全文获取类型
收费全文 | 95125篇 |
免费 | 6992篇 |
国内免费 | 2778篇 |
专业分类
电工技术 | 4182篇 |
技术理论 | 6篇 |
综合类 | 4434篇 |
化学工业 | 17589篇 |
金属工艺 | 4829篇 |
机械仪表 | 6175篇 |
建筑科学 | 5592篇 |
矿业工程 | 2388篇 |
能源动力 | 3133篇 |
轻工业 | 6737篇 |
水利工程 | 1080篇 |
石油天然气 | 5253篇 |
武器工业 | 460篇 |
无线电 | 11399篇 |
一般工业技术 | 14105篇 |
冶金工业 | 5360篇 |
原子能技术 | 1052篇 |
自动化技术 | 11121篇 |
出版年
2024年 | 234篇 |
2023年 | 1469篇 |
2022年 | 2218篇 |
2021年 | 3565篇 |
2020年 | 2648篇 |
2019年 | 2414篇 |
2018年 | 2966篇 |
2017年 | 3163篇 |
2016年 | 2863篇 |
2015年 | 3321篇 |
2014年 | 4415篇 |
2013年 | 5652篇 |
2012年 | 5862篇 |
2011年 | 6723篇 |
2010年 | 5517篇 |
2009年 | 5326篇 |
2008年 | 5110篇 |
2007年 | 4680篇 |
2006年 | 4641篇 |
2005年 | 4185篇 |
2004年 | 2971篇 |
2003年 | 2710篇 |
2002年 | 2497篇 |
2001年 | 2184篇 |
2000年 | 2273篇 |
1999年 | 2482篇 |
1998年 | 2479篇 |
1997年 | 1840篇 |
1996年 | 1804篇 |
1995年 | 1443篇 |
1994年 | 1114篇 |
1993年 | 863篇 |
1992年 | 652篇 |
1991年 | 520篇 |
1990年 | 402篇 |
1989年 | 341篇 |
1988年 | 300篇 |
1987年 | 208篇 |
1986年 | 156篇 |
1985年 | 136篇 |
1984年 | 97篇 |
1983年 | 65篇 |
1982年 | 73篇 |
1981年 | 55篇 |
1980年 | 53篇 |
1979年 | 26篇 |
1977年 | 30篇 |
1976年 | 41篇 |
1975年 | 23篇 |
1974年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Park Sangwon Nam Hyunbin Na Youngsang Kim Hyoungseop Moon Younghoon Kang Namhyun 《Metals and Materials International》2020,26(5):641-649
Metals and Materials International - This study investigated the influence of the initial grain size on the plastic deformation and tunnel defects that occurred from friction stir welding of... 相似文献
93.
Mohammad Reza Gaeeni Morteza Sasani Ghamsari Abbas Majd Abadi Mohammad Hossein Majles Ara Wooje Han Hyung‐Ho Park 《Journal of the American Ceramic Society》2015,98(6):1818-1822
A facile sol–gel procedure has been developed for the synthesis of colloidal alumina nanocrystals. For the first time, optical characterization procedures were employed to study the quantum confinement effects in optical properties of the prepared Al2O3 sol. Accordingly, the hyperbolic band model was used to determine the optical band gap of colloidal alumina nanocrystals. X‐Ray diffraction pattern was used to study the crystallographic phase of the dried gel. Morphological characterization was performed using scanning electron microscopy (SEM). Inductively Coupled Plasma (ICP) emission spectroscopy was used to determination purity of the Al2O3 powder. High‐resolution TEM showed that the diameter of colloidal nanocrystals is about 10 nm. Photoluminescence spectroscopy demonstrated that quantum yields for colloidal nanocrystals are 68% with 300 nm excitation wavelength. The experimental observations confirm that highly stable alumina sol with strong UV emission was synthesized. The mentioned optical properties have not been reported before. 相似文献
94.
95.
Spherical LiNi1/3Co1/3Mn1/3O2 cathode particles were resynthesized by a carbonate co-precipitation method using spent lithium-ion batteries (LIBs) as a raw material. The physical characteristics of the Ni1/3Co1/3Mn1/3CO3 precursor, the (Ni1/3Co1/3Mn1/3)3O4 intermediate, and the regenerated LiNi1/3Co1/3Mn1/3O2 cathode material were investigated by laser particle-size analysis, scanning electron microscopy–energy-dispersive spectroscopy (SEM-EDS), thermogravimetry–differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), inductively coupled plasma–atomic emission spectroscopy (ICP-AES), and X-ray photoelectron spectroscopy (XPS). The electrochemical performance of the regenerated LiNi1/3Co1/3Mn1/3O2 was studied by continuous charge–discharge cycling and cyclic voltammetry. The results indicate that the regenerated Ni1/3Co1/3Mn1/3CO3 precursor comprises uniform spherical particles with a narrow particle-size distribution. The regenerated LiNi1/3Co1/3Mn1/3O2 comprises spherical particles similar to those of the Ni1/3Co1/3Mn1/3CO3 precursor, but with a narrower particle-size distribution. Moreover, it has a well-ordered layered structure and a low degree of cation mixing. The regenerated LiNi1/3Co1/3Mn1/3O2 shows an initial discharge capacity of 163.5 mA h g?1 at 0.1 C, between 2.7 and 4.3 V; the discharge capacity at 1 C is 135.1 mA h g?1, and the capacity retention ratio is 94.1% after 50 cycles. Even at the high rate of 5 C, LiNi1/3Co1/3Mn1/3O2 delivers the high capacity of 112.6 mA h g?1. These results demonstrate that the electrochemical performance of the regenerated LiNi1/3Co1/3Mn1/3O2 is comparable to that of a cathode synthesized from fresh materials by carbonate co-precipitation. 相似文献
96.
97.
98.
Youngseok Lee Cheolmin Park Nagarajan Balaji Youn-Jung Lee Vinh Ai Dao 《Israel journal of chemistry》2015,55(10):1050-1063
Over the past few decades, crystalline silicon solar cells have been extensively studied due to their high efficiency, high reliability, and low cost. In addition, these types of cells lead the industry and account for more than half of the market. For the foreseeable future, Si will still be a critical material for photovoltaic devices in the solar cell industry. In this paper, we discuss key issues, cell concepts, and the status of recent high-efficiency crystalline silicon solar cells. 相似文献
99.
Jinho Choi Sanghun Jung Deok Gun Park Jaegul Choo Niklas Elmqvist 《Computer Graphics Forum》2019,38(3):249-260
The majority of visualizations on the web are still stored as raster images, making them inaccessible to visually impaired users. We propose a deep‐neural‐network‐based approach that automatically recognizes key elements in a visualization, including a visualization type, graphical elements, labels, legends, and most importantly, the original data conveyed in the visualization. We leverage such extracted information to provide visually impaired people with the reading of the extracted information. Based on interviews with visually impaired users, we built a Google Chrome extension designed to work with screen reader software to automatically decode charts on a webpage using our pipeline. We compared the performance of the back‐end algorithm with existing methods and evaluated the utility using qualitative feedback from visually impaired users. 相似文献
100.