全文获取类型
收费全文 | 210篇 |
免费 | 22篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 58篇 |
机械仪表 | 4篇 |
建筑科学 | 15篇 |
能源动力 | 8篇 |
轻工业 | 18篇 |
水利工程 | 2篇 |
无线电 | 15篇 |
一般工业技术 | 45篇 |
冶金工业 | 16篇 |
自动化技术 | 47篇 |
出版年
2024年 | 2篇 |
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 11篇 |
2020年 | 4篇 |
2019年 | 15篇 |
2018年 | 9篇 |
2017年 | 6篇 |
2016年 | 12篇 |
2015年 | 9篇 |
2014年 | 13篇 |
2013年 | 20篇 |
2012年 | 15篇 |
2011年 | 15篇 |
2010年 | 8篇 |
2009年 | 10篇 |
2008年 | 9篇 |
2007年 | 9篇 |
2006年 | 9篇 |
2005年 | 5篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1997年 | 7篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1980年 | 2篇 |
排序方式: 共有232条查询结果,搜索用时 456 毫秒
101.
H Pereira F Matias J Duarte C Martins I Jo?o P Fazendas C Duarte M Carrageta 《Canadian Metallurgical Quarterly》1998,17(11):903-907
The aim of the study was to evaluate the efficacy and safety of abciximab (ReoPro) in primary percutaneous transluminal coronary angioplasty (P.T.C.A.) in patients with myocardial infarction (M.I.). From June 96 to October 97, 16 patients with a mean age of 58 +/- 12 years, 86% males, with myocardial infarction (less than 12 hours of pain) were treated with ReoPro during P.T.C.A. The infarction was anterior in seven patients (44%), inferior in eight patients (50%) and non-Q wave in one patient (6%). Nine patients (47%) had a previous history of angina or myocardial infarction. The mean time from onset of symptoms to hospital arrival was 306 +/- 370 min and the mean time between hospital admission and the beginning of the procedure was 79 +/- 86 min. P.T.C.A. was performed on the anterior descending artery and right coronary in 44% and 56%, respectively. The success rate was 94%. Stents were used in 31%. In patients with angiographic success, we obtained TIMI III flow in 14 patients and TIMI II in one patient. No complications arose during P.C.T.A; no significant changes in platelets or hemoglobin were observed after the procedure. In this group of patients, one case of hematoma was found at the site of puncture with no need for transfusion. During hospitalization, no major coronary events were found. During the follow-up of 10.5 +/- 4.9 months, one patient died after non cardiac surgery and one patient was submitted to coronary artery bypass graft; there was no reinfarction nor new P.T.C.A. CONCLUSIONS: In our experience with ReoPro during direct angioplasty, we obtained good immediate and long term results, with no significant bleeding complications. 相似文献
102.
Angueira P. Ma Velez M. de la Vega D. Prieto G. Guerra D. Matias J.M. Ordiales J.L. 《Broadcasting, IEEE Transactions on》2004,50(1):42-48
This paper presents a field measurement campaign developed to study the influence of the special features of a Single Frequency Network (SFN) reception in the C/N thresholds applicable to portable DTV reception. The measurements presented here were performed inside coverage areas of the nationwide SFN which broadcasts DTV (COFDM 8 K mode) services in Spain. The aim of this paper is to present some network planning reference values for portable reception in urban environments where both multipath and multiple transmitter reception have to be taken into account to ensure a good quality of service. 相似文献
103.
