全文获取类型
收费全文 | 2662篇 |
免费 | 87篇 |
国内免费 | 17篇 |
专业分类
电工技术 | 131篇 |
综合类 | 3篇 |
化学工业 | 340篇 |
金属工艺 | 64篇 |
机械仪表 | 50篇 |
建筑科学 | 147篇 |
矿业工程 | 10篇 |
能源动力 | 87篇 |
轻工业 | 255篇 |
水利工程 | 18篇 |
石油天然气 | 13篇 |
武器工业 | 1篇 |
无线电 | 303篇 |
一般工业技术 | 321篇 |
冶金工业 | 297篇 |
原子能技术 | 17篇 |
自动化技术 | 709篇 |
出版年
2023年 | 12篇 |
2022年 | 28篇 |
2021年 | 43篇 |
2020年 | 24篇 |
2019年 | 43篇 |
2018年 | 85篇 |
2017年 | 59篇 |
2016年 | 52篇 |
2015年 | 46篇 |
2014年 | 90篇 |
2013年 | 197篇 |
2012年 | 171篇 |
2011年 | 137篇 |
2010年 | 172篇 |
2009年 | 180篇 |
2008年 | 208篇 |
2007年 | 131篇 |
2006年 | 157篇 |
2005年 | 140篇 |
2004年 | 73篇 |
2003年 | 97篇 |
2002年 | 83篇 |
2001年 | 42篇 |
2000年 | 51篇 |
1999年 | 54篇 |
1998年 | 34篇 |
1997年 | 34篇 |
1996年 | 30篇 |
1995年 | 31篇 |
1994年 | 21篇 |
1993年 | 23篇 |
1992年 | 24篇 |
1991年 | 17篇 |
1990年 | 19篇 |
1989年 | 20篇 |
1988年 | 13篇 |
1987年 | 10篇 |
1986年 | 16篇 |
1985年 | 10篇 |
1984年 | 13篇 |
1983年 | 15篇 |
1982年 | 8篇 |
1981年 | 12篇 |
1980年 | 10篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1974年 | 3篇 |
排序方式: 共有2766条查询结果,搜索用时 0 毫秒
41.
42.
Private mobile radio (PMR) services are widely used in business and emergency applications. Typically, these services use the UHF 2 band (450–470 MHz). In order to comply with continental practice, the provision of these services in the UK is to be realigned and a new operational assignment will be generated in 2005. However, this can only be achieved with an appropriate model and the ability to make assignments for large regional networks. The purpose of this paper is to bring our experiences of this problem to the wireless arena. We explain the model used when making assignments for UK PMR networks and identify existing techniques and theory which are appropriate for this problem. We demonstrate that improved assignments and estimates of spectral requirements for large operational services can be found. 相似文献
43.
Davidson BS Madigan ML Southward SC Nussbaum MA 《IEEE transactions on bio-medical engineering》2011,58(6):1546-1554
This study investigated the effects of aging and localized muscle fatigue on the neural control of upright stance during small postural perturbations. Sixteen young (aged 18-24 years) and 16 older (aged 55-74 years) participants were exposed to small magnitude, anteriorly-directed postural perturbations before and after fatiguing exercises (lumbar extensors and ankle plantar flexors). A single degree of freedom model of the human body was used to simulate recovery kinematics following the perturbations. Central to the model was a simulated neural controller that multiplied time-delayed kinematics by invariant feedback gains. Feedback gains and time delay were optimized for each participant based on measured kinematics, and a novel delay margin analysis was performed to assess system robustness. A 10.9% longer effective time delay ( p = 0.010) was found among the older group, who also showed a greater reliance upon velocity feedback information (31.1% higher differential gain, p = 0.001) to control upright stance. Based on delay margins, older participants adopted a more robust control scheme to accommodate the small perturbations, potentially compensating for longer time delays or degraded sensory feedback. No fatigue-induced changes in neural controller gains, time delay, or delay margin were found in either age group, indicating that integration of this feedback information was not altered by muscle fatigue. The sensitivity of this approach to changes with fatigue may have been limited by model simplifications. 相似文献
44.
Steve M. Rohde 《International Journal of Mechanical Sciences》1976,18(2):95-101
The descent of a tread element of a tire rolling on a pavement on which a thin viscous fluid film is present is modeled. The tread element is assumed to be flat or curved and the pavement is assumed to possess a microtexture. Asymptotic results for the load supported by the tread element and the descent time are derived for different texture patterns. It is shown that the texture pattern as well as amplitude can significantly change the performance from that predicted by a smooth pavement assumption. 相似文献
45.
