全文获取类型
收费全文 | 731篇 |
免费 | 56篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 12篇 |
综合类 | 1篇 |
化学工业 | 146篇 |
金属工艺 | 18篇 |
机械仪表 | 16篇 |
建筑科学 | 35篇 |
矿业工程 | 1篇 |
能源动力 | 76篇 |
轻工业 | 59篇 |
水利工程 | 5篇 |
石油天然气 | 3篇 |
无线电 | 50篇 |
一般工业技术 | 140篇 |
冶金工业 | 66篇 |
原子能技术 | 5篇 |
自动化技术 | 158篇 |
出版年
2023年 | 3篇 |
2022年 | 15篇 |
2021年 | 22篇 |
2020年 | 25篇 |
2019年 | 11篇 |
2018年 | 19篇 |
2017年 | 21篇 |
2016年 | 34篇 |
2015年 | 28篇 |
2014年 | 39篇 |
2013年 | 55篇 |
2012年 | 31篇 |
2011年 | 45篇 |
2010年 | 47篇 |
2009年 | 36篇 |
2008年 | 59篇 |
2007年 | 48篇 |
2006年 | 28篇 |
2005年 | 27篇 |
2004年 | 29篇 |
2003年 | 28篇 |
2002年 | 21篇 |
2001年 | 10篇 |
2000年 | 8篇 |
1999年 | 2篇 |
1998年 | 13篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 9篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1989年 | 6篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有791条查询结果,搜索用时 9 毫秒
51.
In commercial aluminum with a purity of 99.4 pct, the formation and growth of recrystallization nuclei were studied by techniques
such asin-situ annealing in a high voltage electron microscope, transmission electron microscopy and light microscopy. Sample parameters
were the initial grain size (370 and 19 microns) and the degree of deformation (50 and 90 pct reduction in thickness by cold-rolling).
It was found that the initial grain boundaries and high angle boundaries within the original grains are preferential sites
for recrystallization nuclei, and that the effect of such sites is enhanced by the FeAl3 particles present in the commercial aluminum as impurities. The nucleation temperatures determined by high voltage electron
microscopy and transmission electron microscopy decrease markedly when the initial grain size is decreased both after 50 and
90 pct cold rolling; a less pronounced temperature decrease is obtained by increasing the degree of deformation. The size
of the recrystallization nuclei, the recrystallization temperature and the recrystallized grain size are reported for the
four sample states, and finally the structural and kinetic observations are discussed. 相似文献
52.
Ca-doped ThO2, synthesized by solution combustion method was tested for dehydrogenation of ethane with CO2. Doping ThO2 with Ca resulted in the creation of oxide ion vacancies and an increased conversion of ethane compared to pure ThO2. On Th0.75Ca0.25O2 selectivity to ethene was 97 at 46% ethane conversion at 725 °C. Well-known reference catalysts like 5%Cr/TS-1 or OMS-2 showed significantly lower selectivity, but the former was more active under the same conditions. 相似文献
53.
David Aili Qingfeng Li Erik Christensen Jens Oluf Jensen Niels J Bjerrum 《Polymer International》2011,60(8):1201-1207
Phosphoric acid‐doped polybenzimidazole (PBI) has been suggested as a promising electrolyte for proton exchange membrane fuel cells operating at temperatures up to 200 °C. This paper describes the development of a crosslinking procedure for PBI membranes by post‐treatment with divinylsulfone. The crosslinking chemistry was studied and optimized on a low‐molecular‐weight model system and the results were used to optimize the crosslinking conditions of PBI membranes. The crosslinked membranes were characterized with respect to chemical and physiochemical properties, showing improved mechanical strength and oxidative stability compared with their linear analogues. Fuel cell tests were further conducted in order to demonstrate the feasibility of the crosslinked membranes. Copyright © 2011 Society of Chemical Industry 相似文献
54.
55.
Dr Niels Grabow David P. Martin Klaus‐Peter Schmitz Katrin Sternberg 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2010,85(6):744-751
Stents are structural implants with widespread clinical use in vascular intervention to re‐open stenotic vessels for the treatment of coronary artery disease and peripheral arterial occlusive disease. Apart from their mechanical function, current drug‐eluting stents (DES) utilize local drug delivery from a drug‐incorporated permanent polymer coating to prevent in‐stent restenosis. This delayed closure of the stented vessel is considered one of the major limitations of conventional bare metal stents (BMS). The long‐term safety of DES, however, is still under debate, with reported cases of delayed healing, late thrombosis and hypersensitivity demanding further evolution in this field. A promising approach to circumvent the limitations of first generation DES is the application of degradable polymer coatings in second generation DES, and fully absorbable polymer stents. From a materials and engineering perspective, this paper provides a mini‐review of current clinically relevant DES technology and recent advancements in the development of stents from degradable polymeric materials as an alternative to permanent BMS and DES. This review, includes work on degradable stents and coatings based on blends of polylactic acid and the microbially‐produced poly(4‐hydroxybutyrate). Copyright © 2009 Society of Chemical Industry 相似文献
56.
57.
58.
59.
60.