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991.
The effect of acetic acid (HAc) on the CO2 corrosion of grade X70 steel was investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), polarization tests and electrochemical impedance spectroscopy (EIS). In the absence of acetic acid, a fairly dense layer of iron carbonate (FeCO3/siderite) was formed. At 500 ppm HAc, FeCO3 layer became more porous. In addition, anodic/cathodic polarization curves were activated with the more pronounced effect on the cathodic side. By adding 1000 ppm HAc, similar polarization behavior was obtained and FeCO3 layer became yet more porous than previous conditions. At 2000 ppm HAc, FeCO3 layer disappeared completely, while polarization behavior changed and the limiting diffusive current density was observed in the cathodic side. There were two major increases in the corrosion rate at 500 and 2000 ppm HAc. The EIS results reflected similar behavior for the specimens exposed to the solutions with 0–1000 ppm HAc. Under these conditions, a charge transfer controlled behavior due to the FeCO3 layer was observed which was accelerated by increasing HAc concentration. At 2000 ppm HAc, the corrosion behavior changed considerably and the formation/adsorption of corrosion product followed by the dissolution process was observed. 相似文献
992.
In this work a technique is proposed for solving partial differential equations using radial basis functions. The approach is different from the traditional schemes. The radial basis functions are very suitable instruments for solving partial differential equations of various types. However, the matrices which result from the discretization of the equations are usually ill-conditioned especially in higher-dimensional problems. In the current paper, a stable method will be proposed for solving the partial differential equations and will be generalized to solve higher-dimensional problems. To the contrast of most existing methods, the new technique provides a closed form approximation for the solution. Another advantage of the developed method is that it can be applied to problems with nonregular geometrical domains. 相似文献
993.
Mehdi Babaei Turkemani Hassan Rastegar 《IEEJ Transactions on Electrical and Electronic Engineering》2009,4(5):645-653
One application of turbo-expanders is in the natural gas pressure reduction at city gates gas regulating stations, in place of mechanical valves. Besides, they can drive electrical generators, but, because of instantaneous varying of domestic consumptions, environment temperature and other effective parameters, turbo-expander inlet gas pressure and mass flow-rate vary with time and consequently extracted power has time variant specification. These variations are transferred by coupled generator to the power distribution network and cause some power quality issues such as voltage flicker, voltage sag, etc. So, we need to assess the amount of flicker and voltage sag at the point of common coupling (PCC). Moreover, it is essential to investigate turbo-expander-gearbox-generator stability behavior when a fault has occurred in the power network. Thus, this paper presents a modular model for turbo-expander driven generators in power system studies. Using this model, we show the produced power quality is dependant on inlet gas specifications. Also it is proven that proper modeling of shaft is critical to transient stability study of this system. In addition, the inlet mass flow-rate and inlet pressure variation can produce torsional oscillation on the shaft. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
994.
The possibility of producing wood‐plastic panels using a melt blend/hot press method was studied in this research. The studied panels were compared with conventional medium density fiberboard (MDF) and particleboard (PB) panels. Wood‐plastic panels were made from high density polyethylene (as resin) and MDF waste and PB waste (as natural fiber) at 60, 70, and 80% by weight fiber loadings. Nominal density and dimensions of the panels were 1 g/cm3 and 35 × 35 × 1 cm3, respectively. Mechanical properties of the panels including flexural modulus, flexural strength, screw and nail withdrawal resistances, and impact strength were studied. Results indicated that the mechanical properties of the composites were strongly affected by the proportion of the wood flour and polymer. Maximum values of flexural modulus of wood plastic panels were reached at 70% fiber content. Flexural strength, screw and nail withdrawal resistance, and impact strength of wood plastic composites declined with the increase in fiber content from 60 to 80%. This was attributed to the lack of compatibility between the phases. The produced panels outperformed conventional PB panels regarding their mechanical properties, which were acceptable when compared with MDF panels as well. The best feature in the produced panels was their screw withdrawal resistance, which is extremely important for screw joints in cabinet making. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers 相似文献
995.
