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351.
Molten Salt Assisted Self‐Assembly: Synthesis of Mesoporous LiCoO2 and LiMn2O4 Thin Films and Investigation of Electrocatalytic Water Oxidation Performance of Lithium Cobaltate 下载免费PDF全文
Gülbahar Saat Fadime Mert Balci Elif Pınar Alsaç Ferdi Karadas Ömer Dag 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(1)
Mesoporous thin films of transition metal lithiates (TML) belong to an important group of materials for the advancement of electrochemical systems. This study demonstrates a simple one pot method to synthesize the first examples of mesoporous LiCoO2 and LiMn2O4 thin films. Molten salt assisted self‐assembly can be used to establish an easy route to produce mesoporous TML thin films. The salts (LiNO3 and [Co(H2O)6](NO3)2 or [Mn(H2O)4](NO3)2) and two surfactants (10‐lauryl ether and cethyltrimethylammonium bromide (CTAB) or cethyltrimethylammonium nitrate (CTAN)) form stable liquid crystalline mesophases. The charged surfactant is needed for the assembly of the necessary amount of salt in the hydrophilic domains of the mesophase, which produces stable metal lithiate pore‐walls upon calcination. The films have a large pore size with a high surface area that can be increased up to 82 m2 g?1. The method described can be adopted to synthesize other metal oxides and metal lithiates. The mesoporous thin films of LiCoO2 show promising performance as water oxidation catalysts under pH 7 and 14 conditions. The electrodes, prepared using CTAN as the cosurfactant, display the lowest overpotentials in the literature among other LiCoO2 systems, as low as 376 mV at 10 mA cm–2 and 282 mV at 1 mA cm–2. 相似文献
352.
Havva Elif Lapa Ali Kökce Ahmet Faruk Özdemir İbrahim Uslu Şemsettin Altindal 《Bulletin of Materials Science》2018,41(3):82
Three different thicknesses (50, 150 and 500 nm) Zn-doped polyvinyl alcohol (PVA) was deposited on n-4H-SiC wafer as interlayer by electrospinning method and so, Au/(Zn-doped PVA)/n-4H-SiC metal–polymer–semiconductor structures were fabricated. The thickness effect of Zn-doped PVA on the dielectric constant (\(\varepsilon ^{\prime }\)), dielectric loss (\(\varepsilon ^{{\prime }{\prime }}\)), loss-tangent (tan \(\delta \)), real and imaginary parts of electric modulus (\(M^{\prime }\) and \(M^{{\prime }{\prime }})\) and ac electrical conductivity \((\sigma _{\mathrm{ac}})\) of them were analysed and compared using experimental capacitance (C) and conductance (\(G/\omega \)) data in the frequency range of 1–500 kHz at room temperature. According to these results, the values of \(\varepsilon ^{\prime }\) and \(\varepsilon ^{{\prime }{\prime }}\) decrease with increasing frequency almost exponentially, \(\sigma _{\mathrm{ac}}\) increases especially, at high frequencies. The \(M^{\prime }\) and \(M^{{\prime }{\prime }}\) values were obtained from the \(\varepsilon ^{\prime }\) and \(\varepsilon ^{{\prime }{\prime }}\) data and the \(M^{\prime }\) and \(M^{{\prime }{\prime }}\) vs. f plots were drawn for these structures. While the values of \(\varepsilon ^{\prime }\), \(\varepsilon ^{{\prime }{\prime }}\) and tan \(\delta \) increase with increasing interlayer thickness, the values of \(M^{\prime }\) and \(M^{{\prime }{\prime }}\) decrease with increasing interlayer thickness. The double logarithmic \(\sigma _{\mathrm{ac}}\) vs. f plots for each structure have two distinct linear regimes with different slopes, which correspond to low and high frequencies, respectively, and it is prominent that there exist two different conduction mechanisms. Obtained results were found as a strong function of frequency and interlayer thickness. 相似文献
353.
Multiprocessor task scheduling in multistage hybrid flow-shops: A parallel greedy algorithm approach
Hybrid flow shop scheduling problems have a special structure combining some elements of both the flow shop and the parallel machine scheduling problems. Multiprocessor task scheduling problem can be stated as finding a schedule for a general task graph to execute on a multiprocessor system so that the schedule length can be minimized. Hybrid Flow Shop Scheduling with Multiprocessor Task (HFSMT) problem is known to be NP-hard. In this study we present an effective parallel greedy algorithm to solve HFSMT problem. Parallel greedy algorithm (PGA) is applied by two phases iteratively, called destruction and construction. Four constructive heuristic methods are proposed to solve HFSMT problems. A preliminary test is performed to set the best values of control parameters, namely population size, subgroups number, and iteration number. The best values of control parameters and operators are determined by a full factorial experimental design using our PGA program. Computational results are compared with the earlier works of O?uz et al. [1], [3], and O?uz [2]. The results indicate that the proposed parallel greedy algorithm approach is very effective in terms of reduced total completion time or makespan (Cmax) for the attempted problems. 相似文献
354.
Elif Derya Übeyli 《Expert Systems》2009,26(3):249-259
Abstract: In the present study, the diagnostic accuracy of support vector machines (SVMs) on electrocardiogram (ECG) signals is evaluated. Two types of ECG beats (normal and partial epilepsy) were obtained from the Physiobank database. Decision making was performed in two stages: feature extraction by eigenvector methods and classification using the SVM trained on the extracted features. The present research demonstrates that the power levels of the power spectral densities obtained by eigenvector methods are features which represent the ECG signals well and SVMs trained on these features achieve high classification accuracies. 相似文献
355.
