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61.
The over-phase control method of inverter multiphase (i.e. having number of phases more than four) AC linear drives is developed by the authors of this paper. Its application allows to improve considerably a number of the drive technical-and-economic characteristics (speed of response, reliability, mass-and-overall dimensions, etc.). This control method can be used not only in the field of electrical AC drives, but also in the systems for electromagnetic stirring of molten metals. In these systems the application of one of versions of the over-phase-control for multiphase inverter-fed linear stators allows to increase the intensity of electromagnetic stirring of molten metals by providing with continuous change of the quantity, space location, and configuration of the vortex areas in the metal mass during the process of the above-mentioned stirring. 相似文献
62.
Yuri V. Batygin Sergey F. Golovashchenko Andrey V. Gnatov 《Journal of Materials Processing Technology》2013,213(3):444-452
The paper is dedicated to the study of pulsed electromagnetic attraction processes which can deform ferromagnetic sheet metal materials such as low carbon steels using low frequency discharges. The analytical model based upon the solution of Maxwell equations explains that magnetic forces are prevailing over the Lorentz forces for low frequency discharges. For electromagnetic forming (EMF) processes employing ferromagnetic sheet metal blanks of low electrical conductivity with relatively slow electric discharges, the magnetic forces should be taken into account in order to achieve a correct representation of electromagnetic forces applied to the blank. An engineering estimate on the size of magneto-static forces and Lorentz-forces is the outcome of the analytical work. In addition to analytical work and validation of the proposed engineering estimate of attracting forces, a single turn coil is introduced which is more robust than previous designs with multiple frequencies and interrupted discharges. The simplified setup only requires a rather slow single frequency low voltage electric discharge which allows for using cheaper and longer life capacitors, substantially reduces the safety implications and also extends the life of the coil insulation. 相似文献
63.
We demonstrate the use of the Integrated Volume Method (IVM) to estimate activity coefficients of semi-volatile organic compounds pertinent to ambient/atmospheric aerosols in binary mixtures. We generate binary solution aerosols with different mole fractions of individual components; for each mixture, we measure total change in aerosol volume upon heating from 25 ○ C to 35 ○ C, with the aerosols being at equilibrium in both states. The change in aerosol volume, or in other words, the partitioning between the particle phase and the gas phase, is used to determine activity coefficients of the compounds as a function of their mole fraction in the mixture. We demonstrate this method using the following four model systems. System 1: adipic acid–pimelic acid, which illustrates polar organic–polar organic interactions. Non-ideal behavior was observed with activity coefficients around three at infinite dilution. System 2: adipic acid–dioctyl sebacate, which illustrates polar organic–non-polar organic interactions. The compounds in this experiment did not form a solution. System 3: adipic acid–ammonium sulfate, which illustrates polar organic–inorganic interactions. The compounds in this experiment did not form a solution. System 4: adipic acid–ambient extracts, which illustrates the potential use of the method to study partitioning behavior of individual components in a complex matrix approximating that of real ambient aerosol. The measured activity coefficients of adipic acid were less than unity for the tested range of mixing ratios, indicating suppression of volatility of this compound in ambient organic matrix. 相似文献
64.
Adsorption of methyl mercaptan on activated carbons 总被引:1,自引:0,他引:1
Activated carbons of different origins were studied as methyl mercaptan adsorbents in wet, dry, and oxidizing conditions. The materials were characterized using adsorption of nitrogen, Boehm titration, and thermal analysis. Investigation was focused on the feasibility of the removal of methyl mercaptan on activated carbons and on the role of surface chemistry and porosity in the adsorption/oxidation processes. The results showed relatively high capacities of carbons for removal of CH3SH. The amount adsorbed depends on the surface features. Methyl mercaptan, in general, is oxidized to disulfides, which, depending on the chemistry of the carbon surface, can be converted to sulfonic acid due to the presence of water and active radicals. 相似文献
65.
This article deals with the development of learning methods for an intelligent control system for an autonomous mobile robot.
On the basis of visual servoing, an approach to learning the skill of tracking colored guidelines is proposed. This approach
utilizes a robust and adaptive image processing method to acquire features of the colored guidelines and convert them into
the controller input. The supervised learning procedure and the neural network controller are discussed. The method of obtaining
the learning data and training the neural network are described. Experimental results are presented at the end of the article.
This work was presented, in part, at the Sixth International Symposium on Artificial Life and Robotics, Tokyo, Japan, January
15–17, 2001 相似文献
66.
