全文获取类型
收费全文 | 3355篇 |
免费 | 253篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 21篇 |
综合类 | 4篇 |
化学工业 | 823篇 |
金属工艺 | 135篇 |
机械仪表 | 229篇 |
建筑科学 | 53篇 |
能源动力 | 124篇 |
轻工业 | 377篇 |
水利工程 | 27篇 |
石油天然气 | 2篇 |
无线电 | 566篇 |
一般工业技术 | 677篇 |
冶金工业 | 178篇 |
原子能技术 | 38篇 |
自动化技术 | 367篇 |
出版年
2024年 | 3篇 |
2023年 | 58篇 |
2022年 | 73篇 |
2021年 | 119篇 |
2020年 | 95篇 |
2019年 | 107篇 |
2018年 | 112篇 |
2017年 | 133篇 |
2016年 | 177篇 |
2015年 | 116篇 |
2014年 | 193篇 |
2013年 | 245篇 |
2012年 | 251篇 |
2011年 | 301篇 |
2010年 | 223篇 |
2009年 | 180篇 |
2008年 | 193篇 |
2007年 | 154篇 |
2006年 | 126篇 |
2005年 | 106篇 |
2004年 | 74篇 |
2003年 | 74篇 |
2002年 | 79篇 |
2001年 | 76篇 |
2000年 | 48篇 |
1999年 | 50篇 |
1998年 | 83篇 |
1997年 | 35篇 |
1996年 | 32篇 |
1995年 | 18篇 |
1994年 | 12篇 |
1993年 | 10篇 |
1992年 | 4篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1966年 | 1篇 |
排序方式: 共有3621条查询结果,搜索用时 15 毫秒
101.
Jungyub Woo Seung-Jun Shin Wonchul Seo Prita Meilanitasari 《The International Journal of Advanced Manufacturing Technology》2018,99(9-12):2193-2217
Manufacturing industries have recently promoted smart manufacturing (SM) for achieving intelligence, connectedness, and responsiveness of manufacturing objects consisting of man, machine, and material. Traditional manufacturing platforms, which identify generic frameworks where common functionalities are shareable and diverse applications are workable, mainly focused on remote collaboration, distributed control, and data integration; however, they are limited to incorporating those characteristic achievements. The present work introduces an SM-toward manufacturing platform. The proposed platform incorporates the capabilities of (1) virtualization of manufacturing objects for their autonomy and cooperation, (2) processing of real and various manufacturing data for mediating physical and virtual objects, and (3) data-driven decision-making for predictive planning on those objects. For such capabilities, the proposed platform advances the framework of Holonic Manufacturing Systems with the use of agent technology. It integrates a distributed data warehouse to encompass data specification, storage, processing, and retrieval. It applies a data analytics approach to create empirical decision-making models based on real and historical data. Furthermore, it uses open and standardized data interfaces to embody interoperable data exchange across shop floors and manufacturing applications. We present the architecture and technical methods for implementing the proposed platform. We also present a prototype implementation to demonstrate the feasibility and effectiveness of the platform in energy-efficient machining. 相似文献
102.
Xuebin Qiao Jing Wang Yanlin Huang Peiqing Cai Sun I. L. Kim Hyo‐Jin Seo 《Journal of the American Ceramic Society》2014,97(11):3561-3567
Eu2+‐doped zinc fluoro‐phosphate Zn2[PO4]F was synthesized by the conventional high‐temperature solid‐state reaction. The phase formation was confirmed by X‐ray powder diffraction measurements and the structure refinement. The photoluminescence excitation and emission spectra, and the decay curves were measured. The natures of the Eu2+ emission in inorganic hosts, e.g., the emission and excitation properties, the chromaticity coordinates, the Stokes shifts, the absolute quantum efficiency, and the luminescence thermal stability were reported. Under the excitation of near‐UV light, Eu2+‐doped Zn2[PO4]F presents a narrow blue‐emitting band centered at 423 nm. The thermal stability of the blue luminescence was evaluated by the luminescence intensities as a function of temperature. The phosphor shows an excellent thermal stability on temperature quenching effects. 相似文献
103.
