全文获取类型
收费全文 | 503篇 |
免费 | 11篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 107篇 |
金属工艺 | 4篇 |
机械仪表 | 6篇 |
建筑科学 | 40篇 |
能源动力 | 35篇 |
轻工业 | 69篇 |
水利工程 | 4篇 |
石油天然气 | 1篇 |
无线电 | 32篇 |
一般工业技术 | 86篇 |
冶金工业 | 26篇 |
原子能技术 | 2篇 |
自动化技术 | 99篇 |
出版年
2024年 | 9篇 |
2023年 | 8篇 |
2022年 | 17篇 |
2021年 | 12篇 |
2020年 | 13篇 |
2019年 | 17篇 |
2018年 | 9篇 |
2017年 | 14篇 |
2016年 | 16篇 |
2015年 | 14篇 |
2014年 | 20篇 |
2013年 | 33篇 |
2012年 | 33篇 |
2011年 | 61篇 |
2010年 | 25篇 |
2009年 | 20篇 |
2008年 | 19篇 |
2007年 | 25篇 |
2006年 | 13篇 |
2005年 | 18篇 |
2004年 | 19篇 |
2003年 | 16篇 |
2002年 | 11篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 6篇 |
1989年 | 1篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有514条查询结果,搜索用时 15 毫秒
481.
This study was carried out to investigate whether spray drift of metsulfuron has a potential to negatively affect hawthorn (Crataegus monogyna) hedgerows near agricultural fields. For this purpose four doses of metsulfuron ranging from 5% to 40% of the field dose (4 g metsulfuron per hectare) were sprayed on trees in seven different hawthorn hedgerows. The actual deposition on the leaves was measured by means of a tracer (glycine). Spraying was conducted both at the bud stage and at early flowering. Leaves, flowers, green berries and mature berries were harvested and the number and weight of each were measured. The spraying at the bud stage caused a highly significant reduction in number and dry weight of berries, whereas it had no effects on leaf and flower production. The berry reduction was close to 100% at actual depositions relevant for spray drift under normal conditions. Spraying at early flowering also significantly reduced berries although the effect was smaller than for the spraying at bud stage. The early flower stage spraying caused no reduction in number and size of leaves. The possible ecological consequence is that metsulfuron spray drift from agricultural fields has a potential to reduce the amount of berries available for frugivorous birds in nearby hedgerows. A potential need for regulatory measures to reduce herbicide spray drift to hedgerows situated near agricultural fields with herbicide use is also indicated. 相似文献
482.
Susceptibility of Lactobacillus spp. to antimicrobial agents 总被引:1,自引:0,他引:1
Bacteria used as probiotics or in starter cultures may serve as hosts of antibiotic resistance genes, which can be transferred to pathogenic bacteria. Before launching a starter culture or a probiotic product into the market, it is therefore important to verify that the single bacterial isolates (strains) do not contain transferable resistance genes. A study has been undertaken to establish the levels of susceptibility of Lactobacillus spp. to various antimicrobial agents. This is a prerequisite for differentiating putative transferable resistance from natural resistance. A selection of 62 strains has been screened with the use of the Etest (ABBiodisk, Stockholm, Sweden) for their susceptibility to 25 antimicrobial agents. The strains belonged to the following species: Lactobacillus plantarum/pentosus, L. rhamnosus, L. paracasei, L. sakei, L. curvatus and species of the L. acidophilus group: L. johnsonii, L. crispatus, L. gasseri, and L. acidophilus.The results from the Etests have shown that the level of susceptibility to the antimicrobial agents is species-dependent. For the following antimicrobial agents, susceptibility varied several folds between species: vancomycin, teicoplanin, tetracycline, norfloxacin, ciprofloxacin, fusidic acid, and clindamycin. The differences between the species were more subtle for the rest of the tested antimicrobial agents. On the basis of the result, it was possible to suggest minimal inhibition concentrations (MICs) for the individual Lactobacillus species to be used as a microbiological breakpoint when screening strains for transferable resistance genes. 相似文献
483.
Frits M. Andersen Morten S. Christensen Ole Michael Jensen Niels-Ulrik Kofoed Poul Erik Morthorst 《Energy Policy》2008
In Denmark, electricity consumption in first and second homes has developed quite differently. Since 1990, electricity consumption in ordinary residences has grown moderately, while consumption in weekend and second homes has increased considerably. In turn, this development has been blamed on a growing number of luxury cottages, new legislation permitting senior citizens to have their permanent address in their second home and a growing number of electric appliances. 相似文献
484.
Sorting of normal and abnormal milk at time of milking is done visually for conventional milking systems, but more concrete standards are needed when milking is done in automatic milking systems (AMS). Several panel tests were carried out to find out how different consumer groups, milkers and advisors look at and respond to the visual appearance of milk mixed with blood, in order to set a limit for what they think is acceptable. It is concluded from the test panel results that milk samples with 0.4% or more of blood all will be scored as pink and samples with 0.1% blood (about 6 microM-haemoglobin or 100 mg/l) can be visually detected if they are compared with milk samples without blood. The consumer group scored fewer of the samples with 0-1% blood as normal than did the professional groups. The test panel scored 65% of the samples with 1% blood as normal when milk was presented in a black strip cup, which is the reference method when foremilking takes place in a conventional parlour. Only 2% of the milk samples with 2% blood (about 120 microM-haemoglobin or 2000 mg/l) were scored as normal in a black strip cup and should consequently be detected by conventional as well as automatic systems. One model of AMS was tested for its ability to detect and separate milk coloured by blood. The model separated milk with > or = 6 microM-haemoglobin. Milk mixed with blood injected into the milk stream for a short time at the beginning of milking was not separated. We lack data on how blood is naturally expelled into milk and in what amount. We propose that cow composite milk with > 6 microM-haemoglobin should be separated because at this level milk will have a red tinge. 相似文献
485.
