全文获取类型
收费全文 | 3821篇 |
免费 | 209篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 73篇 |
综合类 | 2篇 |
化学工业 | 872篇 |
金属工艺 | 128篇 |
机械仪表 | 229篇 |
建筑科学 | 94篇 |
矿业工程 | 1篇 |
能源动力 | 143篇 |
轻工业 | 336篇 |
水利工程 | 13篇 |
石油天然气 | 1篇 |
无线电 | 688篇 |
一般工业技术 | 776篇 |
冶金工业 | 240篇 |
原子能技术 | 43篇 |
自动化技术 | 397篇 |
出版年
2023年 | 42篇 |
2022年 | 57篇 |
2021年 | 83篇 |
2020年 | 73篇 |
2019年 | 78篇 |
2018年 | 109篇 |
2017年 | 116篇 |
2016年 | 128篇 |
2015年 | 107篇 |
2014年 | 160篇 |
2013年 | 259篇 |
2012年 | 233篇 |
2011年 | 306篇 |
2010年 | 210篇 |
2009年 | 228篇 |
2008年 | 211篇 |
2007年 | 171篇 |
2006年 | 184篇 |
2005年 | 143篇 |
2004年 | 146篇 |
2003年 | 120篇 |
2002年 | 103篇 |
2001年 | 96篇 |
2000年 | 81篇 |
1999年 | 56篇 |
1998年 | 124篇 |
1997年 | 76篇 |
1996年 | 63篇 |
1995年 | 41篇 |
1994年 | 36篇 |
1993年 | 22篇 |
1992年 | 20篇 |
1991年 | 23篇 |
1990年 | 16篇 |
1989年 | 13篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1985年 | 14篇 |
1984年 | 9篇 |
1981年 | 10篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1972年 | 2篇 |
1969年 | 2篇 |
排序方式: 共有4036条查询结果,搜索用时 15 毫秒
71.
Gait Generation and Stabilization for Nearly Passive Dynamic Walking Using Auto‐distributed Impulses 下载免费PDF全文
We propose a state feedback control design via linearization for flexible walking on flat ground. First, we generate nearly passive limit cycles, being stable or not, using impulsive toe‐off actuations. The term ‘nearly passive’ means that the dynamics is completely passive almost everywhere except at the toe‐off moment. A feature of our gait generation method is that walking gaits are characterized only by amounts of supplied energy, and we observe that other variables, including input torques, are auto‐balanced via our method. After gait generation, we design a feedback controller considering robustness and input saturation. As a result, each limit cycle can be matched with its respective controller classified only by energy levels. We have verified that walking speeds monotonically increase by adding more energy, and the ankle joint plays a significant role in compass‐gait walking. Finally, instead of applying impulsive torques, we discuss a practical issue regarding realistic control inputs that ensure stable gait transitions as energy levels are elevated. 相似文献
72.
User experience has become a major issue lately with user value as one of its key elements. This study proposes a method to evaluate user value using a questionnaire specialized for a mobile device such as smartphones. The questionnaire was developed considering elements of user value, product features, and context of use. Then, a case study with hundreds of participants was conducted via the Internet to verify and screen out questionnaire items in terms of reliability and validity. Finally, a total of 16 questionnaire items were selected for evaluating elements of user value, consisting of self‐satisfaction, pleasure, sociability, customer need, and attachment. The results of this study are expected to help understand potential users and select design alternatives. 相似文献
73.
74.
Sam Dong Jung Jeong Soo Kim Jung Won Park Jong Hwa Won Moon Kyum Kim 《Multimedia Tools and Applications》2015,74(20):9017-9029
A technique is developed to clearly establish the shear resistance of a cellular structure, retaining wall composed of a steel frame and fill materials with both continuous and discontinuous characteristics. To overcome the limitation of the existing analysis approach based on continuum mechanics, in which the shear behavior and interaction between the frames and fill material of this type of structure are difficult to describe, this paper introduces displacement incremental analysis into the distinct element method. The results obtained by using the proposed approach are compared with experimental results to verify its accuracy. The results show an internal friction angle of fill materials and overburdening load are major factor determining the shear resistance of a retaining wall with a cellular structure type. From the results of the parametric study on the shear behavior of this type of structure, this paper also proposes a shear resistance moment-shear displacement formula for designing a retaining wall with a cellular structure type. 相似文献
75.
