全文获取类型
收费全文 | 433188篇 |
免费 | 35790篇 |
国内免费 | 19148篇 |
专业分类
电工技术 | 26606篇 |
技术理论 | 23篇 |
综合类 | 27914篇 |
化学工业 | 68989篇 |
金属工艺 | 25420篇 |
机械仪表 | 27783篇 |
建筑科学 | 31792篇 |
矿业工程 | 12147篇 |
能源动力 | 11495篇 |
轻工业 | 27291篇 |
水利工程 | 8604篇 |
石油天然气 | 24486篇 |
武器工业 | 3559篇 |
无线电 | 48239篇 |
一般工业技术 | 56769篇 |
冶金工业 | 22695篇 |
原子能技术 | 7948篇 |
自动化技术 | 56366篇 |
出版年
2024年 | 1262篇 |
2023年 | 6250篇 |
2022年 | 11135篇 |
2021年 | 16737篇 |
2020年 | 12834篇 |
2019年 | 10647篇 |
2018年 | 12439篇 |
2017年 | 13843篇 |
2016年 | 12708篇 |
2015年 | 16290篇 |
2014年 | 20622篇 |
2013年 | 24786篇 |
2012年 | 27692篇 |
2011年 | 29718篇 |
2010年 | 25814篇 |
2009年 | 25035篇 |
2008年 | 24498篇 |
2007年 | 23060篇 |
2006年 | 22681篇 |
2005年 | 19190篇 |
2004年 | 13901篇 |
2003年 | 12671篇 |
2002年 | 12631篇 |
2001年 | 11418篇 |
2000年 | 10401篇 |
1999年 | 9816篇 |
1998年 | 7845篇 |
1997年 | 6578篇 |
1996年 | 5937篇 |
1995年 | 5113篇 |
1994年 | 4168篇 |
1993年 | 3209篇 |
1992年 | 2766篇 |
1991年 | 2293篇 |
1990年 | 1981篇 |
1989年 | 1761篇 |
1988年 | 1528篇 |
1987年 | 1235篇 |
1986年 | 1052篇 |
1985年 | 895篇 |
1984年 | 811篇 |
1982年 | 768篇 |
1981年 | 731篇 |
1979年 | 768篇 |
1978年 | 788篇 |
1977年 | 751篇 |
1976年 | 773篇 |
1975年 | 727篇 |
1974年 | 723篇 |
1973年 | 729篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Feng Wenran Li Zhen Chen Yingying Chen Jinyang Lang Haoze Wan Jianghong Gao Yan Dong Haitao 《Journal of Materials Science》2022,57(3):1881-1889
Journal of Materials Science - Although chalcogenide materials continue to generate considerable interest due to great potentials for various optoelectronic devices, annealing for a long time in... 相似文献
3.
Xiao Zhu Chen Yanxun Jiang Hongbo Hu Zhenzhen Lui John C. S. Min Geyong Dustdar Schahram 《Wireless Networks》2022,28(7):3305-3322
Wireless Networks - Unmanned aerial vehicles (UAV) have been widely used in various fields because of their high mobility and portability. At the same time, due to the rapid development of... 相似文献
4.
采用直流磁控溅射和后退火氧化工艺在p型GaAs单晶衬底上成功制备了n-VO_2/pGaAs异质结,研究了不同退火温度和退火时间对VO_2/GaAs异质结性能的影响,并分析其结晶取向、化学组分、膜层质量以及光电特性。结果表明,在退火时间2 h和退火温度693 K下能得到相变性能最佳的VO_2薄膜,相变前后电阻变化约2个数量级。VO_2/GaAs异质结在308 K、318 K和328 K温度下具有较好的整流特性,对应温度下的阈值跳变电压分别为6.9 V、6.6 V和6.2 V,该结果为基于VO_2相变特性的异质结光电器件的设计与应用提供了可行性。 相似文献
5.
