全文获取类型
收费全文 | 1735篇 |
免费 | 109篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 21篇 |
化学工业 | 422篇 |
金属工艺 | 36篇 |
机械仪表 | 51篇 |
建筑科学 | 69篇 |
矿业工程 | 6篇 |
能源动力 | 53篇 |
轻工业 | 326篇 |
水利工程 | 21篇 |
石油天然气 | 17篇 |
无线电 | 147篇 |
一般工业技术 | 257篇 |
冶金工业 | 202篇 |
原子能技术 | 10篇 |
自动化技术 | 207篇 |
出版年
2024年 | 4篇 |
2023年 | 21篇 |
2022年 | 72篇 |
2021年 | 87篇 |
2020年 | 41篇 |
2019年 | 70篇 |
2018年 | 77篇 |
2017年 | 69篇 |
2016年 | 76篇 |
2015年 | 50篇 |
2014年 | 83篇 |
2013年 | 149篇 |
2012年 | 104篇 |
2011年 | 112篇 |
2010年 | 90篇 |
2009年 | 90篇 |
2008年 | 80篇 |
2007年 | 78篇 |
2006年 | 66篇 |
2005年 | 34篇 |
2004年 | 32篇 |
2003年 | 25篇 |
2002年 | 27篇 |
2001年 | 19篇 |
2000年 | 18篇 |
1999年 | 29篇 |
1998年 | 62篇 |
1997年 | 38篇 |
1996年 | 33篇 |
1995年 | 20篇 |
1994年 | 10篇 |
1993年 | 22篇 |
1992年 | 4篇 |
1991年 | 8篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 10篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 6篇 |
1968年 | 1篇 |
排序方式: 共有1845条查询结果,搜索用时 15 毫秒
121.
Alexandre Sztajnberg Rodrigo Souza Granja Jeane Cesário André Felipe Almeida Monteiro 《Software》2011,41(1):103-127
Resource management is an important aspect to consider regarding applications that might have different non‐functional or operational requirements, when running in distributed and heterogeneous environments. In this context, it is necessary to provide the means to specify the required resource constraints and an infrastructure that can adapt the applications in light of the changes in resource availability. We adopted a contract‐based approach to describe and maintain parallel applications that have non‐functional requirements in a Computing Grid context, called ZeliGrid. To form the supporting infrastructure we have designed a software architecture that integrates some of the Globus services, the LDAP and the NWS monitoring services. Some modules that map the contract approach into software artifacts were also integrated to this architecture. This paper addresses the architecture and integration issues of our approach, as well as how we put the pieces together highlighting deployment and implementation details, which have to consider diverse aspects such as monitoring, security and dynamic reconfiguration. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
122.
123.
Jacobs R. N. Stoltz A. J. Robinson E. W. Boyd P. R. Almeida L. A. Dinan J. H. Salamanca-Riba L. 《Journal of Electronic Materials》2004,33(6):538-542
The vision of achieving a completely in-vacuum process for fabricating HgCdTe detector arrays is contingent on the availability
of a vacuumcompatible photolithography technology. One such technology for vacuum photolithography involves the use of amorphous-hydrogenated
Si (a-Si:H) as a photoresist. In this work, we deposit a-Si:H resists via plasma-enhanced chemical-vapor deposition (PECVD)
using an Ar-diluted silane precursor. The resists are then patterned via excimer laser exposure and development etched in
a hydrogen plasma where etch selectivities between unexposed and exposed regions exceed 600:1. To determine the best conditions
for the technique, we investigate the effects of different exposure environments and carry out an analysis of the a-Si:H surfaces
before and after development etching. Analysis via transmission electron microscopy (TEM) reveals that the excimer-exposed
surfaces are polycrystalline in nature, indicating that the mechanism for pattern generation in this study is based on melting
and crystallization. To demonstrate pattern transfer, underlying CdTe films were etched (after development of the resist)
in an electron cyclotron resonance (ECR) plasma, where etch selectivities of approximately 8:1 have been achieved. The significance
of this work is the demonstration of laser-induced poly-Si as an etching mask for vacuum-compatible photolithography. 相似文献
124.
J. P. Moitinho de Almeida 《International journal for numerical methods in engineering》2009,77(1):149-150
The following article from International Journal for Numerical Methods in Engineering, Comments on ‘Upper bound solution to elasticity problems: A unique property of the linearly conforming point interpolation method (LC‐PIM)’ by G. R. Liu and G. Y. Zhang, published online on 19 June 2008 in Wiley InterScience (www.interscience.wiley.com), has been retracted by agreement between the authors, the journal Editor‐in‐Chief, Ted Belytschko and John Wiley & Sons, Ltd. The retraction has been agreed due to the article being published out of sequence with a related article and with insufficient citation details. 相似文献
125.
