全文获取类型
收费全文 | 6657篇 |
免费 | 401篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 92篇 |
综合类 | 16篇 |
化学工业 | 1363篇 |
金属工艺 | 190篇 |
机械仪表 | 341篇 |
建筑科学 | 137篇 |
矿业工程 | 3篇 |
能源动力 | 318篇 |
轻工业 | 623篇 |
水利工程 | 20篇 |
石油天然气 | 8篇 |
武器工业 | 1篇 |
无线电 | 1116篇 |
一般工业技术 | 1359篇 |
冶金工业 | 500篇 |
原子能技术 | 59篇 |
自动化技术 | 925篇 |
出版年
2024年 | 10篇 |
2023年 | 85篇 |
2022年 | 122篇 |
2021年 | 213篇 |
2020年 | 168篇 |
2019年 | 160篇 |
2018年 | 193篇 |
2017年 | 192篇 |
2016年 | 227篇 |
2015年 | 207篇 |
2014年 | 306篇 |
2013年 | 424篇 |
2012年 | 465篇 |
2011年 | 509篇 |
2010年 | 371篇 |
2009年 | 362篇 |
2008年 | 380篇 |
2007年 | 294篇 |
2006年 | 238篇 |
2005年 | 232篇 |
2004年 | 200篇 |
2003年 | 173篇 |
2002年 | 155篇 |
2001年 | 130篇 |
2000年 | 121篇 |
1999年 | 118篇 |
1998年 | 224篇 |
1997年 | 146篇 |
1996年 | 127篇 |
1995年 | 83篇 |
1994年 | 56篇 |
1993年 | 62篇 |
1992年 | 32篇 |
1991年 | 26篇 |
1990年 | 23篇 |
1989年 | 23篇 |
1988年 | 24篇 |
1987年 | 23篇 |
1986年 | 10篇 |
1985年 | 21篇 |
1984年 | 12篇 |
1983年 | 15篇 |
1982年 | 8篇 |
1980年 | 15篇 |
1978年 | 12篇 |
1977年 | 10篇 |
1976年 | 10篇 |
1974年 | 7篇 |
1972年 | 10篇 |
1971年 | 10篇 |
排序方式: 共有7071条查询结果,搜索用时 15 毫秒
141.
Ji Hyoun Lim Yili Liu 《IEEE transactions on systems, man, and cybernetics. Part A, Systems and humans : a publication of the IEEE Systems, Man, and Cybernetics Society》2009,39(4):706-714
Understanding and reproducing complex human oculomotor behaviors using computational models is a challenging task. In this paper, two studies are presented, which focus on the development and evaluation of a computational model to show the influences of cyclic top-down and bottom-up processes on eye movements. To explain these processes, reinforcement learning was used to control eye movements. The first study showed that, in a picture-viewing task, different policies obtained from different picture-viewing conditions produced different types of eye movement patterns. In another visual search task, the second study illustrated that feedback information from each saccadic eye movement could be used to update the model's eye movement policy, generating different patterns in the following saccade. These two studies demonstrate the value of an integrated reinforcement learning model in explaining both top-down and bottom-up processes of eye movements within one computational model. 相似文献
142.
Young-Hun Lim Myung-Eui Song Won-Hee Lee Hui-Je Cho Dae-Sung Bae 《Multibody System Dynamics》2009,22(2):145-162
The paper proposes a multibody dynamic simulation to numerically evaluate the generated axial force (GAF) and plunging resistant
force (PRF) practically related to the shudder and idling vibration of an automobile. A numerical analysis of the drive shaft
coupling of a ball joint (BJ) and two plunging type joints, a tripod joint (TJ), and a very low axial force tripod joint (VTJ),
are conducted using the commercial program DAFUL. User-defined subroutines of a friction model illustrating the contacted
parts of the outboard and inboard joint are subsequently developed to overcome the numerical instability and improve the solution
performance. The Coulomb friction effect is applied to describe the contact models of the lubricated parts in the rolling
and sliding mechanisms. The numerical results, in accordance with the joint articulation angle variation, are validated with
experimentation. The offset between spider and housing is demonstrated to be the critical role in producing the third order
component of the axial force that potentially causes the noise and vibration in the vehicle. The VTJ shows an excellent behavior
for the shudder when compared with the TJ. In addition, a flexible nonlinear contact analysis coupled with multibody dynamics
is also performed to show the dynamic strength characteristics of the rollers, housing, and spider. 相似文献
143.
Coverage is an important performance metric for many applications, such as surveillance in wireless sensor networks. Coverage control is used to select as few active nodes as possible from all deployed sensor nodes, such that sufficient coverage of the monitored area can be guaranteed while reducing the energy consumption of each individual sensor node to prolong the network lifetime. This paper classifies three types of coverage control protocols based on the available information about nodes’ distances or locations, and reviews several representative protocols for each type. We also propose a new distributed and localized coverage control protocol, called Layered Diffusion-based Coverage Control (LDCC). The LDCC protocol does not require information about the node location coordinates when selecting active nodes. Instead, it exploits hop count information, which is easily obtained in a WSN, to select active sensor nodes. Furthermore, the LDCC protocol is very simple and does not require any sophisticated computation such as distance or covered area computation. Our simulation results show that the LDCC protocol achieves a high coverage ratio while incurring very low message overhead compared with other existing protocols. Furthermore, simulation results suggest that in a large-scale sensor network with medium to large localization errors, LDCC performs even better than location-based coverage control protocols. 相似文献
144.
A ring cavity system consisting of two hybrid Michelson interferometers coupled together with feedback is constructed. This system shows spatial bifurcation and can be utilized as an all-optical flip-flop device. We demonstrate experimentally a flip-flop operation by use of only a positive pulse in this system. 相似文献
145.
