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21.
This study uses a v2-f turbulence model with a two-phase Eulerian approach. The v2-f model can accurately calculate the near wall fluctuations in y-direction, which mainly represent the anisotropic nature of turbulent flow. The model performance is examined by comparing the rate of particle deposition on a vertical surface with the experimental and numerical data in a turbulent channel flow available in the literature. The effects of lift, turbophoretic, electrostatic and Brownian forces together with turbulent diffusion are examined on the particle deposition rate. The influence of the tilt angle and surface roughness on the particle deposition rate were investigated. The results show that, using the v2-f model predicts the rate of deposition with reasonable accuracy. It is observed that in high relaxation time the effect of lift force on the particle deposition is very important. It is also indicated that decreasing the tilt angle from 90° to 0° enhances the deposition rate especially for large size particles. Furthermore, the results show that increasing the Reynolds number at a specific tilt angle decreases the rate of particle deposition and the tilt angle has insignificant impact on the particle deposition rate in high shear velocity or high Reynolds number.  相似文献   
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This article investigates the thermo-physical properties of plasma sprayed zirconia coatings produced by agglomerates of submicron size particles as the feedstock. The microstructure of these deposits is consisted of splats and non-molten particles. This bimodal structure generally shows a better performance than conventional coatings. The agglomerated feedstock with internal submicron size porosity may significantly affect porosity related properties, such as the thermal diffusivity. In this study different process parameters were used to deposit yttria stabilized zirconia coatings with conventional and bimodal structures. Results showed a good correlation between the shape and distribution of pores and thermal diffusivity of the coatings.  相似文献   
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In this paper, we use a numerical method based on the boundary integral equation (BIE) and an application of the dual reciprocity method (DRM) to solve the second-order one space-dimensional hyperbolic telegraph equation. Also the time stepping scheme is employed to deal with the time derivative. In this study, we have used three different types of radial basis functions (cubic, thin plate spline and linear RBFs), to approximate functions in the dual reciprocity method (DRM). To confirm the accuracy of the new approach and to show the performance of each of the RBFs, several examples are presented. The convergence of the DRBIE method is studied numerically by comparison with the exact solutions of the problems.  相似文献   
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One of the most important challenges in treating cancer is the invasion and the angiogenesis of cancer cells. The synthesis of green nanoparticles (NPs) and their use in therapeutic fields is one of the most effective methods with minimal side effects in cancer treatment. In this study, cytotoxic and anti‐angiogenic effects of silver NPs (AgNPs) coated with palm pollen extract [Ag–PP(NPs)] were evaluated. For this purpose, the cells were treated with NPs and then were subjected to trypan blue testing (48 h). Then, the cancer invasion was evaluated by the scratch procedure and the expressions of the vascular endothelial growth factor (VEGF) and its receptor (VEGF‐R) genes were estimated using real‐time PCR assay. Also, the angiogenesis effect of the NPs was investigated with chick chorioallantoic membrane (CAM) assay. The Ag–PP(NPs) induced cytotoxicity on MCF7 cells. The findings also showed that Ag–PP(NPs) inhibit invasive cancer cells and reduce the expression of VEGF and VEGF‐R and significantly reduced the number and vessels lengths and the lengths and weights of the embryos in CAM assay. Ag–PP(NPs) with the induction of cytotoxic effects, metastatic inhibition and anti‐angiogenesis properties should be considered as an appropriate option for treatment of cancerInspec keywords: nanomedicine, genetics, cellular biophysics, toxicology, patient treatment, silver, cancer, biochemistry, biomedical materials, nanoparticles, nanofabrication, membranesOther keywords: minimal side effects, cancer treatment, silver NPs, cancer invasion, vascular endothelial growth factor, receptor genes, VEGF‐R, real‐time polymerase chain reaction assay, angiogenesis effect, chick chorioallantoic membrane assay, MCF7 cells, invasive cancer cells, cytotoxic effects, putative mechanism, anticancer properties, antiangiogenic effects, antiangiogenesis properties, Ag–PP‐induced cytotoxicity, metastatic inhibition, palm pollen extraction, trypan blue testing, time 48.0 hour, Ag  相似文献   
