全文获取类型
收费全文 | 648篇 |
免费 | 9篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 9篇 |
化学工业 | 122篇 |
金属工艺 | 5篇 |
机械仪表 | 19篇 |
建筑科学 | 27篇 |
能源动力 | 12篇 |
轻工业 | 20篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 165篇 |
一般工业技术 | 79篇 |
冶金工业 | 56篇 |
原子能技术 | 3篇 |
自动化技术 | 141篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 6篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 5篇 |
2017年 | 9篇 |
2016年 | 2篇 |
2015年 | 8篇 |
2014年 | 7篇 |
2013年 | 47篇 |
2012年 | 27篇 |
2011年 | 27篇 |
2010年 | 28篇 |
2009年 | 33篇 |
2008年 | 27篇 |
2007年 | 28篇 |
2006年 | 42篇 |
2005年 | 30篇 |
2004年 | 24篇 |
2003年 | 19篇 |
2002年 | 19篇 |
2001年 | 20篇 |
2000年 | 12篇 |
1999年 | 25篇 |
1998年 | 27篇 |
1997年 | 19篇 |
1996年 | 23篇 |
1995年 | 21篇 |
1994年 | 16篇 |
1993年 | 11篇 |
1992年 | 4篇 |
1991年 | 8篇 |
1990年 | 4篇 |
1989年 | 12篇 |
1988年 | 2篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 9篇 |
1984年 | 2篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 7篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1974年 | 3篇 |
1968年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有660条查询结果,搜索用时 15 毫秒
101.
Chia‐Wei Chen Hung‐Wei Tsai Yi‐Chung Wang Yu‐Chuan Shih Teng‐Yu Su Chen‐Hua Yang Wei‐Sheng Lin Chang‐Hong Shen Jia‐Ming Shieh Yu‐Lun Chueh 《Advanced functional materials》2019,29(48)
In this work, for the first time, the addition of aluminum oxide nanostructures (Al2O3 NSs) grown by glancing angle deposition (GLAD) is investigated on an ultrathin Cu(In,Ga)Se2 device (400 nm) fabricated using a sequential process, i.e., post‐selenization of the metallic precursor layer. The most striking observation to emerge from this study is the alleviation of phase separation after adding the Al2O3 NSs with improved Se diffusion into the non‐uniformed metallic precursor due to the surface roughness resulting from the Al2O3 NSs. In addition, the raised Na concentration at the rear surface can be attributed to the increased diffusion of Na ion facilitated by Al2O3 NSs. The coverage and thickness of the Al2O3 NSs significantly affects the cell performance because of an increase in shunt resistance associated with the formation of Na2SeX and phase separation. The passivation effect attributed to the Al2O3 NSs is well studied using the bias‐EQE measurement and J–V characteristics under dark and illuminated conditions. With the optimization of the Al2O3 NSs, the remarkable enhancement in the cell performance occurs, exhibiting a power conversion efficiency increase from 2.83% to 5.33%, demonstrating a promising method for improving ultrathin Cu(In,Ga)Se2 devices, and providing significant opportunities for further applications. 相似文献
102.
Image content adaptive color breakup index for field sequential color displays using a dominant visual saliency method
下载免费PDF全文
![点击此处可从《Journal of the Society for Information Display》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Zong Qin Ying‐Ju Lin Fang‐Cheng Lin Chia‐Wei Kuo Ching‐Huan Lin Norio Sugiura Han‐Ping David Shieh Yi‐Pai Huang 《Journal of the Society for Information Display》2018,26(2):85-97
An index that can predict the perceptual visibility of color breakup for varying image content is valuable in field sequential color displays, whereas the current indices are usually for fixed patterns. To solve this problem, an image database containing 25 diverse reference images and 125 test cases with various color breakup visibility was first established. Next, visual experiments using a 240‐Hz liquid crystal display were performed to acquire the subjective color breakup scores of the test cases. A theorem based on visual saliency theory was proposed that the color breakup perception is mainly determined by the image regions with visual saliency values higher than a certain threshold, called the dominant visual saliency regions. A computational model based on this theorem was developed to obtain objective color breakup scores of the test cases from retinal images with and without color breakup. An analysis of the objective and subjective results revealed a Pearson linear correlation coefficient as high as 0.82, which matches the top‐level image quality assessment algorithms. Finally, the proposed color breakup index was used to benchmark against several mainstream field sequential color algorithms to determine their performances in color breakup suppression. 相似文献
103.
