全文获取类型
收费全文 | 9033篇 |
免费 | 471篇 |
国内免费 | 59篇 |
专业分类
电工技术 | 161篇 |
综合类 | 33篇 |
化学工业 | 2453篇 |
金属工艺 | 159篇 |
机械仪表 | 280篇 |
建筑科学 | 323篇 |
矿业工程 | 6篇 |
能源动力 | 603篇 |
轻工业 | 970篇 |
水利工程 | 91篇 |
石油天然气 | 124篇 |
无线电 | 821篇 |
一般工业技术 | 1496篇 |
冶金工业 | 383篇 |
原子能技术 | 101篇 |
自动化技术 | 1559篇 |
出版年
2024年 | 32篇 |
2023年 | 189篇 |
2022年 | 418篇 |
2021年 | 546篇 |
2020年 | 386篇 |
2019年 | 427篇 |
2018年 | 535篇 |
2017年 | 467篇 |
2016年 | 476篇 |
2015年 | 329篇 |
2014年 | 449篇 |
2013年 | 843篇 |
2012年 | 535篇 |
2011年 | 667篇 |
2010年 | 453篇 |
2009年 | 399篇 |
2008年 | 331篇 |
2007年 | 254篇 |
2006年 | 234篇 |
2005年 | 169篇 |
2004年 | 138篇 |
2003年 | 140篇 |
2002年 | 102篇 |
2001年 | 82篇 |
2000年 | 87篇 |
1999年 | 56篇 |
1998年 | 94篇 |
1997年 | 47篇 |
1996年 | 60篇 |
1995年 | 53篇 |
1994年 | 49篇 |
1993年 | 53篇 |
1992年 | 37篇 |
1991年 | 34篇 |
1990年 | 36篇 |
1989年 | 22篇 |
1988年 | 36篇 |
1987年 | 30篇 |
1986年 | 20篇 |
1985年 | 17篇 |
1984年 | 29篇 |
1983年 | 23篇 |
1982年 | 23篇 |
1981年 | 16篇 |
1980年 | 20篇 |
1979年 | 16篇 |
1978年 | 17篇 |
1977年 | 13篇 |
1976年 | 18篇 |
1975年 | 19篇 |
排序方式: 共有9563条查询结果,搜索用时 8 毫秒
1.
Efficacy of Crude and Purified Chitinases (SsChi50) Extracted from Offal Red Scorpion Fish in Biological Control of Chickpea Weevil (Callosobruchus maculatus L.) 下载免费PDF全文
2.
3.
4.
5.
Maktabdar Oghaz Mahdi Maarof Mohd Aizaini Rohani Mohd Foad Zainal Anazida Shaid Syed Zainudeen Mohd 《Neural computing & applications》2019,31(6):1835-1853
Neural Computing and Applications - Texture analysis is devised to address the weakness of color-based image segmentation models by considering the statistical and spatial relations among the group... 相似文献
6.
Sonika Sahu Mohd. Zahid Ansari Dehi Pada Mondal Chongdu Cho 《Materials Science & Technology》2019,35(7):856-864
In this paper, cenosphere particles embedded in AA2014 aluminium matrix are used to fabricate syntactic foam by stir casting method. The particle size is about 100?µm and foam density is about 1990?kg?m?3. Compression tests at strain rate 0.001/s are performed on foam samples to characterise their mechanical properties which are then used in numerical analysis on commercial finite element analysis software ABAQUS/CAE with isotropic elastic-plastic material model. Experimental and numerical results show good conformity in deformation behaviour with elastic and plateau zones showing average deviations less than 5% and 20%, respectively. Foams showed high yield stress and energy absorption capabilities that can be useful in making blast and impact resistant structures. 相似文献
7.
Purification,structural data and biological properties of polysaccharide from Prunus amygdalus gum 下载免费PDF全文
Fatma Bouaziz Mohamed Koubaa Claire Boisset Helbert Fatma Kallel Dorra Driss Imen Kacem Raoudha Ghorbel Semia Ellouz Chaabouni 《International Journal of Food Science & Technology》2015,50(3):578-584
This work demonstrates the efficiency of almond gum polysaccharides (AGPs) as bioactive compounds. AGPs were first extracted using H2O2, in the presence of NaOH, at different times and temperatures. The optimal extraction conditions were 4% H2O2 and 2 N NaOH, for 7 h at 50 °C, leading to an extraction yield of 58.2% (w/w). After a purification step, the retained AGPs were characterised using high‐performance liquid chromatography showing a molecular weight of 99.3 kDa. The monosaccharide composition of AGPs were assessed using gas chromatography–mass spectrometry. AGPs were found to be a complex heteropolysaccharide with a repeating unit mainly composed of galactose, arabinose, xylose, mannose, rhamnose, and glucuronic acid with the respective ratios: 45:26:7:10:1:11. The acidic nature of the polysaccharide is due to the presence of glucuronic acid. Total antioxidant activity, free radical‐scavenging activity and reducing power assay of AGPs were investigated. The obtained results showed high antioxidant activities of AGPs. Furthermore, beyond 60 mg mL?1, AGPs exhibited bacterial growth inhibition for five pathogenic strains: Escherichia coli, Staphylococcus aureus, Enterococcus feacalis, Pseudomonas aeruginosa and Salmonella typhimurium. 相似文献
8.
Sakizadeh Mohamad Mohamed Mohamed M. A. Klammler Harald 《Water Resources Management》2019,33(4):1425-1437
Water Resources Management - Overexploitation of groundwater in the Malayer Plain has resulted in a continuous decline of groundwater levels over recent years with associated risks to water... 相似文献
9.
Ali Mohamed 《Journal of Modern Optics》2019,66(13):1392-1407
Anisoplanatic electromagnetic (EM) propagation across a turbulent atmosphere has been recently examined for an unmodulated carrier propagating over an image-bearing transparency through optical lensing, and for the embedded information inside a carrier recovered using heterodyning and digital demodulation. Carrier modulation yielded better recovery than simple lens-based imaging. A possible mitigation strategy is proposed whereby the image information is encrypted on an RF chaotic carrier, thereafter secondarily embedded onto an optical carrier. Results based on the modified von Karman (MVKS) and the Hufnagel-Valley (H-V) models showed that the signal/image recovery under turbulence is improved compared with non-chaotic propagation. The case of time-varying/dynamic images is also taken up; it is demonstrated via cross-correlation products that turbulence is mitigated by the use of chaotic carrier encryption. Overall, transmission via chaos offers mitigation against distortions due to turbulence along with the security feature inherent via the chaos keys which prevent signal recovery without key-matching. 相似文献
10.