全文获取类型
收费全文 | 854篇 |
免费 | 88篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 172篇 |
金属工艺 | 45篇 |
机械仪表 | 72篇 |
建筑科学 | 12篇 |
能源动力 | 35篇 |
轻工业 | 109篇 |
水利工程 | 7篇 |
石油天然气 | 1篇 |
无线电 | 129篇 |
一般工业技术 | 221篇 |
冶金工业 | 54篇 |
原子能技术 | 12篇 |
自动化技术 | 64篇 |
出版年
2024年 | 3篇 |
2023年 | 22篇 |
2022年 | 23篇 |
2021年 | 32篇 |
2020年 | 18篇 |
2019年 | 33篇 |
2018年 | 43篇 |
2017年 | 33篇 |
2016年 | 41篇 |
2015年 | 43篇 |
2014年 | 58篇 |
2013年 | 64篇 |
2012年 | 86篇 |
2011年 | 84篇 |
2010年 | 54篇 |
2009年 | 50篇 |
2008年 | 40篇 |
2007年 | 40篇 |
2006年 | 24篇 |
2005年 | 32篇 |
2004年 | 16篇 |
2003年 | 24篇 |
2002年 | 11篇 |
2001年 | 10篇 |
2000年 | 7篇 |
1999年 | 7篇 |
1998年 | 13篇 |
1997年 | 11篇 |
1996年 | 8篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1990年 | 2篇 |
1987年 | 3篇 |
排序方式: 共有943条查询结果,搜索用时 624 毫秒
41.
Shankara S. Kalanur Jaewoo Heo Il-Han Yoo Hyungtak Seo 《International Journal of Hydrogen Energy》2017,42(26):16901-16908
The ultrathin two-dimensional (2D) nanomaterials display unique properties owing to their ultrahigh specific surface area and strong quantum confinement of electrons in two dimensions. In this work, we fabricated a rapid gasochromic and electrical hydrogen sensing system containing 2D WO3 and Pd nanoparticles. 2D WO3 nano-plates (NP) are synthesized using sol–gel method and Pd nanoparticles are coated on WO3 by green photochemical deposition method. The sensor is fabricated by dispersing the 2D WO3/Pd composite on filter paper. In presence of hydrogen gas, 2D WO3/Pd composite produces visible change in color from brown to dark blue. With the fabricated sensor, as low as 0.1% H2 gas in air at room temperature can be easily detected using electrical sensing scheme whereas for higher concentration from 1 to 100%, eye readable gasochromic scheme can be utilized. The use of 2D WO3 decreased the response time in great deal compared to WO3 nanoparticles indicating the advantage of 2D structure in fabricating rapid response H2 sensors. The proposed method is simple and can be easily employed to large scale fabrication system for commercial applications. 相似文献
42.
Hwa-Jong Lee Jung-A Lee Joon-Hyung Lee Young-Woo Heo Jeong-Joo Kim Seong-Kee Park Jungshik Lim 《Ceramics International》2012
In this study, different amounts of Mg were doped in In2O3(Zn1−xMgxO)3 and their thin films were grown by using the RF magnetron sputtering method. The optical and electrical characteristics of the films revealed that the lattice constant decreased while the optical band gap increased as the Mg content increased, showing an inverse proportional relationship with each other. Therefore, it was found that Mg doping in indium zinc oxide (IZO) is also effective for band gap modulation as it was reported in a Mg-doped ZnO system. When IZO thin films were grown in a more reducing ambient, the carrier concentration increased which resulted in the increase of band gap energy. This was explained due to the Burstein–Moss effect. 相似文献
43.
Seok Heo Geum Joo Yoo Ji Yeon Choi Hyoung Joon Park Sung-Kwan Park 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2016,33(11):1627-1636
A novel, stable, simple and specific ultra-performance liquid chromatography method with ultraviolet detection (205 nm) for the simultaneous analysis of 25 anti-hypertensive substances was developed. The method was validated according to the International Conference of Harmonisation guidelines with respect to linearity, accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ) and stability. From the ultra-performance liquid chromatography results, we identified the LOD and LOQ of solid samples to be 0.20–1.00 and 0.60–3.00 μg ml?1, respectively, while those of liquid samples were 0.30–1.20 and 0.90–3.60 μg ml?1, respectively. The linearity exceeded 0.9999, and the intra- and inter-day precisions were 0.15–6.48% and 0.28–8.67%, respectively. The intra- and inter-day accuracies were 82.25–111.42% and 80.70–115.64%, respectively, and the stability was lower than 12.9% (relative standard deviation). This method was applied to the monitoring of 97 commercially available dietary supplements obtained in Korea, such as pills, soft capsules, hard capsules, liquids, powders and tablets. The proposed method is accurate, precise and of high quality, and can be used for the routine, reproducible analysis and control of 25 anti-hypertensive substances in various dietary supplements. The work presented herein may help to prevent incidents related to food adulteration and restrict the illegal food market. 相似文献
44.
