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991.
Tugrul Cetinkaya Ahsen Akbulut Mehmet O. Guler Hatem Akbulut 《Journal of Applied Electrochemistry》2014,44(2):209-214
A flexible lithium manganese oxide (LiMn2O4)/multi-wall carbon nanotube (MWCNT) composite electrode was produced by casting a slurry-containing powdered LiMn2O4 on a previously prepared MWCNT paper. The structure of this new LiMn2O4/MWCNT composite electrode was characterized using scanning electron microscopy and X-ray diffraction patterns. Furthermore, the surfaces of these electrodes were coated with gold–palladium alloy using an RF magnetron sputtering technique to prevent Mn dissolution. To investigate the electrochemical performance of this flexible LiMn2O4/MWCNT composite electrode, a bare-LiMn2O4 electrode was prepared. The discharge capacity of the produced LiMn2O4/MWCNT nanocomposite electrode was cyclically tested, and the charge transfer resistance of the electrodes was studied using electrochemical impedance spectroscopy. Consequently, the Au–Pd-coated LiMn2O4/MWCNT had a 120 mAh g?1 discharge capacity and 90 % capacity retention after 100 cycles. 相似文献
992.
The photoinduced electron transfer reactions of acylphosphine oxide type photoinitiators with Cu(II)Cl2/N,N,N′,N′′,N′′-pentamethyldiethylenetriamine complex for both atom transfer radical polymerization and copper catalyzed azide-alkyne cycloaddition processes is investigated by laser flash photolysis. The photolytically generated phosphonyl radicals are effective in reducing Cu(II) salts to Cu(I) with rate constants of ∼2 × 109 M−1 s−1. 相似文献
993.
994.
Solid‐state lighting (SSL) technologies such as light emitting diodes (LEDs) have been of interest for the last 15 years. This article focuses on inorganic LED technology and their evolving applications, energy efficiency, and economic impact as well as the effect of thermal management on LED lighting systems. The efficacy of the best commercial 1 W LED packages currently surpasses 120 lm/W, which is more efficient than typical metal‐halide and fluorescent lamps. This high efficacy will eventually allow LED lighting systems to be used in specialty and general illumination applications. However, higher lumen requirements for LED systems will inevitably lead to significant thermal challenges at both the chip and the system level that need to be addressed to enable practical applications at low costs. In this article, the basics of LED lighting will be discussed first. It will be followed by the potential economic benefits for high efficiency LED lighting systems in the general illumination market. We will then discuss the thermal challenges and possible candidate cooling technologies in LED lighting systems. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
995.
Mehmet Oglakci Sibel Akça Yusuf Ziya Halefoglu Tamer Dogan Mehmet Ayvacikli Yüksel Karabulut Mustafa Topaksu Nurdogan Can 《Ceramics International》2019,45(6):7011-7017
NaBaBO3 host material was synthesized using the combustion method. In order to optimize the performance of the material, effects of sintering temperatures varying from 600° to 1000?°C were investigated. The sintering temperature and dwell time were found to have pronounced effects on the pure NaBaBO3 material. X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) techniques were used to confirm the phase formation and examine the surface morphology of the prepared powder material, respectively. TL behavior of NaBaBO3 was studied at various beta doses. It is seen that the sample exhibits well resolved TL glow peak at a peak temperature about 175?°C and corresponding TL intensity increases with the increasing beta dose. However, TL glow peak slightly shifts to lower temperature with the increasing beta dose level. This is the first TL report of a phosphor with a NaBaBO3 host. The TL kinetic parameters were estimated by the peak shape (PS) method and CGCD software. TL glow curves of NaBaBO3 consist of several traps and exhibited second order kinetics. A possible TL mechanism was also discussed using the energy level model. The obtained results can provide valuable knowledge related to the investigation of the intrinsic nature characteristics of NaBaBO3 in research fields pertaining to dosimetry. 相似文献
996.
Selva Çavuş Gülten Gürdağ Muzaffer Yaşar Kubilay Güçlü Mehmet Ali Gürkaynak 《Polymer Bulletin》2006,57(4):445-456
Summary Crosslinked hydroxyethyl cellulose-g-poly(acrylic acid) (HEC-g-pAA) graft copolymer was prepared by grafting of acrylic acid
(AA) onto hydroxyethyl cellulose (HEC) using [Ce(NH4)2(NO3)6]/HNO3 initiator system in the presence of poly(ethyleneglycol diacrylate) (PEGDA) crosslinking agent in 1:1 (v/v) mixture of methanol
and water at 30 °C. Carboxyl content of copolymer was determined by neutralization of –COOH groups with NaOH solution and
sodium salt of copolymer (HEC-g-pAANa) was swelled in distilled water in order to determine the equilibrium swelling value
of copolymer. Both dry HEC-g-pAA and swollen HEC-g-pAANa copolymers were used in the heavy metal ion removal from three different
aqueous ion solutions as follows: a binary ion solution with equal molar contents of Pb2+and Cd2+, a triple ion solution with equal molar contents of Pb2+, Cu2+ and Cd2+, and a triple ion solution with twice Cu2+molar contents of Pb2+and Cd2+. Higher removal values on swollen HEC-g-pAANa were observed in comparison to those on dry polymer. The presence of Cu2+decreased the adsorption values for Pb2+ and Cd2+ ions on both types of HEC copolymer. However, with further increase in Cu2+ content both dry and swollen copolymers became apparently selective to Cu2+ removal and Cu2+ removal values exceeded the sum of adsorption values for Pb2+ and Cd2+. Maximum metal ion removal capacities were 1.79 and 0.85 mmol Me2+/gpolymer on swollen HEC-g-pAANa and dry HEC-g-pAA, respectively. 相似文献
997.