Daily intake of TBT, Cu, Zn, Cd and As for fishermen in Taiwan 总被引:7,自引:0,他引:7
Chien LC Hung TC Choang KY Yeh CY Meng PJ Shieh MJ Ha BC 《The Science of the total environment》2002,285(1-3):177-185
The consumption of contaminated seafood has been reported as an important route of human exposure to metals in Taiwan. We consider the concentrations of TBT, Cu, Zn, Cd, As, and the consumption of oysters of Taiwanese to be the important information related to public health in Taiwan. Therefore, the aim of this study was to evaluate the public health risks associated with TBT, Cu, Zn, Cd and As from shellfish for the general population and fishermen of Taiwan. In general, TBT concentrations in various oysters ranging from 0.32 to 1.51 microg/g dry wt. varied with sampling locations. The highest TBT, Cu, and Zn geometric mean (GM) concentrations in oysters of 1.51, 1180 and 1567 microg/g dry wt. were obtained from the Hsiangshan coastal area. The values of oyster consumption for fishermen were 94.1 and 250 g/day for typically and maximally exposed individuals, respectively. In particular, the highest intake (250 g/day) from fishermen was almost two times greater than that of the general population (139 g/day). The THQ (target hazard quotient) values of Hsiangshan's fishermen are 3.87 and 20.50 for TBT and Cu for maximally exposed individuals are higher than other oyster culture areas. It is interesting that those consuming oysters from Hsiangshan, Lukang, Taishi caused abnormally high THQs of TBT and other metals (100% over 1.0), and TBT was attributed to only 3-21% of the total THQs in different fishermen of Taiwan. Our results suggest that current environmental levels of TBT and other metals are associated with a significant potential threat to human health for fishermen resident in coastal areas of Taiwan. 相似文献
104.
An adaptive recurrent radial basis function network tracking controller for a two-dimensional piezo-positioning stage 总被引:1,自引:0,他引:1
Lin FJ Shieh HJ Huang PK Shieh PH 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2008,55(1):183-198
An adaptive recurrent radial basis function network (ARRBFN) tracking controller for a two-dimensional piezo-positioning stage is proposed in this study. First, a mathematical model that represents the dynamics of the two-dimensional piezo-positioning stage is proposed. In this model, a hysteresis friction force that describes the hysteresis behavior of one-dimensional motion is used; and a nonconstant stiffness with the cross-coupling dynamic due to the effect of bending of a lever mechanism in x and y axes also is included. Then, according to the proposed mathematical model, an ARRBFN tracking controller is proposed. In the proposed ARRBFN control system, a recurrent radial basis function network (RRBFN) with accurate approximation capability is used to approximate an unknown dynamic function. The adaptive learning algorithms that can learn the parameters of the RRBFN on line are derived using Lyapunov stability theorem. Moreover, a robust compensator is proposed to confront the uncertainties, including approximation error, optimal parameter vectors, higher-order terms in Taylor series. To relax the requirement of the value of the lumped uncertainty in the robust compensator, an adaptive law is investigated to estimate the lumped uncertainty. Using the proposed control scheme, the position tracking performance is substantially improved and the robustness to uncertainties, including hysteresis friction force and cross-coupling stiffness, can be obtained as well. The tracking performance and the robustness to external load of the proposed ARRBFN control system are illustrated by some experimental results. 相似文献
105.
We develop a hybrid state-space fuzzy model-based controller with dual-rate sampling for digital control of chaotic systems. A Takagi-Sugeno (TS) fuzzy model is used to model the chaotic dynamic system and the extended parallel-distributed compensation technique is proposed and formulated for designing the fuzzy model-based controller under stability conditions. The optimal regional-pole assignment technique is also adopted in the design of the local feedback controllers for the multiple TS linear state-space models. The proposed design procedure is as follows: an equivalent fast-rate discrete-time state-space model of the continuous-time system is first constructed by using fuzzy inference systems. To obtain the continuous-time optimal state-feedback gains, the constructed discrete-time fuzzy system is then converted into a continuous-time system. The developed optimal continuous-time control law is finally converted into an equivalent slow-rate digital control law using the proposed intelligent digital redesign method. The main contribution of the paper is the development of a systematic and effective framework for fuzzy model-based controller design with dual-rate sampling for digital control of complex such as chaotic systems. The effectiveness and the feasibility of the proposed controller design method is demonstrated through numerical simulations on the chaotic Chua circuit 相似文献
106.
