全文获取类型
收费全文 | 868篇 |
免费 | 44篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 83篇 |
综合类 | 2篇 |
化学工业 | 294篇 |
金属工艺 | 26篇 |
机械仪表 | 21篇 |
建筑科学 | 21篇 |
矿业工程 | 1篇 |
能源动力 | 46篇 |
轻工业 | 80篇 |
水利工程 | 1篇 |
无线电 | 23篇 |
一般工业技术 | 154篇 |
冶金工业 | 33篇 |
原子能技术 | 40篇 |
自动化技术 | 88篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 30篇 |
2020年 | 25篇 |
2019年 | 14篇 |
2018年 | 22篇 |
2017年 | 23篇 |
2016年 | 34篇 |
2015年 | 26篇 |
2014年 | 42篇 |
2013年 | 48篇 |
2012年 | 43篇 |
2011年 | 75篇 |
2010年 | 38篇 |
2009年 | 58篇 |
2008年 | 39篇 |
2007年 | 36篇 |
2006年 | 41篇 |
2005年 | 35篇 |
2004年 | 26篇 |
2003年 | 29篇 |
2002年 | 28篇 |
2001年 | 19篇 |
2000年 | 13篇 |
1999年 | 10篇 |
1998年 | 17篇 |
1997年 | 15篇 |
1996年 | 10篇 |
1995年 | 8篇 |
1994年 | 10篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 1篇 |
1986年 | 6篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1973年 | 3篇 |
排序方式: 共有913条查询结果,搜索用时 421 毫秒
21.
22.
Magneto-mechanical resonators—magnetically-driven vibration devices—are used in many mechanical and electrical devices. We develop topology optimization (TO) to configure the magnetic fields of such resonators to enable large vibrations under specified current input to be attained. A dynamic magneto-mechanical analysis in the frequency domain is considered where we introduce the surface magnetic force calculated from the Maxwell stress tensor. The optimization problem is then formulated involving specifically the maximization of the dynamic compliance. This formulation is implemented using the solid-isotropic-material-with-penalization method for TO by taking into account the relative permeability, Young’s modulus, and the mass density of the magnetic material as functions of the density function. Through the 2D numerical studies, we confirm that this TO method works well in designing magnetic field patterns and providing matching between the external current frequency and eigenfrequency of the vibrating structure. 相似文献
23.
24.
The effect of lutein supplementation on visual fatigue: A psychophysiological analysis 总被引:1,自引:0,他引:1
Akihiro Yagi Kiyoshi Fujimoto Kazumi Michihiro Bevy Goh Daniel Tsi Hajime Nagai 《Applied ergonomics》2009,40(6):1047-1054
We used psychophysiological technology to examine the effect of an oral supplement, a combination of lutein, zeaxanthin and blackcurrant extract (LUT), on visual fatigue, within the context of a randomized, double-blind, placebo-controlled cross-over trial. The LUT supplement and placebo samples were randomly assigned to thirteen participants, who took the samples for two LUT (and vice versa) for another 2 week. Each participant completed visual proof reading tasks for 2 h during each of four testing sessions. Saccade tests were administered before and after the proof reading task, during which the participants moved their eyes back and forth between two targets positioned in the center of two checkerboards. We recorded EEG, EOG, heart rate, and facial muscle potential/performance during the saccade tests. Blood pressure was measured and subjective fatigue and stress scores were collected before and after the proof reading task. We averaged EEG starting at saccade offset in order to analyze eye fixation related potentials (EFRP). Our results suggested that the proof reading task induced visual fatigue. An analysis of EFRP and other psychophysiological data revealed significant differences between the LUT and placebo conditions. These results suggest that supplementation with LUT could help to reduce symptoms of visual fatigue. 相似文献
25.
Takashi Soga Akihiro Musa Koki Okabe Kazuhiko Komatsu Ryusuke Egawa Hiroyuki Takizawa Hiroaki Kobayashi Shun Takahashi Daisuke Sasaki Kazuhiro Nakahashi 《Computers & Fluids》2011,45(1):215-221
The building-cube method (BCM) is a new generation algorithm for CFD simulations. The basic idea of BCM is to simplify the algorithm in all stages of flow computation to achieve large-scale simulations. Calculation of a pressure field using the Successive Over Relaxation (SOR) method consumes most of the total execution time required for BCM. In this paper, effective implementations on modern vector and scalar processors are investigated. NEC SX-9 and Intel Nehalem-EX are the latest vector and scalar processors. Those processors have much higher peak performances than their previous-generation processors. However, their memory bandwidth improvement cannot catch up with the performance improvement of processors. This is the so-called memory wall problem. In our paper, we discuss optimization techniques for implementation of the SOR method based on architectural characteristics of these modern processors, and evaluate their effects on the sustained performances of these processors for BCM. 相似文献
26.
