全文获取类型
收费全文 | 87329篇 |
免费 | 4693篇 |
国内免费 | 2889篇 |
专业分类
电工技术 | 4911篇 |
技术理论 | 26篇 |
综合类 | 6766篇 |
化学工业 | 10795篇 |
金属工艺 | 4074篇 |
机械仪表 | 5313篇 |
建筑科学 | 10659篇 |
矿业工程 | 5515篇 |
能源动力 | 2327篇 |
轻工业 | 7989篇 |
水利工程 | 2258篇 |
石油天然气 | 4164篇 |
武器工业 | 2154篇 |
无线电 | 8412篇 |
一般工业技术 | 4442篇 |
冶金工业 | 4866篇 |
原子能技术 | 348篇 |
自动化技术 | 9892篇 |
出版年
2024年 | 207篇 |
2023年 | 735篇 |
2022年 | 1716篇 |
2021年 | 2302篇 |
2020年 | 2271篇 |
2019年 | 1282篇 |
2018年 | 1167篇 |
2017年 | 1830篇 |
2016年 | 2226篇 |
2015年 | 2521篇 |
2014年 | 6813篇 |
2013年 | 4653篇 |
2012年 | 6669篇 |
2011年 | 7002篇 |
2010年 | 5327篇 |
2009年 | 5424篇 |
2008年 | 4866篇 |
2007年 | 6075篇 |
2006年 | 5505篇 |
2005年 | 4853篇 |
2004年 | 4178篇 |
2003年 | 3822篇 |
2002年 | 3082篇 |
2001年 | 2595篇 |
2000年 | 1986篇 |
1999年 | 1497篇 |
1998年 | 1019篇 |
1997年 | 764篇 |
1996年 | 640篇 |
1995年 | 491篇 |
1994年 | 361篇 |
1993年 | 241篇 |
1992年 | 202篇 |
1991年 | 134篇 |
1990年 | 115篇 |
1989年 | 83篇 |
1988年 | 60篇 |
1987年 | 36篇 |
1986年 | 40篇 |
1985年 | 23篇 |
1984年 | 21篇 |
1983年 | 10篇 |
1982年 | 9篇 |
1981年 | 15篇 |
1980年 | 11篇 |
1979年 | 7篇 |
1978年 | 3篇 |
1964年 | 3篇 |
1958年 | 2篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 500 毫秒
1.
2.
文章首先对智能化电子信息技术进行了深入的研究,而后分析了该技术在应用过程中出现的问题,最后结合该技术的相关特点给出了相应的问题解决措施,希望能够对智能化电子信息技术的发展提供帮助。 相似文献
3.
盘扣式支撑架具有承载力强、方便安全、结实耐用等优点,被广泛应用于地铁施工。本文以广州市轨道交通十八号线万顷沙车辆段为例,对承插型盘扣式支撑架在地铁车辆段工程中的具体应用进行了详细说明,以期为同类工程提供参考。 相似文献
4.
Chunsheng Wang Yishuang Wang Mingqiang Chen Defang Liang Zhonglian Yang Wen Cheng Zhiyuan Tang Jun Wang Han Zhang 《International Journal of Hydrogen Energy》2021,46(7):5852-5874
Given the continuing issues of environment and energy, methane dry reforming for syngas production have sparked interest among researchers, but struggled with the process immaturity owing to catalyst deactivation. This review summarizes the recent advances in the development of efficient and stable catalysts with strong resistance to coking and metal sintering, including the application of novel materials, the assessment of advanced characterizations and the compatibility to improved reaction system. One feasible option is the crystalline oxide catalysts (perovskite, pyrochlore, spinel and LDHs), which feature a fine metal dispersion and surface confinement effect via a metal exsolution strategy and exhibit superior reactivity and stability. Some new materials (h-BN, clays and MOFs) also extend the option because of their unique morphology and microstructure. It also is elaborated that progresses were achieved in advanced characterizations application, leading to success in the establishment of reaction mechanisms and attributions to the formed robust catalysts. In addition, the perspective described the upgrade of reaction system to a higher reaction efficiency and milder reaction conditions. The combination of efficient reaction systems and robust catalysts paves a way for a scaling-up application of the process. 相似文献
5.
