全文获取类型
收费全文 | 1425篇 |
免费 | 153篇 |
国内免费 | 176篇 |
专业分类
电工技术 | 30篇 |
综合类 | 51篇 |
化学工业 | 56篇 |
金属工艺 | 40篇 |
机械仪表 | 58篇 |
建筑科学 | 86篇 |
矿业工程 | 5篇 |
能源动力 | 7篇 |
轻工业 | 25篇 |
水利工程 | 4篇 |
石油天然气 | 5篇 |
武器工业 | 7篇 |
无线电 | 330篇 |
一般工业技术 | 70篇 |
冶金工业 | 18篇 |
原子能技术 | 13篇 |
自动化技术 | 949篇 |
出版年
2024年 | 6篇 |
2023年 | 37篇 |
2022年 | 60篇 |
2021年 | 96篇 |
2020年 | 55篇 |
2019年 | 58篇 |
2018年 | 48篇 |
2017年 | 27篇 |
2016年 | 44篇 |
2015年 | 42篇 |
2014年 | 74篇 |
2013年 | 91篇 |
2012年 | 79篇 |
2011年 | 94篇 |
2010年 | 64篇 |
2009年 | 82篇 |
2008年 | 68篇 |
2007年 | 94篇 |
2006年 | 72篇 |
2005年 | 85篇 |
2004年 | 71篇 |
2003年 | 64篇 |
2002年 | 37篇 |
2001年 | 29篇 |
2000年 | 47篇 |
1999年 | 29篇 |
1998年 | 36篇 |
1997年 | 18篇 |
1996年 | 27篇 |
1995年 | 21篇 |
1994年 | 24篇 |
1993年 | 21篇 |
1992年 | 12篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1976年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有1754条查询结果,搜索用时 15 毫秒
81.
时效和重新训练对Cu-Zn-Al合金组织与记忆性能的影响 总被引:2,自引:0,他引:2
用约束训练法对时效后的Cu-Zn-Al形状记忆合金进行了重新训练。结果表明,在未发生贝氏体转变的条件下,时效所导致的记忆衰减可以通过重新训练予以改善。透射电镜分析指出,重新训练后,发生了马氏体的再取向,因时效而导致的细条状、台阶状变体大部分消除,且变体间的结合方式变为自协作性良好的孪晶关系,从而改善了合金的记忆性能。 相似文献
82.
一种实用电网谐波监测及数据远传系统的设计与实现 总被引:2,自引:0,他引:2
介绍了一种先进的谐波监测和数据传输系统,系统能同时监测系统三相电压和电流的谐波水平,并通过公用的电话网,实现谐波数据的远距离传输,系统下位单位机存储容量大,达1.5M,采用同步锁相环控制,避免了频谱泄漏的产生,使用FAFT算法分析采样数据,不仅速度快精度高,而且抗混叠。上位机采用VB和Access数据库共同完成对数据的通信、分析处理,功能全,人机界面友好。 相似文献
83.
Robert A. Frank Melinda BreartonKonstantin Rybalsky Trevor CessnaSteven Howe 《Food quality and preference》2011,22(1):173-178
The relationship between flavor naming and recognition memory was evaluated in groups of children and young adults who either self-generated flavor names or chose flavor names from a list of four alternatives. The adults were more successful at naming and remembering the flavors, with the age differences in naming performance tending to be larger than differences in memory performance. Differences in recognition memory among the age groups were modest, ranging from 3% to 12%. Providing flavor labels improved naming accuracy, but not naming consistency or memory for younger children (4-7 years old). Labels improved naming accuracy and consistency for the older children (8-11 years old), and showed a trend toward improving memory. Labels improved naming accuracy, consistency and recognition memory in adults. Consistent naming was a powerful predictor of recognition memory for each age group and test condition. Consistently named flavors were remembered correctly on 88% of the trials while inconsistently named flavors showed no evidence of memory. It was concluded that flavor recognition memory and naming consistency were both rooted in successfully matching flavor percepts to a multi-dimensional flavor representation that includes semantic information. 相似文献
84.
