全文获取类型
收费全文 | 1794312篇 |
免费 | 51699篇 |
国内免费 | 19697篇 |
专业分类
电工技术 | 52600篇 |
技术理论 | 58篇 |
综合类 | 26535篇 |
化学工业 | 324088篇 |
金属工艺 | 81169篇 |
机械仪表 | 62325篇 |
建筑科学 | 71402篇 |
矿业工程 | 22631篇 |
能源动力 | 59020篇 |
轻工业 | 130107篇 |
水利工程 | 20123篇 |
石油天然气 | 59454篇 |
武器工业 | 2954篇 |
无线电 | 228796篇 |
一般工业技术 | 313955篇 |
冶金工业 | 165563篇 |
原子能技术 | 36901篇 |
自动化技术 | 208027篇 |
出版年
2022年 | 19087篇 |
2021年 | 27886篇 |
2020年 | 21302篇 |
2019年 | 22134篇 |
2018年 | 23812篇 |
2017年 | 24382篇 |
2016年 | 29695篇 |
2015年 | 29345篇 |
2014年 | 44091篇 |
2013年 | 105824篇 |
2012年 | 55011篇 |
2011年 | 69061篇 |
2010年 | 60972篇 |
2009年 | 68322篇 |
2008年 | 61804篇 |
2007年 | 58404篇 |
2006年 | 62439篇 |
2005年 | 54623篇 |
2004年 | 50437篇 |
2003年 | 49179篇 |
2002年 | 47540篇 |
2001年 | 43569篇 |
2000年 | 42823篇 |
1999年 | 43086篇 |
1998年 | 47315篇 |
1997年 | 42398篇 |
1996年 | 39162篇 |
1995年 | 34409篇 |
1994年 | 31872篇 |
1993年 | 30312篇 |
1992年 | 28172篇 |
1991年 | 24695篇 |
1990年 | 24646篇 |
1989年 | 23473篇 |
1988年 | 21856篇 |
1987年 | 19822篇 |
1986年 | 19033篇 |
1985年 | 22156篇 |
1984年 | 22451篇 |
1983年 | 20334篇 |
1982年 | 19332篇 |
1981年 | 19381篇 |
1980年 | 17944篇 |
1979年 | 18520篇 |
1978年 | 17709篇 |
1977年 | 17125篇 |
1976年 | 17789篇 |
1975年 | 15959篇 |
1974年 | 15510篇 |
1973年 | 15554篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
Wenlong Song Shoujun Wang Yang Lu Xuan Zhang Zixiang Xia Kai Sun Guangming Xin 《Ceramics International》2021,47(9):12631-12640
To enhance the tribological performance of Si3N4/TiC ceramics, MoS2/PTFE composite coatings were deposited on the ceramic substrate through spraying method. The micrographs and basic properties of the MoS2/PTFE coated samples were investigated. Dry sliding friction experiments against WC/Co ball were performed with the coated ceramics and traditional ones. These results showed that the composite coatings could significantly reduce the friction coefficient of ceramics, and protect the substrate from adhesion wear. The primary tribological mechanisms of the coated ceramics were abrasive wear, coating spalling and delamination, and the tribological property was transited from slight wear to serious wear with the increase of load because of the lower surface hardness and shear strength. The possible mechanisms for the effects of MoS2/PTFE composite coatings on the friction performance of ceramics were discussed. 相似文献
172.
173.
Dr. Qian Wang Xinli Fan Nannan Jing Han Zhao Dr. Lijia Yu Prof. Xinjing Tang 《Chembiochem : a European journal of chemical biology》2021,22(11):1901-1907
Small interfering RNA (siRNA) can effectively silence target genes through Argonate 2 (Ago2)-induced RNA interference (RNAi). It is very important to control siRNA activity in both spatial and temporal modes. Among different masking strategies, photocaging can be used to regulate gene expression through light irradiation with spatiotemporal and dose-dependent resolution. Many different caging strategies and caging groups have been reported for light-activated siRNA gene silencing. Herein, we describe a novel caging strategy that increases the blocking effect of RISC complex formation/process through host/guest (including ligand/receptor) interactions, thereby enhancing the inhibition of caged siRNA activity until light activation. This strategy can be used as a general approach to design caged siRNAs for the photomodulation of gene silencing of exogenous and endogenous genes. 相似文献
174.
Bilal Alashkar Alhamwe Daniel P. Potaczek Sarah Miethe Fahd Alhamdan Lukas Hintz Arslan Magomedov Holger Garn 《International journal of molecular sciences》2021,22(9)
Extracellular vesicles (EVs) are membranous structures, which are secreted by almost every cell type analyzed so far. In addition to their importance for cell-cell communication under physiological conditions, EVs are also released during pathogenesis and mechanistically contribute to this process. Here we summarize their functional relevance in asthma, one of the most common chronic non-communicable diseases. Asthma is a complex persistent inflammatory disorder of the airways characterized by reversible airflow obstruction and, from a long-term perspective, airway remodeling. Overall, mechanistic studies summarized here indicate the importance of different subtypes of EVs and their variable cargoes in the functioning of the pathways underlying asthma, and show some interesting potential for the development of future therapeutic interventions. Association studies in turn demonstrate a good diagnostic potential of EVs in asthma. 相似文献
175.
176.
Wireless Personal Communications - Multiple inputs multiple outputs (MIMO) is a reliable technique which can manage the increased wireless data traffic in the future generation of wireless... 相似文献
177.
Wireless Personal Communications - This paper summarizes the ongoing research initiatives based on the advanced multiple access techniques towards the fifth generation (5G) wireless communication... 相似文献
178.
Russian Engineering Research - The modernization of manufacturing by the comprehensive application of digital technology—in both production and management—is considered. Principles are... 相似文献
179.
Dr. Ying Wang Prof. Dr. Andrew Ewing 《Chembiochem : a European journal of chemical biology》2021,22(5):807-813
Exocytosis plays an essential role in the communication between cells in the nervous system. Understanding the regulation of neurotransmitter release during exocytosis and the amount of neurotransmitter content that is stored in vesicles is of importance, as it provides fundamental insights to understand how the brain works and how neurons elicit a certain behavior. In this minireview, we summarize recent progress in amperometric measurements for monitoring exocytosis in single cells and electrochemical cytometry measurements of vesicular neurotransmitter content in individual vesicles. Important steps have increased our understanding of the different mechanisms of exocytosis. Increasing evidence is firmly establishing that partial release is the primary mechanism of release in multiple cell types. 相似文献
180.
The exploitation of recycled carbonaceous catalysts from renewable biomass resources such as chitin is a crucial issue for the development of the sustainable society. In this article, the chitin-based N and O doped carbon microspheres (ChC) were fabricated by a simple dissolution, sol–gel transformation, and the carbonization methods. Subsequently, the novel magnetic Ag-Fe3O4@chitin-based carbon microspheres catalyst (MChC) was successfully constructed through the in situ redox reaction. The as-prepared MChC possessed rich micropores with high-surface area, and a narrow size distribution (50–120 μm). The Ag-Fe3O4 nanoparticles were immobilized through the interaction with C, N, and O atoms in the pores of MChC. The reduction of 4-nitrophenol was applied to evaluate the catalytic activity of MChC. 4-Nitrophenol (4-NP) could be fully reduced to 4-aminophenol (4-AP) in 5 min with the catalyst MChC-45. Moreover, MChC could be collected in solution with an external magnet in 8 s and remained relatively high-catalytic activity after 10 cycle times. This work provided novel ideas for the fabrication of doped carbon material from biomass and promoted its utilization in nanocatalytic applications. 相似文献