JZ Montgomerie A McCary CJ Bennett M Young B Matias F Diaz R Adkins J Anderson 《Canadian Metallurgical Quarterly》1997,35(5):282-285
This paper tends to evaluate the effects of comprehensive prevention and treatment in COPD and cor pulmonale in the communities. A Randomized cohort with stratified design was undertaken in the rural areas with hundred thousand population in Beijing municipality, Lianning and Hubei Provinces, from spring 1992 to spring 1995. RESULTS: (1) the rates to all stratified populations under management were 85.6% among those with high risk, 87.8% among COPD and 83.6% among cor pulmonale, respectively. (2) The levels of KAB were raised more significantly in most intervention group than in control group which up +9.6% to +33.6% and -5.8% to +32.6%, respectively. (3) Comparisons between the two groups revealed: 1. Number of cigarette smokers who smoked more than before increased (20.1% vs 17.8%) but with no statistical significance. 2. The rate of smoking cessation went higher (15.5% vs. 11.3%, P < 0.01). 3. New high risk subjects were reduced (2.8% vs 3.9%, P < 0.01). 4. Number of new cor pulmonale patients decreased (19.9% vs 22.6%, P > 0.05) and mortality rate lowered (4.34% vs 4.78%, P > 0.05). CONCLUSION: preliminary results indicates that the active intervention is effective in reducing COPD and cor pulmonale among population at high risk in communities. However, it is necessary to point out that COPD and cor pulmonale are both having chronic nature which calls for patient and continuous efforts. 相似文献
104.
The morphology of the pineal gland of the yellow‐toothed cavy (Galea Spixii Wagler, 1831) and red‐rumped agouti (Dasyprocta leporina linnaeus, 1758) 下载免费PDF全文
Felipe Venceslau Câmara Igor Renno Guimarães Lopes Gleidson Benevides de Oliveira Ferdinando Vinicius Fernandes Bezerra Radan Elvis Matias de Oliveira Carlos Magno Oliveira Júnior Alexandre Rodrigues Silva Moacir Franco de Oliveira 《Microscopy research and technique》2015,78(8):660-666
The pineal gland is an endocrine gland found in all mammals. This article describes the morphology of this important gland in two species of Caviideae, namely the yellow‐toothed cavy and the red‐rumped agouti. Ten adult animals of the two species used in current analysis were retrieved from the Center for the Multiplication of Wild Animals (CEMAS/UFERSA) and euthanized. The glands were removed and photographed in situ and ex situ. They were fixed in a paraformaldehyde solution 4% or glutaraldehyde 2.5% solution and submitted to routine histological techniques respectively for light and scanning electron microscopy. Macroscopically, the pineal gland with its elongated structure may be found between the cerebral hemispheres facing the rostral colliculi. Microscopically, pinealocytes and some glia cells were predominant. Contrastingly, to the cavy's pineal gland, a capsule covered the organ in the agouti, with the emission of incomplete septa to the interior, which divided it into two lobules. Light and scanning electron microscopes failed to show calcareous concretions in the pineal gland. Based on the topography of the cavy's and agouti's pineal gland, it may be classified as supra‐callosum and ABC type. Microsc. Res. Tech. 78:660–666, 2015. © 2015 Wiley Periodicals, Inc. 相似文献
105.
In recent years wavelets were shown to be effective data synopses. We are concerned with the problem of finding efficiently wavelet synopses for massive data sets, in situations where information about query workload is available. We present linear time, I/O optimal algorithms for building optimal workload-based wavelet synopses for point queries. The synopses are based on a novel construction of weighted inner products and use weighted wavelets that are adapted to those products. The synopses are optimal in the sense that the subset of retained coefficients is the best possible for the bases in use with respect to either the mean-squared absolute or relative errors. For the latter, this is the first optimal wavelet synopsis even for the regular, non-workload-based case. Experimental results demonstrate the advantage obtained by the new optimal wavelet synopses. 相似文献
106.
Bravo J. Matias I.R. Del Villar I. Corres J.M. Arregui F.J. 《Lightwave Technology, Journal of》2006,24(5):2100-2107
The optical characteristics of one multimode fiber (MMF)-hollow core fiber (HCF)-structure when a nanofilm is deposited on it has been theoretically and experimentally studied. The electrostatic self-assembly method has been used as the deposition technique, and the polymers chosen are polydiallyldimethylammonium and Poly R-478. Two different types of HCF have been used for the fabrication of the devices: 10/150 and 50/150 /spl mu/m inner and outer diameters, respectively. Depending on several design parameters, the transmitted optical-power characteristic of the device experiences important changes that could be interesting towards development of several practical optical devices. The length and thickness of the HCF segment, the refractive index of the material deposited, the angle of the light when it reach the HCF section, and the wavelength of the light source will be analyzed. 相似文献
107.
