全文获取类型
收费全文 | 312140篇 |
免费 | 6239篇 |
国内免费 | 1008篇 |
专业分类
电工技术 | 5914篇 |
综合类 | 420篇 |
化学工业 | 47533篇 |
金属工艺 | 12110篇 |
机械仪表 | 11433篇 |
建筑科学 | 7261篇 |
矿业工程 | 1124篇 |
能源动力 | 8446篇 |
轻工业 | 26663篇 |
水利工程 | 2773篇 |
石油天然气 | 4101篇 |
武器工业 | 69篇 |
无线电 | 43812篇 |
一般工业技术 | 60367篇 |
冶金工业 | 51883篇 |
原子能技术 | 5971篇 |
自动化技术 | 29507篇 |
出版年
2022年 | 2024篇 |
2021年 | 3405篇 |
2020年 | 2490篇 |
2019年 | 3020篇 |
2018年 | 4759篇 |
2017年 | 4827篇 |
2016年 | 5320篇 |
2015年 | 3583篇 |
2014年 | 6019篇 |
2013年 | 14619篇 |
2012年 | 9607篇 |
2011年 | 12607篇 |
2010年 | 9841篇 |
2009年 | 10842篇 |
2008年 | 11429篇 |
2007年 | 10885篇 |
2006年 | 9844篇 |
2005年 | 8899篇 |
2004年 | 8548篇 |
2003年 | 8231篇 |
2002年 | 7878篇 |
2001年 | 7621篇 |
2000年 | 7245篇 |
1999年 | 7303篇 |
1998年 | 16259篇 |
1997年 | 11587篇 |
1996年 | 9211篇 |
1995年 | 7279篇 |
1994年 | 6366篇 |
1993年 | 6185篇 |
1992年 | 4974篇 |
1991年 | 4650篇 |
1990年 | 4408篇 |
1989年 | 4131篇 |
1988年 | 3910篇 |
1987年 | 3419篇 |
1986年 | 3284篇 |
1985年 | 3813篇 |
1984年 | 3553篇 |
1983年 | 3168篇 |
1982年 | 2980篇 |
1981年 | 3065篇 |
1980年 | 2873篇 |
1979年 | 2729篇 |
1978年 | 2579篇 |
1977年 | 3052篇 |
1976年 | 3690篇 |
1975年 | 2385篇 |
1974年 | 2364篇 |
1973年 | 2372篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
Harshavardhan Mohan Jeong-Muk Lim Se-Won Lee Min Cho Yool-Jin Park Kamala-Kannan Seralathan Byung-Taek Oh 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2020,95(1):297-307
The cover image is based on the Research Article V2O5/RGO/Pt nanocomposite on oxytetracycline degradation and pharmaceutical effluent detoxification by Mohan, H et al., DOI: 10.1002/jctb.6238 .
102.
Thin Film Thermoelectric Metal–Organic Framework with High Seebeck Coefficient and Low Thermal Conductivity 下载免费PDF全文
103.
104.
105.
Hoang V. Le Phuong T. Pham Ly T. Le Anh D. Nguyen Ngoc Quang Tran Phong D. Tran 《International Journal of Hydrogen Energy》2021,46(44):22852-22863
WO3 is a potential material candidate for construction of photoanode for solar driven water splitting. In this work, μm-thick porous WO3 photoanode is prepared by depositing a stable ink made of WO3 nanoparticles and Aristoflex velvet polymer in water using the doctor blade technique, followed by a sintering in air. The nature of WO3 nanoparticles, its loading mass on F-doped tin oxide electrode as well as sintering temperature are examined in order to optimize the photocatalytic activity of the resultant WO3 photoanode. The operation of WO3 photoanode is investigated by varying the light illumination direction and light incident intensity as well as changing the nature of the electrolyte. Dissolved tungsten in electrolyte is quantified by ICP-MS providing insights into the influences of electrolyte nature and operating conditions to the corrosion of WO3. It is proposed that the H2O2 and OH. radical generated as by-products of the photo-driven water oxidation on the photoanode surface are harmful species that accelerate the dissolution of WO3. 相似文献
106.
