全文获取类型
收费全文 | 669篇 |
免费 | 56篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 10篇 |
综合类 | 1篇 |
化学工业 | 166篇 |
金属工艺 | 12篇 |
机械仪表 | 60篇 |
建筑科学 | 12篇 |
矿业工程 | 1篇 |
能源动力 | 25篇 |
轻工业 | 79篇 |
水利工程 | 2篇 |
无线电 | 132篇 |
一般工业技术 | 126篇 |
冶金工业 | 27篇 |
原子能技术 | 6篇 |
自动化技术 | 67篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 13篇 |
2021年 | 23篇 |
2020年 | 28篇 |
2019年 | 25篇 |
2018年 | 33篇 |
2017年 | 36篇 |
2016年 | 34篇 |
2015年 | 18篇 |
2014年 | 16篇 |
2013年 | 51篇 |
2012年 | 41篇 |
2011年 | 73篇 |
2010年 | 32篇 |
2009年 | 44篇 |
2008年 | 34篇 |
2007年 | 26篇 |
2006年 | 29篇 |
2005年 | 28篇 |
2004年 | 17篇 |
2003年 | 13篇 |
2002年 | 16篇 |
2001年 | 5篇 |
2000年 | 8篇 |
1999年 | 9篇 |
1998年 | 11篇 |
1997年 | 9篇 |
1996年 | 12篇 |
1995年 | 10篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1979年 | 1篇 |
1976年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有726条查询结果,搜索用时 31 毫秒
121.
Kim S Shin DO Choi DG Jeong JR Mun JH Yang YB Kim JU Kim SO Jeong JH 《Small (Weinheim an der Bergstrasse, Germany)》2012,8(10):1563-1569
A highly efficient, ultralarge-area nanolithography that integrates block-copolymer lithography with single-step ZnO nanoimprinting is introduced. The UV-assisted imprinting of a photosensitive sol-gel precursor creates large-area ZnO topographic patterns with various pattern shapes in a single-step process. This straightforward approach provides a smooth line edge and high thermal stability of the imprinted ZnO pattern; these properties are greatly advantageous for further graphoepitaxial block-copolymer assembly. According to the ZnO pattern shape and depth, the orientation and lateral ordering of self-assembled cylindrical nanodomains in block-copolymer thin films could be directed in a variety of ways. Significantly, the subtle tunability of ZnO trench depth enabled by nanoimprinting, generated complex hierarchical nanopatterns, where surface-parallel and surface-perpendicular nanocylinder arrays are alternately arranged. The stability of this complex morphology is confirmed by self-consistent field theory (SCFT) calculations. The highly ordered graphoepitaxial nanoscale assembly achieved on transparent semiconducting ZnO substrates offers enormous potential for photonics and optoelectronics. 相似文献
122.
123.
Kyung Chul Cho Dong Jun Mun Jin Young Kim Joong Kil Park Jae Sang Lee Yang Mo Koo 《Metallurgical and Materials Transactions A》2010,41(6):1421-1428
The effect of boron (B) precipitation behavior on the hot ductility of B containing steel was investigated. Hot ductility
of B containing steel was sensitive to the cooling rate (CR) in the range of 1 to 20 K/s (1 to 20 °C/s), whereas that of B-free
steel showed little change with CR. Increased CR causes deepening and widening of the ductility trough in B containing steel.
Particle tracking autoradiography (PTA) analysis and transmission electron microscope (TEM) image of the samples show that
boron nitride (BN) particles form along prior austenite grain boundaries, and that as CR increases, these particles become
smaller and more numerous. This increase in the number of small BN precipitates may promote intergranular fracture, leading
to a decrease in hot ductility in the lower austenite temperature region (1173 to 1273 K (900 to 1000 °C)). Furthermore, the
formation of filmlike ferrite at ~1123 K (850 °C) causes a decrease in the hot ductility of this steel regardless of B addition
and CR. 相似文献
124.
