全文获取类型
收费全文 | 752篇 |
免费 | 93篇 |
国内免费 | 42篇 |
专业分类
电工技术 | 28篇 |
综合类 | 18篇 |
化学工业 | 131篇 |
金属工艺 | 51篇 |
机械仪表 | 59篇 |
建筑科学 | 34篇 |
矿业工程 | 5篇 |
能源动力 | 30篇 |
轻工业 | 148篇 |
水利工程 | 22篇 |
石油天然气 | 14篇 |
武器工业 | 3篇 |
无线电 | 62篇 |
一般工业技术 | 136篇 |
冶金工业 | 32篇 |
原子能技术 | 14篇 |
自动化技术 | 100篇 |
出版年
2024年 | 9篇 |
2023年 | 23篇 |
2022年 | 37篇 |
2021年 | 68篇 |
2020年 | 53篇 |
2019年 | 42篇 |
2018年 | 43篇 |
2017年 | 51篇 |
2016年 | 48篇 |
2015年 | 38篇 |
2014年 | 36篇 |
2013年 | 66篇 |
2012年 | 37篇 |
2011年 | 47篇 |
2010年 | 23篇 |
2009年 | 26篇 |
2008年 | 18篇 |
2007年 | 17篇 |
2006年 | 12篇 |
2005年 | 13篇 |
2004年 | 7篇 |
2003年 | 15篇 |
2002年 | 18篇 |
2001年 | 13篇 |
2000年 | 6篇 |
1999年 | 10篇 |
1998年 | 12篇 |
1997年 | 17篇 |
1996年 | 7篇 |
1995年 | 10篇 |
1994年 | 14篇 |
1993年 | 13篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1981年 | 1篇 |
1976年 | 2篇 |
排序方式: 共有887条查询结果,搜索用时 484 毫秒
1.
Zhongkai Zhao Yohanes A. Situmorang Ping An Nichaboon Chaihad Jing Wang Xiaogang Hao Guangwen Xu Abuliti Abudula Guoqing Guan 《化学工程与技术》2020,43(4):625-640
In the future, hydrogen will be an important energy carrier and industrial raw material. Catalytic steam reforming of bio-oils is a promising and economically viable technology for hydrogen production. However, during the reforming process, the catalysts are rapidly deactivated due to coke formation and sintering. Thus, maintaining the activity and stability of catalysts is the key issue in this process. Optimized operation conditions could extend the catalyst lifetime by affecting the coke morphology or promoting coke gasification. This article summarizes the recent developments in the field of catalytic steam reforming of bio-oils, focusing on the operation conditions, the properties of the catalysts, and the effects of the catalyst supports. The expected insights into the catalytic steam reforming of bio-oils will provide further guidance for hydrogen production from bio-oils. 相似文献
2.
通过热力学计算,选择Ni_2O_3粉末作原材料,采用反应挤压铸造方法实现了Al与Ni2O3直接压铸反应合成Al3Ni-Al2O3-Al原位复合材料。研究了压铸工艺参数和预制块中纯Al粉的含量对反应合成复合材料过程的影响,并对反应机理做了较深入的分析。结果表明,Ni2O3与Al的反应是为高放热反应,反应是爆发式的,通过调整预制块中Al粉的体积分数控制了反应的剧烈程度,并能获得不同组成和基体含量的复合材料。对反应机理的分析表明,在Al足量的情况下,Ni2O3与Al反应合成复合材料分为两个过程,一是反应过程,即Ni2O3+Al→Al2O3+[Ni];二是凝固过程,即反应后多余的Al与反应生成的[Ni]在随后冷却中的凝固过程,最终形成Al3Ni+α-Al2O3+Al复合材料。 相似文献
3.
晶须取向对SiCw/Al复合材料切削表面质量的影响 总被引:2,自引:0,他引:2
切削与晶须取向方向间的夹角对SiCw/Al复合材料切削表面质量有很大影响。当切削角为45°时,晶须拔出和转动现象均较少,复合材料切削表面粗糙度最低。当切削角为135度时,晶段转动造成的撕裂破坏程度很大,复合材料切削表面粗糙度最大。 相似文献
4.
