全文获取类型
收费全文 | 1995篇 |
免费 | 134篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 37篇 |
综合类 | 4篇 |
化学工业 | 480篇 |
金属工艺 | 72篇 |
机械仪表 | 105篇 |
建筑科学 | 29篇 |
能源动力 | 64篇 |
轻工业 | 204篇 |
水利工程 | 6篇 |
无线电 | 382篇 |
一般工业技术 | 404篇 |
冶金工业 | 131篇 |
原子能技术 | 25篇 |
自动化技术 | 195篇 |
出版年
2024年 | 3篇 |
2023年 | 33篇 |
2022年 | 44篇 |
2021年 | 75篇 |
2020年 | 61篇 |
2019年 | 74篇 |
2018年 | 64篇 |
2017年 | 69篇 |
2016年 | 77篇 |
2015年 | 59篇 |
2014年 | 87篇 |
2013年 | 132篇 |
2012年 | 128篇 |
2011年 | 151篇 |
2010年 | 111篇 |
2009年 | 105篇 |
2008年 | 109篇 |
2007年 | 79篇 |
2006年 | 83篇 |
2005年 | 72篇 |
2004年 | 63篇 |
2003年 | 50篇 |
2002年 | 61篇 |
2001年 | 51篇 |
2000年 | 44篇 |
1999年 | 42篇 |
1998年 | 60篇 |
1997年 | 40篇 |
1996年 | 23篇 |
1995年 | 11篇 |
1994年 | 10篇 |
1993年 | 12篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1976年 | 3篇 |
1973年 | 1篇 |
排序方式: 共有2138条查询结果,搜索用时 15 毫秒
141.
142.
Won-Jae Lee Guoxia Liu Byoung-Chul Shin Geun-Hyoung Lee Il-Soo Kim Nam-Yeal Lee Sang-Ouk Ryu Woong-Chul Shin Jae-Man Lee Jindong Kim 《Journal of Electroceramics》2004,13(1-3):71-75
The phase formation and electrical properties of (Bi, La)4Ti3O12 (BLT) thin film and V-, Sm-doped BLT thin films prepared by the chemical solution deposition method on Pt/TiO2/SiO2/Si substrates have been investigated. It was observed that the microstructure and electrical properties of BLT thin films dramatically varied with V- and Sm-doping. The crystallinity and grain size of BLT thin films were definitely increased by V- and Sm-doping into BLT films, which resulted in the enhancement of remanent polarization in doped BLT films. The remanent polarization (Pr) of Sm-doped BLT films annealed for 3 min by an RTA system was about 9 C/cm2. The V- and Sm-doped BLT films also exhibited good fatigue characteristics under bipolar stressing to 1010 cycles. 相似文献
143.
The interrelationship between defect chemistry, non-stoichiometry, grain boundary transport and chemical stability of proton conducting perovskites (doped alkaline earth cerates and zirconates) has been investigated. Non-stoichiometry, defined as the deviation of the A : M molar ratio in AMO3 from 1 : 1, dramatically impacts conductivity, sinterability and chemical stability with respect to reaction with CO2. In particular, alkaline earth deficiency encourages dopant incorporation onto the A-atom site, rather than the intended M-atom site, reducing the concentration of oxygen vacancies. Transport along grain boundaries is, in general, less favorable than transport through the bulk, and thus only in fine-grained materials does microstructure impact the overall electrical properties. The chemical stability of high conductivity cerates is enhanced by the introduction of Zr. The conductivity of BaCe0.9–x
Zr
x
M0.1O3 perovskites monotonically decreases with increasing x (increasing Zr content), with the impact of Zr substitution increasing in the order M = Yb Gd Nd. Furthermore, the magnitude of the conductivity follows the same sequence for a given zirconium content. This result is interpreted in terms of dopant ion incorporation onto the divalent ion site. 相似文献
144.
We show that the maximum penetration depth of the anomalous quasiclassical Green's function from a superconductor into an adjacent normal metal is directly related to the phase relaxation time
. The latter describes normal-metal phase correlations between two electrons with opposite spins. In the presence of spin-dependent interactions this phase relaxation time differs from the one found in weak localization corrections to the conductivity. The Josephson current measurements in a SINIS-structure could be used to determine
experimentally. 相似文献
145.
So-Hyun Ryu Hyung-Jun Kim Jin-Sung Park Yong-won Kwon Chang-Sung Jeong 《Multimedia Tools and Applications》2007,32(2):209-234
In this paper, we present a Collaborative Object-oriented Visualization Environment (COVE) which provides a flexible and extensible
framework for collaborative visualization. COVE integrates collaborative and parallel computing environments based on a distributed
object model. It is built as a collection of concurrent objects: collaborative and application objects which interact with
one another to construct collaborative parallel computing environments. The former enables COVE to execute various collaborative
functions, while the latter allows it to execute fast parallel visualization in various modes. Also, flexibility and extensibility
are provided by plugging the proper application objects into COVE at run-time, and making them interact with one another through
collaboration objects. For our experiment, three visualization modes for volume rendering are designed and implemented to
support the fast and flexible analysis of volume data in a collaborative environment.
This work has been supported by KIPA-Information Technology Research Center, University research program by Ministry of Information
& Communication, and Brain Korea 21 projects in 2005. 相似文献
146.
