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51.
Kyriazidou CA Contopanagos HF Alexopoulos NG 《Journal of the Optical Society of America. A, Optics, image science, and vision》2006,23(11):2961-2968
We present what we believe is a new class of composite electromagnetic materials characterized by the concept of metamorphism, which we define in general terms. Metamorphic materials exhibit bulk electromagnetic transitions among states characterized by distinct ranges of values of their reflection coefficient. Each such state has unique physical properties induced by the corresponding values of the reflection coefficient. We present a variety of physical realizations of the concept of metamorphic materials in microwave frequencies, showing with specific metallodielectric designs how transitions among metamorphic states can be obtained at the same frequency, for fixed material geometries, by electronic reconfigurability. We further show how a given material exhibiting certain metamorphic states at a given frequency can transform into a different combination of metamorphic states at different frequencies; i.e., metamorphic materials have a useful dispersive degree of freedom. 相似文献
52.
E Tipping B Ketterer L Christodoulides G Enderby 《Canadian Metallurgical Quarterly》1976,157(1):211-216
Ligandin and aminoazo-dye-binding protein A both bind bilirubin at a single site. Quantitative studies of the interactions using difference spectrophotometry show that at pH 7.0, protein A binds the tetrapyrrole with an association constant (K) greater than or equal to 2 X 10(7) litre/mol, whereas binding by ligandin is slightly weaker (K = 7 X 10(6) litre/mol) at this pH. The protein-bilirubin complexes give rise to absorption and fluorescence spectra quite different from those of unbound bilirubin and also to large Cotton effects. It appears that on binding to both proteins, the ligand is forced into a rigid twisted configuration in a hydrophobic environment. Ligandin and protein A resemble serum albumin in their interactions with bilirubin. 相似文献
53.
Abstract: This paper presents the results of a study on short‐term electric power load forecasting based on feedforward neural networks. The study investigates the design components that are critical in power load forecasting, which include the selection of the inputs and outputs from the data, the formation of the training and the testing sets, and the performance of the neural network models trained to forecast power load for the next hour and the next day. The experiments are used to identify the combination of the most significant parameters that can be used to form the inputs of the neural networks in order to reduce the prediction error. The prediction error is also reduced by predicting the difference between the power load of the next hour (day) and that of the present hour (day). This is a promising alternative to the commonly used approach of predicting the actual power load. The potential of the proposed method is revealed by its comparison with two existing approaches that utilize neural networks for electric power load forecasting. 相似文献
54.
Kechagia N Nicolaou C Ioannidou V Kourti E Ioannidis A Legakis NJ Chatzipanagiotou S 《International journal of food microbiology》2007,118(3):326-331
The distribution of Yersinia strains in animal reservoirs was examined in 835 food animals (pigs, chickens, sheep, cows) from different Greek departments (Attica, Fthiotida, Viotia and Evia) over a one year period. The isolated strains were characterized with respect to the presence of chromosomal (yst) and plasmid-encoded virulence determinants (virF, yadA) and their antimicrobial susceptibility was tested.In total, Yersiniaspp. were obtained from 9.94% of the 835 food animals at slaughter that were sampled in this study. There was no statistically significant seasonal distribution, nor was any significant departmental distribution observed. From the 83 isolated Yersinia strains, 76 (91,57%) belonged to Y. enterocolitica (58 were of serotype O:3/biotype 4 and 18 strains were non O:3, non O:9), 3 belonged to Y. pseudotuberculosis, 2 to Y. kristensenii and 2 to Y. intermedia. Y. enterocolitica O:3/4 was mainly isolated from the pigs, while Y. enterocolitica non O:3, non O:9 was from the chickens. The strains were grouped into 5 genotypes, with respect to the presence or absence of the virulence genes. A significant predominance of genotype V, the one carrying all the three virulence genes, was observed in the strains isolated from the pigs. Complete susceptibility to most of the 3rd and to the 4th generation cephalosporins and to ciprofloxacin, was observed among the isolates. Remarkable was the association between the presence of each virulence gene separately and resistance to some antimicrobials, a matter of further investigation. 相似文献
55.
McIntosh C.M. Grandpierre A.G. Christodoulides D.N. Toulouse J. Delavaux J.-M.P. 《Photonics Technology Letters, IEEE》2001,13(4):302-304
We demonstrate that the channel depletion due to stimulated Raman scattering in massive wavelength-division-multiplexed (WDM) systems can be eliminated using high-frequency pass filters. These filters, when inserted appropriately into the transmission link, can effectively suppress the SRS power flow from the WDM channels to lower frequency noise. Numerical simulations carried out on WDM systems indicate that the channel depletion penalties can be kept below 0.25 dB even for a total channel power of 2 W 相似文献
56.
57.
Nicolaos P. Theodossiou 《Water Resources Management》2004,18(2):125-141
The need for rational and overall water resources management has become, during the past decades, a problem ofmajor importance due to the rising water demands. In this paper atechnique is presented through which a management model that combines the useof two separate models, a flow simulation and an optimisation one, isused for groundwater management. The necessary stages for the formulationand the combined use of the two models, along with a number of problemsthat might arise during the development of the management model are alsopresented. This technique is applied to a large-scale case study problemthat forms an optimisation approach with a large number of non-linear decisionvariables. The results of the application of the management modeldemonstrate the importance of the use of such models both in managing rationallyavailable water resources and in reducing the operational cost of theirexploitation. 相似文献
58.
59.
Inmarsat's provision of multimedia services over its current satellites, as well as over a possible new generation of satellites, will enable technologies for support of higher data rates for mobile terminals. Inmarsat's next-generation satellite communications system will extend current capabilities by supporting fully interactive multimedia communications to small portable user terminals 相似文献
60.
Impeller power numbers in closed square vessels with/or without baffles and in closed cylindrical vessels with baffles were studied for impeller Reynolds numbers in the range between 40 and 65000. Flat vertical blade disk style, vertical blade open style and 45° pitched blade open style impellers were used. It was found that the impeller power number is affected by the vessel and impeller size and the system scale up 相似文献