Steve Kolokowsky 《电子测试》2006,(1):49-51
PCI Express(PCIe)是目前最新的高速串行连接技术之一,短期内将无所不在.由于它继承了全球相当普遍的PCI数据总线,因此这项技术具有快速带动PC及外围配备市场的威力和重大意义,因而受到相当大的重视.因各式各样的需求所致,PCIe足迹已遍布各种应用系统和市场中,未来还会出现在哪些应用上呢?本文将与您共同探讨一二. 相似文献
46.
Steve Sunter 《电子设计技术》2011,18(2):35-38
实用模拟BIST有潜力降低IC测试成本,以及产品上市时间。20多年来,研究人员和半导体制造商一直在试图开发一种针对混合信号IC的实用模拟BIST(内置自检)。这种技术能够用数字测试仪作混合信号IC测试,以及简化的多址测试,从而能减少IC测试成本,以及IC上市时间。其它预期优点还有更快的测试开发,以及系统上的自检等。 相似文献
47.
数字版权管理(DRM)与内容保护需要运用特别的通讯协议,在微软的DRM引擎Janus中,底层采用的技术为MTP.MTP可被视为取代传统MSC的方案,能传送受保护的内容.图1是传统海量存储装置应用以及相关的软件堆栈. 相似文献
48.
Steve Subar 《通讯世界》2011,(1):46-47
在应对全球金融危机的大环境下,移动及无线行业在2010年经历了飞速发展与重塑的过程。全球手机数量飙升至13亿部(根据诺基亚数据),而其中20%为智能手机(根据Gartner研究)。 相似文献
49.
Gunhyu Bae Yoo Sang Jeon Min Jun Ko Yuri Kim Seong-Beom Han Ramar Thangam Wonsik Kim Hee Joon Jung Sungkyu Lee Hyojun Choi Sunhong Min Hyunsik Hong Sangwoo Park Seong Yeol Kim Kapil D. Patel Na Li Jeong Eun Shin Bum Chul Park Hyeon Su Park Jun Hwan Moon Yu Jin Kim Uday Kumar Sukumar Jae-Jun Song Soo Young Kim Seung-Ho Yu Yun Chan Kang Steve Park Seung Min Han Dong-Hwee Kim Ki-Bum Lee Qiang Wei Liming Bian Ramasamy Paulmurugan Young Keun Kim Heemin Kang 《Advanced functional materials》2021,31(37):2103409
Developing materials with the capability of changing their innate features can help to unravel direct interactions between cells and ligand-displaying features. This study demonstrates the grafting of magnetic nanohelices displaying cell-adhesive Arg-Gly-Asp (RGD) ligand partly to a material surface. These enable nanoscale control of rapid winding (“W”) and unwinding (“UW”) of their nongrafted portion, such as directional changes in nanohelix unwinding (lower, middle, and upper directions) by changing the position of a permanent magnet while keeping the ligand-conjugated nanohelix surface area constant. The unwinding (“UW”) setting cytocompatibility facilitates direct integrin recruitment onto the ligand-conjugated nanohelix to mediate the development of paxillin adhesion assemblies of macrophages that stimulate M2 polarization using glass and silicon substrates for in vitro and in vivo settings, respectively, at a single cell level. Real time and in vivo imaging are demonstrated that nanohelices exhibit reversible unwinding, winding, and unwinding settings, which modulate time-resolved adhesion and polarization of macrophages. It is envisaged that this remote, reversible, and cytocompatible control can help to elucidate molecular-level cell–material interactions that modulate regenerative/anti-inflammatory immune responses to implants. 相似文献
50.
Gregorio Martinez Perez Antonio F. Gomez Skarmeta Steve Zeber Joe Spagnolo Tim Symchych 《Communications Magazine, IEEE》2006,44(11):58-64
This article reports the latest results of an R&D effort to develop a prototype implementation of a dynamic policy-based network management (PBNM) system that can be used to configure and manage a secure network for a coalition environment across an unsecured wide area network. The prototype, based on a distributed architecture, includes capabilities for policy creation and management, dynamic policy negotiation, and dynamic policy provisioning. The policy negotiation facilitates the rapid deployment of a coalition network while the dynamic policy provisioning automates the configuration and management of network services including firewalls, virtual private network connections, routing, quality of service (QoS), and domain name services. Such a PBNM system enhances an organization's ability to react to network incidents identified by a network situational awareness assessment. Although the focus of the current research is a military coalition environment, the system can be used in any distributed enterprise or collaborative environment 相似文献