Elif Derya Übeyli 《Expert systems with applications》2009,36(1):501-509
Various methodologies of automated diagnosis have been adopted, however the entire process can generally be subdivided into a number of disjoint processing modules: pre-processing, feature extraction/selection, and classification. Features are used to represent patterns with minimal loss of important information. The feature vector, which is comprised of the set of all features used to describe a pattern, is a reduced-dimensional representation of that pattern. Medical diagnostic accuracies can be improved when the pattern is simplified through representation by important features. By identifying a set of salient features, the noise in a classification model can be reduced, resulting in more accurate classification. In this study, a signal-to-noise ratio (SNR) saliency measure was employed to determine saliency of input features of probabilistic neural networks (PNNs) used in classification of electroencephalogram (EEG) signals. In order to extract features representing the EEG signals, eigenvector methods were used. The PNNs used in the EEG signals classification were trained for the SNR screening method. The application results of the SNR screening method to the EEG signals demonstrated that classification accuracies of the PNNs with salient input features are higher than that of the PNNs with salient and non-salient input features. 相似文献
356.
Elif Derya Übeyli 《International journal of systems science》2013,44(7):669-683
This article intends to give an integrated view of the automated diagnostic systems combined with spectral analysis techniques in the detection of arterial disorders. The article includes illustrative and detailed information about implementation of automated diagnostic systems and feature extraction/selection from signals recorded from ophthalmic arteries. The major objective of the article is to be a guide for readers who want to develop an automated diagnostic systems for detection of arterial disorders. Towards achieving this objective, this article presents the techniques which should be considered in developing automated diagnostic systems. The author suggests that the content of the article will assist people in gaining a better understanding of the techniques in the detection of arterial disorders. 相似文献
357.
Ayse Elif Sanlı 《国际能源研究杂志》2013,37(12):1488-1497
Hydrogen peroxide (H2O2) and the reduction/oxidation by‐products of peroxide are non‐toxic to humans and the environment. Simple, low‐concentration hydrogen‐peroxide solutions used as fuel and direct peroxide/peroxide fuel cells (DPPFCs) face significant challenges in the development of a new class of power generators. A power density of 10 mWcm?2 at a cell potential of 0.55 V have been achieved with a DPPFC composed of carbon‐paper‐supported nickel as the anode catalyst and carbon‐paper PbSO4 as the cathode catalyst. The catalysts have been prepared by electroless deposition. Using non‐precious metals rather than platinum in our FC makes the cell cost effective comparable to that of PEMFCs. Additionally, as a low‐price fuel, H2O2 reduces the cost of this FC. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
358.
Arzu KAHVECI Elif ARI Hakki ARIKAN Mehmet KOC Serhan TUGLULAR Cetin OZENER 《Hemodialysis international. International Symposium on Home Hemodialysis》2010,14(1):91-93
We report the case of a 54-year-old hemodialysis patient who presented with recurrent fever due to Streptococcus bovis bacteremia related to colonic tubulovillous adenoma. Following polypectomy and broad-spectrum antibiotic therapy, the patient totally recovered. In this paper, we discussed the relation between S. bovis bacteremia, colonic adenomas, and hemodialysis. Awareness of this association is critical for early diagnosis and management. 相似文献
359.
Fuat Dursun Seyda Korkut Ozoner Ali Demirci Mesut Gorur Faruk Yilmaz Elif Erhan 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(1):95-104
BACKGROUND: Newly synthesized composite films of P(glycidyl methacrylate85‐co‐vinylferrocene15)/Poly(glutaraldehyde)/ Polypyrrole [P(GMA85‐co‐VFc15)/PGA/PPy] and Poly(3‐methylthienyl methacrylate85‐co‐vinylferrocene15)/Polypyrrole [P (MTM85‐co‐VFc15)/PPy] were used as matrices for tyrosinase based working electrodes. Direct covalent attachment of enzyme was carried out via the pendant epoxy groups of P(GMA85‐co‐VFc15) film, and the entrapment of enzyme was achieved for electrode containing P(MTM85‐co‐VFc15) film via electropolymerization of pyrrole in the presence of enzyme. The aim of the study is amperometric determination of various phenolics and investigation of the effect of interfacial interactions between enzyme and matrices on biosensor response. RESULTS: The lowest detection limit and the highest sensitivity for a P(GMA85‐co‐VFc15) based working electrode was found to be 0.113 µmol L?1 for 4‐methoxyphenol, 40 nA (µmol L?1)?1 for pyrocatechol, respectively. Results showed that sensitivities were at least 8500–55000 times higher than the results in previous P(GMA‐co‐VFc) related studies. CONCLUSION: Facilitated electron transfer was achieved by means of mediator incorporated in conductive composites of VFc based redox copolymers. The effect was greater when enzyme was covalently bonded via epoxy groups due to the proximity of enzyme, mediator and electrode surface. Results showed that a multifunctional surface was provided on electrodes since the suggested copolymers could mediate an electrochemical reaction, and the multifunctional surface was capable of coating with conductive PPy. Copyright © 2011 Society of Chemical Industry 相似文献
360.
Alp Batman F. Gul Bagriyanik Z. Elif Aygen Ömer Gül Mustafa Bagriyanik 《Renewable & Sustainable Energy Reviews》2012,16(8):5678-5686
The application of renewable energy sources in electric power systems is increasing. There is a growing need for economic evaluation to inform photovoltaic (PV) allocation decisions for a range of decision-makers. In this study, power output and temperature data collected from PV modules in Istanbul, Turkey in 2009 have been analyzed to determine solar power generation potential. In addition to the measurements, technical and commercial parameters were also used to perform the evaluation. Different tariffs such as time-of-use and feed-in tariffs were considered in this study. 相似文献