Flórez AB Danielsen M Korhonen J Zycka J von Wright A Bardowski J Mayo B 《The Journal of dairy research》2007,74(3):262-268
In order to establish cut-off values for Lactococcus lactis to six antibiotics to distinguish susceptible and intrinsically resistant strains from those having acquired resistances, the minimum inhibitory concentration (MIC) of tetracycline, erythromycin, clindamycin, streptomycin, chloramphenicol and vancomycin was determined in 93 different Lc. lactis strains using the Etest. These bacterial strains were originally isolated from dairy and animal sources in widely separated geographical locations. Cut-offs were defined on the basis of the distribution of the MICs frequency of the studied antibiotics, which in the absence of acquired determinants should approach to a normal statistical distribution. In general, the new cut-off values proposed in this study are higher than previously defined (European Commission, 2005. The EFSA Journal 223, 1-12). Based on these new values, all the strains tested were susceptible to erythromycin, chloramphenicol and vancomycin, and 79 susceptible to all six antibiotics. However, 11 strains (around 12%) were considered resistant to tetracycline (six of which had been identified after screening of a large collection of lactococci strains for tetracycline resistance) and five (5.4%) resistant to streptomycin. Of these, two fish isolates proved to be resistance to both tetracycline and streptomycin. From the tetracycline resistant strains, tet(M) and mosaic tet(L/S) genes were amplified by PCR, demonstrating they harboured acquired antibiotic resistance determinants. 相似文献
486.
487.
Rivers R Monaco R Mygind J Aaroe M Koshelets V 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2008,366(1877):2871-2880
If superconductors change as fast as possible as they pass through a phase transition, then the initial domain structure is constrained by causality. We shall see that Josephson junctions do indeed display such behaviour. However, we shall argue that causal bounds arise through the Gaussian nature of the order parameter, which can be thought of as a consequence of instabilities growing as fast as possible. 相似文献
488.
Xiaodong Zhang Le Luo Yu Yang Yingzi Li Christopher M. Schlick Morten Grandt 《国际生产研究杂志》2013,51(13):3471-3501
Human behaviour and organisational structure impact collaborative product development outcome on a large scale. Therefore, companies are continuously seeking new opportunities to increase the efficiency, effectiveness and predictability of their collaborative product development projects, and to develop innovative principles for organisational design and management such as multi-functional teams. However, there are many factors which have to be considered and assessed to systematically optimise organisational planning in respect of team configuration, structure organisation, and human behaviour. This paper proposes an agent-based simulation methodology to evaluate and improve the organisational planning in complex product development projects. An agent-based integrated simulation model is formulated which can explicitly represent human behaviour, organisational interactions, and tasks networks. Based on the model, the design agent structure and behaviour protocols are studied in detail, and a simulation platform is developed. Finally, the methodology is evaluated in a collaborative roadway design project, and several management insights are established, which are proven to be effective for the organisational optimisation. The results of the case study also show that the methodology can effectively support the evaluation and improvement of organisational planning. 相似文献
489.
This paper describes the principles, architecture and design details for using the Blender Game Engine in real-time production device emulation. An emulation system for a real material transport and handling production installation was implemented based on this. A prototype of a distributed production control system was run on top of the device emulation system to evaluate feasibility. A cardinal architectural principle is the clear distinction between production controllers and production devices. This principle, applicable through flexible communication middleware, enables the implementation of portable production controllers that execute transparently on either the emulated or the real production system. Production system engineers may take advantage of this approach to develop and gain confidence in complex production control solutions. 相似文献
490.
Richard Sikkema Monika Steiner Martin Junginger Wolfgang Hiegl Morten Tony Hansen Andre Faaij 《Biofuels, Bioproducts and Biorefining》2011,5(3):250-278
The wood pellet market is booming in Europe. The EU 2020 policy targets for renewable energy sources and greenhouse gas (GHG) emissions reduction are among the main drivers. The aim of this analysis is to map current European national wood pellet demand and supplies, to provide a comprehensive overview of major market types and prices, and to discuss the future outlook in light of raw material supply. Approximately 650 pellet plants produced more than 10 million tonnes of pellets in 2009 in Europe. Total European consumption was about 9.8 million tonnes, of which some 9.2 million tonnes is within the EU‐27, representing a modest 0.2% of Gross Energy Consumption (75 EJ level in 2008). The prices of most pellet types are increasing. While most markets of non‐industrial pellets are largely self‐sufficient, industrial pellet markets depend on the import of wood pellets from outside the EU‐27. Industrial pellet markets are relatively mature, compared to non‐industrial ones, because of their advanced storage facilities and long‐term price‐setting. However, industrial pellet markets are unstable, depending mainly on the establishment or the abolishment of public support schemes. Following our scenarios, additional 2020 demand for woody biomass varies from 105 million tonnes, based on market forecasts for pellets in the energy sector and a reference growth of the forest sector, to 305 million tonnes, based on maximum demand in energy and transport sectors and a rapid growth of the forest sector. Additional supply of woody biomass may vary from 45 million tonnes from increased harvest levels to 400 million tonnes after the recovery of slash via altered forest management, the recovery of waste wood via recycling, and the establishment of woody energy plantations in the future. Any short‐term shortages within the EU‐27 may be bridged via imports from nearby regions such as north west Russia or overseas. © 2011 Society of Chemical Industry and John Wiley & Sons, Ltd 相似文献