全文获取类型
收费全文 | 11763篇 |
免费 | 1436篇 |
国内免费 | 916篇 |
专业分类
电工技术 | 1648篇 |
技术理论 | 1篇 |
综合类 | 619篇 |
化学工业 | 1033篇 |
金属工艺 | 195篇 |
机械仪表 | 474篇 |
建筑科学 | 2273篇 |
矿业工程 | 297篇 |
能源动力 | 535篇 |
轻工业 | 244篇 |
水利工程 | 43篇 |
石油天然气 | 157篇 |
武器工业 | 631篇 |
无线电 | 2073篇 |
一般工业技术 | 1987篇 |
冶金工业 | 405篇 |
原子能技术 | 271篇 |
自动化技术 | 1229篇 |
出版年
2024年 | 55篇 |
2023年 | 255篇 |
2022年 | 346篇 |
2021年 | 347篇 |
2020年 | 410篇 |
2019年 | 353篇 |
2018年 | 340篇 |
2017年 | 422篇 |
2016年 | 583篇 |
2015年 | 502篇 |
2014年 | 738篇 |
2013年 | 656篇 |
2012年 | 795篇 |
2011年 | 887篇 |
2010年 | 693篇 |
2009年 | 674篇 |
2008年 | 696篇 |
2007年 | 769篇 |
2006年 | 775篇 |
2005年 | 568篇 |
2004年 | 478篇 |
2003年 | 460篇 |
2002年 | 392篇 |
2001年 | 338篇 |
2000年 | 283篇 |
1999年 | 219篇 |
1998年 | 187篇 |
1997年 | 165篇 |
1996年 | 123篇 |
1995年 | 87篇 |
1994年 | 109篇 |
1993年 | 71篇 |
1992年 | 83篇 |
1991年 | 54篇 |
1990年 | 44篇 |
1989年 | 35篇 |
1988年 | 33篇 |
1987年 | 15篇 |
1986年 | 15篇 |
1985年 | 16篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
P. K. Khare J. M. Keller M. S. Gaur Ranjeet Singh S. C. Datt 《Polymer International》1994,35(4):337-343
The electrical conductivity of solution-grown ethyl cellulose (EC) films, 5–30 μm thick, has been studied in the sandwich configuration (metal–EC–metal) as a function of iodine concentration from 0.5 to 5.0 wt% ratio. The studies were conducted in the temperature range 333–383 K, while the field was varied over the range (3.0–5.5) × 104V/cm. Aluminium was used as the lower electrode, while the upper electrode was of Al, Ag, Cu, Au or Sn. Certain transient effects such as a large burst of current immediately after the application of field were observed. An attempt was made to identify the nature of the current by comparing the observed dependence on electric field, electrode material and temperature with the respective characteristic features of the existing theories of electrical conduction. The results show that the electrical conduction follows Ohm's law at lower fields, while at higher fields, space-charge limited current (SCLC) was observed. It was also found that Richardson–Schottky emission was responsible, to some extent, for the transport of charge carriers in the polymer. The conductivity of the films increased on doping with iodine. The dopant molecules are considered to act as additional trapping centes and provide links between the polymer molecules in the amorphous region, thus resulting in the formation of charge transfer complexes. 相似文献
32.
33.
34.
Solving regularized least squares with qualitatively controlled adaptive cross‐approximated matrices
The adaptive cross‐approximation (ACA) technique is applied to accelerating an inverse‐problem solver that estimates charge distribution on a dielectric spacer. The ACA generates an approximated system‐matrix that enables us to carry out high‐speed inverse calculation. We designed an approximation procedure based on ACA with some additional concepts, that is, (a) partitioning of matrix based on algebraic information, (b) approximation quality control based on matrix norms, and so on. The tested solver (LSQR for regularized least squares) with ACA demonstrates about 10 times faster performance than that without ACA. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(3): 10–18, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20326 相似文献
35.
36.
空间的塑造--厦门海湾公园设计 总被引:1,自引:1,他引:0
海湾公园利用植物、地形、大海与湖泊的周边环境等景观要素,运用隐喻、对比的手法,创造丰富、神秘、变化的空间,注重空间灵活的使用功能及其良好的人性化. 相似文献
37.
Microhardness measurements have been performed on untreated (virgin) and electrically stressed, solvent‐cast laboratory‐prepared samples of pure poly(phenylene oxide) (PPO), pure polystyrene (PS), and PPO : PS polyblends with different weight proportions. Results of such measurement on untreated polyblend sample show that microhardness (Hv) increases with increase in the content of PS up to 10 wt %, which attributed to the existence of homogeneous phase morphology. However, this feature is not observable in samples containing higher content of PS. Electrical stress is found to modify considerably the mechanical property of polymer. The effect of electric field on the microhardness of such samples (PPO : PS :: 90 : 10) has been characterized by the existence of a peak. Trapping of charge carriers in electrically stressed samples imparts hardening to the polyblend up to an applied step field of 190 kV/cm. However, the excessive charging beyond this step field value destroys this characteristic. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
38.
ABSTRACT: Popcorn was oiled and coated in a tumble drum nonelectrostatically and electrostatically with sugar, cornstarch, salt, cellulose, maltodextrin, all-purpose flour, whole-wheat flour, or soy flour. Particle size, density, flowability, and chargeability were correlated to transfer efficiency using regression analysis. Of the various methods to measure chargeability, charge-to-mass and adhesion improvement were the most significant. For nonelectrostatic coating, small, dense, free-flowing powders were most efficient. Small, free-flowing highly charging powders were most efficient for electrostatic coating. Percent improvement was the highest for the least efficient powders. The greatest benefit with electrostatic coating was for low density, highly charging powders with no effect of size. 相似文献
39.
40.
本文以中国雕版印刷博物馆及扬州博物馆设计为例,从空间意象、理水设计、造形元素等方面对特定历史条件、自然条件下的建筑创作进行了探讨。 相似文献