全文获取类型
收费全文 | 99583篇 |
免费 | 11147篇 |
国内免费 | 6349篇 |
专业分类
电工技术 | 7965篇 |
技术理论 | 7篇 |
综合类 | 8332篇 |
化学工业 | 14690篇 |
金属工艺 | 5785篇 |
机械仪表 | 6709篇 |
建筑科学 | 8054篇 |
矿业工程 | 3634篇 |
能源动力 | 2890篇 |
轻工业 | 7418篇 |
水利工程 | 2334篇 |
石油天然气 | 4689篇 |
武器工业 | 1279篇 |
无线电 | 11919篇 |
一般工业技术 | 10406篇 |
冶金工业 | 4439篇 |
原子能技术 | 1325篇 |
自动化技术 | 15204篇 |
出版年
2024年 | 531篇 |
2023年 | 1709篇 |
2022年 | 3427篇 |
2021年 | 4729篇 |
2020年 | 3487篇 |
2019年 | 2812篇 |
2018年 | 3107篇 |
2017年 | 3483篇 |
2016年 | 3151篇 |
2015年 | 4558篇 |
2014年 | 5523篇 |
2013年 | 6603篇 |
2012年 | 7566篇 |
2011年 | 7772篇 |
2010年 | 7134篇 |
2009年 | 6733篇 |
2008年 | 6558篇 |
2007年 | 5930篇 |
2006年 | 5650篇 |
2005年 | 4824篇 |
2004年 | 3346篇 |
2003年 | 2888篇 |
2002年 | 3282篇 |
2001年 | 2837篇 |
2000年 | 2097篇 |
1999年 | 1676篇 |
1998年 | 1035篇 |
1997年 | 882篇 |
1996年 | 777篇 |
1995年 | 697篇 |
1994年 | 508篇 |
1993年 | 367篇 |
1992年 | 339篇 |
1991年 | 244篇 |
1990年 | 182篇 |
1989年 | 137篇 |
1988年 | 116篇 |
1987年 | 72篇 |
1986年 | 64篇 |
1985年 | 36篇 |
1984年 | 24篇 |
1983年 | 14篇 |
1982年 | 27篇 |
1981年 | 23篇 |
1980年 | 37篇 |
1979年 | 13篇 |
1978年 | 9篇 |
1976年 | 7篇 |
1959年 | 14篇 |
1951年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
To improve the electrochemical properties of rare-earth–Mg–Ni-based hydrogen storage alloys, the effects of stoichiometry and Cu-substitution on the phase structure and thermodynamic properties of the ... 相似文献
43.
Metamerism phenomenon can be used in illuminant detection to ensure the accuracy of light source. A method based on Long‐, Middle‐, Short‐ wavelength cones(LMS) weighting algorithm to evaluate metamerism degree is proposed. The chromatic relationship between the degree of metamerism mismatch and the light source is studied. Herein, the consistency between the metameric indices (MIs) and CIE1976 L*a*b* color difference ranking is analyzed by SRCC, KRCC, PLCC and RMSE. A statistically sampling method to obtain practical LMS cone fundamentals to evaluate metamerism degree is employed. The analysis results obtained show that the method based on LMS weighting algorithm has good evaluation ability and stability in simulation experiments and statistically sampling experiments, which are in line with visual characteristics of human. Proposed method meets the requirements of selecting metameric pairs used in light source detection. The analysis results have certain guiding significance. 相似文献
44.
ABSTRACTImproving the hydration resistance of CaO particle in manufacturing and application of free CaO-containing materials has practical significance. In this study, CaO granules was made from Ca(OH)2 particles, which were fabricated by the granulation method. The results showed that the hydration resistance of the CaO granules which was prepared under 1700?r?min?1 was the best, the CaO granules was sintered well in calcination process, the shell of CaO granules was relatively dense, which improves the hydration resistance of CaO granules, and the rate of hydration weight increment was 0.58% after placed in the air for 20 days under a temperature of 10–14°C and a relative humidity of 57–81%. 相似文献
45.
Research funding has been seen as one of the most important resource in the reward system of science. And usage of publications denotes an interesting perspective of user behavior in scientific communication. This study aims to address the relationship between funding and Usage Count, which is a new metrics item established on the platform of Web of Science. Full records of 300,010 articles published in 2013 were downloaded in October 2015, and divided into six disciplines, including information science library science, education educational research, economics, computer science, materials science, and chemistry. Seven indicators were proposed to measure the impact, including Funding rate, Citation per paper, Usage rate, Usage per paper, Citation difference, Usage difference, and Conversion rate. It concluded funding has impact on usage and citation, and funded papers attract more usage, but varying in different disciplines. Usage Count can be used in the extension of citation metrics but with limits. This study originally engages with usage metrics and detected that there is positive correlation between usage and funding. 相似文献
46.
47.
Qiang Xia Tao Feng Xiaowei Lou Ying Wang Yangying Sun Daodong Pan Jinxuan Cao 《International Journal of Food Science & Technology》2020,55(2):669-680
As a decisive attribute, flavour could be influenced by HP treatments through multiple physical and chemical pathways within the high pressure (HP)-assisted meat curing process. This investigation aimed to identify the major pathway influencing volatile flavour patterns of two representative vinasse-cured duck (VCD) products with HP treatments (150–300 MPa/15 min), including wet and dry types, by employing headspace fingerprinting as an untargeted approach. Results suggested that HP treatments greatly lowered moisture contents and increased Warner-Bratzler shear force and thiobarbituric acid reactive substances of the cured samples. According to multivariate models, the volatile flavour patterns of the HP-processed VCD could be clearly separated from the unprocessed samples, but the VCD pressurised at different intensities represented similar volatile fingerprinting, which was validated by e-nose analysis. The discriminant analysis (OPLS-DA) model outlined vinasse-derived ethanol, acetic acid, 3-methyl-1-butanol, 2-methyl-1-butanol, phenethyl alcohol and 2-methyl-3-octanone as the major discriminant aromas across the unpressurised and pressurised samples. 相似文献
48.
49.
随着掘进工作面自动化程度的提高,掘进巷道速度也在日益加快,而现有的顺槽皮带机机尾移动缓慢且移动时工作量大,需要两三人配合操作,存在一定的安全隐患。针对以上问题,研发可调偏迈步式胶带自移机尾,具有与悬挂二运皮带转载机搭接行程长,可以迈步式前进,自动调偏等功能,同时,可以降低工人的劳动强度,加快巷道掘进速度。 相似文献
50.
人像智能分析指的是对视频或录像中的人像进行结构化和可视化分析,对目标人物进行性别、年龄、发型等特征的智能识别,这项技术在视频侦查中有极高的应用价值。人像识别早期的算法是通过人工提取特征,通过学习低级视觉特征来针对不同属性进行分类学习,这种基于传统方法的模型表现常常不尽如人意。在计算机视觉领域,通过海量图像数据学习的神经网络比传统方法有更丰富的信息量和特征可以被提取。文章尝试通过深度学习技术训练神经网络模型对行人进行检测和识别,对于衣着不同的行人进行智能识别,具有更好的鲁棒性,提升了视频人像识别的准确率,拓展了人工智能技术在身份识别领域的应用。 相似文献