全文获取类型
收费全文 | 1024篇 |
免费 | 49篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 12篇 |
化学工业 | 217篇 |
金属工艺 | 23篇 |
机械仪表 | 52篇 |
建筑科学 | 39篇 |
矿业工程 | 1篇 |
能源动力 | 41篇 |
轻工业 | 49篇 |
水利工程 | 18篇 |
石油天然气 | 9篇 |
无线电 | 165篇 |
一般工业技术 | 156篇 |
冶金工业 | 84篇 |
原子能技术 | 6篇 |
自动化技术 | 204篇 |
出版年
2024年 | 1篇 |
2023年 | 21篇 |
2022年 | 29篇 |
2021年 | 45篇 |
2020年 | 36篇 |
2019年 | 43篇 |
2018年 | 50篇 |
2017年 | 33篇 |
2016年 | 63篇 |
2015年 | 28篇 |
2014年 | 37篇 |
2013年 | 66篇 |
2012年 | 72篇 |
2011年 | 68篇 |
2010年 | 43篇 |
2009年 | 48篇 |
2008年 | 43篇 |
2007年 | 40篇 |
2006年 | 34篇 |
2005年 | 26篇 |
2004年 | 22篇 |
2003年 | 21篇 |
2002年 | 18篇 |
2001年 | 15篇 |
2000年 | 10篇 |
1999年 | 14篇 |
1998年 | 27篇 |
1997年 | 26篇 |
1996年 | 10篇 |
1995年 | 14篇 |
1994年 | 10篇 |
1993年 | 6篇 |
1992年 | 9篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1974年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有1076条查询结果,搜索用时 24 毫秒
91.
Vo-Gia Loc Se-goh Roh Ig Mo Koo Duc Trong Tran Ho Moon Kim Hyungpil Moon Hyouk Ryeol Choi 《Robotics and Autonomous Systems》2010,58(5):666-675
In this paper, a general study on improving adaptability of quadruped walking and climbing robot in complex environment is presented. First, a sensing system composed of range and gyroscope sensors in a novel arrangement is developed. By combining the sensing signals and the internal state of the robot, the surface geometry of the environment is sufficiently reconstructed in real-time. Secondly, a planning algorithm for the robot to overcome the reconstructed environment is conducted. Based on the reshaped surface, the planning algorithm not only provides the exact body trajectory and foot positions but also the adaptability of the robot in a specific environment. A method to improve the adaptability of the walking and climbing robot is also introduced. Thanks to the adherent ability of the robot, the center of gravity of the robot is allowed to move outside the support polygon to increase the reach-ability of the next swing leg. Finally, the effectiveness of the proposed approach is verified by the performances of the experiments in complex environments using a quadruped walking and climbing robot named MRWALLSPECT IV. 相似文献
92.
Multi-Camera Human Activity Monitoring 总被引:1,自引:0,他引:1
Loren Fiore Duc Fehr Robot Bodor Andrew Drenner Guruprasad Somasundaram Nikolaos Papanikolopoulos 《Journal of Intelligent and Robotic Systems》2008,52(1):5-43
With the proliferation of security cameras, the approach taken to monitoring and placement of these cameras is critical. This
paper presents original work in the area of multiple camera human activity monitoring. First, a system is presented that tracks
pedestrians across a scene of interest and recognizes a set of human activities. Next, a framework is developed for the placement
of multiple cameras to observe a scene. This framework was originally used in a limited X, Y, pan formulation but is extended to include height (Z) and tilt. Finally, an active dual-camera system for task recognition at multiple resolutions is developed and tested. All
of these systems are tested under real-world conditions, and are shown to produce usable results.
This work has been supported by the NSF through grants #IIS-0219863, #CNS-0224363, #CNS-0324864, #IIP-0443945, #CNS-0420836,
#IIP-0726109, and #CNS-0708344. 相似文献
93.
Radisic V. Samoska L. Micovic M. Ming Hu Janke P. Ngo C. Nguyen L. 《Microwave and Wireless Components Letters, IEEE》2001,11(8):325-327
In this letter a monolithic voltage-controlled oscillator (VCO) operating in the 77.5-83.5 GHz range is presented. InP HEMTs are used for both the active device and varactor. The VCO demonstrated a tuning range of 6 GHz and an output power better than 12.5 dBm in the entire tuning range 相似文献
94.