Miniaturized Flexible Electronic Systems with Wireless Power and Near‐Field Communication Capabilities
下载免费PDF全文
![点击此处可从《Advanced functional materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jeonghyun Kim Anthony Banks Zhaoqian Xie Seung Yun Heo Philipp Gutruf Jung Woo Lee Sheng Xu Kyung‐In Jang Fei Liu Gregory Brown Junghyun Choi Joo Hyun Kim Xue Feng Yonggang Huang Ungyu Paik John A. Rogers 《Advanced functional materials》2015,25(30):4761-4767
A class of thin, lightweight, flexible, near‐field communication (NFC) devices with ultraminiaturized format is introduced, and systematic investigations of the mechanics, radio frequency characteristics, and materials aspects associated with their optimized construction are presented. These systems allow advantages in mechanical strength, placement versatility, and minimized interfacial stresses compared to other NFC technologies and wearable electronics. Detailed experimental studies and theoretical modeling of the mechanical and electromagnetic properties of these systems establish understanding of the key design considerations. These concepts can apply to many other types of wireless communication systems including biosensors and electronic implants. 相似文献
45.
A low-cost broadband millimetre-wave planar 30/spl times/30 array antenna is presented. The antenna is fed by a microstrip feed network in the H-plane to decrease fabrication costs, and a waveguide feed network in the E-plane to reduce the feed line loss. The waveguide and microstrip feed network are coupled through the proposed slot pair. The slots are placed one quarter of a guided-wavelength distance apart, so that the reflected waves from the slots cancel each other. A conductive bar is laid above the slots to increase the coupling, which increases the antenna gain by about 1 dBi. The maximum gain is 30.5 dBi at 41.5 GHz. The measured bandwidth is as broad as 7.1%. 相似文献
46.
Chang Hwa Jung Jiyun Ahn Seok Hyun Heo Tae-Youl Ha 《Food science and biotechnology》2014,23(3):889-893
In this study, we investigated the anti-adipogenic effects of Eleutherococcus senticosus and its active compounds in vitro to examine new functions. We first analyzed the active compounds in E. senticosus growing in Korea using HPLC and found that the concentration of eleutheroside B and E was higher in stems and roots than in other plant parts. There were no significant (p<0.05) differences in eleutheroside concentration between plant ages. Anti-adipogenic effects of E. senticosus on lipid accumulation in 3T3-L1 cells were examined. Extracts of stems and roots more effectively inhibited lipid accumulation in 3T3-L1 cells than extracts of other plant parts. Eleutheroside E was responsible for the pharmacological anti-adipogenic effects via regulation of the mTOR pathway. This is the first report of an anti-adipogenic effect of E. senticosus and the active compound eleutheroside E. 相似文献
47.
48.
Mixed-effects linear regression models have become more widely used for analysis of repeatedly measured outcomes in clinical trials over the past decade. There are formulae and tables for estimating sample sizes required to detect the main effects of treatment and the treatment by time interactions for those models. A formula is proposed to estimate the sample size required to detect an interaction between two binary variables in a factorial design with repeated measures of a continuous outcome. The formula is based, in part, on the fact that the variance of an interaction is fourfold that of the main effect. A simulation study examines the statistical power associated with the resulting sample sizes in a mixed-effects linear regression model with a random intercept. The simulation varies the magnitude (Δ) of the standardized main effects and interactions, the intraclass correlation coefficient (ρ), and the number (k) of repeated measures within-subject. The results of the simulation study verify that the sample size required to detect a 2×2 interaction in a mixed-effects linear regression model is fourfold that to detect a main effect of the same magnitude. 相似文献
49.
With the development of nanomaterial-based nanodevices, it became inevitable to develop cost-effective and simple nanofabrication technologies enabling the formation of nanomaterial assembly in a controllable manner. Herein, we present suspended monolithic carbon single nanowires and nanomeshes bridging two bulk carbon posts, fabricated in a designed manner using two successive UV exposure steps and a single pyrolysis step. The pyrolysis step is accompanied with a significant volume reduction, resulting in the shrinkage of micro-sized photoresist structures into nanoscale carbon structures. Even with the significant elongation of the suspended carbon nanowire induced by the volume reduction of the bulk carbon posts, the resultant tensional stress along the nanowire is not significant but grows along the wire thickness; this tensional stress gradient and the bent supports of the bridge-like carbon nanowire enhance structural robustness and alleviate the stiction problem that suspended nanostructures frequently experience. The feasibility of the suspended carbon nanostructures as a sensor platform was demonstrated by testing its electrochemical behavior, conductivity-temperature relationship, and hydrogen gas sensing capability. 相似文献
50.
Young-Sun Heo Jay G. Sanjayan Cheon-Goo Han Min-Cheol Han 《Construction and Building Materials》2011,25(6):2928-2938
In this paper, a construction application of a technique to improve the fire resistance of high strength concrete is presented. Before the construction application, fire tests of three hours duration were carried out in accordance with ISO-834. Three types of mitigating methods, namely, a specimen with no protection (control), with fireproof panel protection and with the combination of polypropylene fibre reinforcement and metal mesh confinement (Fibre/Mesh), were applied to full sized columns for comparison purposes. The fire resistance performance of all columns was tested under loads. After the fire tests, the severity of spalling of specimens was assessed, and the best performing technique, Fibre/Mesh, for spalling protection was selected for an application in practice. The process of the construction application is described in detail, including pumping, pouring and compacting of the concrete. The concrete quality was examined and the behaviour of the concrete was observed. Consequently, it was verified that this new spalling resistance technique is feasible in practice. 相似文献