Changmin Lee Youngjae Hong Dongho Kim Younghwan Lim Jang Wook Choi Sung-Yoon Chung 《Advanced functional materials》2023,33(44):2303763
Protons in aqueous electrolytes can perform as an additional type of charge carrier for insertion/extraction in addition to the primary carrier cations in aqueous rechargeable batteries. Despite many diverse claims regarding the effect of protons, mutually conflicting experimental results and their interpretations without direct evidence have been reported over the last decade. Systematic examinations and analyses are thus imperative to clarify the conditions of proton insertion in aqueous rechargeable batteries. Utilizing V2O5 as a model cathode and beaker-type cells with a sufficient amount of ZnSO4 aqueous electrolytes in this work, it is demonstrated that protons are inserted into the cathode prior to Zn-ions in low-pH conditions (pH ≤ 3.0). In stark contrast, the influence of protons on the discharge voltage and capacity is insignificant, when either the pH becomes higher (pH ≥ 4.0) or the electrolyte volume is considerably low in coin-type cells. Similar behavior of pH-dependent proton insertion is also verified in Na–, Mg–, and Al-ion electrolytes. Providing a resolution to the controversy regarding proton insertion, the present study emphasizes that the influence of protons substantially varies depending on the pH and relative volume of electrolytes in aqueous batteries. 相似文献
146.
Min Seong Kim Yung Lee Junseong Ahn Seonggi Kim Kyungnam Kang Hyuneui Lim Byeong-Soo Bae Inkyu Park 《Advanced functional materials》2023,33(3):2208792
Conventional elastomeric polymers used as substrates for wearable platforms have large positive Poisson's ratios (≈0.5) that cause a deformation mismatch with human skin that is multidirectionally elongated under bending of joints. This causes practical problems in elastomer-based wearable devices, such as delamination and detachment, leading to poorly reliable functionality. To overcome this issue, auxetic-structured mechanical reinforcement with glass fibers is applied to the elastomeric film, resulting in a negative Poisson's ratio (NPR), which is a skin-like stretchable substrate (SLSS). Several parameters for determining the materials and geometrical dimensions of the auxetic-structured reinforcing fillers are considered to maximize the NPR. Based on numerical simulation and digital image correlation analysis, the deformation tendencies and strain distribution of the SLSS are investigated and compared with those of the pristine elastomeric substrate. Owing to the strain-localization characteristics, an independent strain-pressure sensing system is fabricated using SLSS with a Ag-based elastomeric ink and a carbon nanotube-based force-sensitive resistor. Finally, it is demonstrated that the SLSS-based sensor platform can be applied as a wearable device to monitor the physical burden on the wrist in real time. 相似文献
147.
Halder Sajal Lim Kwan Hui Chan Jeffrey Zhang Xiuzhen 《Knowledge and Information Systems》2022,64(4):963-993
Knowledge and Information Systems - Personalized itinerary recommendation has garnered wide research interests for their ubiquitous applications. Recommending personalized itineraries is complex... 相似文献
148.
Zheng Jianbing Gao Ming Lim Ee-Peng Lo David Jin Cheqing Zhou Aoying 《Knowledge and Information Systems》2022,64(7):1967-1996
Knowledge and Information Systems - Network robustness measures how well network structure is strong and healthy when it is under attack, such as vertices joining and leaving. It has been widely... 相似文献
149.
Janina Wirth Kory K. Green Megan O'Connor Shuang F. Lim 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(6)
Upconverting nanoparticles show potential applications in the field of photovoltaics and array‐based detection devices. While fluorescence enhancement using interference of incident radiation is well known in Stokes‐shift type systems such as fluorescent dyes; the effect of such interference geometry in nonlinear Anti‐Stokes type emission, such as in upconversion rare earth photophysics is demonstrated for the first time. This work describes in detail the influence of the interference modulation on both the excitation (interion energy transfer) and radiative decay with nonradiative decay processes active between emissive levels. These effects are illustrated in the thickness dependence of the decay rate and rise time. Single particle upconverted spectra and time‐resolved measurements show concurrent optimization of the infrared absorption and emission at 540 and 650 nm, with an average enhanced emission of 20 times at λ = 540 and 45 times at λ = 650 nm, dependent on the interference layer thickness and on the excitation intensity. The experimental results are correlated with finite element modeling. Both experiments and calculations show emission enhancement at an interference layer thickness of about 740 ± 20 nm, where such tolerance and the planar design, leads to ease in implementation in applications. 相似文献
150.
Yi Huang Lian Xiao Tingting An Wenxiang Lim Teckneng Wong Handong Sun 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(34)
Microfluidic systems have become a superior platform for explorations of fascinating fluidic physics at microscale as well as applications in biomedical devices, chemical reactions, drug delivery, etc. Exploitations of this platform are built upon the fundamental techniques of flow visualizations. However, the currently employed fluorescent materials for microfluidic visualization are far from satisfaction, which severely hinders their widespread applications. Here fluorescent carbon nanodots are documented as a game‐changer, applicable in versatile fluidic environment for the visualization in microfluidics with unprecedented advantages. One of the fastest fluorescent imaging speeds up to 2500 frames per second under a normal contionous wave (CW) laser line is achieved by adopting carbon nanodots in microfluidics. Besides better visualizations of the fluid or interface, fluorescent carbon nanodots‐based microparticles enable quantitative studies of high speed dynamics in fluids at microscale with a more than 90% lower cost, which is inaccessible by traditionally adopted fluorescent dye based seeding particles. The findings hold profound influences to microfluidic investigations and may even lead to revolutionary changes to the relevant industries. 相似文献