全文获取类型
收费全文 | 2637篇 |
免费 | 144篇 |
国内免费 | 51篇 |
专业分类
电工技术 | 36篇 |
综合类 | 283篇 |
化学工业 | 379篇 |
金属工艺 | 24篇 |
机械仪表 | 20篇 |
建筑科学 | 1472篇 |
矿业工程 | 24篇 |
能源动力 | 56篇 |
轻工业 | 216篇 |
水利工程 | 17篇 |
石油天然气 | 58篇 |
武器工业 | 6篇 |
无线电 | 21篇 |
一般工业技术 | 71篇 |
冶金工业 | 91篇 |
原子能技术 | 8篇 |
自动化技术 | 50篇 |
出版年
2024年 | 3篇 |
2023年 | 12篇 |
2022年 | 34篇 |
2021年 | 52篇 |
2020年 | 49篇 |
2019年 | 38篇 |
2018年 | 42篇 |
2017年 | 57篇 |
2016年 | 69篇 |
2015年 | 62篇 |
2014年 | 165篇 |
2013年 | 120篇 |
2012年 | 151篇 |
2011年 | 162篇 |
2010年 | 160篇 |
2009年 | 212篇 |
2008年 | 164篇 |
2007年 | 232篇 |
2006年 | 169篇 |
2005年 | 158篇 |
2004年 | 165篇 |
2003年 | 139篇 |
2002年 | 101篇 |
2001年 | 88篇 |
2000年 | 54篇 |
1999年 | 37篇 |
1998年 | 23篇 |
1997年 | 17篇 |
1996年 | 17篇 |
1995年 | 22篇 |
1994年 | 10篇 |
1993年 | 12篇 |
1992年 | 9篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1988年 | 2篇 |
1987年 | 7篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1974年 | 1篇 |
1961年 | 1篇 |
1955年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有2832条查询结果,搜索用时 62 毫秒
1.
Investigation on the miniaturized parallel multichannel-based devices packed with glass beads to improve the mass exchange execution is the critical focal point of the current study. One of the essential parameters to specify the miniaturized devices' flow distribution is the residence time distribution (RTD). In the present context, the RTDs of a liquid tracer were investigated for the air-water multiphase flows (concurrent) across the multichannel-based miniaturized devices (comprising of 11 similar dimensional parallel channels). The devices were variable in height and packed with glass beads. The conductivity estimations generated the RTD curves and were addressed by the axial dispersion model (ADM). The fluid-flow rates differed within the range of 5–23 ml min−1. The axial dispersion coefficients and the rate of the specific energy dispersion were investigated. The effects of pressure difference and geometry on the hydrodynamic attributes and mixing properties were well-illustrated, and the new correlations were suggested. 相似文献
2.
The mechanical property of age‐hardenable Al‐alloys is governed by the state of ageing, which determines the microstructure and consequently, their corrosion behavior which is a vital aspect for a number of applications. This article presents a comparative assessment of corrosion behavior of under‐, peak‐ and over‐aged Al‐Mg‐Si alloy. Corrosion characteristics have been determined via immersion tests in 0.1 M ortho‐phosphoric acid solution and intergranular corrosion (IGC) tests. Corroded surfaces are examined by field emission scanning electron micrographs‐energy dispersive spectroscopy and 3D optical profilometer. The obtained results reveal that the corrosion rate at a specific immersion time as well as the depth of IGC increases in the order for under‐, peak‐, and over‐aged states. Irrespective of the state of ageing, corrosion loss increases linearly but the rate of corrosion decreases rapidly with increasing immersion time. The dominant mode of corrosion in under‐aged alloy is identified as localized pitting, while peak‐aged is highly susceptible to IGC in contrast extensive pitting corrosion is observed for over‐aged alloy. The observed differences in corrosion behavior are explained considering characteristics of precipitates. Formation of β (Mg2Si) in case of over‐aged alloy and presence of inclusions like AlFeMnSi particles are found to accelerate pitting corrosion. 相似文献
3.
Thanapalan Murugesan G. S. Venkat Rathnam S. Panduranga Rao P. Gangadhar Rao 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,63(3):290-294
In the present study of gas–liquid contactors, mean residence/contact time was calculated from knowledge of superficial velocity and the gas phase hold-up, for various gas rates and impeller geometry and speeds, and compared with values obtained from RTD measurements. A new correlation, involving Flow Number, Froude Number, system geometry and the physical properties, is proposed. This uses the authors data and those available in literature. 相似文献
4.
现代住区规划的几点思考 总被引:2,自引:0,他引:2
通过对居住区规划中住区交通组织、环境建设,以及住宅配套现实处理方法的分析,指出现代住区的规划要根据当地实际情况,因地制宜组织住区交通网络,合理整合住宅内外环境,适度超前建设配套设施。 相似文献
5.
就住宅电气设计中,常常被忽略的细节问题进行阐述,提出了在住宅室内几个功能区内,如何使灯具和插座的布置更合理,以最大限度地满足居住者的需求。 相似文献
6.
在鱼罐喷粉预处理水模实验数据的基础上,进一步利用线性回归确定各工艺操作参数对喷吹基本参数(均混时间、粉剂穿透比和粉剂停留时间)的影响,得出各传输动力学基本参数的函数关系式。 相似文献
7.
在已经得到的描述鱼雷罐喷粉处理基本参数具体表达式的基础上,运用多目标非线性优化方法,对工艺操作参数进行优化。 相似文献
8.
9.
This paper shows that Danckwerts’ law for mean residence time in a vessel with continuous and steady throughflow holds for a stochastic model based on a Markov chain for the particle spatial position, under a set of three very general conditions on the transfer probabilities. These are natural conditions and represent mass balance conditions on the transfer between spatial regions in the process. It is shown that a stochastic model for particle residence time distribution with these three conditions may describe almost any physical flow configuration, and also covers published mathematical RTD models, independent of their mathematical form or the nature of the associated boundary conditions, models for which Danckwert's law has hitherto been shown to be satisfied on a case-by-case basis. Two examples, namely those birth-death Markov chains and fluidized bed models are discussed. 相似文献
10.
论老年教育的地位、作用和发展方向 总被引:1,自引:0,他引:1
赵周明 《石油化工管理干部学院学报》2002,(3):58-59
老年教育在社会中具有重要的地位和作用。它是终身教育的重要组成部分,是社会发展的客观需要,是解决老龄问题的重要途径和方法。探讨了随着社会经济的发展和老龄化社会进程的加快,在21世纪老年教育的发展方向。 相似文献