全文获取类型
收费全文 | 779篇 |
免费 | 78篇 |
国内免费 | 24篇 |
专业分类
电工技术 | 8篇 |
综合类 | 122篇 |
化学工业 | 47篇 |
金属工艺 | 14篇 |
机械仪表 | 12篇 |
建筑科学 | 475篇 |
矿业工程 | 8篇 |
能源动力 | 3篇 |
轻工业 | 9篇 |
水利工程 | 4篇 |
石油天然气 | 11篇 |
武器工业 | 4篇 |
无线电 | 21篇 |
一般工业技术 | 119篇 |
冶金工业 | 5篇 |
自动化技术 | 19篇 |
出版年
2023年 | 11篇 |
2022年 | 13篇 |
2021年 | 22篇 |
2020年 | 24篇 |
2019年 | 13篇 |
2018年 | 15篇 |
2017年 | 21篇 |
2016年 | 16篇 |
2015年 | 26篇 |
2014年 | 38篇 |
2013年 | 32篇 |
2012年 | 53篇 |
2011年 | 70篇 |
2010年 | 54篇 |
2009年 | 60篇 |
2008年 | 54篇 |
2007年 | 62篇 |
2006年 | 69篇 |
2005年 | 42篇 |
2004年 | 39篇 |
2003年 | 42篇 |
2002年 | 26篇 |
2001年 | 23篇 |
2000年 | 23篇 |
1999年 | 11篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1985年 | 1篇 |
1980年 | 2篇 |
排序方式: 共有881条查询结果,搜索用时 0 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.
Removal of gold from basic solutions containing [Au(CN)2]? has been demonstrated using the inherently conducting polymer polypyrrole. Polymers containing sulfonated aromatic dopants have been found to display a significant ability to remove gold from such solutions. Experiments performed in solutions containing both gold and copper cyanide complexes indicate that the recovery process is not highly selective. However, the polypyrroles used display significantly faster rates of gold recovery than activated carbon. © 2003 Society of Chemical Industry 相似文献
5.
Shou-ren Wang Hao-ran Geng Lin-hai Hui Ying-zi Wang 《Journal of Materials Engineering and Performance》2007,16(1):113-118
A multiphase reticulated porous ceramic (RPC) as Si3N4–Al2O3–SiO2 was fabricated by replication techniques. Proper volumes of additives and twice sinter- twice immerse process endow the RPC
an excellent crack healing and submerging property. The compressive strength and fracture toughness improved owing to the
crack bridging behavior. The existence of pores in struts in RPC blunt the crack tip and increased the external force needed
to propagate the crack. The mechanisms play a beneficial role in enhancing the compressive strength and fracture strength.
Si3N4 RPC with additives of 5%Al and 5% Al2O3 yielded the compressive strength of 9.8 MPa and fracture toughness of 0.3 MPa m1/2. 相似文献
6.
板锥网壳结构是一种受力性能合理 ,技术经济效益良好的新型空间结构形式。对板锥网壳结构的自振特性及其影响因素进行了系统分析研究 ,并与普通双层网壳结构进行比较 ,得出了可应用于工程实践的重要结论 相似文献
7.
8.
K8型单层球面网壳支座减震 总被引:1,自引:0,他引:1
于志伟 《哈尔滨工业大学学报》2009,41(4):7-11
为了对跨度为60 m的K8型单层球面网壳进行了减震分析,分别将结构的支座设置成弹性支座和弹性阻尼支座,对结构进行减震控制.结合对结构在有控和无控状态下自振特性的分析,阐述了单层球面网壳结构的减震控制原理.在常遇地震作用下,得到网壳结构的最大水平位移、减震支座的最大水平位移、最大支座反力和最大杆件内力.通过改变支座的刚度和阻尼系数,对两种减震方案的减震效果进行比较.研究结果表明:两种减震装置均有效地控制了K8型单层球面网壳结构的支座反力,弹性阻尼支座还可以明显地降低减震支座的水平位移. 相似文献
9.
研究索穹顶与单层网壳组合的新型空间结构的受力性能.设计肋环型索穹顶与肋环双斜杆型单层网壳组合的结构,对其进行下部索穹顶预应力张拉试验以及结构在全跨和半跨荷载下的静力性能试验.根据试验结果对试验的计算模型进行修正,并将结构在全跨和半跨荷载下的试验实测数据与理论分析结果进行比较.结果表明,实测数据与理论分析之间差异较小,模型设计和试验方法合理,理论分析方法正确.修正的计算模型能准确反映结构的力学性能. 相似文献
10.
单层球面网壳与支承结构整体强震失效特征 总被引:4,自引:1,他引:3
为了研究支承结构对单层球面网壳在强震作用下失效特征的影响,建立了更为精细化的数值模型.采用动力荷载域全过程分析方法研究了单层球面网壳与支承结构整体在强震作用下的特征响应,得到了考虑下部支承结构的单层球面网壳在强震作用下两种不同的失效特征,并建立了网壳结构极限承载力的判别准则,研究了下部支承结构、矢跨比、屋面质量等参数对网壳结构在强震作用下动力响应的影响.结果表明:下部支承对网壳结构在强震作用下的失效特征有显著的影响;随网壳矢跨比和屋面质量减小,结构的极限承载力显著提高,并且塑性程度加深,延性增强. 相似文献