Masood Parang Rao V. Arimilli Satish P. Ketkar 《International Communications in Heat and Mass Transfer》1985,12(2):179-189
A special boundary integral method developed for two-dimensional regions containing circular holes is used to calculate temperature and heat transfer on the boundaries of several selected regions. The geometrical configuration of the region is arbitrary and convective boundary conditions are assumed. An important feature of the method is analytic representation of temperature and its normal derivative on the interior circular holes in the form of a harmonic series. This makes the application of the boundary integral method convenient and free from conditioning problems associated with small interior boundaries. Heat transfer from circular isothermal interior holes are calculated for several illustrative examples using three terms of the harmonic series representation for heat transfer at each of the circular boundaries. The results are presented and discussed. 相似文献
5.
S.F. Lee P. Lovenitti M.K. Lam S.H. Masood 《The International Journal of Advanced Manufacturing Technology》2002,20(3):180-189
This paper describes the design and development of a precision calliper system to measure the surface profile of an outboard
marine engine propeller blade. Several instruments that are commonly used for measuring the surface profile of a propeller
blade are reviewed in this paper. These include the pitch meter, the profilometer and the computer numerical control coordinate-measuring
machine (CNC-CMM). However, the operating practices and availability of different facilities in industry necessitate a more
cost-effective approach. An alternative method using a precision calliper system is therefore proposed. Details of the design
criteria, principles of operation and the testing and verification of the system are presented. The paper concludes that the
precision calliper system is a cost-effective method for measuring the surface profile of a propeller. 相似文献
6.
经过20余年的高速发展,特别是最近10余年乌江、澜沧江等多个特大流域梯级水电站群的集中投产,我国逐步形成了世界水电史上极其罕见的大规模互联水电系统.受持续攀升的系统规模、急剧增加的电站数目、形式各异的运行约束、复杂多变的调度需求等综合因素影响,大规模水电调度维数灾问题日益凸显,已成为制约我国能源高效配置的关键基础科学难题.为此,本文围绕我国快速发展的大规模水电系统,深入剖析了维数灾问题的产生根源,总结了国内外相关研究进展,提出了未来需要深入开展研究的方向建议,以期为我国水电调度理论发展提供有益参考. 相似文献
7.
本文对SiC_w/6061Al复合材料的组织与性能进行了研究,结果表明,压铸法可以制备出高强度、高模量的各向同性复合材料,挤压使复合材料的强度由压铸态的582MPa提高到639MPa,并使材料变为各向异性,这可以由晶须的定向排列和基体的高密度位错得到解释。复合材料的抗高温性能要比基体高150℃,透射电镜观察还发现,层错是SiC晶须中常见的一种面缺陷。 相似文献
8.
Finite-time stability in dynamical systems theory involves systems whose trajectories converge to an equilibrium state in finite time. In this paper, we use the notion of finite-time stability to apply it to the problem of coordinated motion in multiagent systems. Specifically, we consider a group of agents described by fully actuated Euler–Lagrange dynamics along with a leader agent with an objective to reach and maintain a desired formation characterized by steady-state distances between the neighboring agents in finite time. We use graph theoretic notions to characterize communication topology in the network determined by the information flow directions and captured by the graph Laplacian matrix. Furthermore, using sliding mode control approach, we design decentralized control inputs for individual agents that use only data from the neighboring agents which directly communicate their state information to the current agent in order to drive the current agent to the desired steady state. Sliding mode control is known to drive the system states to the sliding surface in finite time. The key feature of our approach is in the design of non-smooth sliding surfaces such that, while on the sliding surface, the error states converge to the origin in finite time, thus ensuring finite-time coordination among the agents in the network. In addition, we discuss the case of switching communication topologies in multiagent systems. Finally, we show the efficacy of our theoretical results using an example of a multiagent system involving planar double integrator agents. 相似文献
9.
Jason Hochreiter Zhongkai HanSyed Zain Masood Spencer FonteMarshall Tappen 《Image and vision computing》2014
In this paper, we propose an album-oriented face-recognition model that exploits the album structure for face recognition in online social networks. Albums, usually associated with pictures of a small group of people at a certain event or occasion, provide vital information that can be used to effectively reduce the possible list of candidate labels. We show how this intuition can be formalized into a model that expresses a prior on how albums tend to have many pictures of a small number of people. We also show how it can be extended to include other information available in a social network. Using two real-world datasets independently drawn from Facebook, we show that this model is broadly applicable and can significantly improve recognition rates. 相似文献
10.