Pham Duc Chinh 《Canadian Metallurgical Quarterly》2001,127(9):955-958
A kinematic method is developed to determine the shakedown limits of elastic-perfectly plastic steel-reinforced concrete beams under quasi-static and dynamic cyclic loads. This procedure, like the respective kinematic approach of plastic limit analysis, is visual and easy to use in engineering applications. The load parameters (amplitudes, frequency) versus yield moment diagrams, constructed from possible collapse modes, should assist in choosing the reinforcement scheme and amounts of reinforcement to meet the load bearing requirements for the structures. 相似文献
95.
Xu S. Ngo K. D. T. Nishida T. Chung G.-B. Sharma A. 《Power Electronics, IEEE Transactions on》2007,22(1):63-68
A pulsed-resonant ac-dc converter and an integrated circuit (IC) controller have been designed, fabricated, and tested for harvesting energy from low-voltage (1.2V), low-power (1-100muW) energy transducers with output frequency in the 10-Hz-1-kHz range. Simulations using foundry models suggest that the silicon loss could be as low as 0.6muW, and the efficiency could reach 70%. With the IC experimentally packaged, the measured efficiency is between 50% and 70%, depending on the size and the loss in the resonant inductor 相似文献
96.
97.
Thang Ngoc Ngo Tuan Thanh Dang Alexander Villinger Peter Langer 《Advanced Synthesis \u0026amp; Catalysis》2016,358(8):1328-1336
We have developed a palladium(0)‐catalyzed tandem process which involves the cross‐coupling reaction of N‐tosylhydrazones with dibromide compounds followed by a sequence of intramolecular 5‐exo‐trig, 3‐exo‐trig cyclization, ring opening, and β‐hydride elimination to produce 6‐endo‐trig cyclized products. The strategy was successfully applied for the regioselective synthesis of substituted benzo[b]naphtho[2,1‐d]thiophenes, naphtho[1,2‐b]benzofurans, and benzo[a]carbazoles in moderate to excellent yields.
98.
Mechanisms underlying the effects of membrane fouling on the nanofiltration of trace organic contaminants 总被引:3,自引:0,他引:3
The influence of membrane fouling on the retention of four trace organic contaminants - namely sulfamethoxazole, ibuprofen, carbamazepine, and triclosan - by nanofiltration membranes was investigated in this study. Humic acid, alginate, bovine serum albumin, and silica colloids were selected as model foulants to simulate various organic fractions and colloidal matter that are found in secondary treated effluent and surface water. The effects of membrane fouling on the separation process was delineated by comparing retention values of clean and fouled membranes and relate them to the membrane properties (under both clean and fouled conditions) as well as physicochemical characteristics of the trace organic contaminants. Membrane fouling was dependent on the physicochemical properties of the model foulants. Initial foulant-membrane interaction could probably be a major factor governing the process of membrane fouling particularly by the organic foulants. Such membrane-foulant interaction was also a dominating factor governing the effects of membrane fouling on the membrane separation efficacy. In good agreement with our previous study (Nghiem and Hawkes, 2007 [1]), the effects of fouling on retention were found to be membrane pore size dependent. In addition, results reported here suggest that these effects could also be foulant dependent. It was probable that the influence of membrane fouling on trace organic retention could be governed by four distinctive mechanisms: modification of the membrane charge surface, pore blocking, cake enhanced concentration polarisation, and modification of the membrane hydrophobicity. The presence of the fouling layer could affect the retention behavior of charged solutes by altering the membrane surface charge density. While the effect of surface charge modification was clear for inorganic salts, it was less obvious for the negatively charged pharmaceutical species (sulfamethoxazole and ibuprofen) examined in this investigation, possibly due to the interference of the pore blocking mechanism. Evidence of the cake enhanced concentration polarisation effect was quite clear, particularly under colloidal fouling conditions. In addition, organic fouling could also interfere with the solute-membrane interaction, and therefore, exerted considerable influence on the separation process of the hydrophobic trace organic contaminant triclosan. 相似文献
99.
100.
天然裂缝性储层的特征 总被引:2,自引:0,他引:2
Tom Bratton Dao Viet Canh Nguyen Van Que Nguyen V.Duc Paul Gillespie David Hunt BingjianLi Richard Marcinew Satyaki Ray Bernard Montaron Ron Nelson David Schoderbek Lars Sonneland 《国外测井技术》2008,23(1):47-66
天然裂缝性储层给开采带来了一个矛盾难题。这类储层包括低油气采收率储层,这些储层最初可能表现出高产,但产能下降得非常快。此外,这类储层还经常出现早期见气或见水等问题。而另一方面,一些天然裂缝性储层也是全球最大、产量最高的储层。这类储层的这种矛盾特性激发业界尽力去深入了解其特征,以便更有把握地对其进行模拟分析。 相似文献