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1.
Theoretical Foundations of Chemical Engineering - Moderate hydrate forming conditions of tetra-n-butylammonium salts have made these compounds as attractive materials to store the cold in air...  相似文献   
2.
Lanthanum zirconate is a promising thermal barrier coating material owing to its excellent thermophysical properties and La plays the key role in its corrosion resistance. Here, an amorphous precursor is used as raw feedstock material so as to synthesize lanthanum zirconate coatings with tailorable composition by atmospheric plasma spray (APS). Three lanthanum zirconate coatings of La1.7Zr2.3O7.15, La2.0Zr2.0O7.0 and La2.3Zr1.7O6.85 are fabricated. Furthermore, the corrosion resistance of the as-sprayed coatings against CaO-MgO-Al2O3-SiO2 at 1250℃ is investigated. The increased La content promotes the formation of a sealing layer of the crystalline Ca2La8(SiO4)6O2 apatite, which slows down the penetration of molten CaO-MgO-Al2O3-SiO2. Therefore, the infiltration rate of the La2.3Zr1.7O6.85 coating decreased up to 42.6 % compared with the other two coatings. This work develops a feasible preparation strategy to control the La composition for the improved corrosion resistance, which is expected to guide the future coating design and synthesis for the materials with big composition changes during the APS process.  相似文献   
3.
Moosaei  H.  Ketabchi  S.  Razzaghi  M.  Tanveer  M. 《Neural Processing Letters》2021,53(2):1545-1564
Neural Processing Letters - In this paper, we propose two efficient approaches of twin support vector machines (TWSVM). The first approach is to reformulate the TWSVM formulation by introducing...  相似文献   
4.
Children with dyslexia have reduced sensitivity to phonological sounds and words, and this deficiency in lexical processing causes many problems for them. Word exercise games based on phonological awareness have emphasized the mistakes of students with dyslexia, attempting to help children avoid these mistakes. This study was conducted to investigate the effect of Persian-language word exercise games on the spelling of students with dyslexia. The design of the present study was quasi-experimental, with a pretest and posttest of an experimental group and a control group. Participants were 30 students with dyslexia from second grade to fifth grade in elementary schools in Bojnord, who completed the spelling test as a pretest and posttest. The experimental group played eleven 40-min sessions of word exercise games. The results showed that the word exercise programme improved the spelling of the children with dyslexia. This suggests that basing training on the phonological mistakes of students with dyslexia and using the word exercise games can improve their spelling.  相似文献   
5.
In this article, the transient heat transfer in a furnace wall, which is made of functionally graded materials (FGMs), is investigated based on the hyperbolic-type dual-phase-lag (DPL) heat conduction model to consider the microstructural interactions in the fast transient process of heat conduction. All material properties of the furnace wall are assumed to vary following a power-law form along the radial direction with arbitrary non-homogeneity indices. For simplicity, the values of the phase lags are taken constant. A semi-analytical solution for the temperature field is obtained in the Laplace domain. The transformed temperature solution is inverted to the physical quantity by using numerical inversion of the Laplace transform. A comparison between the hyperbolic-type DPL model and thermal wave model in the temperature responses of the furnace wall is made. Effects of different phase-lag values on the behavior of heat transfer are also investigated.  相似文献   
6.
The aggregate in the ballast layer of the railway track structure degrades due to the splitting of single particles and the abrasion of the angular corners, resulting in a ballast course comprised of degraded aggregate with a lower drainage potential. In the present study, the hydraulic conductivity of clean, degraded and clay-fouled degraded ballast specimens was evaluated considering the initial particle size distribution of aggregate and the degradation mechanism to investigate the permeability of ballast fouled by both internal and external factors. First, degraded ballast aggregate was generated by using a large-scale impact loading testing apparatus. Then, a large-scale constant head permeability test was performed to estimate the hydraulic conductivity of degraded ballast aggregate contaminated with clay. Based on the obtained results, the flow regime through extremely degraded ballast remained between a completely turbulent regime (observed in the case of clean ballast) and a laminar flow regime. Darcy’s law was shown to be valid for degraded aggregate samples contaminated with clay. While the degradation of the aggregate had the expected effect of reducing hydraulic conductivity, the abrasion of asperities was shown to have an even greater impact on hydraulic conductivity. Also, the further degradation of aggregate under impact loading was shown to accelerate the reduction in the permeability of clay-fouled degraded ballast to an unacceptable extent.  相似文献   
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8.
Crosstalk noise (CT) is a limiting factor to increase the number of channels in analog Time-Division-Multiplexing (TDM)-based Wireless Neural Recording microsystems (WNRs). This paper proposes a novel approach to mitigate and decrease the effect of the CT by combining TDM with Frequency-Division-Multiplexing (FDM). In particular, we evaluate some possible configurations of the TDM-FDM combination and present a system that has less CT than other configurations. A 12-channel WNR based on the proposed system is designed in both system and circuit-level. In this system, channels are first divided into three 4-channel groups and after multiplexing in time domain, they are combined together with FDM method. While the group containing the marker pulse is located in the base-band, the second and third group are shifted to the frequency domain by employing quadrature modulation. The circuit-level of the system is designed and simulated by using 0.18 μm CMOS technology. The designed circuit consumes a power of 1.4 mW at a supply voltage of 1.8 V. The performance of the proposed system is also compared with simple TDM-based WNR. Simulations shows that in the proposed system the CT is considerably decreased.  相似文献   
9.
In this work, ZnO NPs were successfully synthesized by the sol–gel method without any organic additives or post annealing. The effect of the preparation process on the structural and optical properties of the resulting NPs was investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. The structural characterization demonstrated clearly that the NPs crystallize in pure ZnO würtzite structure without any other secondary phases. Furthermore, we show that it is possible to perform the control of the crystalline growth orientation of ZnO NPs, which is a key parameter when seeking to develop ZnO NPs with piezoelectric properties for nano-transducer applications. In fact, TEM observations show that the reduction of the NaOH flow changes the NPs shape from hexagonal NPS to short nanorods grown along the c-axis. The PL spectra of the obtained NPs excited at 280 nm, present an UV emission centered at approximately 380 nm with a slight shift when varying the synthesis temperature and/or the NaOH flow. Moreover, as the visible region (from 400 to 650 nm) is concerned, it was shown that the increasing of the synthesis temperature affects strongly the kind of interstitial defects (Oi, Zni and VoZni) formed in ZnO nanostructures. However, the excitation at 320 nm revealed a broad deep-level emission for all the samples that can be deconvoluted into two Gaussian peaks centered at 514 nm (P1) and 581 nm (P2). These last results have been discussed in the light of a physical mechanism based on the Schottky barrier.  相似文献   
10.
In the thermal radiation analysis via Monte Carlo method, the ray tracing algorithm often consumes a significant fraction of CPU time. As such, an efficient grid traversal algorithm can considerably affect the performance of the Monte Carlo method. This paper presents a new grid traversal acceleration algorithm by merging adjacent small empty voxels in a preprocessing step due to the fact that larger empty space, named “macro-voxel”, allows for traversing a ray over a large distance at a smaller cost. The proposed algorithm is validated theoretically, and the results are examined for a gray box with diffuse surfaces. Timing results of the new algorithm are compared with the USD method in a typical 3D radiation furnace with concave geometry and the speedup ratio of both the macro-voxel algorithm and the USD method with respect to direct method are calculated for an optimal grid of voxels. For the considered geometry, the macro-voxel algorithm is found to be clearly superior to the USD even if the size of the problem is large and the geometry is not convex.  相似文献   
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