全文获取类型
收费全文 | 369篇 |
免费 | 16篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 5篇 |
综合类 | 1篇 |
化学工业 | 81篇 |
金属工艺 | 9篇 |
机械仪表 | 15篇 |
建筑科学 | 6篇 |
能源动力 | 17篇 |
轻工业 | 21篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 64篇 |
一般工业技术 | 101篇 |
冶金工业 | 24篇 |
原子能技术 | 7篇 |
自动化技术 | 36篇 |
出版年
2023年 | 6篇 |
2022年 | 14篇 |
2021年 | 15篇 |
2020年 | 7篇 |
2019年 | 16篇 |
2018年 | 18篇 |
2017年 | 15篇 |
2016年 | 16篇 |
2015年 | 16篇 |
2014年 | 16篇 |
2013年 | 27篇 |
2012年 | 35篇 |
2011年 | 24篇 |
2010年 | 14篇 |
2009年 | 23篇 |
2008年 | 15篇 |
2007年 | 15篇 |
2006年 | 13篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 8篇 |
1997年 | 9篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1975年 | 3篇 |
1973年 | 1篇 |
排序方式: 共有390条查询结果,搜索用时 31 毫秒
101.
P. Chakraborty S.S. Mahato M.K. Bera S.K. Samanta C.K. Maiti 《Microelectronic Engineering》2009,86(3):299-302
Potential of high-k dielectric films for future scaled charge storage non-volatile memory (NVM) device applications is discussed. To overcome the problems of charge loss encountered in conventional flash memories with silicon-nitride (Si3N4) films and polysilicon-oxide-nitride-oxide-silicon (SONOS) and nonuniformity issues in nanocrystal memories (NC), such as Si, Ge and metal, it is shown that the use of high-k dielectrics allows more aggressive scaling of the tunnel dielectric, smaller operating voltage, better endurance, and faster program/erase speeds. Charge-trapping characteristics of high-k AlN films with SiO2 as a blocking oxide in p-Si/SiO2/AlN/SiO2/poly-silicon (SOHOS) memory structures have been investigated in detail. The experimental results of program/erase characteristics obtained as the functions of gate bias voltage and pulse width are presented. 相似文献
102.
TaYOx-based metal-insulator-metal (MIM) capacitors with excellent electrical properties have been fabricated. Ultra-thin TaYOx films in the thickness range of 15-30 nm (EOT ∼ 2.4-4.7 nm) were deposited on Au/SiO2 (100 nm)/Si (100) structures by rf-magnetron co-sputtering of Ta2O5 and Y2O3 targets. TaYOx layers were characterized by X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) to examine the composition and crystallinity. An atomic percentage of Ta:Y = 58.32:41.67 was confirmed from the EDX analysis while XRD revealed an amorphous phase (up to 500 °C) during rapid thermal annealing. Besides, a high capacitance density of ∼3.7-5.4 fF/μm2 at 10 kHz (εr ∼ 21), a low value of VCC (voltage coefficients of capacitance, α and β) have been achieved. Also, a highly stable temperature coefficient of capacitance, TCC has been obtained. Capacitance degradation phenomena in TaYOx-based MIM capacitors under constant current stressing (CCS at 20 nA) have been studied. It is observed that degradation depends strongly on the dielectric thickness and a dielectric breakdown voltage of 3-5 MV/cm was found for TaYOx films. The maximum energy storage density was estimated to be ∼5.69 J/cm3. Post deposition annealing (PDA) in O2 ambient at 400 °C has been performed and further improvement in device reliability and electrical performances has been achieved. 相似文献
103.
