全文获取类型
收费全文 | 1021篇 |
免费 | 28篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 71篇 |
综合类 | 5篇 |
化学工业 | 236篇 |
金属工艺 | 24篇 |
机械仪表 | 44篇 |
建筑科学 | 14篇 |
能源动力 | 89篇 |
轻工业 | 82篇 |
无线电 | 80篇 |
一般工业技术 | 193篇 |
冶金工业 | 60篇 |
原子能技术 | 45篇 |
自动化技术 | 107篇 |
出版年
2023年 | 5篇 |
2022年 | 10篇 |
2021年 | 15篇 |
2020年 | 12篇 |
2019年 | 8篇 |
2018年 | 15篇 |
2017年 | 15篇 |
2016年 | 19篇 |
2015年 | 17篇 |
2014年 | 25篇 |
2013年 | 57篇 |
2012年 | 35篇 |
2011年 | 59篇 |
2010年 | 45篇 |
2009年 | 55篇 |
2008年 | 64篇 |
2007年 | 53篇 |
2006年 | 34篇 |
2005年 | 47篇 |
2004年 | 49篇 |
2003年 | 43篇 |
2002年 | 27篇 |
2001年 | 29篇 |
2000年 | 23篇 |
1999年 | 26篇 |
1998年 | 27篇 |
1997年 | 28篇 |
1996年 | 27篇 |
1995年 | 20篇 |
1994年 | 15篇 |
1993年 | 5篇 |
1992年 | 9篇 |
1991年 | 11篇 |
1990年 | 3篇 |
1989年 | 8篇 |
1988年 | 14篇 |
1987年 | 10篇 |
1986年 | 13篇 |
1985年 | 13篇 |
1984年 | 11篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1974年 | 3篇 |
1968年 | 1篇 |
排序方式: 共有1050条查询结果,搜索用时 687 毫秒
71.
Kusumoto M Suzuki R Nishiya Y Okitsu T Oka M 《Journal of Bioscience and Bioengineering》2004,97(6):406-411
IS1203v is an insertion sequence (IS) which is identical to the most abundant IS elements in the genome of Escherichia coli O157:H7. However, there is no sequence homologous to IS1203v in the genome of E. coli K-12. We constructed a system to analyze the excision frequency of IS1203v, and demonstrated that the frequency in E. coli O157:H7 was approximately 10(5) times higher than that in E. coli K-12. We also investigated the excision frequencies of IS1203v in various E. coli isolates, and showed that the excision frequencies of IS1203v-possessing strains were approximately 10(3) times higher than those of IS1203v-nonpossessing strains. The results suggest that the IS1203v-possessing strains use a common system to enhance IS1203v excision. 相似文献
72.
The polarization characteristics of a terahertz (THz) wave transmitted through two-dimensional (2-D) metallic photonic crystals (MPCs) are investigated. The 2-D MPCs studied in this paper are metal slabs perforated periodically with circular holes. We measured the polarization characteristics of the THz wave using a THz time-domain spectroscopic system with wire grid polarizers in the time and frequency domains. The linearly polarized incident THz wave changes its polarization direction and becomes elliptic after it transmits through the sample. This phenomenon is highly sensitive to the incident angle. It is shown that the frequency range at which the polarization rotation occurs is related to the lattice constant of a photonic crystal, indicating the importance of photonic band modes of the 2-D MPC in the mechanism of the phenomenon. 相似文献
73.
In this study, the spatial local optimization method was improved to obtain high precision of optical flow for cases in which
the object movement changes substantially and a method to trace the loci of moving objects was considered. In the spatial
local optimization method, the precision of the optical flow when the object movement changes substantially becomes a problem.
Therefore, to make the object movement relatively small, we obtained flow vectors from the image sequence to drop the resolution
of the original input image sequence to half the initial resolution. flow vectors were then obtained from the original input
image sequence that were smaller than the threshold value. We show that the precision of the optical flow when the object
movement changes substantially is improved by this method. Method used to trace the loci of moving objects was demonstrated.
We obtained clusters from histograms of flow vectors and pursued each cluster. We show that it is possible to trace moving
objects by this method.
This work was presented, in part, at the 7th International Symposium on Artificial Life and Robotics, Oita, Japan, January
16–18, 2002 相似文献
74.