Krutov D. A. 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2021,55(4):519-527
Power Technology and Engineering - Measures for slope protection were developed and installed. The reliability of the proposed protective structures was confirmed by calculation studies using the... 相似文献
107.
Sleptsov V. V. Kukushkin D. Yu. Kulikov S. N. Diteleva A. O. 《Russian Engineering Research》2021,41(5):416-418
Russian Engineering Research - Thin-film vacuum technology permits the creation of new electrode materials on the basis of a flexible carbon matrix with a highly developed surface. Supercapacitor... 相似文献
108.
D. Kherifi H. Belhouchet S. Ramesh K.Y. Sara Lee A. Kenzour S. Djoualah M.K.G. Abbas Y.H. Wong S. Ramesh 《Ceramics International》2021,47(12):16483-16490
In this work, the sintering behaviour of fluorapatite (FAp)–silicate composites prepared by mixing variable amounts of natural quartz (2.5 wt% to 20 wt%) and FAp was studied. The composites were pressureless sintered in air at temperatures from 1000 °C to 1350 °C. The effects of temperatures on the densification, phase formation, chemical bonding and Vickers hardness of the composites were evaluated. All the samples exhibited mixed phase, comprising FAp and francolite as the major constituents along with some minor phases of cristobalite, wollastonite, dicalcium silicate and/or whitlockite dependent on the quartz content and sintering temperature. The composite containing 2.5 wt% quartz exhibited the best sintering properties. The highest bulk density of 3 g/cm3 and a Vickers hardness of >4.2 GPa were obtained for the 2.5 wt% quartz–FAp composite when sintered at 1100 °C. The addition of quartz was found to alter the microstructure of the composites, where it exhibited a rod-like morphology when sintered at 1000 °C and a regular rounded grain structure when sintered at 1350 °C. A wetted grain surface was observed for composites containing high quartz content and was believed to be associated with a transient liquid phase sintering. 相似文献
109.
Upconversion phosphors are known as a material system that can convert near-infrared light into visible/ultraviolet emissions by sequentially absorbing multiple photons. The studies on upconversion materials often use two rare earth (RE) ions as a sensitizer-activator pair. We investigated the influences on luminescence intensity depending on Cr-doping content (x) of hexagonal NaLu0.98–xCrxF4Er0.02 (x = 0–0.9) upconversion material by substituting Lu3+ ions with Cr3+in the absence of Gd3+. The change in upconversion luminescence intensity appears with saddle-like shape. We suggest that Cr3+ ions play the dual role as a constituent in host lattice and a sensitizer in the upconversion process. Optimal conditions for gaining the strongest upconversion emission correspond to x = 0.3–0.5, where there are effective energy transfers between Cr3+ and Er3+ ions and CrEr dimers. Apart from these values, the emission intensity decreases rapidly which can be ascribed to the absence of multiple-photon absorption for the case of low Cr3+ contents, and to the coupling between Cr3+ and/or Er3+ ions for the case of high Cr3+ contents. Magnetization and electron-spin-resonant measurements were performed to understand the correlation between the optical and magnetic properties. 相似文献
110.
V.A. Dekhtyarenko T.V. Pryadko D.G. Savvakin V.I. Bondarchuk G.S. Mogylnyy 《International Journal of Hydrogen Energy》2021,46(11):8040-8047
The influence of phase composition and microstructure of Ti42.75Zr27Mn20.25V10 alloy on its hydrogenation kinetic and phase composition of hydrogenated product was studied. It is established that the process of dissociation of hydrogen molecules begins on the surface of Laves phase crystallites. The dissolution of atomic hydrogen in the material volume leads to the formation of cracks in the intermetallic crystallites, which further appear as additional centers of dissociation of hydrogen molecules and noticeably accelerate the diffusion of hydrogen into the bulk material. It was shown that the Laves phase acts as a donor of atomic hydrogen for the BCC solid solution during hydrogenation of two-phase structure, initiating intensive hydrogenation of the BCC phase at room temperature. 相似文献