Yufeng Wang Akihiro Nakao Athanasios V. VasilakosJianhua Ma 《Computer Communications》2011,34(3):241-249
This paper thoroughly investigates the evolutionary dynamics of soft security mechanism, namely, reciprocity-based incentive mechanism, in P2P systems based on Evolutionary Game Theory (EGT). By soft security mechanism, it means social control mechanisms to overcome peers’ selfish (rational) behaviors, and encourage cooperation in P2P systems. Specifically, there exist three strategies in P2P systems: always cooperative (ALLC), always defect (ALLD) and reciprocator (R). Instead of existing work which take it for granted that, like ALLC users, R users did not bear any information-seeking cost, we assume small reciprocation cost, and study generalized mutation-selection dynamics. Our contributions are threefold: firstly, we prove and illustrate that, in a well-mixed P2P structure, ALLD is the only strict Nash equilibrium; secondly, we infer the specific condition under which evolution dynamics exhibits rock-scissors-paper oscillation in a structured P2P population. That is, the population cycles from ALLD to R to ALLC and back to ALLD; finally, we theoretically illustrate that the intensity of selection plays an important role in the evolutionary dynamics of P2P incentive mechanism. That is, when the intensity of selection is relatively weak and reciprocation cost limits to zero, the time average can be mostly concentrated on reciprocator. In brief, considering the existence of reciprocation cost and the small mutation in P2P incentive mechanisms, unlike existing work, it is impossible to simply achieve the “absolute cooperative” in P2P incentive mechanisms. On the other hand, stochastic evolution in P2P incentive mechanism with finite population and network structure still favor reciprocation. 相似文献
27.
Akihiro Sugimoto 《Journal of Mathematical Imaging and Vision》2000,13(2):115-130
This paper presents a study, based on conic correspondences, on the relationship between two perspective images acquired by an uncalibrated camera. We show that for a pair of corresponding conics, the parameters representing the conics satisfy a linear constraint. To be more specific, the parameters that represent a conic in one image are transformed by a five-dimensional projective transformation to the parameters that represent the corresponding conic in another image. We also show that this transformation is expressed as the symmetric component of the tensor product of the transformation based on point/line correspondences and itself. In addition, we present a linear algorithm for uniquely determining the corresponding point-based transformation from a given conic-based transformation up to a scale factor. Accordingly, conic correspondences enable us to easily handle both points and lines in uncalibrated images of a planar object. 相似文献
28.
Chuanyong Gui Akihiro Sato Yuefeng Gu Hiroshi Harada 《Metallurgical and Materials Transactions A》2005,36(11):2921-2927
We proposed a new method for developing Ni-base turbine disc alloy for application at temperatures above 700 °C by mixing
a Ni-base superalloy U720LI with a two-phase alloy Co-16.9 wt pct Ti in various contents. The microstructure and phase stability
of the alloys were analyzed using an optical microscope, a scanning electron microscope, energy-dispersive spectroscopy, and
an X-ray diffractometer. The yield strength was studied by compression tests at temperatures ranging from 25 °C to 1200 °C.
The results show that all the alloys had a dendritic structure. Ni3Ti (η) phase was formed in the interdendritic region in the alloys with the addition of Co-16.9 wt pct Ti, and its volume fraction
increased with the increase in the addition of Co-16.9 wt pct Ti. The results of exposure at 750 °C show that the addition
of Co-16.9 wt pct Ti to U720LI had a great effect on suppressing the formation of σ phase due to the reduced Cr content in the γ matrix. Compared to U720LI, the alloys with the addition of Co-16.9 wt pct Ti possessed higher yield strength. The solid-solution
strengthening of γ and γ′ and higher volume fraction of γ′ were assumed to cause this strength increase. 相似文献
29.
Takuro Tomita Ayahito Uetake Tsutomu Asahina Kentaro Kayanuma Akihiro Murayama Yasuo Oka 《Journal of Superconductivity and Novel Magnetism》2005,18(3):405-410
Spin injection processes in the double quantum dots of ZnSe-based diluted magnetic semiconductors are discussed. Double quantum
dots are fabricated from ZnSe-based double quantum wells by electron beam lithography and wet etching. In these samples, the
photo-excited carriers in the magnetic dots are injected into the non-magnetic dots. The circular polarization degrees of
photoluminescence from the non-magnetic dots are measured by micro-photoluminescence measurement system under the magnetic
field up to 5 T. The maximum spin polarization degrees of injected carriers determined from our experiment are 10% for double
quantum wells and 15% for double quantum dots. The spin injection efficiency was estimated both from the observed circular
polarization degree and the diffusion length of carriers. We concluded that the spin injection efficiency is increased in
the double quantum dots. 相似文献
30.
Gene insertion and deletion are basic phenomena found in DNA processing or RNA editing in molecular biology. The genetic mechanism
and development based on these evolutionary transformations have been formulated as a formal system with two operations of
insertion and deletion, called insertion-deletion systems (Kari and Thierrin, 1996; Kari et al., 1997).We investigate the generative power of insertion-deletion systems (InsDel systems),
and show that the family INS
1
1
DEL
1
1 is equal to the family of recursively enumerable languages. This gives a positive answer to an open problem posed in Kari
et al. (1997) where it was conjectured contrary.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献