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781.
Diffusivity of propolis compounds in Polylactic acid polymer for the development of anti-microbial packaging films 总被引:1,自引:0,他引:1
Erika Mascheroni Valérie Guillard Federico Nalin Luigi Mora Luciano Piergiovanni 《Journal of food engineering》2010
A major research gap is the lack of packaging materials that can provide the release of active compounds at rates suitable for a wide range of food packaging applications. For this reason an anti-microbial/antioxidant release system for food packaging applications was realized by incorporation of propolis into Polylactic acid (PLA) film. The composition of the films was modified by adding polyethylene glycol (PEG) and calcium bentonite (CB) to the initial PLA casting solution; dispersed structures in fact open the molecular network and increase migration rates. The presence of the anti-microbial compound is required essentially at the food surface where the microorganisms are numerous and where they are intended to grow. The diffusivity of four polyphenols was measured in water and ethanol as food simulating liquids (FSL) and the concentration of additives at the interface PLA/Food Simulant was calculated using Fickian models. The external mass transfer coefficient at the interface polymer/FSL could be neglected (with Bi number higher than 200). This is due to the low diffusivity values of propolis polyphenols in the PLA matrix (0.03–0.83 × 10–13 m2/s) which lead to a predominant internal mass transfer phenomenon compared to the external one in the system PLA/water. The concentration at interface at equilibrium was different for each substance and depended of the thermodynamical parameter K. Such a delivery system for direct contact with liquid aqueous medium would be a very efficient delivery system because some active agents (polyphenols acids) would be released in relevant quantity in the food whereas others (flavonoids) would remain in the polymer to act at the polymer/food interface. 相似文献
782.
In the High Frequency (HF) field, the primary power standard is maintained through reference sensors calibrated in terms of effective efficiency ηe. These devices are in turn used to transfer the power standard by means of direct comparison on the same matched generator. For this kind of operation, the only knowledge of the effective efficiency of the device is not enough and additional parameters of the reference sensor are necessary.The paper describes the methods and techniques used at INRIM to disseminate the “HF power standard”, with emphasis to all the technical aspects involved, in order to provide a thorough explanation of the procedures implemented. 相似文献
783.
784.
This paper compares two different methods for combining PCA and ANOVA for sensory profiling data. One of the methods is based on first using PCA on raw data and then relating dominating principal components to the design variables. The other method is based on first estimating ANOVA effects and then using PCA to analyse the different effect matrices. The properties of the methods are discussed and they are compared on a data set based on sensory analysis of a candy product. Some new plots are also proposed for improved interpretation of results. 相似文献
785.
Sequential modeling of a low noise amplifier with neural networks and active learning 总被引:1,自引:0,他引:1
Dirk Gorissen Luciano De Tommasi Karel Crombecq Tom Dhaene 《Neural computing & applications》2009,18(5):485-494
The use of global surrogate models has become commonplace as a cost effective alternative for performing complex high fidelity
computer simulations. Due to their compact formulation and negligible evaluation time, global surrogate models are very useful
tools for exploring the design space, what-if analysis, optimization, prototyping, visualization, and sensitivity analysis. Neural networks have been proven particularly
useful in this respect due to their ability to model high dimensional, non-linear responses accurately. In this article, we
present the results of an extensive study on the performance of neural networks as compared to other modeling techniques in
the context of active learning. We investigate the scalability and accuracy in function of the number design variables and
number of datapoints. The case study under consideration is a high dimensional, parametrized low noise amplifier RF circuit
block. 相似文献
786.
