全文获取类型
收费全文 | 76186篇 |
免费 | 9028篇 |
国内免费 | 6433篇 |
专业分类
电工技术 | 7024篇 |
综合类 | 8573篇 |
化学工业 | 9313篇 |
金属工艺 | 5312篇 |
机械仪表 | 5983篇 |
建筑科学 | 5965篇 |
矿业工程 | 3513篇 |
能源动力 | 2022篇 |
轻工业 | 8527篇 |
水利工程 | 2478篇 |
石油天然气 | 2724篇 |
武器工业 | 1347篇 |
无线电 | 7977篇 |
一般工业技术 | 6002篇 |
冶金工业 | 2940篇 |
原子能技术 | 1210篇 |
自动化技术 | 10737篇 |
出版年
2024年 | 272篇 |
2023年 | 1309篇 |
2022年 | 3227篇 |
2021年 | 4199篇 |
2020年 | 2859篇 |
2019年 | 1875篇 |
2018年 | 2032篇 |
2017年 | 2363篇 |
2016年 | 2108篇 |
2015年 | 3472篇 |
2014年 | 4322篇 |
2013年 | 5077篇 |
2012年 | 6572篇 |
2011年 | 6755篇 |
2010年 | 6396篇 |
2009年 | 6030篇 |
2008年 | 6217篇 |
2007年 | 6065篇 |
2006年 | 5177篇 |
2005年 | 4138篇 |
2004年 | 2982篇 |
2003年 | 1969篇 |
2002年 | 1868篇 |
2001年 | 1665篇 |
2000年 | 1414篇 |
1999年 | 521篇 |
1998年 | 132篇 |
1997年 | 103篇 |
1996年 | 85篇 |
1995年 | 56篇 |
1994年 | 43篇 |
1993年 | 51篇 |
1992年 | 37篇 |
1991年 | 27篇 |
1990年 | 33篇 |
1989年 | 43篇 |
1988年 | 17篇 |
1987年 | 14篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 13篇 |
1983年 | 9篇 |
1982年 | 8篇 |
1981年 | 11篇 |
1980年 | 20篇 |
1979年 | 14篇 |
1959年 | 11篇 |
1951年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
4.
5.
Zhenkun Ke Xin Cao Chuanli Shan Lifen Shi Pingping Wang Yong Yang Fengyang Zhao Jiedong Cui Jinwei Li Gang Zhou Min Guan Tao Yu 《Ceramics International》2021,47(14):19605-19613
The purpose of the current work was to research the effect of alkali metal oxide on the structure, thermal properties, viscosity and chemical stability in the glass system (R2O–CaO–B2O3–SiO2) systematically. Because the glass would emulsify when Li2O was added to the glass batch, this article did not discuss Li2O. The results showed that when the amount of Na2O was less than 4 mol.%, there was a higher interconnectivity of borate and silicate sub-networks in glass, as more mixed Si–O–B bonds were present in glass. The glass samples exhibited excellent thermal properties and chemical stabilities. As the amount of Na2O exceeded 4 mol.%, the interconnectivity of borate and silicate sub-networks was weakened. The thermal properties and chemical stabilities of the glass samples were reduced. The connectivity of the silicate sub-network was weakened slightly as the Na/K ratio varied, and the coefficient of thermal expansion (CTE) of the glass samples gradually increased, and the resistance to thermal shock (RTS) value gradually decreased. Moreover, the viscosity of the glass samples decreased with the ratio of Na/Si and Na/K increased. 相似文献
6.
7.
Kexin Jiao Laurence J. Walsh Sao Ivanovski Pingping Han 《International journal of molecular sciences》2021,22(9)
Periodontitis is a chronic complex inflammatory disease associated with a destructive host immune response to microbial dysbiosis, leading to irreversible loss of tooth-supporting tissues. Regeneration of functional periodontal soft (periodontal ligament and gingiva) and hard tissue components (cementum and alveolar bone) to replace lost tissues is the ultimate goal of periodontal treatment, but clinically predictable treatments are lacking. Similarly, the identification of biomarkers that can be used to accurately diagnose periodontitis activity is lacking. A relatively novel category of molecules found in oral tissue, circular RNAs (circRNAs) are single-stranded endogenous, long, non-coding RNA molecules, with covalently circular-closed structures without a 5’ cap and a 3’ tail via non-classic backsplicing. Emerging research indicates that circRNAs are tissue and disease-specific expressed and have crucial regulatory functions in various diseases. CircRNAs can function as microRNA or RNA binding sites or can regulate mRNA. In this review, we explore the biogenesis and function of circRNAs in the context of the emerging role of circRNAs in periodontitis pathogenesis and the differentiation of periodontal cells. CircMAP3K11, circCDK8, circCDR1as, circ_0062491, and circ_0095812 are associated with pathological periodontitis tissues. Furthermore, circRNAs are expressed in periodontal cells in a cell-specific manner. They can function as microRNA sponges and can form circRNA–miRNA–mRNA networks during osteogenic differentiation for periodontal-tissue (or dental pulp)-derived progenitor cells. 相似文献
8.
基于柴油产品质量升级的需求,中国石化大连石油化工研究院(FRIPP)开发了FHIDW加氢改质技术及配套FF-46加氢精制催化剂、FC-14B加氢改质催化剂和FDW-3临氢降凝催化剂.该技术及催化剂级配体系在格尔木炼油厂0.8 Mt·a-1加氢改质装置上的工业应用情况表明,级配催化剂体系对原料适应性强,装置运转平稳,操作灵活性高,催化剂失活速率慢,产品分布合理且质量优异,在降低柴油产品凝点的同时可以明显改善其密度和十六烷值,解决了改造前装置生产重柴油密度偏低的问题,为炼油厂生产符合国V质量标准的柴油提供了技术保障. 相似文献
9.
10.