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Efficiency optimization of induction motor (IM) drives is a major subject based on these drives' extensive use in the industry. Among the different proposed methods, a model-based approach (MBA) seems to be the fast one. However, this method needs the motor parameters that must be correctly identified. On the other hand, a search-based approach (SBA) is a parameter-independent method but needs a greater convergence time. In this paper, a novel model-based loss-minimization approach is presented, which is combined with a backstepping direct torque control of the IM drive. An improved search-based method for efficiency optimization is also introduced. The proposed controller is realized in the stationary reference frame and has a fast-tracking capability of rotor flux and electromagnetic torque. Moreover, a sliding-mode rotor-flux observer is introduced, which is employed for simultaneous determination of rotor-flux space vector, rotor speed, and rotor time constant. The proposed control idea is experimentally implemented in real time using a field-programmable gate-array board synchronized with a personal computer. Simulation and experimental results are finally presented to verify the effectiveness of the method proposed.   相似文献   
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In this paper, we propose an actually novel and simple method for detection of transmitted symbols in MIMO channels. This method is based on the energy level of the received signals. At the receiver, we assume the knowledge of channel state information which can be estimated by different methods, e.g. by sending pilots. So, we can determine all possible levels of energy. This computation of energy levels is done only once for the quasi-static channels. Energy of the received signals is a criterion by which we can estimate the transmitted symbols. Detection of transmitted signal is made based on the nearest energy level and the points which lie on it. In other words, we have restricted our search space to a new smaller space with different levels of energy. Simulation results confirm approximately the same performance between the maximum-likelihood detector and the proposed approach especially in high signal-to-noise ratios with a remarkable reduction in the computational complexity.  相似文献   
29.
We consider a cross-docking system in which there is no temporary storage and trucks are permissible not to load or unload all of their products but are held and come back to the dock to continue their tasks in case they are needed. Scheduling the trucks in such systems is a nondeterministic polynomial time-hard problem that motivates us to apply two well-known meta-heuristics-named genetic algorithm and electromagnetism-like algorithm for scheduling trucks with the objective of minimizing total flow time of the system, which is achieved through the best sequence of truck pairs. To attain the best robustness of these algorithms Taguchi’s robust design method is employed. To demonstrate the effectiveness of the proposed methods especially for large-sized problems, various test problems are solved, and the computational results show that our proposed methods perform better than Yu (2002)’s methods.  相似文献   
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Reliable transmission is a challenging task over wireless LANs since wireless links are known to be susceptible to errors. Although the current IEEE802.11 standard ARQ error control protocol performs relatively well over channels with very low bit error rates (BERs), this performance deteriorates rapidly as the BER increases. This paper investigates the problem of reliable transmission in a contention free wireless LAN and introduces a packet embedded error control (PEEC) protocol, which employs packet-embedded parity symbols instead of ARQ-based retransmission for error recovery. Specifically, depending on receiver feedback, PEEC adaptively estimates channel conditions and administers the transmission of (data and parity) symbols within a packet. This enables successful recovery of both new data and old unrecovered data from prior transmissions. In addition to theoretically analyzing PEEC, the performance of the proposed scheme is extensively analyzed over real channel traces collected on 802.11b WLANs. We compare PEEC performance with the performance of the IEEE802.il standard ARQ protocol as well as contemporary protocols such as enhanced ARQ and the hybrid ARQ/FEC. Our analysis and experimental simulations show that PEEC outperforms all three competing protocols over a wide range of actual 802.11b WLAN collected traces. Finally, the design and implementation of PEEC using an adaptive low-density-parity-check (A-LDPC) decoder is presented.  相似文献   
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