Renewable energy sources have been developed rapidly all around the world, and one of these green energy sources is hydrogen energy. The fuel cell systems have become prominent in renewable energy sources because of its minimal dimensions and energy conversion method. There have been developed, some applications, especially in domestic and automotive areas, and fuel cell systems are also have been started to use in grid connected systems. Fuel cell systems must have some electrical connection standards while they connected to an electrical grid. One of these electrical conditions and may be the most important one is unplanned islanding condition. Islanding is a very dangerous situation because it can damage to the fuel cell and related electrical systems and also working people have been at risk in islanding situation on the grid. In this study, a novel islanding detection method was introduced for grid connected fuel cell systems. 0.5 kW solid oxide fuel cell (SOFC) system used in developed experimental system and a novel anti islanding detection method was researched by using an effective method. The proposed method was also developed by using Matlab Simulink and its useful tools. The developed islanding detection method is robust, reliable and has a fast response time, according to present methods. The results confirm the suggested conditions, and it can be seen in this method, it can also be adapted easily to the grid connected fuel cell systems. 相似文献
998.
Volkan Cecen Mehmet Sarikanat Yoldas Seki Hasan Yildiz Ismail H. Tavman 《Polymer Composites》2008,29(3):262-273
The primary purpose of the study was to investigate the anisotropic behavior of different noncrimp stitched fabric reinforced polyester composites. The effects of geometric variables on composite structural integrity and strength are illustrated. Hence, tensile, three‐point bending flexural and short beam shear tests were conducted up to failure on specimens strengthened with different layouts of fibrous plies in noncrimp stitched fabric. The remark, based on the observations while tensile testing, is that the stress–strain curves of polyester based composites were linear in the direction of fibers. However, in the matrix dominated orientations nonlinear relation between the stress and the strain was observed. Another aim of the present work was to investigate the interaction between glass fiber and polyester matrix. The experiments, in conjunction with scanning electron photomicrographs of fractured surfaces of composites, were interpreted in an attempt to explain the interaction between glass fiber and polyester and were interpreted in an attempt to explain the instability of polyester resin–glass fiber interfaces. It was concluded that the polymer was either deposited between adjacent fibers or as widely separated islands on the fiber surface. Infrared spectra of the cured polyester and its glass fiber composite were obtained by Fourier transform infrared spectroscopy. POLYM. COMPOS., 2008. © 2007 Society of Plastics Engineers 相似文献
999.
The main idea of reinforcement learning is evaluating the chosen action depending on the current reward. According to this concept, many algorithms achieved proper performance on classic Atari 2600 games. The main challenge is when the reward is sparse or missing. Such environments are complex exploration environments like Montezuma’s Revenge, Pitfall, and Private Eye games. Approaches built to deal with such challenges were very demanding. This work introduced a different reward system that enables the simple classical algorithm to learn fast and achieve high performance in hard exploration environments. Moreover, we added some simple enhancements to several hyperparameters, such as the number of actions and the sampling ratio that helped improve performance. We include the extra reward within the human demonstrations. After that, we used Prioritized Double Deep Q-Networks (Prioritized DDQN) to learning from these demonstrations. Our approach enabled the Prioritized DDQN with a short learning time to finish the first level of Montezuma’s Revenge game and to perform well in both Pitfall and Private Eye. We used the same games to compare our results with several baselines, such as the Rainbow and Deep Q-learning from demonstrations (DQfD) algorithm. The results showed that the new rewards system enabled Prioritized DDQN to out-perform the baselines in the hard exploration games with short learning time. 相似文献
1000.
Electrooxidation of hydrogen peroxide and sodium borohydride on Ni deposited carbon fiber electrode for alkaline fuel cells 总被引:1,自引:0,他引:1
Aylin Aytaç Mehmet GürbüzA. Elif Sanli 《International Journal of Hydrogen Energy》2011,36(16):10013-10021
In this study, Ni deposited carbon fiber electrode (Ni/CF) prepared by electroless deposition method was examined for their redox process and electrocatalytic activities during the oxidation of hydrogen peroxide and sodium borohydride in alkaline solutions. The Ni/CF catalyst was characterized by X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM) and electrochemical voltammetry analysis. The electrocatalytic activity of the Ni/CF for oxidation of hydrogen peroxide and sodium borohydride in alkaline solutions was investigated by cyclic voltammetry. The anodic peak current density is found to be three times higher on Ni/CF catalyst for sodium borohydride compared to that for hydrogen peroxide. Preliminary tests on a single cell of a direct borohydride/peroxide fuel cell (DBPFC) and direct peroxide/peroxide fuel cell (DPPFC) indicate that DBPFC with the power density of 5.9 mW cm−2 provides higher performance than DPPFC (3.8 mWcm−2). 相似文献