This paper shows the optical setup of a radial in-plane digital speckle pattern interferometer which uses an axis-symmetrical diffractive optical element (DOE) to obtain double illumination. The application of the DOE gives in-plane sensitivity which only depends on the grating period of the DOE instead of the wavelength of the laser used as illumination source. A compact optical layout was built in order to have a portable optical strain sensor with a circular measurement area of about 5 mm in diameter. In order to compare its performance with electrical strain sensors (strain gauges), mechanical loading was generated by a four-point bending device and simultaneously monitored by the optical strain sensor and by two-element strain gauge rosettes. Several mechanical stress levels were measured showing a good agreement between both sensors. Results showed that the optical sensor could measure applied mechanical strains with a mean uncertainty of about 5% and 4% for the maximum and minimum principal strains, respectively. 相似文献
108.
Sancho MI Almandoz MC Blanco SE Castro EA 《International journal of molecular sciences》2011,12(12):8895-8912
The solvatochromic characteristics of flavone and 7-hydroxyflavone were investigated in neat and binary solvent mixtures. The spectral shifts of these solutes were correlated with the Kamlet and Taft parameters (α, β and π*) using linear solvation energy relationships. The multiparametric analysis indicates that both specific hydrogen bond donor ability and non-specific dipolar interactions of the solvents play an important role in absorption maxima of flavone in pure solvents. The hydrogen bond acceptor ability of the solvent was the main parameter affecting the absorption maxima of 7-hydroxyflavone. The simulated absorption spectra using a TD-DFT method were in good agreement with the experimental ones for both flavones. Index of preferential solvation was calculated as a function of solvent composition. Preferential solvation by ethanol was detected in cyclohexane-ethanol and acetonitrile-ethanol mixtures for flavone and in acetonitrile-ethanol mixtures for 7-hydroxyflavone. These results indicate that intermolecular hydrogen bonds between solute and solvent are responsible for the non-linear variation of the solvatochromic shifts on the mole fraction of ethanol in the analyzed binary mixtures. 相似文献
109.
Rong Ren Jianguo Wei Eduardo Juarez Matias Garrido Cesar Sanz Fernando Pescador 《Signal Processing: Image Communication》2013,28(10):1303-1314
In this paper, an energy estimation methodology based on performance monitor counters (PMC) is proposed to estimate the energy consumption of RVC-CAL video codec specifications. The proposed PMC-driven methodology is able to automatically identify the most appropriate events and training data to cover the main application characteristics. In addition, knowledge of the hardware platform employed is not required. Therefore, this methodology can be easily implemented on other PMC-available systems while keeping the estimation accuracy. It is worth noting that this is an attractive asset to analyze the energy consumption of RVC-CAL codec specifications. Besides, the methodology reduces the PMC redundancy and, thus, the overhead introduced when applied to on-line power management. Experimenting on two RVC-CAL decoders, H.264 and MPEG4 Part2 SP, a coarse estimation model based on instructions per cycle (IPC) and the proposed PMC-driven model are compared. The results show that the PMC-driven model can achieve for the H.264 and MPEG4 Part2 SP decoders average estimation errors of 5.95% and 5.01%, respectively, in comparison to the 17.11% and 13.65% average errors obtained with the IPC-based model. As a consequence, this methodology is suggested to be combined into the RVC framework to help the designer to have an overview of the energy consumption of the specification actors at earlier design stages. 相似文献
110.
Cornejo Andres Landeros-Ayala Salvador Matias Jose M. Ortiz-Gomez Flor Martinez Ramon Salas-Natera Miguel 《Neural Processing Letters》2022,54(4):2959-2995
Neural Processing Letters - Rain attenuation events are one of the foremost drawbacks in satellite communications, impairing satellite link availability. For this reason, it is necessary to foresee... 相似文献