P. Bera S. Kapoor Manish K. Khandelwal 《International Journal of Heat and Mass Transfer》2012,55(23-24):7079-7092
In this article, double-diffusive mixed convection in a vertical pipe under local thermal non-equilibrium state has been investigated. The non-Darcy Brinkman–Forchheimer-extended model has been used and solved numerically by spectral collocation method. Special attention is given to understand the effect of buoyancy ratio (N) and thermal non-equilibrium parameters: inter phase heat transfer coefficient (H) as well as porosity scaled thermal conductivity ratio (γ) on the flow profiles as well as on rates of heat and solute transfer. Judged from the influence of buoyancy ratio on velocity profile, when both the buoyancy forces: thermal as well as solutal are in favor of each other and for given any value of H considered in this study, it has been found that for N equal to 10 as well as 100, the basic velocity profile shows back flow for small subdomain of the domain of the flow. When two buoyancy forces are opposing to each other (RaT = ?1000), velocity profile possesses a kind of distortion, in which the number of zeroes increases on increasing N. Corresponding variation of heat transfer rate in the (N, Nuf)-plane shows a sinusoidal pattern. The flow separation on the flow profile dies out on increasing H for N = 0. It has been also found that for each N, when N < 0.7, there exists a minimum value of H such that the velocity profile becomes free from flow separation. Influence of H on the profiles of solid temperature as well as solute, in both situations are similar. Overall, the impact of LTNE parameters, specially γ, on heat transfer rate of double-diffusive convection is not straight forward. 相似文献
104.
105.
Jonathan A. Webb Indrajit Charit 《JOM Journal of the Minerals, Metals and Materials Society》2014,66(6):943-952
The development of the optimum processing path for ultrahigh-temperature W-UO2 cermet fuels is of great importance. While W-UO2 is the main point of interest, as part of a scoping study, a set of experiments was conducted to determine the suitability of spark-plasma sintering (SPS) for producing W-CeO2 specimens with CeO2 serving as a surrogate for UO2 fuel kernels. The experiments confirmed that SPS takes place via diffusional mass transfer; however, the densification process is rapidly accelerated because of the effects of current densities within the consolidating specimen. The SPS process yielded dense W-CeO2 specimens with a finer microstructure than other sintering techniques. The specimens were examined using scanning electron microscopy, energy-dispersive spectroscopy, and electron-backscattered diffraction techniques. Also, great care must be taken to ensure that the particles remain spherical in geometry under the influence of a uniaxial stress as applied during SPS, which involves mixing different fuel kernel sizes to reduce the porosity. Particle mixing techniques are shown to be capable of producing consolidated cermets but with a less than desirable microstructure. The work presented herein will help in the development of high performance cores of very high-temperature reactors for terrestrial and space missions in the future. 相似文献
106.
Ahmed M. Mahmoud Hussein H. Ammar Osama M. Mukdadi Indrajit Ray Fatemeh S. Imani An Chen Julio F. Davalos 《NDT & E International》2010,43(7):635-641
The objective of this work is to utilize surface acoustic waves (SAWs) for non-destructive structural health monitoring of concrete specimens externally bonded with carbon fiber-reinforced polymer (CFRP) composites and subjected to accelerated aging conditions. Both experimental testing and signal processing schemes of ultrasonic wave propagation through the CFRP substrate are described. The surface waves are generated and received at the external face of the CFRP using narrow-band transducers with a 110-kHz center frequency. The received signals are filtered and amplified then digitized and processed to extract various parameters in both time and frequency domains including average power (PAvg), maximum amplitude (Vmax), and maximum power–frequency ratio ((P/F)max). Changes in these parameters due to water-immersion aging at different temperatures were monitored over 12 weeks. Results indicated a marked decrease in measured ultrasonic parameters over time, particularly after the first 2 weeks, indicating a possible debonding or deterioration in the samples. Ultrasonic results showed good agreement with the findings of a parallel destructive study on mode-II fracture loading of CFRP–concrete samples, tested to obtain fracture energy (Gf) and define traction–separation response under temperature and water-immersion aging effects. It was observed that all ultrasonic parameters exhibit good correlations (|r|>0.5, P<0.05) with the fracture energy at all temperatures. Moreover, when the measurements at all temperatures were incorporated and linear relationships between destructive and non-destructive parameters were assumed, correlations of r=0.84, 0.80, and 0.80 were found between Gf and PAvg, Vmax, and (P/F)max, respectively. This study paves the way for developing a non-destructive testing protocol for structural health monitoring of bridges and concrete structures undergoing repair and rehabilitation with CFRP composites. 相似文献
107.
