全文获取类型
收费全文 | 2682篇 |
免费 | 86篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 192篇 |
综合类 | 5篇 |
化学工业 | 793篇 |
金属工艺 | 80篇 |
机械仪表 | 75篇 |
建筑科学 | 44篇 |
能源动力 | 137篇 |
轻工业 | 303篇 |
水利工程 | 9篇 |
石油天然气 | 1篇 |
无线电 | 178篇 |
一般工业技术 | 506篇 |
冶金工业 | 73篇 |
原子能技术 | 139篇 |
自动化技术 | 241篇 |
出版年
2023年 | 11篇 |
2022年 | 35篇 |
2021年 | 56篇 |
2020年 | 31篇 |
2019年 | 44篇 |
2018年 | 54篇 |
2017年 | 43篇 |
2016年 | 54篇 |
2015年 | 39篇 |
2014年 | 95篇 |
2013年 | 156篇 |
2012年 | 129篇 |
2011年 | 191篇 |
2010年 | 138篇 |
2009年 | 142篇 |
2008年 | 149篇 |
2007年 | 146篇 |
2006年 | 128篇 |
2005年 | 120篇 |
2004年 | 92篇 |
2003年 | 101篇 |
2002年 | 90篇 |
2001年 | 53篇 |
2000年 | 47篇 |
1999年 | 50篇 |
1998年 | 50篇 |
1997年 | 42篇 |
1996年 | 42篇 |
1995年 | 42篇 |
1994年 | 51篇 |
1993年 | 30篇 |
1992年 | 21篇 |
1991年 | 24篇 |
1990年 | 22篇 |
1989年 | 24篇 |
1988年 | 13篇 |
1987年 | 22篇 |
1986年 | 18篇 |
1985年 | 23篇 |
1984年 | 16篇 |
1983年 | 23篇 |
1982年 | 20篇 |
1981年 | 18篇 |
1980年 | 25篇 |
1979年 | 14篇 |
1978年 | 5篇 |
1977年 | 7篇 |
1976年 | 11篇 |
1975年 | 5篇 |
1972年 | 4篇 |
排序方式: 共有2776条查询结果,搜索用时 15 毫秒
71.
As a model-based reinforcement learning technique, linearly solvable Markov decision process (LMDP) gives an efficient way to find an optimal policy by making the Bellman equation linear under some assumptions. Since LMDP is regarded as model-based reinforcement learning, the performance of LMDP is sensitive to the accuracy of the environmental model. To overcome the problem of the sensitivity, linearly solvable Markov game (LMG) has been proposed, which is an extension of LMDP based on the game theory. This paper investigates the robustness of LMDP- and LMG-based controllers against modeling errors in both discrete and continuous state-action problems. When there is a discrepancy between the model used for building the control policy and dynamics of the tested environment, the LMG-based control policy maintained good performance while that of the LMDP-based control policy deteriorated drastically. Experimental results support the usefulness of LMG framework when acquiring an accurate model of the environment is difficult. 相似文献
72.
A switched reluctance (SR) motor has a doubly salient pole structure. The performance of the SR motor strongly depends on the magnetic properties of the core material, since it consists only of an iron core and copper windings. This study experimentally evaluates the performance of an SR motor made of permendur (Fe–49% Co alloy), which has very high saturation flux density and low core loss. Two types of SR motors that have the same dimensions but different core materials are used: one motor is made of the conventional nonoriented Si steel, and the other is made of permendur. Comparison of the characteristics of the two motors shows that the performance of the permendur SR motor surpasses that of the conventional one in terms of output power and efficiency. © 2014 Wiley Periodicals, Inc. Electr Eng Jpn, 187(1): 51–57, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22431 相似文献
73.
Kenji Takizawa Hirokazu Takagi Tayfun E. Tezduyar Ryo Torii 《Computational Mechanics》2014,54(4):895-910
In patient-specific arterial fluid–structure interaction (FSI) computations the image-based arterial geometry comes from a configuration that is not stress-free. We present a method for estimation of element-based zero-stress (ZS) state. The method has three main components. (1) An iterative method, which starts with an initial guess for the ZS state, is used for computing the element-based ZS state such that when a given pressure load is applied, the image-based target shape is matched. (2) A method for straight-tube geometries with single and multiple layers is used for computing the element-based ZS state so that we match the given diameter and longitudinal stretch in the target configuration and the “opening angle.” (3) An element-based mapping between the arterial and straight-tube configurations is used for mapping from the arterial configuration to the straight-tube configuration, and for mapping the estimated ZS state of the straight tube back to the arterial configuration, to be used as the initial guess for the iterative method that matches the image-based target shape. We present a set of test computations to show how the method works. 相似文献
74.
