全文获取类型
收费全文 | 611篇 |
免费 | 34篇 |
国内免费 | 3篇 |
学科分类
工业技术 | 648篇 |
出版年
2024年 | 2篇 |
2023年 | 12篇 |
2022年 | 14篇 |
2021年 | 24篇 |
2020年 | 17篇 |
2019年 | 19篇 |
2018年 | 23篇 |
2017年 | 22篇 |
2016年 | 27篇 |
2015年 | 25篇 |
2014年 | 26篇 |
2013年 | 46篇 |
2012年 | 36篇 |
2011年 | 43篇 |
2010年 | 22篇 |
2009年 | 27篇 |
2008年 | 28篇 |
2007年 | 17篇 |
2006年 | 30篇 |
2005年 | 16篇 |
2004年 | 18篇 |
2003年 | 9篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 8篇 |
1998年 | 16篇 |
1997年 | 3篇 |
1996年 | 18篇 |
1995年 | 11篇 |
1994年 | 3篇 |
1993年 | 8篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1980年 | 2篇 |
1973年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有648条查询结果,搜索用时 15 毫秒
11.
Maher El��Arbi Mohamed Koubaa Maha Charfeddine Chokri Ben Amar 《Multimedia Tools and Applications》2011,55(3):579-600
In this paper, we propose a video watermarking algorithm which embeds different parts of a single watermark into different shots of a video under the wavelet domain. Based on a Motion Activity Analysis, different regions of the original video are separated into perceptually distinct categories according to motion information and region complexity. Thus, the localizations of the watermark are adjusted adaptively in accordance with the human visual system and signal characteristics, which makes them perceptually invisible and less vulnerable to automated removal. In addition, contrary to traditional methods where the watermark remains at a fixed position on the screen, the watermark moves along with moving objects and thus motion artefacts can be avoid. The multi-frame based extraction strategy ensures that the watermark can be correctly recovered from a very short segment of video. Individual frames extracted from the video also contain watermark information. Experimental results show that the inserted watermark is not only less perceptible but also robust against common video processing attacks. 相似文献
12.
Chaabouni Souad Benois-pineau Jenny Tison François Ben Amar Chokri Zemmari Akka 《Multimedia Tools and Applications》2017,76(21):22527-22546
Multimedia Tools and Applications - Studies of visual attention of patients with Dementia such as Parkinson’s Disease Dementia and Alzheimer Disease is a promising way for non-invasive... 相似文献
13.
Rigaud V. Coste-Maniere E. Aldon M.J. Probert P. Perrier M. Rives P. Simon D. Lang D. Kiener J. Casal A. Amar J. Dauchez P. Chantler M. 《Robotics & Automation Magazine, IEEE》1998,5(1):25-35
The main goal of the UNION ESPRIT Basic Research Action is to develop methods for increasing the autonomy and intelligence of underwater remotely operated vehicles (ROVs). The project focuses mainly on the development of coordinated control and sensing strategies for combined manipulator and vehicle systems. Both fundamental theories and methods for the design of these heterogeneous systems are investigated. A complex canonical mission in the field of offshore inspection maintenance and repair tasks was chosen as an integration guideline of all the results 相似文献
14.
Eric Sultan Arezki Boudaoud Martine Ben Amar 《Journal of Engineering Mathematics》2004,50(2-3):209-222
The stability of evaporating very thin films of a polar liquid is investigated. The microscopic interaction with the substrate
and capillarity are taken into account in a lubrication equation. The stability of a flat interface is studied when evaporation
is limited by the diffusion of the vapour in the gas phase. The evaporation rate is computed and evaporation is shown to be
stabilizing. A stability phase diagram is obtained. A weakly nonlinear analysis leads to a film-thickness amplitude equation
that is non local in space. Physical consequences of the results are eventually discussed. 相似文献
15.
Md. Mamunur Rashid Muhammad Amar Iqbal Gondal Joarder Kamruzzaman 《Applied Intelligence》2016,45(3):638-651
Bearings play a crucial role in rotational machines and their failure is one of the foremost causes of breakdowns in rotary machinery. Their functionality is directly relevant to the operational performance, service life and efficiency of these machines. Therefore, bearing fault identification is very significant. The accuracy of fault or anomaly detection by the current techniques is not adequate. We propose a data mining-based framework for fault identification and anomaly detection from machine vibration data. In this framework, to capture the useful knowledge from the vibration data stream (VDS), we first pre-process the data using Fast Fourier Transform (FFT) to extract the frequency signature and then build a compact tree called SAFP-tree (sliding window associated frequency pattern tree), and propose a mining algorithm called SAFP. Our SAFP algorithm can mine associated frequency patterns (i.e., fault frequency signatures) in the current window of VDS and use them to identify faults in the bearing data. Finally, SAFP is further enhanced to SAFP-AD for anomaly detection by determining the normal behavior measure (NBM) from the extracted frequency patterns. The results show that our technique is very efficient in identifying faults and detecting anomalies over VDS and can be used for remote machine health diagnosis. 相似文献
16.