Noriyuki?Aibe Ryosuke?Mizuno Masanori?Nakamura Moritoshi?YasunagaEmail author Ikuo?Yoshihara 《Artificial Life and Robotics》2004,8(2):208-213
The probabilistic neural network (PNN) is one of the most promising neural networks, and is now applied to some real-world applications. In order to speed up the PNN calculation considerably, we have developed a PNN hardware system for video image recognition. The performance of the PNN hardware cannot be evaluated precisely until the evaluation system is completed. In this study, we developed a performance evaluation system for the PNN hardware and demonstrated it using the developed evaluation system.This work was presented, in part, at the 8th International Symposium on Artificial Life and Robotics, Oita, Japan, January 24–26, 2003 相似文献
75.
Masanori?SugisakaEmail author Kouta?Imamura Kouji?Tokuda Maoki?Masuda 《Artificial Life and Robotics》2004,8(1):1-4
Recently, a biologically inspired, bipedal, dynamic, humanoid robot was developed at the Artificial Life and Robotics Laboratory of Oita University. This bipedal humanoid robot is able to walk dynamically and to go up and down stairs. The central pattern generator developed produces various types of walking pattern. This robot has a pair of small CMOS color CCD cameras, a speaker, and a microphone in the head part, and will have a GPS, a portable telephone, and other sensors in the body part, so that the integration of locomotion and behavior to achieve specific demonstrations will be realized. This project develops dynamic mobility and the ability for autonomous recognition and navigation using the biological central nervous system, the brain system, and the real-time control system. Also, the design principles that demonstrate the dynamic interaction between neural and mechanical controls will be clarified. In Phase I, the platform of a small, bipedal, humanoid robot is used to develop autonomous locomotion and autonomous sensing and navigation. In Phase II of the project, an iteration on the platform design for human-size, bipedal, humanoid robots will be performed for operational testing. The development of bipedal humanoid robots that capture biological systems with unique principles and practices could dramatically increase their performance in tasks for national security needs.This work was presented in part at the 8th International Symposium on Artificial Life and Robotics, Oita, Japan, January 24–26, 2003 相似文献
76.
Ichikawa S Akita T Okumura M Haruta M Tanaka K Kohyama M 《Journal of electron microscopy》2003,52(1):21-26
Three-dimensional (3-D) nanostructures of gold catalysts supported on TiO2 were analysed by electron holography and high-resolution electron microscopy. The contact angle of the gold particle on TiO2 tended to be >90 degrees in the case of gold particles with a size (height) of >4 nm and it tended to be <90 degrees for gold particles with a height of <2 nm. The change in morphology increases the perimeter at the Au/TiO2 interface as the particle size decreases. This change in 3-D structure should be attributed to a change in electronic structure at the interface. It was found that electron holography enabled 3-D analysis at the atomic level and was effective for analysing nanostructured particles. 相似文献
77.
78.
Kolmogorov introduced the concept of -entropy to analyze information in classical continuous systems. The fractal dimension of a geometric set was introduced by Mandelbrot as a new criterion to analyze the geometric complexity of the set. The -entropy and the fractal dimension of a state in a general quantum system were introduced by one of the present authors (MO) in order to characterize chaotic properties of general states.In this paper, we show that -entropy of a state includes Kolmogorov's -entropy, and that the fractal dimension of a state describes fractal structure of Gaussian measures. 相似文献
79.
Masanori Katagiri Shigeyuki Izumi Jun’ya Hori Yoshiko Fujii Keisaku Hatanaka 《Journal of Low Temperature Physics》2007,148(3-4):127-132
The heat transfer properties of 3He bubbles in the nucleate boiling state have been investigated in liquid 3He below 1.0 K by using the shadowgraph method. The temperature difference between the copper surface and liquid 3He temperature was also measured as a function of heat flux in steady state. The size and number of bubbles departing from
the surface in a specific time were compared using photograph recorded by a high-speed video camera at various heat flux and
liquid 3He temperature of 0.5, 0.7 and 1.0 K. 相似文献
80.
Takuya Otani Kenji Hashimoto Takaya Isomichi Akira Natsuhara Masanori Sakaguchi Yasuo Kawakami 《Advanced Robotics》2013,27(22):1197-1206
In previous studies, various stabilizing control methods for humanoids during the stance phase while hopping and running were proposed. Although these methods contribute to stability while hopping and running, it is possibility that the control during the flight phase could also affect the stability. In this study, we investigated whether the control during the flight phase can affect the stability of a humanoid while running. To achieve stable hopping, we developed a control system that accounts for the angular momentum of the whole body during the flight phase. In this system, the angular momentum generated by the motion of the lower body in each time interval is calculated during the flight phase, and the trunk joints are controlled to generate the angular momentum necessary to compensate for the deviation of the waist posture, which is used as the reference point for the motion coordinate system of the robot. Once the proposed control system was developed and simulated, we found that the hopping duration in the unconstrained state was extended. 相似文献