Vandana Bali Manab B. Bera John F. Kennedy 《Critical reviews in food science and nutrition》2016,56(5):817-834
In the modern era, there is great need for food preservation in both developing and developed countries due to increasing demand for extending shelf life and prevention of spoilage of food material. With the emergence of new pathogens and ability of micro-organisms to undergo changes, exploration of new avenues for the food preservation has gained importance. Moreover, awareness among consumers regarding harmful effects of chemical preservatives has been increased. Globally, altogether there is increasing demand by consumers for chemical-free and minimal processed food products. Potential of bacteriocin and its application in reducing the microbiological spoilages and in the preservation of food is long been recognized. Bacteriocins are normally specific to closely related species without disrupting the growth of other microbial populations. A number of applications of bacteriocin have been reported for humans, live stock, aquaculture etc. This review is focused on recent trends and applications of bacteriocins in different areas in addition to their biopreservative potential. 相似文献
108.
ZnO Nanorods on a LaAlO3–SrTiO3 Interface: Hybrid 1D–2D Diodes with Engineered Electronic Properties
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ashok Bera Weinan Lin Yingbang Yao Junfeng Ding James Lourembam Tom Wu 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(6):802-809
Integrating nanomaterials with different dimensionalities and properties is a versatile approach toward realizing new functionalities in advanced devices. Here, a novel diode‐type heterostructure is reported consisting of 1D semiconducting ZnO nanorods and 2D metallic LaAlO3–SrTiO3 interface. Tunable insulator‐to‐metal transitions, absent in the individual components, are observed as a result of the competing temperature‐dependent conduction mechanisms. Detailed transport analysis reveals direct tunneling at low bias, Fowler–Nordheim tunneling at high forward bias, and Zener breakdown at high reverse bias. Our results highlight the rich electronic properties of such artificial diodes with hybrid dimensionalities, and the design principle may be generalized to other nanomaterials. 相似文献
109.
Margi Jani Dhyey Raval Ranjan Kumar Pati Indrajit Mukhopadhyay Abhijit Ray 《Bulletin of Materials Science》2018,41(1):22
Spray-pyrolysed zinc oxy-sulphide Zn(O,S) has been doped with varying concentrations of indium (In) to improve its electrical and optical properties for possible application as buffer layer in thin film solar cells. The In-doping in Zn(O,S) is found to change the electron carrier concentration from \(10^{19}\) to \(10^{18}\,\hbox {cm}^{-3}\) and a subsequent annealing in argon atmosphere is found to improve its electrical conductivity. Moreover, annealing in air atmosphere reduces the carrier concentration to a range of \(10^{13}\)–\(10^{15}\,\hbox {cm}^{-3}\) making it useful as a buffer layer. The reduction in degeneracy of In-doped Zn(O,S) is desirable for its application as buffer material, whereas annealing in argon makes it suitable as electron membrane (window layer) in thin film solar cell. 相似文献
110.
S. Viswanathan L. Mohan Manjusha Chakraborty Chitra Mandal Parthasarathi Bera 《Materials and Manufacturing Processes》2018,33(10):1121-1127
Carbon plasma immersion ion implantation (PIII-C) has been performed on Ni?Ti alloy surface using methane as a precursor gas at low temperature and it has been followed by deposition of diamond-like carbon (DLC) coating. Untreated and coated alloys are characterized with field emission scanning electron microscopy, atomic force microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Electrochemical impedance spectroscopy, and corrosion testing in Hanks’ solution which is simulated body fluid show that corrosion resistance has been enhanced in PIII-C?+?DLC-coated alloy compared to untreated alloy. The in vitro studies of untreated and PIII-C?+?DLC-coated alloys have been evaluated using osteoblast-like cells (MG-63). Cellular behavior in terms of cell morphology along with the viability and cell spreading has been evaluated using scanning electron microscopy and in vitro cell culture assay, respectively. In comparison to Ni–Ti alloy, the coated alloy exhibits better cell viability indicating their biocompatibility. 相似文献