J. M. Martínez H. Amarís J. Sanz 《Electrical Engineering (Archiv fur Elektrotechnik)》2006,88(5):403-409
The use of conventional low voltage induction motors fed by pulse width modulated (PWM) inverters has begun to present important problems. These waveforms consist of steep-fronted pulses having very short rise times (about 100 ns in modern IGBT bridges) and high frequency repetition rates (up to 20 kHz) whose immediate consequences are additional electrical stresses in an induction motors insulation system. In this paper a frequency domain model for the analysis and characterization of the internal voltage distribution in random wound coils is presented. The model allows voltage prediction in time domain when an inverse fast Fourier transform (FFT) transformation is performed, and requires only a few frequency domain impedance measurements. This methodology will be useful for accurately predicting the voltage distribution in motor windings during the design stage, and reducing the risk of premature failure in motor insulation. Experimental and theoretical results are presented and compared and model effectiveness using different approximations is studied. 相似文献
17.
The 24-H Knowledge Factory facilitates collaboration between geographically and temporally distributed teams. The teams themselves
form a strategic partnership whose joint efforts contribute to the completion of a project. Project-related tasks are likewise
distributed, allowing tasks to be completed on a continuous basis, regardless of the constraints of any one team’s working
hours. However, distributing a single task between multiple teams necessitates a handoff process, where one team’s development
efforts and task planning are communicated from one team ending their shift to the next that will continue the effort. Data
management is, therefore, critical to the success of this business model. Efficiency in data management is achieved through
a strategic leveraging of key tools, models, and concepts. 相似文献
18.
Study of effect of old corrugated cardboard in properties of polypropylene composites: Study of mechanical properties,thermal behavior,and morphological properties 下载免费PDF全文
Nacera Chibani Hocine Djidjelli Alain Dufresne Amar Boukerrou Samira Nedjma 《乙烯基与添加剂工艺杂志》2016,22(3):231-238
The investigation of the economical use of lignocellulose waste, which is one of the environmental problems facing nations, is ongoing. In this study, waste cardboard paper fiber reinforcing polypropylene (PP) composites was developed. In order to modify the PP matrix maleated PP (MA‐g‐PP) a 5 wt% and a grafting rate of 1 and 2 wt% was used as a compatibilizer. The effects of fiber and compatibilizer content as well as graft content are evaluated by mechanical, thermal property measurements, and scanning electron microscopy (SEM). The compatibilizer improved all mechanical properties significantly. Thus, the tensile strength of MA‐g‐PP‐containing composites increases compared to PP/cardboard composites paper content increases. However, the tensile modulus of a PP‐based composite increases with an increase in paper fiber with the compatibilizer having little effect. SEM revealed that the addition of MA‐g‐PP generates strong interactions between a PP matrix and paper fibers. However, the addition of the MA‐g‐PP compatibilizing agent gives a significant improvement on the crystallization of the composites, whereas the compatibilized PP/old corrugated cardboard (OCC) composites have higher crystallinity (Xc) than uncompatibilized PP/OCC composites. The MA‐g‐PP also diminished the water absorption in the composites. J. VINYL ADDIT. TECHNOL., 22:231–238, 2016. © 2014 Society of Plastics Engineers 相似文献
19.
Unidirectional (UD) hybrid laminates based on glass fibers (GF) and high performance polyethylene fibers (PEF) were prepared with partially polymerized methyl methacrylate (MMA) at room temperature followed by heating at 55°C (well below the softening point of PEF) for 2 h. Izod impact strength of the composites was then measured. An interesting observation of the study was the change in impact strength that was largely dependent on the position of GF and PEF ply/plies present within the hybrid laminates. When the ply/plies of PEF were at the impacted surface, the impact strength showed a higher value than that of the case when GF ply/plies were at the impacted surface of the hybrid laminates. © 1996 John Wiley & Sons, Inc. 相似文献
20.
Claire Mangeney Zhengran Qin Si Amar Dahoumane Alain Adenier Frédéric Herbst Jean-Paul Boudou Jean Pinson Mohamed M. Chehimi 《Diamond and Related Materials》2008,17(11):1881-1887
We report a novel and very handful strategy for the functionalization of diamond nanoparticles (NDs), based on the ultrasound-assisted grafting of aryl groups from the electroless reduction of diazonium salts. For this study, 4-nitrobenzenediazonium salt was used as a model molecule and the reaction was investigated in neutral and acidic aqueous media. Spectroscopic evidence for the successful attachment of aryl groups to nanodiamonds (NDs) was given by IR and XPS which clearly detect characteristic NO2 peaks. Moreover, the absence of any peaks from the +N≡N group in the IR spectra is a clear indication of the chemical reduction of the parent diazonium salt at the surface of NDs. This spontaneous chemical modification of NDs by aryl diazonium salts was confined to the surface of the ND particles; indeed, XRD measurements have shown that the crystalline structure of the bulk of the particles was unaffected. It opens up new possibilities towards the control of the surface chemical composition of NDs using simple protocols operated in very soft conditions, i.e. in water at room temperature. It shows conclusively that the chemistry toolbox of experts interested in nanodiamonds should contain aryl diazonium salts, given their versatility in forming active platforms. 相似文献