Kelin Hu Feipeng Wang Yuyang Yan Hongcheng Liu Zijia Shen 《Ceramics International》2021,47(11):15228-15236
In this paper, a novel hybrid structure of Pd doped ZnO/SnO2 heterojunction nanofibers with hexagonal ZnO columns was one step synthesized from electrospun precursor nanofibers. Due to the synergistic effect of hexagonal ZnO, SnO2 and Pd, the structure exhibited excellent hydrogen (H2) gas sensing properties. At low-temperature of 120 °C, the response (Ra/Rg) to 100 ppm H2 gas exceeded 160, the response/recovery time was only 20 s and 6 s respectively and the limit of detection was only 0.5 ppm. Meanwhile, it also had good selectivity for H2 gas and excellent linearity. In addition, the materials were characterized by XRD, FESEM, HRTEM, XPS, and the synthesis mechanism and gas sensing mechanism were proposed. 相似文献
6.
Jincheng Yu Yabin Chang Ewa Jakubczyk Bing Wang Feridoon Azough Robert Dorey Robert Freer 《Journal of the European Ceramic Society》2021,41(9):4859-4869
Ca3Co4O9 is a promising p-type thermoelectric oxide material having intrinsically low thermal conductivity. With low cost and opportunities for automatic large scale production, thick film technologies offer considerable potential for a new generation of micro-sized thermoelectric coolers or generators. Here, based on the chemical composition optimized by traditional solid state reaction for bulk samples, we present a viable approach to modulating the electrical transport properties of screen-printed calcium cobaltite thick films through control of the microstructural evolution by optimized heat-treatment. XRD and TEM analysis confirmed the formation of high-quality calcium cobaltite grains. By creating 2.0 at% cobalt deficiency in Ca2.7Bi0.3Co4O9+δ, the pressureless sintered ceramics reached the highest power factor of 98.0 μWm?1 K-2 at 823 K, through enhancement of electrical conductivity by reduction of poorly conducting secondary phases. Subsequently, textured thick films of Ca2.7Bi0.3Co3.92O9+δ were efficiently tailored by controlling the sintering temperature and holding time. Optimized Ca2.7Bi0.3Co3.92O9+δ thick films sintered at 1203 K for 8 h exhibited the maximum power factor of 55.5 μWm?1 K-2 at 673 K through microstructure control. 相似文献
7.
8.
Xin Li Yurui Wang Minxuan Xu Yueqin Shi Hemiao Wang Xin Yang Haoting Ying Qi Zhang 《应用聚合物科学杂志》2021,138(19):50406
Polymer electrets have revealed great potential application in electromechanical devices because of the low weight, large quasi-piezoelectric sensitivity, and excellent flexibility. For an electret, a permanent and macroscopic electric field exists on the surface, principally led by a macroscopic electrostatic charge on the surface or a net orientation of polar groups inside the object. Here, progress in the development of polymer electrets is reviewed. After a brief retrospect of the research courses and those typical polymer electrets that are classified into fluorine polymer and nonfluorine polymer, we present a survey on the charging methods, including corona, soft X-ray, contact, thermal and monoenergetic particle beams. The latest representative applications (i.e., power harvesting, sensors, field effect transistors, and biomedicine) based on polymer electrets are also summarized. Finally, we complete this review with a discussion on perspectives and challenges in this field. 相似文献
9.
Kuznetsov Yu. A. Markov M. A. Kravchenko I. N. Krasikov A. V. Bykova A. D. 《Refractories and Industrial Ceramics》2021,62(4):421-425
Refractories and Industrial Ceramics - The paper introduces a promising technology for utilizing a traditional scheme for implementing a flow-through micro-arc oxidation method to restore localized... 相似文献
10.
Chumakov Yu. A. Knyazeva A. G. Pribytkov G. A. 《Theoretical Foundations of Chemical Engineering》2021,55(3):490-503
Theoretical Foundations of Chemical Engineering - On the basis of the classic concepts of the theory of solid-phase combustion, for the first time, a model with a detailed scheme of chemical... 相似文献