全文获取类型
收费全文 | 2382篇 |
免费 | 185篇 |
专业分类
电工技术 | 13篇 |
综合类 | 1篇 |
化学工业 | 764篇 |
金属工艺 | 13篇 |
机械仪表 | 28篇 |
建筑科学 | 107篇 |
矿业工程 | 7篇 |
能源动力 | 38篇 |
轻工业 | 757篇 |
水利工程 | 19篇 |
石油天然气 | 20篇 |
无线电 | 87篇 |
一般工业技术 | 326篇 |
冶金工业 | 190篇 |
原子能技术 | 9篇 |
自动化技术 | 188篇 |
出版年
2024年 | 3篇 |
2023年 | 14篇 |
2022年 | 92篇 |
2021年 | 135篇 |
2020年 | 66篇 |
2019年 | 54篇 |
2018年 | 69篇 |
2017年 | 76篇 |
2016年 | 92篇 |
2015年 | 73篇 |
2014年 | 101篇 |
2013年 | 175篇 |
2012年 | 154篇 |
2011年 | 211篇 |
2010年 | 129篇 |
2009年 | 146篇 |
2008年 | 136篇 |
2007年 | 129篇 |
2006年 | 92篇 |
2005年 | 85篇 |
2004年 | 70篇 |
2003年 | 69篇 |
2002年 | 58篇 |
2001年 | 29篇 |
2000年 | 19篇 |
1999年 | 27篇 |
1998年 | 31篇 |
1997年 | 26篇 |
1996年 | 28篇 |
1995年 | 22篇 |
1994年 | 25篇 |
1993年 | 21篇 |
1992年 | 14篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1987年 | 3篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 9篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 8篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1965年 | 1篇 |
排序方式: 共有2567条查询结果,搜索用时 31 毫秒
11.
In these times of global change, many facility emphases are competing for limited resources. Competing factors include, but are not limited to, sustainable design or green buildings; security, hardening or force protection; accessibility; historic preservation; aesthetics; and functionality. Yet, unlimited resources are seldom, if ever, available to fulfill all of these competing requirements in private or public construction. The Georgia Institute of Technology designed a decision matrix to allow owners and planners to balance these competing requirements on a project-by-project basis and to document the rationale. 相似文献
12.
13.
Here, we describe the development of a reacting flow multi-species/combustion methodology, implemented as an extension to the differential reduced ejector analysis (DREA) computer program [Mathematical and computer modeling, vol. 31, 2000, p. 21; Appl. Math. Model. 25 (2001) 427; Comput. Math. Appl. 43(10–11); NASA Contractor Report, 1998]. Use of the single fluid IVP solver framework that was developed for the original DREA model has been directly coupled into the combustion formulation. With these modifications, the analysis has an elementary single step reaction Fuel+Oxidizer→Product combustion capability. Though approximate in nature, the simplicity and efficiency of the DREA formulation make it suitable for its original niche, namely design and preliminary design environments where more complex and expensive models may be inappropriate. 相似文献
14.
15.
Vincenzo Augelli Teresa Ligonzo Roberto Murri Luigi Schiavulli 《Thin solid films》1989,170(2):163-170
Hydrogenated and chlorinated silicon films were used to deposit Schottky barrier solar cells. Photovoltaic characterization, together with the results of electronic transport measurements, led to the conclusion that the presence of chlorine is detrimental to the properties of this kind of device. 相似文献
16.
Naiara Azurmendi Iñaki Caro Amador C. Caballero Teresa Jardiel Marina Villegas 《Journal of the American Ceramic Society》2006,89(4):1232-1236
Bismuth titanate-based ceramics, pure and doped with 5 mol% WO3 , were prepared by reaction-sintering using a microwave oven. High densities, ≥96% of theoretical density were achieved with very short thermal treatments, with soaking time ranging from 5 to 15 min. Relatively small platelet-like grains were formed, and microstructure seemed not to be strongly affected by doping nor soaking time. Electrical measurements were performed and, as expected, a decrease of electrical conductivity was observed in WO3 -doped materials. The results of reaction-sintered samples, both conventional as well as microwave sintered, are compared with those of samples prepared with previously calcined powders and sintered using microwaves as well as a conventional electric furnace. 相似文献
17.
18.
Teresa A Morrison J Raymond Kessler Ronald D Hatfield Dwayne R Buxton 《Journal of the science of food and agriculture》1994,65(2):133-139
To ascertain the temporal relationships of phcnylpropanoid and lignin pathway enzymes, phenylalanine ammonia-lyase (PAL) and cinnamyl alcohol- NADPH dehydrogenase(CAD), with lignin concentration, PAL and CAD activities and lignin concentrations were assessed during progressive development of the 10th internode in maize (Zea mays L). Enzyme activities were quantified and lignin concentrations were determined by the detergent system of fiber fractiona- tion from lower, middle, and upper sections of the elongating internode harvested 3, 5, 7, 9, 11, 13, and 15 days after the internode had reached 10 mm in length. Over 15 days, a coordinated, sequential, and basipetal pattern of enzyme activities and lignin accumulation evolved through the internode, spanning the stages of rapid elongation, cellular differentiation, and secondary cell wall formation. PAL activity was initiated first, rising to peak activity in elongating tissue, and falling basipetally in tissues as they matured. CAD activity rose in fully elongated, maturing internode tissue where PAL activity was waning following its peak activity. Lignin accumulated in tissues with high CAD activity. CAD activity and lignin deposition patterns were similar: simultaneously increasing in activity and deposition over time while activity and deposition also shifting basipetally through the internode, keeping pace with secondary cell wall formation. Lignin concentration correlated significantly with CAD, but not with PAL. 相似文献
19.
Acoustic emission generated on thermal shocks makes it possible to investigate the processes of cracking that take place in high alumina refractories separately at heating and cooling stages, as well as on successive thermal shocks. It is dependent on the raw material type, technological process and the microstructure of products (i.e. number, size and shape of pores and cracks). The damage present after 20 thermal shocks in the material tested was illustrated by the microstructure examinations. 相似文献
20.
Teresa Mikołajczyk Grażyna Janowska Mariusz Wójcik Maciej Boguń Andrzej Kurzak 《应用聚合物科学杂志》2008,109(4):2513-2521
The rheological properties of spinning solutions of polyacrylonitrile in dimethyl formamide (DMF) containing various amounts of a ferromagnetic nanoaddition were investigated. The porous structure, the strength and thermal properties of fibers obtained from these solutions were assessed, as well as the uniformity of the nanoaddition distribution on the fiber surface was estimated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献