全文获取类型
收费全文 | 26125篇 |
免费 | 1743篇 |
国内免费 | 132篇 |
专业分类
电工技术 | 411篇 |
技术理论 | 1篇 |
综合类 | 115篇 |
化学工业 | 5939篇 |
金属工艺 | 1049篇 |
机械仪表 | 1613篇 |
建筑科学 | 548篇 |
矿业工程 | 51篇 |
能源动力 | 1086篇 |
轻工业 | 2211篇 |
水利工程 | 127篇 |
石油天然气 | 134篇 |
武器工业 | 10篇 |
无线电 | 4297篇 |
一般工业技术 | 5461篇 |
冶金工业 | 1711篇 |
原子能技术 | 340篇 |
自动化技术 | 2896篇 |
出版年
2024年 | 22篇 |
2023年 | 327篇 |
2022年 | 373篇 |
2021年 | 860篇 |
2020年 | 619篇 |
2019年 | 632篇 |
2018年 | 850篇 |
2017年 | 820篇 |
2016年 | 940篇 |
2015年 | 758篇 |
2014年 | 1189篇 |
2013年 | 1694篇 |
2012年 | 1773篇 |
2011年 | 2115篇 |
2010年 | 1598篇 |
2009年 | 1612篇 |
2008年 | 1489篇 |
2007年 | 1109篇 |
2006年 | 988篇 |
2005年 | 898篇 |
2004年 | 805篇 |
2003年 | 721篇 |
2002年 | 696篇 |
2001年 | 613篇 |
2000年 | 520篇 |
1999年 | 530篇 |
1998年 | 784篇 |
1997年 | 484篇 |
1996年 | 464篇 |
1995年 | 297篇 |
1994年 | 219篇 |
1993年 | 172篇 |
1992年 | 132篇 |
1991年 | 120篇 |
1990年 | 92篇 |
1989年 | 108篇 |
1988年 | 80篇 |
1987年 | 69篇 |
1986年 | 54篇 |
1985年 | 49篇 |
1984年 | 43篇 |
1983年 | 35篇 |
1982年 | 35篇 |
1981年 | 31篇 |
1980年 | 30篇 |
1979年 | 17篇 |
1977年 | 24篇 |
1976年 | 33篇 |
1975年 | 17篇 |
1974年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 160 毫秒
31.
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
32.
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
33.
34.
Ha-Nul Lee Joo-Hee Choi Ji-Yeon Park Jae-Hun Ahn Da Eun Jang Jae Gun Shim Jong-Hwan Park Young-Min Kim 《Food science and biotechnology》2021,30(4):583
Vegetable soup (VS), a plant-based functional food, has been used as a traditional folk medicine and is attracting attention for its ability to enhance the immune response. β-Glucan, a well-established and effective immunomodulator, has synergistic effects when used in combination with some bioactive compounds. In the present study, we aimed to evaluate the synergistic immunomodulatory effects of the combination of VS and β-glucan on macrophage-mediated immune responses. β-Glucan was demonstrated to synergistically enhance the VS-stimulated immune response, including the production of interleukin-6, tumor necrosis factor-α, and nitric oxide, mainly through the mitogen-activated protein kinase pathway in macrophages. In addition, this combination has the potential for further development in functional foods with immune-enhancing activity.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10068-021-00888-x. 相似文献
35.
36.
S.J. Choi K. Djordjev Zhen Peng Qi Yang Sang Jun Choi P.D. Dapkus 《Photonics Technology Letters, IEEE》2004,16(10):2266-2268
All-buried InP-InGaAsP ring resonators laterally coupled to bus waveguides are demonstrated. The buried configurations offer a lower built-in refractive index step along the resonator periphery, which affords enhanced optical coupling coefficients between the waveguides and reduced scattering losses caused by the resonator sidewall imperfections. Very low optical intensity attenuations of 0.4 cm/sup -1/ and coupling-limited quality factors of greater than 10/sup 5/ are observed from 200-/spl mu/m-radii ring resonators. The measured spectral linewidth is as narrow as 0.0145 nm. 相似文献
37.
Spectral shape tunable band-rejection filter using a long-period fiber grating with divided coil heaters 总被引:2,自引:0,他引:2
Jun Kye Bae Sang Hyuck Kim Jun Hee Kim Jinho Bae Sang Bae Lee Je-Myung Jeong 《Photonics Technology Letters, IEEE》2003,15(3):407-409
We have developed a new type of tunable band rejection filter, which provides high spectral-shaping flexibility in a wide tuning range. The filter consists of a long-period fiber grating (LPFG) with divided coil heaters. Each of the divided coil heaters is controlled individually to adjust a temperature distribution along the LPFG and to modify the spectral shape of the LPFG filter. The tunable band rejection filter is demonstrated to function properly when applied as an erbium-doped fiber amplifier gain-flattening filter. 相似文献
38.
Young-Geun Han Sang Hyuck Kim Sang Bae Lee Un-Chul Paek Youngjoo Chung 《Electronics letters》2003,39(15):1107-1108
A novel fabrication method of the core mode blocker by exposing H/sub 2/-loaded Ge-B codoped fibres to local electric arc discharge for application to the LPFGs-based tunable all-fibre bandpass filter with 6.5 nm bandwidth and 40 nm tuning range is presented. 相似文献
39.
The aim of this study was to evaluate the use of total coliforms (TC) and faecal coliforms (FC) using a membrane filtration method for precise monitoring of faecal pollution in Korean surface water. The samples were collected in Korea from both main rivers and their tributaries. Presumptive TC * FC were enumerated. The ratios of presumptive FC to TC were not constant, but varied widely, and TC were difficult to enumerate because of overgrowth by background colonies. For FC this was not the case. Seven hundred and three purified strains of presumptive TC * FC and their background colonies were biotyped using API 20E. Among 272 presumptive TC, non-faecal related species, Aeromonas hydrophila dominated (34.6%) and E. coli accounted for only 5.1%. In contrast, E. coli made up 89% of the 209 presumptive FC. Furthermore, of 164 background colonies on Endo Agar LES, 54.9% was A. hydrophila, while background colonies on m-FC Agar were few (58 strains), and despite their atypical colony appearance, most of them were biotyped as enteric bacteria. These results reveal that the detection of FC rather than TC using m-FC Agar is more appropriate for faecal pollution monitoring in eutrophicated surface water located in a temperate region. 相似文献
40.
Soo Jin Kim Wha Young Lee Yeungho Park Wansoo Huh Young Gwan Ko 《Polymer Engineering and Science》2003,43(5):1011-1017
Supported zirconcene catalysts on a new support, MgO, were prepared and tested in ethylene polymerization. Three types of impregnation methods were employed to find an optimum supporting method for MgO. The direct impregnation of Cp2ZrCl2 on MgO showed low metal loading and polymerization activity, while the catalyst had a higher metal loading and polymerization activity when MgO was treated with methylaluminoxane (MAO) before supporting. Treatment of MgO with MAO during the supporting step invoked two types of catalytic sites, which was evidenced by the bimodal molecular weight distribution of the polymer products. MgO is considered to have potential as a support for metallocenes. 相似文献