全文获取类型
收费全文 | 131篇 |
免费 | 29篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 13篇 |
综合类 | 5篇 |
化学工业 | 38篇 |
金属工艺 | 7篇 |
机械仪表 | 8篇 |
建筑科学 | 9篇 |
矿业工程 | 10篇 |
轻工业 | 11篇 |
水利工程 | 4篇 |
石油天然气 | 5篇 |
武器工业 | 2篇 |
无线电 | 11篇 |
一般工业技术 | 29篇 |
冶金工业 | 2篇 |
原子能技术 | 2篇 |
自动化技术 | 15篇 |
出版年
2024年 | 5篇 |
2023年 | 9篇 |
2022年 | 12篇 |
2021年 | 16篇 |
2020年 | 7篇 |
2019年 | 20篇 |
2018年 | 14篇 |
2017年 | 12篇 |
2016年 | 8篇 |
2015年 | 8篇 |
2014年 | 10篇 |
2013年 | 5篇 |
2012年 | 4篇 |
2011年 | 5篇 |
2010年 | 5篇 |
2009年 | 4篇 |
2008年 | 6篇 |
2007年 | 2篇 |
2006年 | 4篇 |
2005年 | 8篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2002年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1989年 | 1篇 |
排序方式: 共有171条查询结果,搜索用时 15 毫秒
1.
Medard M. Lumetta S. Liuyang Li 《Selected Areas in Communications, IEEE Journal on》2002,20(4):822-833
We describe an architecture for an optical local area network (LAN) or metropolitan area network (MAN) access. The architecture allows for bandwidth sharing within a wavelength and is robust to both link and node failures. The architecture can be utilized with an arbitrary, link-redundant mesh network (node-redundancy is necessary only to handle all node failures), and assumes neither the use of a star topology nor the ability to embed such a topology within the physical mesh. Reservation of, bandwidth is performed in a centralized fashion at a (replicated) head end node, simplifying the implementation of complex sharing policies relative to implementation on a distributed set of routers. Unlike a router, however, the head end does not take any action on individual packets and, in particular, does not buffer packets. The architecture thus avoids the difficulties of processing packets in the optical domain while allowing for packetized shared access of wavelengths. We describe the route construction scheme and prove its ability to recover from single link and single node failures, outline a flexible medium access protocol and discuss the implications for implementing specific policies, and propose a simple implementation of the recovery protocol in terms of state machines for per-link devices 相似文献
2.
X‐ray diffraction methods, DSC thermal analysis, and polarized light microscopy (PLM) were used to investigate the structural changes of nylon 66/clay nanocomposites. PA 66/clay nanocomposites were prepared by the method of melt intercalation. The results indicate that the addition of the intercalated organo‐montmorillonite (OMMT) can induce generation of the β‐form crystal of PA 66 and substantially affect the arrangement of molecules in the α‐form crystal, although the crystallinity scarcely changes. Also, the DSC results indicate that the addition of OMMT in the PA 66 matrix leads to increases of crystallization temperatures and the full width at half maximum (FWHM) of the exothermic peaks. Moreover, the viscosity factor is the main influence on FWHM of the exothermic peaks of PA 66/clay nanocomposites. The results of nonisothermal crystallization kinetics show that OMMT has the effect of heterogeneous nucleation and leads to the decrease of the size of the spherocrystal. The heterogeneous nucleation effects of OMMTs influence the mechanism of crystallization and the growth mode of PA 66 crystals. PLM photographs verify that the size of spherocrystal is decreased and visually confirm the theory of crystallization kinetics. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 756–763, 2005 相似文献
3.
4.
To handle the communication constraint imposed by the serial communication channel in networked control systems (NCSs), we discuss a popular dynamic scheduling protocol called Maximum-Error-First (MEF) protocol. An important parameter in this protocol is the maximum allowable transmission interval (MATI), which indicates the communication cost for the task of control. To take as large MATI as possible under the constraint of guaranteeing stability is one formalization of the design requirement to consume as little communication resources as possible with the control performances ensured. A method to estimate this parameter based on the ? p norm is suggested in this paper, which gives larger estimation than some methods do in the literature through simulation examples. 相似文献
5.
Experimental and numerical investigations on compressive properties of porous twisted wire materials
Wire diameter, sintering parameter, and porosity have great influences on porous structures and compressive properties of the stainless steel porous twisted wire materials with 30–92% porosities. Finer wires, higher sintering temperature, and longer sintering time will lead to narrower pore-size distributions, more compact porous structures, and stronger compressive yield strength. A random pore model and a twisted wire framework model are put forward to simulate the compressive process. The compressive deformation mechanism is a continuous densification process. The simulated and experimental stress-strain curves all exhibit elastic stage, plastic yield platform stage, and final densification stage. 相似文献
6.
7.
为探究并改善液黏离合器旋转动密封的泄漏特性,采用Tr1-6Kr-22A变速试验台开展其密封性能试验,对比分析操作参数和结构参数对各个泄漏通道泄漏量的影响规律。结果表明:操纵油泄漏量整体偏大,润滑油泄漏通道受压力影响最小;随着操纵油压力的增加,各泄漏通道泄漏量亦随之上升,但高压工况下泄漏量增势平缓;各泄漏通道泄漏量与转速存在正相关关系,但油压对密封泄漏量影响较转速更为明显;密封环带宽度对泄漏量影响较大,较宽的密封环带可有效降低密封总体泄漏量;采用较宽密封环带的试验工装各个通道泄漏量最小,且受操作参数影响较小,适用于压力波动较大的场合,而在转速波动较大时密封泄漏量出现阶跃特性。 相似文献
8.
针对应用视觉系统进行工件抓取时,工件相互遮挡导致识别工件不准确且抓取效率较低的问题,提出基于视觉的机械臂轨迹优化方法。由相机采集工件图像信息,通过标定机械臂坐标系、工件坐标系及相机坐标系,建立“手眼”坐标关系,基于点云数据对工件识别与定位;提出改进遗传-鲸鱼混合轨迹规划算法,以控制工件抓取过程。对机械臂的3个重要关节进行了运动仿真与实验测试。仿真结果显示:改进的遗传-鲸鱼混合算法收敛速度更快,搜索能力更强,优化后的抓取时间比基本遗传算法优化的抓取时间减少了2.3 s。实验结果表明:基于点云识别的机械臂抓取成功率达到93.75%,极大提高了抓取效率,验证了算法的有效性。 相似文献
9.
10.
Han Liuyang Zhang Saisai Zhang Bowen Zhang Bo Hari Bala Zhang Zhanying 《Journal of Porous Materials》2022,29(1):269-278
Journal of Porous Materials - Aimed at detecting methane (CH4) gas at low operating temperature, porous ZnO/SnO2 nanocomposites were constructed through a simple two-step method. Pure SnO2 with a... 相似文献