well specified and detailed. On the other hand, detailed contracts can force the entrepreneurs to use less environmentally friendly and uneconomical alternatives. A mathematical model with binary variables is developed to evaluate the environmental and the economical effects of more optimized bus sizes. Computational results from a bus service provider are reported. The results of the model indicate that the emissions decrease considerably by using less detailed contracts. The results of a sub case indicate that the costs could be reduced as well, depending on how efficient the additional buses can be planned. The process of choosing the best bid in the public procurement process will be more complicated when the contracts are less detailed compared to current situations. 相似文献
999.
《International Journal of Hydrogen Energy》2004,29(9):955-960
The performance of a Nickel/Metal Hydride (Ni/MH) battery closely depends on the characteristics of the negative MH electrode. Exchange current density, high-rate dischargeability, discharge potential and apparent activation energy of a MH electrode are very important properties, among which the high-rate dischargeability and discharge potential of a MH electrode determine the specific energy and specific power of electric vehicles (EVs) when Ni/MH batteries are applied to EVs. Significant improvements in exchange current density, high-rate dischargeability and discharge potential of a MH electrode have been observed for a % copper coated LaNi4.7Al0.3 MH electrode. The high-rate dischargeabilities were determined to be 88.4% for the LaNi4.7Al0.3 electrode and 99.4% for Cu-coated LaNi4.7Al0.3 electrode. The discharge potential for the Cu-coated LaNi4.7Al0.3 electrode is lower (i.e. more negative) than that for the LaNi4.7Al0.3 electrode, especially at a large discharge current density (i.e. ). The discharge potentials of the Cu-coated LaNi4.7Al0.3 electrode are almost the same value (i.e. vs. Hg/Hgo) at both 20 and discharge current densities. There is no significant difference between the two apparent activation energies for the electrode reactions for the electrodes with and without the microencapsulation of the MH powders at the same hydrogen concentration. 相似文献
1000.
《Journal of power sources》2004,129(1):101-106
Electrochemical performance and spectroscopic characterization of native and TiO2-coated LiNi0.8Co0.2O2 were investigated. The electrochemical results showed TiO2-coated materials exhibited better cycle stability in the different potential regions (i.e. 3.0–4.3 and 3.0–4.6 V) and the decomposition of the electrolytes was suppressed on coated materials surface. In addition, FT-IR and temperature-programmed desorption–mass spectroscopy (TPD–MS) results demonstrated that different oxidation products were formed on the native and coated electrodes. A possible decomposition mechanism of the electrolytes has been proposed based on our results. 相似文献