Dae‐Hyeon Kim Mi‐Ri Joung In‐Tae Seo Joon Hur Jong‐Hyun Kim Bo‐Yun Kim Hwack‐Joo Lee Sahn Nahm 《Journal of the American Ceramic Society》2014,97(12):3897-3903
Dielectric and piezoelectric properties of CuO‐added KNbO3 (KN) ceramics were investigated. The CuO reacted with the Nb2O5, formed a CuO–Nb2O5‐related liquid phase during the sintering, and assisted the densification of the KN ceramics at low temperatures. Moreover, some of the Cu2+ ions replaced the Nb5+ ions in the matrix and behaved as a hardener. The dielectric and piezoelectric properties of the KN ceramics were considerably influenced by the relative density. The 1.0 mol% CuO‐added KN ceramic sintered at 960°C for 1.0 h, which showed a maximum relative density, exhibited a high phase angle of 86.9°, Pr of 14.8 μC/cm2, and Ec of 1.8 kV/mm. This specimen also exhibited good dielectric and piezoelectric properties: εT33/εo of 364, d33 of 122 pC/N, kp of 0.29, and Qm of 611. 相似文献
104.
In this study, the rubber forming process is used to fabricate a micro‐channel titanium plate for a PEM fuel cell. The micro‐channel plate is fabricated using a 200 ton hydraulic press, and various parameters (punch speed, press pressure, rubber thickness, rubber hardness) are investigated in order to evaluate the formability. TiN films are deposited by reactive DC magnetron sputtering (DCMS) with an electromagnetic field system (EMFS). For the uncoated titanium and TiN‐coated titanium substrates, the hardness, surface roughness, and corrosion resistance are estimated by nano‐indentation and electrochemical methods, respectively. The improved corrosion resistance of the TiN films can be attributed to the densification of the film caused by enhancement of nitrification with increasing high reactive nitrogen radicals. The uncoated titanium and TiN‐coated titanium bipolar plates are combined with a unit cell for a performance test, and respective current densities of 0.396 and 0.888 A cm−2 at 0.6 V are obtained. 相似文献
105.
新一代超小型DIP-IPM 总被引:1,自引:0,他引:1
为了满足空调、洗衣机、冰箱等白色家电对高效、高性能的需要,三菱电机开发了新一代超小型第四代(Ver.4)双列直插封装的智能功率模块(Dual-In-linePackageIntelligentPowerModule,简称DIP-IPM)。本文首先分析了第四代超小型DIP-IPM内部电路的构成和功能,然后详细介绍了第四代DIP-IPM生产过程中的关键技术,包括无铅化、高热传导性绝缘片、chip-to-chip导线直接连接以及ASIC技术,最后与第三代(Ver.3)DIP-IPM进行了比较。 相似文献
106.
Avanish Bharati Prakhyat Hejmady Tom Van der Donck Jin Won Seo Ruth Cardinaels Paula Moldenaers 《应用聚合物科学杂志》2020,137(9):48433
An approach to induce conductivity in immiscible polystyrene/polypropylene (PS/PP) blends is described using a percolated conducting polyaniline/polyamide (PANI/PA) filler combined with a polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene-graft-maleic anhydride compatibilizer. The approach is based on the ability of the compatibilizer to concomitantly stabilize the cocontinuous morphology and to improve the state of dispersion of the PANI/PA filler. Selective localization of PANI/PA in the PS phase with improved filler dispersion is achieved with the optimal master batch (MB) preparation technique followed by its optimized sequence addition to the blend components. This results in an increase in the dc conductivity by six decades as compared with that of the neat compatibilized blend at an effective 4.8-wt % PANI concentration. An investigation of the effect of functionality and concentration of the filler and the compatibilizer on the filler connectivity in the blend is performed. The prevailing specific interactions are analyzed by Fourier transform infrared spectroscopy and thermogravimetric analysis of the MBs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48433. 相似文献
107.
Human umbilical-cord-derived mesenchymal stem cells (hUC-MSC) are a type of mesenchymal stem cells and are more primitive than other MSCs. In this study, we identify novel genes and signal-activating proteins involved in the neural differentiation of hUC-MSCs induced by Low-Intensity Sub-Sonic Vibration (LISSV). RNA sequencing was used to find genes involved in the differentiation process by LISSV. The changes in hUC-MSCs caused by LISSV were confirmed by PLXNA4 overexpression and gene knockdown through small interfering RNA experiments. The six genes were increased among genes related to neurons and the nervous system. One of them, the PLXNA4 gene, is known to play a role as a guide for axons in the development of the nervous system. When the PLXNA4 recombinant protein was added, neuron-related genes were increased. In the PLXNA4 gene knockdown experiment, the expression of neuron-related genes was not changed by LISSV exposure. The PLXNA4 gene is activated by sema family ligands. The expression of SEMA3A was increased by LISSV, and its downstream signaling molecule, FYN, was also activated. We suggest that the PLXNA4 gene plays an important role in hUC-MSC neuronal differentiation through exposure to LISSV. The differentiation process depends on SEMA3A-PLXNA4-dependent FYN activation in hUC-MSCs. 相似文献
108.