How to efficiently integrate and manage lifecycle data of a nuclear power plant has gradually become an important object of study. Because plants usually have a very long period of operation and maintenance, the plant design data need to be presented in a computer-interpretable form and to be independent of any commercial systems. The conversion of plant design data from various design systems into neutral model data is therefore an important technology for the effective operation and maintenance of plants. In this study, a neutral model for the efficient integration of plant design data is chosen from among the currently available options and extended in order to cover the information model requirements of nuclear power plants in Korea. After the mapping of the neutral model and the data model of a specification-driven plant design system, a plant data translator is also implemented in accordance with the schema mapping results. 相似文献
125.
Bongjin S. Mun Zhi Liu Md Abdul Motin Probir C. Roy Chang Min Kim 《International Journal of Hydrogen Energy》2018,43(18):8655-8661
The interaction of H2 molecules with a ZnO (0001) single crystal surface has been studied over a wide pressure (10?6–0.25 Torr) and temperature (300–600 K) range using ambient pressure X-ray photoelectron spectroscopy (AP-XPS). ZnO is well-known for interstitial hydrogen and hydrogen atoms in ZnO are believed to be incorporated by the dissociative adsorption of H2 molecules in the atmosphere and their subsequent diffusion into the bulk. The dissociative adsorption of H2 has been investigated at elevated pressures because H2 molecules are not dissociated on the ZnO single crystal surface under ultrahigh vacuum (UHV) conditions. When the pressure is increased to several mTorr, the dissociative adsorption of H2 takes place to form OH bonds on the surface. At 0.25 Torr, the ZnO surface is saturated with H atoms and the coverage is estimated to be 1.1 × 1015 atoms/cm2 at 300 K. At higher surface temperatures, the equilibrium between the dissociative adsorption of gas-phase H2 molecules and the associative desorption of surface H atoms is established. While maintaining the equilibrium, the surface has been monitored successfully in situ by utilizing AP-XPS. 相似文献
126.
Ki Young Lee Ki-Young Shin Hyo Shin Kim Joung Hwan Mun 《International Journal of Precision Engineering and Manufacturing》2009,10(3):147-153
The principal objective of this study was to estimate biceps brachii muscle fatigue using the fatiguing time (FT) and the
initial slope (Sinit) of the high to low frequency band ratio (H/LFB) in EMG during isotonic exercise until the endurance time (ET) at which the
subject could no longer follow the fixed speed. Surface EMG was measured on the biceps brachii muscle of ten subjects (5 males
and 5 females) as the subject performed repetitive elbow contraction tasks. The first task was with no load (“no load” task).
The other tasks were performed until exhaustion (“load” task) with a load weighted at 10%, 20% and 30% of the subject’s maximum
voluntary contraction (MVC). We extracted decreasing parameters of the EMG, such as median frequency (MDF) and three types
of H/LFB (H1; 95∼500Hz, H2; 150∼350Hz, H3; 470∼500Hz and LFB; 15∼45Hz). Statistical analysis was conducted to select an appropriate
parameter. The FT was defined as the time at which the selected H/LFB became smaller than the threshold (50% at 10% MVC, 60%
at 20% MVC, and 65% at 30% MVC) with respect to the initial value, and Sinit was defined as the slope of the linear regression line using H/LFB from the onset of exercise to FT. In order to predict
ET, we proposed using an analytical method that employed a multiple linear regression model with two independent variables,
FT and Sinit. The results from this novel model were compared with those of previously established methods. In the “no load” task, there
was no FT in the MDF and three H/LFBs. In the “load” task, the MDF and three H/LFBs gradually decreased, but the H3/LFB decreased
most rapidly. A significant difference between the “no load” task and the “load” task at a 95% significant level was only
observed in H3/LFB. ETs of all subjects were predicted at an error of approximately 30.4%. This error was better than that
obtained using other methods (34.8% by Mathiassen’s method, 39.7% by Ma?setti’s method). FT detected from H3/LFB was a useful
indicator to distinguish the EMG in the “load” task from that observed in the “no load” task, and the ET of a subject could
be predicted using FT and Sinit. Therefore, the H3/LFB provides more information on muscle fatigue than the other features under isotonic conditions, and
may be suited to specific experimental protocols in workplace fatigue studies. 相似文献
127.
