全文获取类型
收费全文 | 104492篇 |
免费 | 6438篇 |
国内免费 | 3961篇 |
专业分类
电工技术 | 4476篇 |
技术理论 | 26篇 |
综合类 | 7723篇 |
化学工业 | 19935篇 |
金属工艺 | 7988篇 |
机械仪表 | 5069篇 |
建筑科学 | 10763篇 |
矿业工程 | 5554篇 |
能源动力 | 3397篇 |
轻工业 | 10269篇 |
水利工程 | 2047篇 |
石油天然气 | 5159篇 |
武器工业 | 2214篇 |
无线电 | 8835篇 |
一般工业技术 | 6267篇 |
冶金工业 | 4967篇 |
原子能技术 | 620篇 |
自动化技术 | 9582篇 |
出版年
2024年 | 161篇 |
2023年 | 1188篇 |
2022年 | 2195篇 |
2021年 | 2922篇 |
2020年 | 2962篇 |
2019年 | 1999篇 |
2018年 | 1802篇 |
2017年 | 2565篇 |
2016年 | 2821篇 |
2015年 | 3058篇 |
2014年 | 7399篇 |
2013年 | 5647篇 |
2012年 | 7442篇 |
2011年 | 8127篇 |
2010年 | 6176篇 |
2009年 | 6577篇 |
2008年 | 5849篇 |
2007年 | 7189篇 |
2006年 | 6514篇 |
2005年 | 5639篇 |
2004年 | 4826篇 |
2003年 | 4389篇 |
2002年 | 3615篇 |
2001年 | 3057篇 |
2000年 | 2416篇 |
1999年 | 1769篇 |
1998年 | 1294篇 |
1997年 | 972篇 |
1996年 | 888篇 |
1995年 | 675篇 |
1994年 | 539篇 |
1993年 | 427篇 |
1992年 | 353篇 |
1991年 | 285篇 |
1990年 | 246篇 |
1989年 | 153篇 |
1988年 | 113篇 |
1987年 | 87篇 |
1986年 | 91篇 |
1985年 | 72篇 |
1984年 | 69篇 |
1983年 | 30篇 |
1982年 | 53篇 |
1981年 | 50篇 |
1980年 | 42篇 |
1979年 | 24篇 |
1978年 | 27篇 |
1977年 | 18篇 |
1976年 | 17篇 |
1975年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
N. Clament Sagaya Selvam Lijie Du Bao Yu Xia Pil J. Yoo Bo You 《Advanced functional materials》2021,31(12):2008190
Electroreduction of small molecules such as H2O, CO2, and N2 for producing clean fuels or valuable chemicals provides a sustainable approach to meet the increasing global energy demands and to alleviate the concern on climate change resulting from fossil fuel consumption. On the path to implement this purpose, however, several scientific hurdles remain, one of which is the low energy efficiency due to the sluggish kinetics of the paired oxygen evolution reaction (OER). In response, it is highly desirable to synthesize high-performance and cost-effective OER electrocatalysts. Recent advances have witnessed surface reconstruction engineering as a salient tool to significantly improve the catalytic performance of OER electrocatalysts. In this review, recent progress on the reconstructed OER electrocatalysts and future opportunities are discussed. A brief introduction of the fundamentals of OER and the experimental approaches for generating and characterizing the reconstructed active sites in OER nanocatalysts are given first, followed by an expanded discussion of recent advances on the reconstructed OER electrocatalysts with improved activities, with a particular emphasis on understanding the correlation between surface dynamics and activities. Finally, a prospect for clean future energy communities harnessing surface reconstruction-promoted electrochemical water oxidation will be provided. 相似文献
3.
Developing non-platinum group metal (non-PGM) electrocatalysts for the hydrogen oxidation reaction (HOR) represents the efforts towards the more economical use of hydrogen fuel cells and hydrogen energy, which has attracted tremendous attention recently. However, non-PGM electrocatalysts for the HOR are still in their early development stages as compared with the significant advances in those for the oxygen reduction reaction and hydrogen evolution reaction. Herein, this paper summarizes the recent progresses and highlights the key challenges for the rational design of non-PGM electrocatalysts, aiming to promote the development of non-PGM HOR electrocatalysts. Fundamental understandings of the HOR mechanism are firstly reviewed, where theoretical interpretations on the low HOR kinetics in alkaline media, including the hydrogen binding energy theory, the bifunctional mechanism, and the water molecule reorganization, are particularly discussed. Subsequently, progresses of typical non-PGM HOR electrocatalysts in acid and alkaline media are summarized separately. For the HOR under alkaline conditions, the superiorities and challenges of Ni-based catalysts are discussed with a particular focus as they are the most promising non-PGM electrocatalysts. Finally, this paper highlights the challenges and provide perspectives on the future development directions of non-PGM HOR electrocatalysts. 相似文献
4.
5.
本文采用超星学习通线上教学平台,以 “高电压技术”课程为对象,实施了规模为120余人的线上线下混合式教学。基于线上教学和传统教学的优势互补,设计了“高电压技术”多个教学环节。归纳分析了混合式教学在各个教学环节取得的效果和问题,并根据学生反馈提出了持续性的改进措施。 相似文献
6.
纵观当今的发展格局,是科学技术高速发展的时代。随着5G时代的来临,网络技术在各个领域中扮演着越来越重要的角色。特别是在医疗方面,为医院的日常工作奠定了坚实的基础。今天就5G网络技术在医院只能服务中的应用展开谈论。 相似文献
7.
为解决沧州市涉地税源管理手段单一等问题,文中提出以测绘地理信息技术为支撑,通过对多源数据组织管理,建立风险分析指标,采用多种GIS空间分析方法构建了涉地风险税源识别模式并在沧州进行应用。结果表明:该模式能有效识别多种涉地风险,为涉地税源管理提供了支撑。 相似文献
8.
分析近年来RTO装置发生的安全事故,找出了该类环保装置存在的安全风险,并在储罐与污水池废气分类处理、在线废气浓度检测仪与废气切断阀的位置设置、新风稀释及风机控制、阻火器与爆破片、操作压力、储罐呼吸阀后采用非接触废气罩收集、风机材质等方面提出了建议。 相似文献
9.
10.
《International Journal of Hydrogen Energy》2022,47(10):6638-6649
Developing low cost, highly efficient, and long-term stability electrocatalysts are critical for direct oxidation methanol fuel cell. Despite huge efforts, designing low-cost electrocatalysts with high activity and long-term durability remains a significant technical challenge. Here, we prepared a new kind of platinum-nickel catalyst supported on silane-modified graphene oxide (NH2-rGO) by a two-step method at room temperature. Powder X-ray diffraction, UV–vis spectroscopy, Raman, FTIR spectroscopy and X-ray photoelectron spectroscopy results confirm that GO was successfully modified with 3-aminopropyltriethoxysilane (APTES), which helps to uniformly disperse PtNi nanoparticles. Cyclic voltammetry, chronoamperometry, CO-stripping and rotating disk electrode (RDE) results imply that PtNi/NH2-rGO catalyst has significantly higher catalytic activity, enhance the CO toxicity resistance, higher stability and much faster kinetics of methanol oxidation than commercial Pt/C under alkaline conditions. 相似文献