Tapered fiber bundles are often used to combine the output power of several semiconductor lasers into a multimode optical fiber for the purpose of pumping fiber lasers and amplifiers. It is generally recognized that the brightness of such combiners does not exceed the brightness of the individual input fibers. We report that the brightness of the tapered fibers (and fiber bundles) depends on both the taper ratio and the mode-filling properties of the beams launched into the individual fibers. Brightness, therefore, can be increased by selection of sources that fill a small fraction of the input fiber's modal capacity. As proof of concept, we present the results of measurements on tapered fiber-bundle combiners having a low-output étendue. Under low mode-filling conditions per input multimode fiber (i.e., fraction of filled modes < or =0.29), we report brightness enhancements of 8.0 dB for 19 x 1 bundles, 6.7 dB for 7 x 1 bundles, and 4.0 dB for 3 x 1 combiners. Our measured coupling efficiency variations of approximately 1%-2% among the various fibers in a given bundle confirm the uniformity and quality of the fabricated devices. 相似文献
67.
Kudryashova Elena V.; Artemova Tatiana M.; Vinogradov Alexei A.; Gladilin Alexander K.; Mozhaev Vadim V.; Levashov Andrey V. 《Protein engineering, design & selection : PEDS》2003,16(4):303-309
Formation of enzymeoligoamine complexes was suggestedas an approach to obtain biocatalysts with enhanced resistancetowards inactivation in waterorganic media. Complex formationresults in broadening (by 2040% v/v ethanol) of the rangeof cosolvent concentrations where the enzyme retains its catalyticactivity (stabilization effect). At moderate cosolvent concentrations(2040% v/v) complex formation activates the enzyme (by36 times). The magnitude of activation and stabilizationeffects increases with the number of possible electrostaticcontacts between the protein surface and the molecules of oligoamines(OA). Circular dichroism spectra in the far-UV region show thatcomplex formation stabilizes protein conformation and preventsaggregation in waterorganic solvent mixtures. Two populationsof the complexes with different thermodynamic stabilities werefound in -chymotrypsin (CT)OA systems depending on theCT/OA ratio. The average dissociation constants and stoichiometriesof both low- and high-affinity populations of the complexeswere estimated. It appears that it is the low-affinity siteson the CT surface that are responsible for the activation effect. 相似文献
68.
Lik-Kwan Shark Author Vitae Andrey A. Kurekin Author Vitae Author Vitae 《Pattern recognition》2007,40(5):1432-1450
By extending the previously proposed geometric branch-and-bound algorithm with bounded alignment for point pattern matching, the paper presents the development and evaluation of a new and fast algorithm for image registration based on line segments. Using synthetically generated data sets with randomly distributed line segments and hard test cases with highly symmetric line patterns, as well as real remote sensing images, the developed algorithm is shown to be computationally fast, highly robust, capable of handling severely corrupted data sets with considerable line segment position errors as well as significant fragmented and spurious line segments in the images to be matched. 相似文献
69.
Numerical method for modeling the E-polarized wave scattering by electrically large quasioptical two-dimensional (2-D) reflectors is presented. Reflectors are assumed zero-thickness and perfectly electrically conducting. Efficient numerical solution is obtained from the coupled singular integral equations discretized using new quadrature formulas of interpolation type. It has controlled accuracy and deals with small-size matrices. To simulate a small-horn feeding, the incident field is taken as a beam generated by a complex-source-point (CSP) current. Presented numerical results validate empirical rule of -10 dB edge illumination needed to provide the best electromagnetic performance of reflector 相似文献
70.
Andrey Sarikov Jens Schneider Martin Muske Ina Sieber Stefan Gall 《Thin solid films》2007,515(19):7465-7468
The aluminium-induced layer-exchange process allows to grow thin large-grained polycrystalline Si films on foreign substrates. A characteristic feature of these films is the preferential (100) orientation of Si grains, favourable for subsequent epitaxial thickening at low temperatures. In this work, a model based on the preferential nucleation is proposed, which elucidates a possible origin of the preferential (100) orientation and its sensitivity to the preparation and process conditions. The probability of Si nuclei to have respective orientation is attributed to the nucleation barrier, i.e. the critical value of the change of the Gibbs energy during nucleation. The preferential orientation is formed statistically by the nuclei having the lowest nucleation barriers. 相似文献