Mohammad Ali Ghayyem Mohammad Zare Khormizi Mehdi Rostami 《Petroleum Science and Technology》2019,37(16):1855-1860
Gas hydrate is a crystalline mixture obtained from gas molecules trapped in the cavity of hydrogen bonding water. To date, an essential step in the development of natural gas industry has been the acquisition of knowledge in the operation and handling of gas under high pressure without hydrate formation. Since there are several ways to predict hydrate formation, this study investigates predicting hydrate formation using the Katz method. In addition, several new models for accurate estimation of gas hydrate formation conditions will be provided. These models are based on artificial neural network (ANN) requirements. To create the model, predictive experimental data published in books and journals, as well as data extracted from Katz graph (Katz chart), estimate the formation conditions of gas hydrate. We validate the model created with the use of various statistical parameters such as mean squared error (MSE) and R2-value. The result of these parameters in models created to predict the formation of hydrates accurately and efficiently is evaluated. In this study, our goals are to use an artificial intelligence neural network to predict the formation of gas hydrates. 相似文献
996.
Mehdi Bayat B. B. Sahari M. Saleem A. M. S. Hamouda J. N. Reddy 《International Journal of Mechanics and Materials in Design》2009,5(3):263-279
A thermo elastic analysis is presented for axisymmetric rotating disks made of functionally graded material (FGM) with variable
thickness. Material properties are assumed to be temperature-dependent and graded in the radial direction according to a grading
index power law distribution. The temperature field considered is assumed to be uniformly distributed over the disk surface
and varied in the radial direction. Semi-analytical solutions for the displacement field are given for solid disk and annular
disk under free-free and fixed-free boundary conditions. The effects of the thermal field, the material grading index and
the geometry of the disk on the displacement and stress fields are investigated. Results of this study emphasize on the crucial
role of the temperature-dependent properties in a high temperature environment. A comparison of these results with the reported
ones in the literature that is temperature-dependent versus temperature-independent suggests that a functionally graded rotating
disk with concave thickness profile can work more efficiently than the one with uniform thickness irrespective of whether
the material properties are assumed to be temperature-dependent or temperature-independent. 相似文献
997.
A one-pot process for the synthesis of various sulfonyl azides (RSO2N3) by treating sulfonic acids with triphenylphosphine/trichloroisocyanuric acid/sodium azide at room temperature is described. A wide range of arenesulfonyl and alkanesulfonyl azides was obtained in excellent yields under mild conditions. 相似文献
998.
999.
A pH-responsive polymer derived from polyethyleneimine with zwitterionic function was used as a shell around super paramagnetic iron oxide nanoparticles (SPIONs), to introduce an efficient drug carrier for cancer drug delivery and imaging. Core–shell magnetic Fe3O4@FA-PEI-SUC (SUC: Succinate conjugated) nanoparticles were attained and characterized. Right chemical attachments, 61.34% modification of primary amino groups of poly(ethyleneimine) (PEI) in PEI–SUC, spherical shape, core–shell structure, crystal structure of SPIONs, 18.23% polymer coating of NPs, 8% decrease in magnetization following polymer coating around SPIONs, doxorubicin loading efficiency 85.19%, two times more released amount in acidic pH, and proper toxicity results were obtained by different analysis methods. 相似文献
1000.
The goal of this study was to optimize fibrous filter media by increasing the dust holding capacity (DHC) while maintaining the β ratio and initial pressure drop of the filter media. The key was the use of microstructure models to optimize the filter media. The microstructure of three different variations of a filter media for oil filtration was modeled by using the FiberGeo module of the GeoDict® software package. It was found that by optimizing the fiber volume distribution over the height of the filter media, higher DHC values could be achieved while keeping the pressure drop considerably low. This confirms the hypothesis that the macroscopic properties of the filter element can be improved by modifying the microstructure of the filter media. 相似文献