全文获取类型
收费全文 | 888篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 18篇 |
综合类 | 1篇 |
化学工业 | 124篇 |
金属工艺 | 43篇 |
机械仪表 | 9篇 |
建筑科学 | 14篇 |
矿业工程 | 3篇 |
能源动力 | 187篇 |
轻工业 | 20篇 |
水利工程 | 2篇 |
石油天然气 | 3篇 |
无线电 | 125篇 |
一般工业技术 | 157篇 |
冶金工业 | 15篇 |
原子能技术 | 7篇 |
自动化技术 | 162篇 |
出版年
2024年 | 6篇 |
2023年 | 91篇 |
2022年 | 108篇 |
2021年 | 95篇 |
2020年 | 110篇 |
2019年 | 69篇 |
2018年 | 43篇 |
2017年 | 28篇 |
2016年 | 36篇 |
2015年 | 19篇 |
2014年 | 32篇 |
2013年 | 21篇 |
2012年 | 13篇 |
2011年 | 7篇 |
2010年 | 8篇 |
2009年 | 13篇 |
2008年 | 3篇 |
2007年 | 11篇 |
2006年 | 21篇 |
2005年 | 16篇 |
2004年 | 6篇 |
2003年 | 4篇 |
2002年 | 10篇 |
2001年 | 12篇 |
2000年 | 6篇 |
1999年 | 15篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 8篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 6篇 |
1987年 | 18篇 |
1986年 | 14篇 |
1985年 | 2篇 |
排序方式: 共有890条查询结果,搜索用时 31 毫秒
51.
52.
《International Journal of Hydrogen Energy》2020,45(35):17174-17190
The study investigated the synergistic effects of rGO and Pt over TiO2 for the HER via artificial photosynthesis under UVB and visible light irradiation. The introduction of glycerol and industrial wastewater to the system as sacrificial reductants signifies that the major reaction pathway is photocatalytic partial water splitting. The material characterizations revealed successful heterojunction formation and provided insight into chemistry behind the activity of the photocatalysts. Amongst various combinations of rGO on TiO2, 1GNT exhibited an HER yield five times that of bare TiO2 under UVB light. Addition of Pt led to the formation of a strong Schottky barrier at the heterojunction and consequently boosted HER performance. 1P0.5 GT presented the highest of 28.5 mmol g−1 h−1 with glycerol and 9.6 mmol g−1 h−1 with wastewater under UVB light respectively. For both binary and ternary photocatalysts, the HER performances dwindled under visible light irradiation, accentuating the insufficient activation of the TiO2. In addition, 1PT outperformed all the other photocatalysts thereby elucidating the impression that rGO and Pt does not work well together in enhancing HER despite quenching the exciton recombination rate of TiO2 significantly. The role of pH in the synthesis and the experiments has been discussed. Finally, the underlying mechanisms in the photodeposition and photoreformation have been proposed. 相似文献
53.
《Journal of Mechanical Working Technology》1987,14(2):159-172
Some particular metal alloys offer excellent stability of deformation, this property being termed superplasticity. In the aeronautical industry, superplastic forming associated with diffusion-bonding techniques allows the manufacturing of complex shapes in one operation. The purpose of this paper is to contribute to a better knowledge of the influence of parameters such as bulging pressure vs. time, lubricant, die geometry, etc. The superplastic forming of a Ti6Al4V alloy sheet at 927°C into a long, rectangular box-section has been studied. Sticking contact and Coulomb friction have been considered. The model presented here will be used to choose parameters — such as the friction coefficient — to be introduced subsequently into a more sophisticated model, such as one employing the three-dimensional finite-element method. 相似文献
54.
《Ceramics International》2017,43(13):9945-9950
Co3O4, as a promising anode material for the next generation lithium ion batteries to replace graphite, displays high theoretical capacity (890 mAh g−1) and excellent electrochemical properties. However, the drawbacks of its poor cycle performance caused by large volume changes during charge-discharge process and low initial coulombic efficiency due to large irreversible reaction impede its practical application. Herein, we have developed a porous hollow Co3O4 microfiber with 500 nm diameter and 60 nm wall thickness synthesized via a facile chemical precipitation method with subsequent thermal decomposition. As an advanced anode for lithium ion batteries, the porous hollow Co3O4 microfibers deliver an obviously enhanced electrochemical property in terms of lithium storage capacity (1177.4 mA h g−1 at 100 mA g−1), initial coulombic efficiency (82.9%) and cycle performance (76.6% capacity retention at 200th cycle). This enhancement could be attributed to the well-designed microstructure of porous hollow Co3O4 microfibers, which could increase the contact surface area between electrolyte and active materials and accommodate the volume variations via additional void space during cycling. 相似文献
55.