Won Sun Park Jeonghan Lee Giyoun Na SaeGwang Park Su-Kil Seo Jung Sik Choi Won-Kyo Jung Il-Whan Choi 《International journal of molecular sciences》2022,23(3)
Inflammasomes are a group of intracellular multiprotein platforms that play important roles in immune systems. Benzyl isothiocyanate (BITC) is a constituent of cruciferous plants and has been confirmed to exhibit various biological activities. The modulatory effects of BITC on inflammasome-mediated interleukin (IL)-1β expression and its regulatory mechanisms in Pseudomonas aeruginosa (P. aeruginosa) LPS/ATP-stimulated THP-1 cells was investigated. Monocytic THP-1 cells were treated with phorbol myristate acetate (PMA) to induce differentiation into macrophages. Enzyme-linked immunosorbent assays (ELISA) were performed to measure the levels of IL-1β produced in P. aeruginosa LPS/ATP-exposed THP-1 cells. Western blotting was performed to examine the BITC modulatory mechanisms in inflammasome-mediated signaling pathways. BITC inhibited IL-1β production in P. aeruginosa LPS/ATP-induced THP-1 cells. BITC also inhibited activation of leucine-rich repeat protein-3 (NLRP3) and caspase-1 in P. aeruginosa LPS/ATP-induced THP-1 cells. Furthermore, we show that mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) activation in P. aeruginosa LPS was attenuated by BITC. These BITC-mediated modulatory effects on IL-1β production may have therapeutic potential for inflammasome-mediated disorders such as a nasal polyp. 相似文献
109.
Hyeyoung Ha Youngshin Kwak Hyosun Kim Young-jun Seo 《Color research and application》2020,45(4):622-631
The Images in an immersive head-mounted display (HMD) for virtual reality provide the sole source for visual adaptation. Thus, significant, near-instantaneous increases in luminance while viewing an HMD can result in visual discomfort. Therefore, the current study investigated the luminance change necessary to induce this discomfort. Based on the psychophysical experiment data collected from 10 subjects, a prediction model was derived using four complex images and one neutral image, with four to six levels of average scene luminance. Result showed that maximum area luminance has a significant correlation with the discomfort luminance level than average, median, or maximum pixel luminance. According to the prediction model, the discomfort luminance level of a head-mounted display was represented as a positive linear function in log10 units using the previous adaptation luminance when luminance is calculated as maximum area luminance. 相似文献
110.
Salmonellosis caused by Salmonella Enteritidis (SE) is a significant cause of foodborne illnesses in the United States. Consumption of undercooked eggs and egg-containing products has been the primary risk factor for the disease. The importance of the bacterial enumeration technique has been enormously stressed because of the quantitative risk analysis of SE in shell eggs. Traditional enumeration methods mainly depend on slow and tedious most-probable-number (MPN) methods. Therefore, specific, sensitive, and rapid methods for SE quantitation are needed to collect sufficient data for risk assessment and food safety policy development. We previously developed a real-time quantitative PCR assay for the direct detection and enumeration of SE and, in this study, applied it to naturally contaminated ice cream samples with and without enrichment. The detection limit of the real-time PCR assay was determined with artificially inoculated ice cream. When applied to the direct detection and quantification of SE in ice cream, the real-time PCR assay was as sensitive as the conventional plate count method in frequency of detection. However, populations of SE derived from real-time quantitative PCR were approximately 1 log higher than provided by MPN and CFU values obtained by conventional culture methods. The detection and enumeration of SE in naturally contaminated ice cream can be completed in 3 h by this real-time PCR method, whereas the cultural enrichment method requires 5 to 7 days. A commercial immunoassay for the specific detection of SE was also included in the study. The real-time PCR assay proved to be a valuable tool that may be useful to the food industry in monitoring its processes to improve product quality and safety. 相似文献