AV Albright JT Shieh T Itoh B Lee D Pleasure MJ O'Connor RW Doms F González-Scarano 《Canadian Metallurgical Quarterly》1999,73(1):205-213
Microglia are the main human immunodeficiency virus (HIV) reservoir in the central nervous system and most likely play a major role in the development of HIV dementia (HIVD). To characterize human adult microglial chemokine receptors, we analyzed the expression and calcium signaling of CCR5, CCR3, and CXCR4 and their roles in HIV entry. Microglia expressed higher levels of CCR5 than of either CCR3 or CXCR4. Of these three chemokine receptors, only CCR5 and CXCR4 were able to transduce a signal in microglia in response to their respective ligands, MIP-1beta and SDF-1alpha, as recorded by single-cell calcium flux experiments. We also found that CCR5 is the predominant coreceptor used for infection of human adult microglia by the HIV type 1 dementia isolates HIV-1DS-br, HIV-1RC-br, and HIV-1YU-2, since the anti-CCR5 antibody 2D7 was able to dramatically inhibit microglial infection by both wild-type and single-round luciferase pseudotype reporter viruses. Anti-CCR3 (7B11) and anti-CXCR4 (12G5) antibodies had little or no effect on infection. Last, we found that virus pseudotyped with the DS-br and RC-br envelopes can infect cells transfected with CD4 in conjunction with the G-protein-coupled receptors APJ, CCR8, and GPR15, which have been previously implicated in HIV entry. 相似文献
107.
A series of pH-thermoreversible hydrogels exhibiting volume phase transition were synthesized by three degrees of neutralization
(DN) of acrylic acid (AA) and N-isopropylacrylamide (NIPAAm). The influence of environmental conditions, such as temperature and pH, on the swelling behavior
of these copolymeric gels is investigated in this article. Results show that the negatively charged hydrogels exhibit different
equilibrium swelling ratios at different pH values depending on the ionic composition. The pH-sensitivities of these gels
also strongly depend on the DN of AA in the copolymeric gels. The results show that the higher the DN, the higher the gel
pH-sensitivity. These hydrogels based on a temperature-sensitive hydrogel demonstrate a larger change of equilibrium swelling
in aqueous media between a highly solvated, swollen gel state and a collapsed dehydrated network in response to a variation
of temperature. On the other hand, a significant phenomenon that was found in the gel swelling kinetics was an overshooting
under high temperature conditions. The presented hydrogels were used for release of model drugs that occur at the changes
of surrounding conditions, such as temperature and pH, in this study. It was also found that the higher the DN of AA, the
higher the gel transition temperature and the larger the release in a high temperature environment and, at the same time,
the larger the swelling ratios. 相似文献
108.
This paper presents an observer-based multi-objective robust feedback controller to achieve robust pole clustering within a vertical strip and disturbance rejection with an H∞-norm constraint for the uncertain linear systems. The systems of interest include both matched and mismatched uncertain linear systems with structured uncertainties existing in both the system and input matrices. The controller is obtained by solving two Riccati equations (one for the controller and the other for the observer) and checking three conditions (two for robust pole clustering). A set of tuning parameters is incorporated to enhance flexibility in finding the controller. © 1998 John Wiley & Sons, Ltd. 相似文献
109.
Vinyl trimethoxysilane grafting reactions of low-density polyethylene (LDPE) were performed in an extruder, followed by crosslinking with boiled water. The thermal properties of both silane-grafted and silane-grafted water-crosslinked LDPE were investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC data showed that the silane grafts on the LDPE molecules were thermal stable in the absence of moisture under 130°C under which the silane-grafted LDPE could be processed or recycled. The silane grafts on the LDPE molecules reduced the melting point of LDPE and gave rise to an endotherm shoulder at about 85°C. TGA data showed that the decomposition temperature of the silane-grafted LDPE was much higher than that of LDPE. It was demonstrated that the cause of the increase in the decomposition temperature was not due to the silane grafts but due to the peroxide-induced crosslinking reactions during the silane grafting reactions performed in an extruder. Silane-grafted water-crosslinked LDPE displayed multiple melting behavior resulting from phase separation during crosslinking of LDPE with water. The phase separation gave rise to two melting points, including one at about 94°C, and the other at about 107°C. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1075–1082, 1998 相似文献
110.
2-(6-Oxido-6H-dibenz 〈c,e〉〈1,2〉 oxaphosphorin-6-yl) dimethyl itaconate (ODOP-DI) was prepared by the addition reaction between 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and dimethyl itaconate while DOPO was synthesized through multistep reaction from o-phenylphenol and phosphorus trichloride. The compound (ODOP-DI) was used as a reactive flame retardant in polyethylene 1,4-terephthalate (PET) and polyethylene 2,6-naphthalate (PEN) for film, fiber, and electronic applications. The thermal properties of the resulted copolyesters were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Owing to the incorporation of the rigid structure of DOPO and pendant P groups, the resulted phosphorus containing copolyesters exhibited better flame retardancy, higher char yield, and thermal stability than homopolymers of PET and PEN. UL 94-VO rating could be achieved with a phosphorus content of as low as 0.75% for PET, 0.5% for PEN, and no fume and toxic gas emission were observed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1959–1964, 1998 相似文献