Donggyu Lee Daehee Lee Yulim Won Hyeonaug Hong Yongjae Kim Hyunwoo Song Jae‐Chul Pyun Yong Soo Cho Wonhyoung Ryu Jooho Moon 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(11):1446-1457
Effective insertion of vertically aligned nanowires (NWs) into cells is critical for bioelectrical and biochemical devices, biological delivery systems, and photosynthetic bioenergy harvesting. However, accurate insertion of NWs into living cells using scalable processes has not yet been achieved. Here, NWs are inserted into living Chlamydomonas reinhardtii cells (Chlamy cells) via inkjet printing of the Chlamy cells, representing a low‐cost and large‐scale method for inserting NWs into living cells. Jetting conditions and printable bioink composed of living Chlamy cells are optimized to achieve stable jetting and precise ink deposition of bioink for indentation of NWs into Chlamy cells. Fluorescence confocal microscopy is used to verify the viability of Chlamy cells after inkjet printing. Simple mechanical considerations of the cell membrane and droplet kinetics are developed to control the jetting force to allow penetration of the NWs into cells. The results suggest that inkjet printing is an effective, controllable tool for stable insertion of NWs into cells with economic and scale‐related advantages. 相似文献
147.
An increasingly widespread interest in developing fully adaptable e-learning systems (e.g., intelligent tutoring systems) has led to the development of a wide range of adaptive processes and techniques. In particular, advances in these systems are based on optimization for each user's learning style and characteristics, to enable a personalized learning experience. Current techniques are aimed at using a learner's personality traits and its effect on learning preferences to improve both the initial learning experience and the information retained (e.g., top-down or bottom-up learning organization). This study empirically tested the relationship between a learner's personality traits, analyzed the effects of these traits on learning preferences, and suggested design guidelines for adaptive learning systems. Two controlled experiments were carried out in a computer-based learning session. Our first experiment showed a significant difference in the learning performance of participants who were identified as introverts vs. those who were identified as being extroverts, according to the MBTI scale. As the distinction between extroverted personality types vs. introverted personality types showed the strongest correlation in terms of different learning styles, we used this criteria in our second experiment to determine whether design guidelines for appropriate content organization could reinforce the aforementioned correlation between personality type and learning experience. 相似文献
148.
S. Manivannan Je Hwang Ryu Han Eol Lim M. Nakamoto Jin Jang Kyu Chang Park 《Journal of Materials Science: Materials in Electronics》2010,21(1):72-77
Transparent conducting single-walled carbon nanotube (SWCNT) films were fabricated using the spin coating technique. UV-ozone
treated and poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) coated glass substrates together with SWCNT
dispersed in 1,2-dichlorobenzene were used to promote the adhesion of SWCNT at room temperature. The produced film had a sheet
resistance of 430 Ω/□ for 80% optical transparency at 550 nm. The spin coated SWCNT film after a post fabricated treatment
in a mixer of isopropyl alcohol and nitric acid solution had a sheet resistance as low as 120 Ω/□ for 80% optical transparency
at 500 nm. Besides reduction in sheet resistance, we obtained stable and strongly adherent SWCNT films on substrate that could
serve as an alternative to transparent conducting oxides in display and optoelectronic applications. 相似文献
149.
Hyun Jin Ryu Kyeong Keun Oh Young Soo Kim 《Journal of Industrial and Engineering Chemistry》2009,15(4):471-475
Microalgae fix CO2 as energy source and afford biomass and high valued products such as carotenoids, pigments, proteins, and vitamins that can be used for the production of nutraceuticals, pharmaceuticals, animal feed additives, cosmetics, etc. Carbon dioxide is the sole source of carbon and it is supplied continuously for the microalgal cultivation. But undissolved CO2 is lost by outgassing and sufficient dissolved CO2 should be provided to avoid carbon limitation. The effect of CO2 mass transfer with different CO2 concentrations, aeration rate of gas, bubble size, baffle type and baffle number on the growth of Chlorella sp. AG10002 was investigated and the optimized conditions for the enhancement of biomass productivity were determined. We confirm that these results can be provided as basic data to improve the CO2 mass transfer ability for the high density culture of Chlorella sp. and some microalgae having commercial value. 相似文献
150.
Development and application of gas hydrate reservoir simulator based on depressurizing mechanism 总被引:6,自引:0,他引:6
Won-Mo Sung Dae-Gee Huh Byong-Jae Ryu Ho-Seob Lee 《Korean Journal of Chemical Engineering》2000,17(3):344-350
Natural gas hydrates are known to occur in vast quantities at the ocean floor or in permafrost regions. In-situ hydrate contains
great volumes of methane gas, which indicates a potential future energy resource. In this study, we have developed a three-dimensional,
multi-phase (gas, water, and hydrate) flow finite-difference model by using implicit pressure explicit saturation technique
in order to investigate simultaneous flow through ice-liked hydrate reservoir. The developed model is based on the depressurizing
method as producing mechanism. The model evaluates local gas generation dissociated from the hydrate with the aid of kinetic
dissociation theory proposed by Kim-Bishnoi. The computation of kinetic dissociation uses the empirical dissociation rate
as a function of specific surface area between phases and pressure difference. With the developed model, a one-dimensional
system has been simulated for analyzing the production performance of a hydrate reservoir and for investigating the effect
of hydrate saturation on absolute permeability and relative permeability characteristics. Also, for the three-dimensional
field-scaled reservoir system, a number of numerical exercises have been conducted to understand the effect of mass transfer
and to characterize the flowing mechanism under the conditions of increased permeability resulting from the dissociation hydrate. 相似文献