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101.
102.
We study in this paper the feasibility of using general purpose distributed memory parallel computers to implement some functions of high speed networks. We concentrate on the switching problem of the xtp high performance protocol (dealing with the network and transport layers of the osi stack), and on smds (switched multimegabit data service). We use methods and tools developed within the Pampa project (parallelizing methods, formal specification tools) to parallelize and prototype these kinds of switching systems on parallel architectures, and to make performance evaluations.  相似文献   
103.
DIVA is an expert system for turbine generator diagnosis. Its aim is to help a plant operator interpret vibration evolution to diagnose developing faults. Interpretation of vibration evolution is primarily a recognition process which is achieved by a particular model of heuristic classification. DIVA tries to recognize the observed situation among a hierarchy of typical situations.The purpose of this paper is to present the model we used for heuristic classification, based on prototypes. Prototypes represent typical problem situations and may also be seen as experts with special knowledge of what to do in such situations. We argue that this model presents significant advantages to deal with complex problems such as vibration surveillance.  相似文献   
104.
Energy computations of some (100), (110) and (111), planar defects were performed using an ionic bond model for stoichiometric uranium dioxyde. The repulsive contribution to the fault was estimated in two different ways, i.e. using the Born-Mayer classical treatment, or potentials derived from shell model calculations. The stability of the various defect configurations has been studied; on the basis of our numerical values, we may conclude that dislocation dissociation is unlikely in stoichiometric uranium dioxyde.  相似文献   
105.
Limited specific hydrolysis of casein byStaphylococcus aureus V8 protease was used to produce 2% and 6.7% hydrolysates (2 and 6.7% of the peptide bonds hydrolyzed), each containing five polypeptides (by gel filtration) ranging in size from ∼ 16,000 to ∼1,000 daltons. The mixtures of polypeptides had substantially increased solubilities at pH 4.0–4.5, near the isoelectric point of casein. In general, the emulsifying activity index was less for the hydrolysates than for casein; the emulsion stability was higher for the 2% hydrolysate than was the emulsion from casein. Phosphorylation of zein markedly increased the water solubility of zein above and below pH 4. When the free amino acids tryptophan and/or lysine were added to zein in the presence of POC13, some amino acids were covalently bound to zein, in addition to covalent attachment of phosphate groups. Threonine did not become incorporated into zein by this method. These derivatives were much more soluble than zein above and below pH 4, the minimum solubility point. A derivative containing 0.98 mol P/mol of zein, along with 1.05% tryptophan and 0.24% lysine, had a relative growth effect onTetrahymena thermophili of 49% that of casein, in comparison to 4.5% for unmodified zein. All the modified zeins had improved emulsifying activity indices.  相似文献   
106.
In this paper, we derive the asymptotic bias and variance of conventional bispectrum estimates of 2-D signals. Two methods have been selected for the estimation: the first one – the indirect method – is the Fourier Transform of the weighted third order moment, while the second one – the direct method – is the expectation of the Fourier component product. Most of the developments are known for 1-D signals and the first contribution of this paper is the rigorous extension of the results to 2-D signals. The calculation of the bias of the direct method is a totally original contribution. Nevertheless, we did all calculations (bias and variance) for both method in order to be able to compare the results. The second contribution of this paper consists of the comparison of the theoretical bispectrum estimate bias and variance with the measured bias and variance for two 2-D signals. The first studied signal is the output of a non-minimal phase linear system driven by a non-symmetric noise. The second signal is the output of a non-linear system with Gaussian input data. In order to assess the results, we performed the comparison for both methods with different sets of parameters. We show that the maximum bias coefficient is the one of the 1-D case multiplied by the dimensionality of the signal for both methods. We also show that the estimate variance coefficient is the 1-D case coefficient with a power equal to the signal dimensionality.Received October 21, 2002; Revised December 2003; Accepted March 25, 2004; First Online Version published in December 2004  相似文献   
107.
108.
Gelcasting of dense and porous ceramics by using a natural gelatine   总被引:1,自引:0,他引:1  
An improved gel-casting procedure was successfully exploited to produce porous ceramic bodies having controlled porosity features in terms of mean pore size, total pore volume as well as pore geometry. The gel-casting process in which a natural gelatine for food industry is used as gelling agent was firstly set-up to prepare dense alumina and zirconia components. Then, commercial PE spheres, sieved to select proper dimensional ranges, were added to the starting slurries as pore-forming agent. Both alumina and zirconia porous bodies were then produced, having a porosity ranging between 40 and 50 vol%. The fired components were characterised by spherical pores surrounded by highly dense ceramic walls and struts, having a homogeneous and fine microstructure. Their mean pore size was directly dependent on the sieved fraction of the starting PE spheres selected as pore-forming phase.  相似文献   
109.
A combined solar photo-Fenton and biological treatment is proposed for the decontamination of a mixture of five commercial pesticides commonly used in intensive agriculture Vydate (10% Oxamyl), Metomur (20% Methomyl), Couraze (20% Imidacloprid), Ditimur-40 (40% Dimethoate) and Scala (40% Pyrimethanil). Photo-Fenton experiments were conducted in a solar pilot reactor consisting of four compound parabolic collectors in which the pesticide mixture was treated at an original dissolved organic carbon (DOC) concentration of 200 mg/L in the presence of Fe2+ or Fe3+ concentration of 5, 20 and 55 mg/L. Ferrous ions were marginally more active than ferric in terms of active ingredient degradation, which followed zero order kinetics, more so in the early reaction stages. Photo-Fenton was also far more effective (by at least two orders of magnitude) than the respective dark reaction under identical experimental conditions.Irradiation for 50–100 min (normalized at 30 W/m2 light intensity) at 20 mg/L Fe2+ was able to completely eliminate the active ingredients, and reduce DOC by about 15–50% and COD by 40–70%, respectively. At these conditions, ecotoxicity to the marine bacteria V. fischeri was substantially lessened, while aerobic biodegradability in tests with activated sludge was enhanced.  相似文献   
110.
This paper presents for the first time the investigation of TiO2 photocatalysis for the removal of pesticides in gas phase. Dichlorvos was used as a model pesticide, and experiments were carried out using both static and dynamic reaction systems to explore the different aspects of the process. Thus, adsorption, reaction kinetics, and the influence of several operational parameters such as relative humidity (RH), inlet concentration, flow rate, and association of TiO2 with activated carbon (AC) were all examined in detail. Furthermore, a special attention was devoted to the analysis of reaction products by means of various analytical techniques such as Fourier transform infrared spectroscopy, automated thermal desorption technique coupled to gas chromatography-mass spectrometry instrument, gas chromatography equipped with a pulse discharge helium photoionization detector, and ion chromatography. The results showed an immediate and total removal of dichlorvos at ppbv levels (50-350 ppbv) along with a high mineralization extent (50-85%) into harmless final products (CO2, HCl, PO43-). Moreover, RH was found to significantly affectthe mineralization extent and the formation of reaction intermediates. On the basis of identification data, direct charge transfer and chlorine radical (Cl*) attack were shown to play a key role in the reaction mechanism at low RH, whereas at high RH, HO* radicals were the predominant active species.  相似文献   
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