Min Ho Kim Yun Chan Kang Sang Mun Jeong Yun Ju Choi Yang Soo Kim 《Materials Chemistry and Physics》2013
Nanosized 0.6Li2MnO3·0.4LiCoO2 composite cathode powders are prepared by spray pyrolysis. The micron-sized composite powders are converted into nanosized powders by a simple milling process. The mean sizes of the composite powders measured from the TEM images increase from 20 to 170 nm when the post-treatment temperatures increase from 650 to 900 °C. The Brunauer–Emmett–Teller surface areas of the composite powders post-treated at 650 and 900 °C are 24 and 3 m2 g−1, respectively. The XRD patterns indicate that the layered composite powders post-treated at 800 and 900 °C have high crystallinity and low cation mixing. The mean crystallite sizes of the powders, measured from the (003) peak widths of the XRD patterns using Scherrer's equation, are 35 and 56 nm at post-treatment temperatures of 800 and 900 °C, respectively. The initial discharge capacities of the 0.6Li2MnO3·0.4LiCoO2 composite are 262, 267, 264, and 263 mAh g−1 when the post-treat temperatures of the powders are 650, 700, 800, and 900 °C, respectively. The discharge capacity of the composite powders post-treated at 900 °C abruptly decreases from 263 to 214 mAh g−1 by the seventh cycle and then slowly decreases to 198 mAh g−1 with increasing cycle number, up to 30. 相似文献
128.
Anand Bhojan Ananda L. Akhihebbal Mun Choon Chan Rajesh Krishna Balan 《Mobile Networks and Applications》2012,17(1):21-28
With the improved processing power, graphic quality and high-speed wireless connection in recent generations of mobile phones,
it looks more attractive than ever to introduce networked games on these devices. However, these games consume higher levels
of energy. While device features and application resource requirements are rapidly growing, the battery technologies are not
growing at the same pace. Therefore, the main concern is the limitation of the battery power of such portable devices to support
potentially long-hour of game play. In this paper we present ARIVU, a scalable power aware middleware that dynamically controls
the energy consumption of wireless interface based on the game and system state while maintaining the user experience. The
middleware is able to save up to 60% of the total energy consumed by the 802.11 g wireless interfaces for First Person Shooting
(FPS) games and up to 35% of the total energy for Massively Multiplayer Online Role Playing Games (MMORPG). 相似文献
129.
Acacia auriculiformis heartwood and bark were obtained, dried under shelter for 2 weeks and pulverized into powdered form to be extracted with the following extraction temperatures of 35, 55 and 75 °C and methanol solvent percentages of 55, 65 and 75 % for 3 h in a water bath. The material ratio used was 1:20 (pulverized samples: solvent). The total phenolics and flavonoids yield was determined by using a Thermo Scientific Genesys 10 UV–Visible Spectrophotometer. The optimum total phenolics and flavonoids yield were achieved by extraction with an extraction temperature of 75 °C and a methanol solvent percentage of 75 % for both the heartwood [75.44 % (total phenolics) and 36.64 % (total flavonoids)] and bark [87.18 % (total phenolics) and 99.10 % (total flavonoids)] of A. auriculiformis trees. 相似文献
130.
Flexible electronic and photonic devices have been demonstrated in the past decade, with significant promise in low-cost, light-weighted, transparent, biocompatible, and portable devices for a wide range of applications. Herein, we demonstrate a flexible metamaterial (Metaflex)-based photonic device operating in the visible-IR regime, which shows potential applications in high sensitivity strain, biological and chemical sensing. The metamaterial structure, consisting of split ring resonators (SRRs) of 30 nm thick Au or Ag, has been fabricated on poly(ethylene naphthalate) substrates with the least line width of ~30 nm by electron beam lithography. The absorption resonances can be tuned from middle IR to visible range. The Ag U-shaped SRRs metamaterials exhibit an electric resonance of ~542 nm and a magnetic resonance of ~756 nm. Both the electric and magnetic resonance modes show highly sensitive responses to out-of-plane bending strain, surrounding dielectric media, and surface chemical environment. Due to the electric and magnetic field coupling, the magnetic response gives a sensitivity as high as 436 nm/RIU. Our Metaflex devices show superior responses with a shift of magnetic resonance of 4.5 nm/nM for nonspecific bovine serum albumin protein binding and 65 nm for a self-assembled monolayer of 2-naphthalenethiol, respectively, suggesting considerable promise in flexible and transparent photonic devices for chemical and biological sensing. 相似文献