Resistive switching memory characteristics of Ge/GeOx nanowires and evidence of oxygen ion migration
Amit Prakash Siddheswar Maikap Sheikh Ziaur Rahaman Sandip Majumdar Santanu Manna Samit K Ray 《Nanoscale research letters》2013,8(1):220
The resistive switching memory of Ge nanowires (NWs) in an IrOx/Al2O3/Ge NWs/SiO2/p-Si structure is investigated. Ge NWs with an average diameter of approximately 100 nm are grown by the vapor–liquid-solid technique. The core-shell structure of the Ge/GeOx NWs is confirmed by both scanning electron microscopy and high-resolution transmission electron microscopy. Defects in the Ge/GeOx NWs are observed by X-ray photoelectron spectroscopy. Broad photoluminescence spectra from 10 to 300 K are observed because of defects in the Ge/GeOx NWs, which are also useful for nanoscale resistive switching memory. The resistive switching mechanism in an IrOx/GeOx/W structure involves migration of oxygen ions under external bias, which is also confirmed by real-time observation of the surface of the device. The porous IrOx top electrode readily allows the evolved O2 gas to escape from the device. The annealed device has a low operating voltage (<4 V), low RESET current (approximately 22 μA), large resistance ratio (>103), long pulse read endurance of >105 cycles, and good data retention of >104 s. Its performance is better than that of the as-deposited device because the GeOx film in the annealed device contains more oxygen vacancies. Under SET operation, Ge/GeOx nanofilaments (or NWs) form in the GeOx film. The diameter of the conducting nanofilament is approximately 40 nm, which is calculated using a new method. 相似文献
85.
Remy Chevallier Emmanuelle Encrenaz-Tiphene Laurent Fribourg Weiwen Xu 《Formal Methods in System Design》2009,34(1):59-81
Using a variant of Clariso-Cortadella’s parametric method for verifying asynchronous circuits, we analyse some crucial timing
behaviors of the architecture of SPSMALL memory, a commercial product of STMicroelectronics. Using the model of parametric
timed automata and model checker HYTECH, we formally derive a set of linear constraints that ensure the correctness of the
response times of the memory. We are also able to infer the constraints characterizing the optimal setup timings of input
signals. We have checked, for two different implementations of this architecture, that the values given by our model match
remarkably with the values obtained by the designer through electrical simulation.
Partially supported by project MEDEA+ Blueberries.
A preliminary version appeared in the Proceedings of 4th International Conference on Formal Modelling and Analysis of Timed
Systems (FORMATS’06), Sept. 2006. 相似文献
86.
Process models and their applications have gradually become an integral part of the design, maintenance and automation of modern buildings. The following state machine model outlines a new approach in this area. The heating power described by the model is based on the recent inputs as well as on the past inputs and outputs of the process, thus also representing the states of the system. Identifying the model means collecting, assorting and storing observations, but also effectively utilizing their inherent relationships and nearest neighbours. The last aspect enables to create a uniform set of data, which forms the characteristic, dynamic behaviour of the HVAC process. The state machine model is non-parametric and needs no sophisticated algorithm for identification. It is therefore suitable for small microprocessor devices equipped with a larger memory capacity. The first test runs, performed in a simulated environment, were encouraging and showed good prediction capability. 相似文献
87.
A nonvolatile organic field-effect transistor (OFET) with a polymeric electret as gate insulator and spun cast film of lead phthalocyanine (PbPc) as semiconductor channel is reported. Hysteresis induced by gate–bias stress was exploited to study nonvolatile memory effects. The observation of the hysteresis and memory window is proposed to originate from charge storage in the polymeric electret. The on state retention time for the OFET memory device is more than 5 h and the device can reproduce continuous write–read–erase–read switching cycles. 相似文献
88.
汪辰 《青岛大学学报(工程技术版)》1994,(1)
论述了Intel80386,80486,PentiumCPU的平面内存模式,及在Windows3.1操作系统下实现的方法。 相似文献
89.
从计算机用户的角度出发,说明如何在DOS操作系统下更好地使用更多的内存资源,并给出了有关扩充内存的高级编程方法。 相似文献
90.
Bat Baoxing 《长春理工大学学报(自然科学版)》1994,(4)
本文叙述了在80286\386\486微机系统中如何运用超越640KB基本内存的主存储器扩增技术,并从实用角度介绍了扩充存储器的“XMS”规则及其管理程序和扩展存储器的“UMB”映射以及EMM386驱动程序的使用方法。 相似文献