全文获取类型
收费全文 | 265篇 |
免费 | 19篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 49篇 |
金属工艺 | 21篇 |
机械仪表 | 12篇 |
建筑科学 | 14篇 |
能源动力 | 20篇 |
轻工业 | 26篇 |
水利工程 | 2篇 |
石油天然气 | 2篇 |
无线电 | 14篇 |
一般工业技术 | 60篇 |
冶金工业 | 15篇 |
原子能技术 | 1篇 |
自动化技术 | 47篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 8篇 |
2020年 | 6篇 |
2019年 | 9篇 |
2018年 | 6篇 |
2017年 | 13篇 |
2016年 | 13篇 |
2015年 | 13篇 |
2014年 | 16篇 |
2013年 | 28篇 |
2012年 | 18篇 |
2011年 | 18篇 |
2010年 | 17篇 |
2009年 | 23篇 |
2008年 | 20篇 |
2007年 | 8篇 |
2006年 | 13篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 1篇 |
2002年 | 3篇 |
2001年 | 6篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有284条查询结果,搜索用时 15 毫秒
71.
Virtual CNC system. Part I. System architecture 总被引:5,自引:1,他引:4
Chi-Ho Yeung Yusuf Altintas Kaan Erkorkmaz 《International Journal of Machine Tools and Manufacture》2006,46(10):1107-1123
The paper presents a comprehensive virtual simulation model of a realistic and modular CNC system. The Virtual CNC architecture represents an actual CNC, but with modular feed drives, sensors, motors, and amplifiers. The CNC software library includes a variety of trajectory interpolation and axis control laws. Constant, trapezoidal and cubic acceleration profiles can be selected as a trajectory generation module. The control laws can be selected ranging from a simple PID to complex Pole Placement, Generalized Predictive Control or Sliding Mode Controller with friction compensation. When the Virtual CNC is assembled, its performance can be tested using frequency and time domain response analyses, which are automated. The Virtual CNC includes both analytical tuning methods for linear controllers, as well as Fuzzy Logic based expert auto-tuning system for Adaptive Sliding Mode Control. The paper includes detailed experimental verification of the Virtual CNC. 相似文献
72.
The purpose of this study is to experimentally analyze the performance and the pollutant emissions of a four-stroke spark-ignition engine operating on natural gas–hydrogen blends of 0%, 10%, 20% and 30% at full load and 65% load for different excess air ratios. This present work was carried out on a Ford engine. This is a four-stroke cycle four-cylinder spark-ignition engine with a bore × stroke of 80.6 × 88 mm and a compression ratio of 10:1. Experiments were made at a constant engine speed of 2000 rpm. CO, CO2 and HC emission values and cylinder pressures were measured. The results showed that while the excess air ratio increases, CO and CO2 emission values decrease. 相似文献
73.
74.
Iranian Polymer Journal - This study presents the tribological behavior of epoxy matrix composites containing two different fillers. The composites contain fillers with different particle sizes... 相似文献
75.
Salep samples obtained from 10 different Orchidaceae spp., namely Dactylorhiza osmanica var. osmanica, Ophrys mammosa, Orchis anatolica, Orchis coriophora, Orchis italica, Orchis morio, Orchis palustris, Orchis simia, Orchis tridentata and Serapias vomeracea ssp. orientalis, in Anatolia, were analyzed for moisture, glucomannan, starch, protein, ash contents, pH and viscosity values. Depending on the species, the samples showed statistically significant differences in glucomannan, starch and viscosity values. It was observed that the salep samples obtained from the tubers of O. italica, O. morio, O. anatolica and O. tridentata and S. vomeracea ssp. orientalis, respectively, had higher glucomannan contents and viscosities. To ensure a supply of high-quality salep, the uncontrolled collection of tubers from the wild, especially the species O. italica, O. morio and O. anatolica, should be prevented, and research into methods of cultivation should be carried out. 相似文献
76.
Jonathan Mumm Bilge Mutlu 《Computers in human behavior》2011,27(5):1643-1650
The present study draws on theories of attribution, social comparison, and social facilitation to investigate how computers might use principles of motivation and persuasion to provide user feedback. In an online experiment, 192 participants performed a speed-reading task. The independent variables included whether or not the verbal feedback from the computer involved praise, whether the objective feedback showed that the participants were performing better or worse from their peers, and whether or not the feedback was presented by an on-screen agent. The main dependent variables included a subjective measure of participants’ intrinsic motivation and an objective measure of their task persistence. Results showed that providing participants with praise or comparative information on others’ performance improved intrinsic motivation. When praised, participants whose performances were comparatively low persisted in the task longer than those whose performances were comparatively high did. Additionally, the mere presence of an embodied agent on the screen increased participants’ motivation. Together, these results indicate that praise and social comparison can serve as effective forms of motivational feedback and that humanlike embodiment further improves user motivation. 相似文献
77.
78.
This paper introduces two spatial methods in order to embed watermark data into fingerprint images, without corrupting their features. The first method inserts watermark data after feature extraction, thus preventing watermarking of regions used for fingerprint classification. The method utilizes an image adaptive strength adjustment technique which results in watermarks with low visibility. The second method introduces a feature adaptive watermarking technique for fingerprints, thus applicable before feature extraction. For both of the methods, decoding does not require original fingerprint image. Unlike most of the published spatial watermarking methods, the proposed methods provide high decoding accuracy for fingerprint images. High data hiding and decoding performance for color images is also observed. 相似文献
79.
Automatic detection of facial expressions attracts great attention due to its potential applications in human–computer interaction as well as in human facial behavior research. Most of the research has so far been performed in 2D. However, as the limitations of 2D data are understood, expression analysis research is being pursued in 3D face modality. 3D can capture true facial surface data and is less disturbed by illumination and head pose. At this junction we have conducted a comparative evaluation of 3D and 2D face modalities. We have investigated extensively 25 action units (AU) defined in the Facial Action Coding System. For fairness we map facial surface geometry into 2D and apply totally data-driven techniques in order to avoid biases due to design. We have demonstrated that overall 3D data performs better, especially for lower face AUs and that there is room for improvement by fusion of 2D and 3D modalities. Our study involves the determination of the best feature set from 2D and 3D modalities and of the most effective classifier, both from several alternatives. Our detailed analysis puts into evidence the merits and some shortcomings of 3D modality over 2D in classifying facial expressions from single images. 相似文献
80.
Utku Seven Tunc Akbas Kaan Can Fidan Kemalettin Erbatur 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2012,16(11):1959-1976
The two-legged humanoid structure has advantages for an assistive robot in the human living and working environment. However, the control of bipedal walk is a challenge. Walking performance on solely even floor is not satisfactory. This paper presents a study on bipedal walk on inclined planes with changing slopes. A Zero Moment Point (ZMP) based gait synthesis technique is employed. The pitch angle reference for the foot sole plane—as expressed in a coordinate frame attached at the robot body—is adjusted online by a fuzzy logic system to adapt to different walking surface slopes. Ankle pitch torques and the average value of the body pitch angle, computed over a history of a predetermined number of sampling instants, are used as the inputs to this system. The proposed control method is tested via walking experiments with the 29 degrees-of-freedom human-sized full-body humanoid robot SURALP (Sabanci University Robotics Research Laboratory Platform) on even floor and inclined planes with different slopes. The results indicate that the approach presented is successful in enabling the robot to stably enter, ascend and leave inclined planes with 15?% (8.5°) grade. This, to the best knowledge of the authors, constitutes the steepest ascend reported to date, with a transition from even floor, by a blind walking biped robot. 相似文献