《Intermetallics》2017
Ti-22Al-25Nb alloy specimens with different surface roughness were joined, through diffusion bonding at 975 °C at 12.5 MPa. The interfacial-microstructure evolution during this process was characterized via scanning electron microscopy combined with electron probe microanalysis and electron backscatter diffraction analysis. Further, the interfacial void-shrinkage mechanism and the quality of the bonded joints were determined through atomic force microscopy, which revealed the three-dimensional morphologies of the surfaces, and shear strength testing of the joints. The results revealed that fine equiaxed α2 grains are precipitated in the bonding interface of specimens with ground surfaces. These interfacial α2 grains were formed via phase transformation and recrystallization processes, which were triggered by asperity deformation at the contact plane and unavoidable oxygen contamination. Two types of fracture occurred during the shear strength tests, where the bonds generated from (i) polished surfaces failed predominantly along the bond line, and (ii) ground surfaces failed predominantly in the base material away from the bond line. This indicated that the mechanism controlling the void-shrinkage process associated with the contact between two rough surfaces during diffusion bonding varied with the surface roughness: the void-shrinkage process of specimens with (i) polished surfaces is controlled by diffusion, and (ii) ground surfaces was controlled by both diffusion and plastic deformation. 相似文献
56.
《Food Control》2017
The bactericidal effect of pulsating direct current (PC) generated at a very low amperage (0.01 A) with a frequency of 5 Hz or 14 kHz against two marine fish pathogens, Edwardsiella tarda and Vibrio parahaemolyticus, in circulating seawater at 15 and 25 °C in comparison with the effect of direct current (DC) of the same amperage was investigated. The bactericidal effect was directly correlated with the generation of active chlorine species (ACS) and the treatment duration. PC treatment at 14 kHz resulted in complete bacterial inactivation when the ACS level reached 0.11–0.12 mg/L after 45–60 min of treatment. PC treatment at 5 Hz required generation of only 0.03–0.07 mg/L ACS to achieve complete bacterial inactivation, although a slightly longer treatment duration (60–90 min) was needed. DC treatment resulted in complete disinfection within a shorter time (30 min) due to greater ACS production. The bactericidal effect and ACS generation were weaker at the higher temperature (25 °C) due to more rapid evaporation of Cl2 gas. The pH of the seawater maintained at ∼8.0. A disinfection study in circulating non-chloride Na2SO4 solution at pH 8.0 showed that the electric pulsation did not have notable bactericidal effect up to 14 kHz at 0.2 A. 相似文献
57.
58.
A controllable approach to the formation of III- nitride nanocrystalline structures using hydrothermal assisted method is presented. The structural and morphological properties of the prepared nanostructures are analyzed using X-ray diffraction, Fast Fourier Transformation and transmission electron microscope techniques. The temperature dependent structural formation of nitride nanostructures have been systematically investigated using X-ray diffraction. Raman spectra of the samples grown at optimized condition exhibited different phonon modes of the respective nitrides (GaN, InN and InxGa1−xN). Nanoparticles and nanorods formation of the indium nitride and indium gallium nitride are observed in the TEM micrographs. FFT analysis revealed that the synthesized III-nitride nanostructures are of good crystalline quality. Nanorods of these nitrides showed better crystalline quality than the nanoparticles in the FFT reflections. 相似文献
59.
In the present work, anatase TiO2 films are prepared by sol–gel spin coating method. The structural and optical properties of the films have been studied at different post-annealing temperatures. The photocatalytic activity and electrochromic performance of the films are investigated. The films annealed at 400 °C exhibit the highest photocatalytic activity with a rate constant of 4.56×10−3 min−1. The electrochromic performance for the films annealed at 400 °C expressed in terms of difference in optical density (ΔOD) at 550 nm between coloured and bleached state is 0.5493. This combination of photocatalysis and electrochromism makes the sol–gel derived titania thin films as promising candidates for self-cleaning smart window applications. 相似文献
60.
The use of a thermophilic acidophilic iron-oxidizing archaeon, Acidianus brierleyi, was investigated for oxidation and immobilization of As(III) from acidic refinery waste water. Some As(III) oxidation was measured in all Ac. brierleyi cultures independently of the presence or concentration of Fe(II) in bulk solution; the exception was at initial Fe(II) concentration ([Fe(II)]ini) of 1000 mg l−1 where As(III) oxidation became markedly facilitated and consequently approximately 70% of As was immobilized as amorphous ferric arsenate. Providing 1000 mg l−1 Fe(III) instead of Fe(II) did not show the same effect, implying the importance of Fe(III) be microbially-produced and complexed in the archaeal EPS (extracellular polymeric substances) region for effective As(III) oxidation. The reaction towards secondary mineral formation shifted from ferric arsenate to jarosite at [Fe(II)]ini of >1000 mg l−1. Furthermore addition of jarosite seed crystals retarded the As(III) oxidation rate at [Fe(II)]ini of 1000 mg l−1. The observations indicate that by setting the appropriate bulk Fe(II)/As(III) ratio in Ac. brierleyi culture to achieve a certain concentration of Fe(III) within the EPS region, but at the same time to avoid jarosite formation, it is possible to maximize the As(III) oxidation rate and thus As immobilization efficiency. This study describes for the first time microbially-mediated simultaneous oxidation and immobilization of As(III) as ferric arsenate, using a thermoacidophilic iron-oxidizing archaeon, Ac. brierleyi. 相似文献