全文获取类型
收费全文 | 2902篇 |
免费 | 245篇 |
国内免费 | 158篇 |
专业分类
电工技术 | 39篇 |
综合类 | 269篇 |
化学工业 | 269篇 |
金属工艺 | 117篇 |
机械仪表 | 57篇 |
建筑科学 | 937篇 |
矿业工程 | 231篇 |
能源动力 | 104篇 |
轻工业 | 61篇 |
水利工程 | 454篇 |
石油天然气 | 114篇 |
武器工业 | 9篇 |
无线电 | 24篇 |
一般工业技术 | 142篇 |
冶金工业 | 457篇 |
原子能技术 | 5篇 |
自动化技术 | 16篇 |
出版年
2024年 | 5篇 |
2023年 | 14篇 |
2022年 | 54篇 |
2021年 | 55篇 |
2020年 | 67篇 |
2019年 | 53篇 |
2018年 | 63篇 |
2017年 | 77篇 |
2016年 | 87篇 |
2015年 | 100篇 |
2014年 | 160篇 |
2013年 | 158篇 |
2012年 | 206篇 |
2011年 | 209篇 |
2010年 | 166篇 |
2009年 | 194篇 |
2008年 | 145篇 |
2007年 | 223篇 |
2006年 | 168篇 |
2005年 | 155篇 |
2004年 | 134篇 |
2003年 | 135篇 |
2002年 | 113篇 |
2001年 | 101篇 |
2000年 | 91篇 |
1999年 | 90篇 |
1998年 | 51篇 |
1997年 | 50篇 |
1996年 | 41篇 |
1995年 | 33篇 |
1994年 | 30篇 |
1993年 | 19篇 |
1992年 | 17篇 |
1991年 | 19篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1959年 | 1篇 |
排序方式: 共有3305条查询结果,搜索用时 15 毫秒
1.
Chengkai Li Zheyi Zhang Haifei Zhan Zhuoqun Zheng Jingshuai Bai Yuantong Gu 《大分子材料与工程》2021,306(10):2100292
Low-dimensional carbon nanostructures are ideal nanofillers to reinforce the mechanical performance of polymer nanocomposites due to their excellent mechanical properties. Through molecular dynamics simulations, the mechanical performance of poly(vinyl alchohol) (PVA) nanocomposites reinforced with a single-layer diamond – diamane is investigated. It is found the PVA/diamane exhibits similar interfacial strengths and pull-out characteristics with the PVA/bilayer-graphene counterpart. Specifically, when the nanofiller is fully embedded in the nanocomposite, it is unable to deform simultaneously with the PVA matrix due to the weak interfacial load transfer efficiency, thus the enhancement effect is not significant. In comparison, diamane can effectively promote the tensile properties of the nanocomposite when it has a laminated structure as it deforms simultaneously with the matrix. With this configuration, the interlayer sp3 bonds endows diamane with a much higher resistance under compression and shear tests, thus the nanocomposite can reach very high compressive and shear stress. Overall, enhancement on the mechanical interlocking at the interface as triggered by surface functionalization is only effective for the fully embedded nanofiller. This work provides a fundamental understanding of the mechanical properties of PVA nanocomposites reinforced by diamane, which can shed lights on the design and preparation of next generation high-performance nanocomposites. 相似文献
2.
3.
Ph. D. Candidate:Chen Xue-fengState Key Laboratory of Offshore Coastal Engineering Dalian University of Technology Dalian China e-mail: cxfeng @ student dlut. edu.cn 《水动力学研究与进展(B辑)》2003,15(6)
The reflection coefficient of perforated caissons and the total horizontal forces acting on them were experimentally and numerically analyzed and discussed when wave propagates normally. To consider the viscosity effect of fluid and nonlinear action of waves on structures, the VOF (Volume Of Fluid) method combined with the k-ε turbulence model was used to simulate the interaction between waves and structures. Governing equations were solved with the finite difference method. Through 2D experimental study in the wave flume, the empirical relationship between the reflection coefficient of perforated caissons and the main affecting factors were obtained from the experimental data using the least square method. Also the correlation between the ratio of the total horizontal force acting on perforated caisson and the force acting on solid caisson and the main affecting factors were regressed from the experimental data. 相似文献
4.
5.
6.
An experimental investigation was carried out to examine the tribological behavior of NAO (non-asbestos organic) type brake linings containing different volume ratios of graphite and antimony trisulfide (Sb2S3). A scale dynamometer was used for friction tests and particular emphases were given to the effect of applied pressure, sliding speed, and temperature on the coefficient of friction according to the relative amounts of the two solid lubricants. Results showed that the brake linings with both solid lubricants exhibited better friction stability and less speed sensitivity than the friction materials containing a single solid lubricant. In particular, the brake lining containing higher concentrations of graphite showed better fade resistance than others during high-temperature friction test. 相似文献
7.
8.
对导热油加热炉炉壁温度升高的原因进行了分析,介绍了新型复合内衬的特点,并对其技术特点、施工工艺及应用效果进行了简单阐述。 相似文献
9.
阐述了石灰竖窑的预热带、煅烧带和冷却带工作衬砖蚀损机理,并讨论了如何根据耐火砖性能和石灰竖窑不同区域的蚀损机理,选择耐火材料。 相似文献
10.