Patient-specific computer modeling of blood flow in cerebral arteries with aneurysm and stent 总被引:2,自引:2,他引:0
Kenji Takizawa Kathleen Schjodt Anthony Puntel Nikolay Kostov Tayfun E. Tezduyar 《Computational Mechanics》2012,50(6):675-686
We present the special arterial fluid mechanics techniques we have developed for patient-specific computer modeling of blood flow in cerebral arteries with aneurysm and stent. These techniques are used in conjunction with the core computational technique, which is the space?Ctime version of the variational multiscale (VMS) method and is called ??DST/SST-VMST.?? The special techniques include using NURBS for the spatial representation of the surface over which the stent mesh is built, mesh generation techniques for both the finite- and zero-thickness representations of the stent, techniques for generating refined layers of mesh near the arterial and stent surfaces, and models for representing double stent. We compute the unsteady flow patterns in the aneurysm and investigate how those patterns are influenced by the presence of single and double stents. We also compare the flow patterns obtained with the finite- and zero-thickness representations of the stent. 相似文献
75.
76.
Kenji Takizawa Tayfun E. Tezduyar Austin Buscher Shohei Asada 《Computational Mechanics》2014,54(4):955-971
To address the computational challenges associated with contact between moving interfaces, such as those in cardiovascular fluid–structure interaction (FSI), parachute FSI, and flapping-wing aerodynamics, we introduce a space–time (ST) interface-tracking method that can deal with topology change (TC). In cardiovascular FSI, our primary target is heart valves. The method is a new version of the deforming-spatial-domain/stabilized space–time (DSD/SST) method, and we call it ST-TC. It includes a master–slave system that maintains the connectivity of the “parent” mesh when there is contact between the moving interfaces. It is an efficient, practical alternative to using unstructured ST meshes, but without giving up on the accurate representation of the interface or consistent representation of the interface motion. We explain the method with conceptual examples and present 2D test computations with models representative of the classes of problems we are targeting. 相似文献
77.
This paper presents the silicon based on-chip antenna using a LC resonator. The proposed antenna consists of a stacked capacitor and a spiral inductor on silicon substrate. The spiral inductor structure without underpass was proposed for improvement the performance of the silicon based-antenna. The resonant frequency of the fabricated antenna was measured as 465 MHz. Its return loss was 23.4 dB at resonant frequency. The antenna has a gain of ?35.75 dBi due to small size and silicon substrate. However, the fabricated antenna has good performance in the near-field. 相似文献
78.
Yusei Maruyama Tsugiko Takase Masateru Yoshida Kensuke Kogure Kenji Suzuki Kazuyuki Tohji 《Fullerenes, Nanotubes and Carbon Nanostructures》2013,21(2):211-221
Abstract Single-walled carbon nanotubes (SWCNT) prepared by a DC-Arc-Discharge and purified by a hydrothermal treatment followed by several steps of procedures including heating, burning, extracting and acid-washing are investigated by a conventional STM technique morphologically and spectroscopically. The electical resistivities of compacted pellets (mats) of SWCNT are measured as a function of temperature in the range from the room-temperature to 1.5K. The behaviors seems to be essentially originated in the metallic nature of individual SWCNT. 相似文献
79.
Caifang Gao Mu-Pai Lee Mengjiao Li Ko-Chun Lee Feng-Shou Yang Che-Yi Lin Kenji Watanabe Takashi Taniguchi Po-Wen Chiu Chen-Hsin Lien Wen-Wei Wu Shu-Ping Lin Wenwu Li Yen-Fu Lin Junhao Chu 《Advanced functional materials》2021,31(5):2005182
The human brain is often likened to an incredibly complex and intricate computer, rather than electrical devices, consisting of billions of neuronal cells connected by synapses. Different brain circuits are responsible for coordinating and performing specific functions. The reward pathway of the synaptic plasticity in the brain is strongly related to the features of both drug addiction and relief. In the current study, a synaptic device based on layered hafnium disulfide (HfS2) is developed for the first time, to emulate the behavioral mechanisms of drug dosage modulation for neuroplasticity. A strong gate-dependent persistent photocurrent is observed, arising from the modulation of substrate-trapping events. By controlling the polarity of gate voltage, the basic functions of biological synapses are realized under a range of light spiking conditions. Furthermore, under the control of detrapping/trapping events at the HfS2/SiO2 interface, positive/negative correlations of the An/A1 index, which significantly reflected the weight change of synaptic plasticity, are realized under the same stimulation conditions for the emulation of the drug-related addition/relief behaviors in the brain. The findings provide a new advance for mimicking human brain plasticity. 相似文献
80.
Yoonsang Park Hossein Daneshpajooh Timo Scholehwar Eberhard Hennig Kenji Uchino 《Journal of the European Ceramic Society》2021,41(12):5900-5908
The IEEE standard to determine physical parameters of piezoceramics has been utilized for decades by many researchers, yet it omits presence of important loss factors and possesses serious deficits that restrict accurate parameter determination. To resolve these issues, the partial electrode (PE) method was previously proposed, though the focus has been merely made on development of the method itself. In this study, we provide method simplification and more detailed analysis. The omission of unnecessary samples greatly boosts experiment and analysis process. To prove that the PE method is reliable, possible causes of errors were investigated; it is shown that they were either negligibly small or can be resolved with proper calibration. Furthermore, Applicability of PE method to various types of piezoceramic materials and compatibility with impedance analyzers are shown. Finally, PE method is proved to be reliable and can be alternative to IEEE Standard on Piezoelectricity. 相似文献