Luciano Pecetti Aldo Tava Mario A Pagnotta Luigi Russi 《Journal of the science of food and agriculture》2007,87(6):985-991
Native Bituminaria bituminosa (L.) Stirt. accessions from central and southern Italy were evaluated for chemical composition to assess their nutritional value as forages. The germplasm was evaluated subjectively ex situ for intensity of ‘oil’ smell and analysed for fibre fraction, crude protein and water‐soluble carbohydrate contents as well as furanocoumarin (psoralen and angelicin) concentration. Total phenolics and their antioxidant activity were also evaluated. The quality parameters indicated this species as a good forage source, showing nutritive values similar to those of other wild legume species. Psoralen and angelicin contents ranged from 2.8 to 5.4 and from 2.3 to 4.7 mg g?1 dry weight respectively, while total phenolic concentrations were between 11.2 and 13.5 mg g?1 dry weight. Correlations among forage quality parameters, chemical components and climatic features at sites of origin were also assessed. Copyright © 2007 Society of Chemical Industry 相似文献
787.
788.
Laura Franzetti Stefano Martinoli Luciano Piergiovanni Antonietta Galli 《Packaging Technology and Science》2001,14(6):267-274
The effectiveness of an innovative foam plastic tray, provided with absorbers for volatile amines and liquids, on the shelf‐life of different fish products packed under a modified atmosphere (40%CO2:60%N2), was evaluated in comparison with a standard tray. Fillets of sole (Solea solea), steaks of cod (Merluccius merluccius) and whole cuttlefish (Sepia fillouxi), placed in the two different kinds of trays, were kept at 3°C. Microbiological (TBC‐, Gram‐negative‐, H2S‐producing bacteria and lactic acid bacteria) and chemical (surface pH, TMA headspace) analyses were carried out after 3, 7 and 10 days of storage. The new packaging, associated with a rigorous control of storage temperature, increased the shelf‐life up to 10 days. In fact, the innovative tray sequestrated the greater part of trimethylamine from the headspace and led to delayed microbial growth, especially of Gram‐negative and H2S‐producing bacteria, and in addition it favoured the growth of bacterial strains such as Moraxella phenylpiruvica , which are not involved in off‐flavouring production (especially H2S), because of their lypolitic activity. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
789.
Luciano Baresi Elisabetta Di Nitto Carlo Ghezzi Sam Guinea 《Service Oriented Computing and Applications》2007,1(1):75-91
The basic paradigm of service-oriented architectures—publication, discovery, and use—can be interpreted in different ways.
Current technologies assume a static and rigid approach: UDDI was conceived with the idea of a centralized repository for
service publication and BPEL only supports design–time bindings between the orchestrated workflow and the external services.
The trend, however, is towards more flexibility and dynamism. The single centralized repository is being substituted by dedicated
repositories that cooperate and exchange information about stored services on demand. Design–time compositions are complemented
by mechanisms to allow for the selection and binding of services at runtime.
This paper presents the research results of our group in delivering a framework for the deployment of adaptable Web service
compositions. The publication infrastructure integrates existing heterogeneous repositories and makes them cooperate for service
discovery. The deployment infrastructure supports BPEL-like compositions that can select services dynamically, and also adjust
their behavior in response to detected changes and unforeseen events. The framework also provides a monitoring-based validation
of running compositions: we provide suitable probes to oversee the execution of deployed compositions. The various parts of
the framework are exemplified on a common case study taken from the automotive domain.
This research is partially supported by the European IST project SeCSE (Service Centric System Engineering) and the Italian FIRB project ARTDECO (Adaptive infRasTructures for DECentralized Organizations). 相似文献
790.
Valmir Calsavara Mauro Luciano Baesso Nádia Regina Camargo Fernandes-Machado 《Fuel》2008,87(8-9):1628-1636
ZSM-5 zeolites modified by iron incorporation through post-synthesis ion exchange and those synthesized with iron addition to the synthesis medium were compared in the reaction of liquid hydrocarbons production from ethanol. AA, TPR, FTIR, XRD, SEM, nitrogen adsorption and photoacoustic spectroscopy were used for the samples characterization. Acid leaching and ammonium exchange were tested for obtaining the acid form of the zeolite, with similar results, the major difference being a faster deactivation in the latter case. The best yield of liquid hydrocarbons was obtained with the samples with low iron content. The product distribution in both gaseous and liquid phases was independent of the way the zeolite was obtained or the iron was introduced, with major variations only with time (due to deactivation). 相似文献