全文获取类型
收费全文 | 2675篇 |
免费 | 122篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 24篇 |
综合类 | 12篇 |
化学工业 | 601篇 |
金属工艺 | 131篇 |
机械仪表 | 46篇 |
建筑科学 | 48篇 |
矿业工程 | 7篇 |
能源动力 | 193篇 |
轻工业 | 182篇 |
水利工程 | 35篇 |
石油天然气 | 23篇 |
无线电 | 330篇 |
一般工业技术 | 607篇 |
冶金工业 | 302篇 |
原子能技术 | 31篇 |
自动化技术 | 235篇 |
出版年
2024年 | 9篇 |
2023年 | 51篇 |
2022年 | 82篇 |
2021年 | 129篇 |
2020年 | 86篇 |
2019年 | 109篇 |
2018年 | 129篇 |
2017年 | 110篇 |
2016年 | 114篇 |
2015年 | 59篇 |
2014年 | 117篇 |
2013年 | 248篇 |
2012年 | 131篇 |
2011年 | 182篇 |
2010年 | 107篇 |
2009年 | 122篇 |
2008年 | 128篇 |
2007年 | 73篇 |
2006年 | 63篇 |
2005年 | 55篇 |
2004年 | 46篇 |
2003年 | 46篇 |
2002年 | 40篇 |
2001年 | 31篇 |
2000年 | 38篇 |
1999年 | 31篇 |
1998年 | 49篇 |
1997年 | 38篇 |
1996年 | 38篇 |
1995年 | 35篇 |
1994年 | 34篇 |
1993年 | 29篇 |
1992年 | 26篇 |
1991年 | 20篇 |
1990年 | 19篇 |
1989年 | 16篇 |
1988年 | 24篇 |
1987年 | 20篇 |
1986年 | 14篇 |
1985年 | 17篇 |
1984年 | 14篇 |
1983年 | 11篇 |
1982年 | 12篇 |
1981年 | 13篇 |
1980年 | 12篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1976年 | 8篇 |
1975年 | 4篇 |
1973年 | 3篇 |
排序方式: 共有2807条查询结果,搜索用时 31 毫秒
1.
Deepika M. Malini Raajan N. R. Srinivasan A. 《Multimedia Tools and Applications》2022,81(9):12701-12724
Multimedia Tools and Applications - The three-dimensional models of brain tumors serve as diagnostic assistance for physicians, surgeons, and radiologists. The proposed system establishes an... 相似文献
2.
Wireless Personal Communications - Internet of Things (IoT) is one of the emerging technologies, which is widely used across the globe. As the idea of a smart city was founded, IoT has been... 相似文献
3.
Wireless Personal Communications - Internet of Things (IoT) offers complex networks of connected devices, which are used to serve in the real-time environment. Interestingly, Wireless Sensor... 相似文献
4.
Dhirendra Kumar Mishra Gopal Pugazhenthi Tamal Banerjee 《International Journal of Hydrogen Energy》2021,46(29):15773-15779
The current work explores the usage of novel synthesized Deep Eutectic Solvent (DES) as a catalyst cum solvent media for the thermal dehydrogenation of chemical hydrides, namely Ammonia Borane (AB) and Ethylene diamine bisborane (EDAB). In the first instance, the quantum chemistry based COSMO-SAC (COnductor like Screening MOdel Segment Activity Coefficient) model was used for the selection of the pertinent solvent. 1-Butyl-3-methylimidazolium methanesulfonate: Imidazole ([BMIM][MeSO3]:[Im]) turned out to be an ideal eutectic mixture with the highest predicted solubility with amine boranes. The DES was synthesized by combining the Hydrogen Bond Acceptor (HBA), namely 1-Butyl-3-methylimidazolium methanesulfonate and Imidazole as Hydrogen Bond Donor (HBD) at a molar ratio of 1:2 and T = 70 °C. The formation of DES was confirmed by recording the NMR spectra. Further, the thermal dehydrogenation study was performed at a vacuum of 4 × 10?2 mbar (gauge pressure) of AB/DES and EDAB/DES systems at 105 °C, where a hydrogen equivalent of 1.40 and 2.55 was produced, respectively. The residual samples were further analyzed through 1H NMR analysis for the reaction mechanism and to confirm the role of Ionic Liquid-based DES as catalyst cum solvent media. 相似文献
5.
ABSTRACTA mathematical model has been developed by coupling genetic algorithm (GA) with heat and material balance equations to estimate rate parameters and solid-phase evolution related to the reduction of iron ore-coal composite pellets in a multi-layer bed Rotary hearth Furnace (RHF). The present process involves treating iron ore-coal composite pellets in a crucible over the hearth in RHF. The various solid phases evolved at the end of the process are estimated experimentally, and are used in conjunction with the model to estimate rate parameters. The predicted apparent activation energy for the wustite reduction step is found to be lower than those of the reduction of higher oxides. The thermal efficiency is found to decrease significantly with an increase in the carbon content of the pellet. Thermal efficiency was also found to increase mildly up to three layers. Multilayer bed remains as a potential design parameter to increase thermal efficiency. 相似文献
6.
Wireless Personal Communications - In this paper the conventional circular patch has been reshaped by two circular arcs with the FR4 Epoxy material for substrate. This is supported by the... 相似文献
7.
Dr. Kathrin Schindl Dr. Deepika Sharma Prof. Dr. Dieter Spiteller 《Chembiochem : a European journal of chemical biology》2020,21(21):3151-3157
When Streptomyces violaceoruber grows together with Streptomyces sp. MG7-G1, it reacts with strongly induced droplet production on its aerial mycelium. Initially the metabolite profile of droplets from S. violaceoruber in co-culture with Streptomyces sp. MG7-G1 was compared to samples from S. violaceoruber in single-culture by using high-performance liquid chromatography-mass spectrometry (HPLC-MS). Then, the exudate from agar plates of co-cultures and single cultures (after freezing and thawing) was also analysed. Several compounds were only observed when S. violaceoruber was grown in co-culture. Based on their high-resolution ESI mass spectra and their comparable retention times to the calcium-dependent antibiotics (CDAs) produced by S. violaceoruber, the new compounds were suspected to be deacylated calcium-dependent antibiotics (daCDAs), lacking the 2,3-epoxyhexanoyl residue of CDAs. This was verified by detailed analysis of the MS/MS spectra of the daCDAs in comparison to the CDAs. The major CDA compounds present in calcium ion-supplemented agar medium of co-cultures were daCDAs, thus suggesting that Streptomyces sp. MG7-G1 expresses a deacylase that degrades CDAs. 相似文献
8.
9.
10.