全文获取类型
收费全文 | 19728篇 |
免费 | 1418篇 |
国内免费 | 794篇 |
专业分类
电工技术 | 1014篇 |
技术理论 | 4篇 |
综合类 | 1022篇 |
化学工业 | 3592篇 |
金属工艺 | 882篇 |
机械仪表 | 1175篇 |
建筑科学 | 1327篇 |
矿业工程 | 521篇 |
能源动力 | 551篇 |
轻工业 | 1075篇 |
水利工程 | 289篇 |
石油天然气 | 1119篇 |
武器工业 | 127篇 |
无线电 | 2611篇 |
一般工业技术 | 2623篇 |
冶金工业 | 1026篇 |
原子能技术 | 166篇 |
自动化技术 | 2816篇 |
出版年
2024年 | 62篇 |
2023年 | 308篇 |
2022年 | 520篇 |
2021年 | 751篇 |
2020年 | 548篇 |
2019年 | 509篇 |
2018年 | 568篇 |
2017年 | 587篇 |
2016年 | 548篇 |
2015年 | 681篇 |
2014年 | 890篇 |
2013年 | 1210篇 |
2012年 | 1131篇 |
2011年 | 1273篇 |
2010年 | 990篇 |
2009年 | 1024篇 |
2008年 | 1003篇 |
2007年 | 964篇 |
2006年 | 1014篇 |
2005年 | 914篇 |
2004年 | 610篇 |
2003年 | 596篇 |
2002年 | 519篇 |
2001年 | 442篇 |
2000年 | 525篇 |
1999年 | 579篇 |
1998年 | 528篇 |
1997年 | 458篇 |
1996年 | 441篇 |
1995年 | 317篇 |
1994年 | 300篇 |
1993年 | 213篇 |
1992年 | 170篇 |
1991年 | 139篇 |
1990年 | 125篇 |
1989年 | 95篇 |
1988年 | 77篇 |
1987年 | 52篇 |
1986年 | 44篇 |
1985年 | 37篇 |
1984年 | 21篇 |
1983年 | 18篇 |
1982年 | 30篇 |
1981年 | 22篇 |
1980年 | 15篇 |
1979年 | 10篇 |
1978年 | 11篇 |
1977年 | 11篇 |
1976年 | 12篇 |
1971年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Jiaao Yan Gao Zhiming Tan Qingchao Yang Xian Hu Wenbin 《Protection of Metals and Physical Chemistry of Surfaces》2020,56(5):965-972
Protection of Metals and Physical Chemistry of Surfaces - The Al2O3 powder was added as a filler to polyurea and the effect of doping amount on Shore hardness and wetting property were... 相似文献
3.
Baizhan Li Chenqiu Du Hong Liu Wei Yu Jie Zheng Meilan Tan Zhenxing Jin Wenjie Li Jing Wu Lu Chen Runming Yao 《Indoor air》2019,29(2):308-319
The extensive research interests in environmental temperature can be linked to human productivity / performance as well as comfort and health; while the mechanisms of physiological indices responding to temperature variations remain incompletely understood. This study adopted a physiological sensory nerve conduction velocity (SCV) as a temperature‐sensitive biomarker to explore the thermoregulatory mechanisms of human responding to annual temperatures. The measurements of subjects’ SCV (over 600 samples) were conducted in a naturally ventilated environment over all four seasons. The results showed a positive correlation between SCV and annual temperatures and a Boltzmann model was adopted to depict the S‐shaped trend of SCV with operative temperatures from 5°C to 40°C. The SCV increased linearly with operative temperatures from 14.28°C to 20.5°C and responded sensitively for 10.19°C‐24.59°C, while tended to be stable beyond that. The subjects’ thermal sensations were linearly related to SCV, elaborating the relation between human physiological regulations and subjective thermal perception variations. The findings reveal the body SCV regulatory characteristics in different operative temperature intervals, thereby giving a deeper insight into human autonomic thermoregulation and benefiting for built environment designs, meantime minimizing the temperature‐invoked risks to human health and well‐being. 相似文献
4.
5.
Vu Hoa T. Nguyen Manh B. Vu Tan M. Le Giang H. Pham Trang T. T. Nguyen Trinh Duy Vu Tuan A. 《Topics in Catalysis》2020,63(11-14):1046-1055
Topics in Catalysis - Nano Fe-BTC/graphene oxide (GO) composites were successfully synthesized by hydrothermal treatment with a microwave-assisted method. Samples were characterized by X-ray... 相似文献
6.
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
7.
De-rui Tan 《中国铸造》2018,(5)
正Five Dynasties and Ten Kingdoms Period (963 A.D. and 967 A.D.)The western tower was damaged and is now incomplete. The eastern tower is 7.7 m high.There are two towers, called the eastern tower and the western tower, which were built in 963 A.D. and 967 A.D.,respectively, and are the earliest extant iron towers. There are 1,024 Buddha statues cast on each side of the tower body.The whole tower is made up of 17 castings, which are stacked layer by layer, and each casting is made to be a single 相似文献
8.
In this paper, we study scheduling games under mixed coordination mechanisms on hierarchical machines. The two scheduling policies involved are ‐ and ‐, where ‐ (resp., ‐) policy sequences jobs in nondecreasing order of their hierarchies, and jobs of the same hierarchy in nonincreasing (resp., nondecreasing) order of their processing times. We first show the existence of a Nash equilibrium. Then we present the price of anarchy and the price of stability for the games with social costs of minimizing the makespan and maximizing the minimum machine load. All the bounds given in this paper are tight. 相似文献
9.
Ye Wan Jun Tan Guangling Song Chuanwei Yan 《Metallurgical and Materials Transactions A》2006,37(7):2313-2316
The focused ion beam technique was employed to investigate the atmospheric corrosion morphology of AZ91D. It was found that
the α matrix of the alloy was preferentially corroded in the areas adjacent to intermetallic phases. The most interesting
finding was that the corrosion products in corrosion cavities were pelletlike, which has never been reported before. 相似文献
10.
P(DBF-VA)型柴油低温流动性改进剂的研制 总被引:1,自引:1,他引:0
针对新疆地产柴油蜡含量较高的特点,以游离基聚合法合成了富马酸双链混合酯和醋酸乙烯酯共聚物型[P(DBF-VA)]柴油低温流动改进剂,利用正交实验研究了单体配比,引发剂用量,溶剂用量,聚合温度对聚合物降冷滤效果的影响。共聚物用IR进行表征,利用XRD初步探讨了该降凝剂的降凝机理。结果表明:该剂能使吐哈—10~#、0~#柴油冷滤点降低10℃和7℃;使独山子0~#柴油冷滤点下降12℃;使石化0~#柴油冷滤点下降8℃;使克拉玛依0~#柴油的冷滤点下降8℃。 相似文献