6.
《Ceramics International》2022,48(12):16877-16884
Oxygen selective membrane on the base of cermet δ-Bi2O3/Ag with an interpenetrating structure has the maximum potential efficiency of air separation. However, the degradation processes, including the phase degradation of fluorite δ-Bi2O3, do not make it possible to create a membrane with the required perfection and durability. In this work, the ordering of oxygen vacancies with the transformation of fluorite into the rhombohedral phase (S.G. R-3) was studied by powder HT XRD in situ at 600 °C on dense Bi0.78Er0.2Hf0.02O1.51 ceramics. Fast regeneration of disordered fluorite occurs at T = 640–700 °C. The phase degradation of fluorite due to the segregation of dopants at the second stage leads into stable phases - sillenite, tetragonal or rhombohedral phase (S.G. R-3m), depending on the composition of δ-Bi2O3. Fast regeneration of fluorite occurs when heated to 820 °C, which is unacceptable for membranes. Analysis of all available data allows us to propose approaches to optimize the composition of δ-Bi2O3 and technical solutions for creating durable oxygen selective membranes with promising use in distributed multigeneration. As a result of the analysis, a new solid electrolyte with better parameters was obtained. 相似文献
7.
《Ceramics International》2022,48(8):10921-10931
Coatings were obtained by vacuum electro-spark alloying (VESA), pulsed cathodic arc evaporation (PCAE), magnetron sputtering (MS) techniques and VESA-PCAE-MS hybrid technology using Cr3C2–NiAl electrodes. The structure of the coatings was analyzed using scanning and transmission electron microscopy, X-ray diffraction and energy-dispersive spectroscopy. Mechanical properties were determined by nanoindentation, while tribological properties were assessed using pin-on-disk tribometer. Corrosion resistance was estimated by voltammetry in 1 N H2SO4 and 3.5%NaCl solutions. Oxidation resistance tests were performed at 800°С in air. The VESA coating had the highest thickness, low friction coefficient and high wear resistance. PCAE coating demonstrated the highest hardness (24 GPa) and elastic recovery (59%), oxidation resistance and superior corrosion resistance both in 1 N H2SO4 (icorr = 70 μА/cm2) and 3.5%NaCl (icorr = 0.74 μА/cm2) solutions. The MS coating had average mechanical properties and low corrosion current density (71 μА/cm2) in 1 N H2SO4. Deposition of coatings using VESA-PCAE-MS hybrid technology led to an increase in corrosion and oxidation resistance at least by 1.5 times in comparison with the VESA coating. 相似文献
8.
《Ceramics International》2022,48(6):7593-7604
The ceramic core, produced by hot injection molding, is one of the critical components for manufacturing high-performance aircraft engine turbine blades. However, the injection molding process will cause defects such as burrs and flashes in the fine structure of the formed ceramic core. Manual trimming is necessary, but the trimming quality is poor, and the yield is low. In this paper, the online trimming method of ceramic cores is studied. Based on the orthogonal experiment method, the optimal laser parameters for processing the ceramic core's porous multi-scale particle structure material were obtained. Further, the problems of the match head and tail phenomenon and dimensional accuracy improvement in trimming ceramic cores have been studied. A path optimisation method is proposed to improve the quality and accuracy of the trimming profile effectively. Finally, the overall process flow of ceramic core trimming is elaborated, and experimental verification is given. The results show that the ceramic core online trimming method proposed in this paper has advantages of high precision and high yield compared with the manual method, which will have substantial potential application value in the aviation field. 相似文献
9.
10.
华治国 《混凝土与水泥制品》2020,(6):70-72
选择了几份典型的外墙外保温系统标准,通过对这几份标准中胶粘剂和抹面胶浆的成型和检测方法的比较,分析了现有检测技术的优劣,并结合工作实践提出了建议。 相似文献