Dong-Hyuk Lee Hyungpil Moon Ja Choon Koo Hyouk Ryeol Choi 《International Journal of Control, Automation and Systems》2013,11(1):127-135
This paper presents a map building method for an in-pipe robot to navigate inside urban gas pipelines autonomously, whose configuration is unknown or partially known. In the first, we explain the reason why the navigation in the pipeline is difficult and then, present a method for obtaining a robot’s posture by using a pipeline’s unique geometrical features. The robot can obtain its heading direction by detecting the standardized geometries of pipe elements. Based on the method, we propose a robot controller consisting of discrete and continuous controllers. The discrete controller is activated by pre-defined events and generates appropriate paths for exploration. The continuous controller receives the desired path and physically moves the robot to the desired path. The method is implemented in an in-pipe robot, called MRINSPECT-V and its effectiveness is validated. 相似文献
76.
Development of a quadruped walking robot AiDIN-III using biologically inspired kinematic analysis 总被引:1,自引:0,他引:1
Ig Mo Koo Duc Trong Tran Yoon Haeng Lee Hyungpil Moon Ja Choon Koo Sangdeok Park Hyouk Ryeol Choi 《International Journal of Control, Automation and Systems》2013,11(6):1276-1289
This paper presents a bio-inspired mechanism design for a quadruped walking robot. The approach is derived from the observation on the behaviors of quadruped locomotion, skeletal structure, and the study on the stability of walking based on morphological analysis. In the first, we define the design parameters such as the dimensions of the body and limbs, the center of mass position, and locomotion mechanisms based on surveys on the literatures from biologists. Then, by using the parameters, we propose an useful framework for determining the design parameters of a quadruped walking robot. For implementations, we manufacture a dog-type self-contained quadruped walking robot, named AiDIN-III (Artificial Digitigrade for Natural Environment version III) and the effectiveness of the proposed idea is validated via experimental works. 相似文献
77.
Nanoporous polyimide films were prepared from triblock copolyimides. A thermally labile polymer, poly(propylene glycol), was incorporated into polyimides based on 4,4-(hexafluoroisopropylidene)diphthalic anhydride to obtain triblock copolyimides. Nanofoams were formed by thermolysis of the labile block. The thermal properties of the copolymers were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The nanopores were characterized by scanning electron microscopy (SEM). 相似文献
78.
Hwan Seong Moon Jae Suk Lee Sung Wook Han Jong Wan Park Jae Hak Lee Seung Kee Yang Hyung Ho Park 《Journal of Materials Science》1994,29(6):1545-1548
Tantalum oxide film formation by plasma-enhanced chemical vapour deposition (PECVD) using TaCl5 as a source material was examined. The effects of deposition temperature on the formation, structure and electric properties of the Ta2O5 film were investigated for Al/Ta2O5/ p-Si (MTS) capacitors. The deposition rate and refractive index increased with increasing deposition temperature. It was found that the structure of Ta2O5 deposited by PECVD was amorphous as-deposited. However, crystalline -Ta2O5 of hexagonal structure was formed by a 700 °C, 1 h heat treatment in argon. Capacitance and relative dielectric constant of the PECVD Ta2O5 were found to be 2.54 fF m–2 and 23.5, respectively. The PECVD films obtained in this study have higher dielectric constants and remarkably better general film characteristics than those obtained by other deposition methods. 相似文献
79.
80.
Jangwon Moon Junwoo Kim Hoon Lee Youngjin Moon Yongsu Lee Youngjo Bang Kyungyeol Sohn Jungsook Bae Kwangseon Kim Seungjae Bahng Heesoo Lee 《ETRI Journal》2023,45(5):781-794
Uncrewed aerial vehicles (UAVs) have become a vital element in nonterrestrial networks, especially with respect to 5G communication systems and beyond. The use of UAVs in support of 4G/5G base station (uncrewed aerial vehicle base station [UAV-BS]) has proven to be a practical solution for extending cellular network services to areas where conventional infrastructures are unavailable. In this study, we introduce a UAV-BS system that utilizes a high-capacity wireless backhaul operating in millimeter-wave frequency bands. This system can achieve a maximum throughput of 1.3 Gbps while delivering data at a rate of 300 Mbps, even at distances of 10 km. We also present the details of our testbed implementation alongside the performance results obtained from field tests. 相似文献