F.F. CamargoC.M. Almeida G.A.O.P. CostaR.Q. Feitosa D.A.B. OliveiraC. Heipke R.S. Ferreira 《Expert systems with applications》2012,39(1):541-554
This paper introduces a new open source, knowledge-based framework for automatic interpretation of remote sensing images, called InterIMAGE. This framework exhibits a flexible modular architecture, in which image processing operators can be associated to both root and leaf nodes of a semantic network, which accounts for a differential strategy in comparison to other object-based image analysis platforms currently available. The architecture, main features as well as an overview on the interpretation strategy implemented in InterIMAGE are presented. The paper also reports an experiment on the classification of landforms. Different geomorphometric and textural attributes obtained from ASTER/Terra images were combined with fuzzy logic to drive the interpretation semantic network. Object-based statistical agreement indices, estimated from a comparison between the classified scene and a reference map, were used to assess the classification accuracy. The InterIMAGE interpretation strategy yielded a classification result with strong agreement and proved to be effective for the extraction of landforms. 相似文献
126.
Dithiocarbamates have been regarded as alternative anchor groups to thiols on gold surfaces, and claimed to be formed in situ through the reaction between secondary amines and carbon disulphide. In this paper, we further exploit this methodology for a convenient one step biomolecule immobilisation onto gold surfaces. First, the reactivity between CS2 and electroactive compounds containing amines, primary (dopamine), secondary (epinephrine), and an amino acid (tryptophan) has been investigated by electrochemical methods. Cyclic voltammetric characterisation of the modified electrodes confirmed the immobilisation of all the target compounds, allowing the estimation of their surface concentration. The best result was obtained with epinephrine, a secondary amine, for which a typical quasi-reversible behaviour of surface confined electroactive species could be clearly depicted. Electrochemical reductive desorption studies enabled to infer on the extent of the reaction and on the relative stability of the generated monolayers. Bio-functionalisation studies have been accomplished through the reaction of CS2 with glucose oxidase in aqueous medium, and the catalytic activity of the immobilised enzyme was evaluated towards glucose, by electrochemical methods in the presence of a redox mediator. Scanning tunnelling microscopy (STM) and Atomic force microscopy (AFM) were used respectively, to characterize the gold electrodes and Glucose Oxidase coverage and distribution on the modified surfaces. 相似文献
127.
Baptista MS de Almeida LO Slaets JF Köberle R Grebogi C 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2008,366(1864):345-357
Is the characterization of biological systems as complex systems in the mathematical sense a fruitful assertion? In this paper we argue in the affirmative, although obviously we do not attempt to confront all the issues raised by this question. We use the fly's visual system as an example and analyse our experimental results of one particular neuron in the fly's visual system from this point of view. We find that the motion-sensitive 'H1' neuron, which converts incoming signals into a sequence of identical pulses or 'spikes', encodes the information contained in the stimulus into an alphabet composed of a few letters. This encoding occurs on multilayered sets, one of the features attributed to complex systems. The conversion of intervals between consecutive occurrences of spikes into an alphabet requires us to construct a generating partition. This entails a one-to-one correspondence between sequences of spike intervals and words written in the alphabet. The alphabet dynamics is multifractal both with and without stimulus, though the multifractality increases with the stimulus entropy. This is in sharp contrast to models generating independent spike intervals, such as models using Poisson statistics, whose dynamics is monofractal. We embed the support of the probability measure, which describes the distribution of words written in this alphabet, in a two-dimensional space, whose topology can be reproduced by an M-shaped map. This map has positive Lyapunov exponents, indicating a chaotic-like encoding. 相似文献
128.
129.
Marcelo Fernandes Cipreste Michele Rocha de Rezende Marlon Luiz Hneda Anderson Maia Peres Alexandre Alberto Chaves Cotta Verônica de Carvalho Teixeira Waldemar Augusto de Almeida Macedo Edésia Martins Barros de Sousa 《Ceramics International》2018,44(15):17800-17811
Hydroxyapatite (HA) nanoparticles (NPs) doped with different radioisotopes for use as theranostic systems play an important role in scientific research nowadays due to their ability to simultaneously act in the treatment and diagnosis of various types of cancers. In this work, we describe the synthesis and characterization of a hydroxyapatite/tenorite nanocomposite functionalized with folic acid, representing a nanotheranostic material with potential for application as an agent in positron emission tomography imaging systems and to act specifically in the treatment and diagnosis of osteosarcoma. 64Cu and 32P were produced by nuclear activation in the TRIGA reactor at CDTN. The obtained samples were characterized by XRD with Rietveld refinement, XAFS, SEM, BET, TGA, FTIR, CHN, ICP-AES, XPS and gamma spectroscopy. We investigated how CuO grows in HA NPs, the stability of the interactions between CuO and HA constituents and the interactions between folic acid and the surface of the HA NPs. The results indicate the formation of a second phase (tenorite) besides hydroxyapatite, and that the interactions between the two phases are stable, resulting in a nanocomposite. Furthermore, the activation of 64Cu and 32P inside the HA matrix, through the exposition to a neutron flux, produces a theranostic material of interest for biological tests. 相似文献
130.
Pedro S. Moura Gregorio L. López José I. Moreno Aníbal T. De Almeida 《Energy Efficiency》2013,6(4):621-639
The traditional electricity grid has remained the same for most of last century, without major architectural improvements. However, its requirements, guidelines and goals do have changed, especially during the last few years, driven by the sustainability in energy generation and energy efficiency principles. Thus, taking greenhouse gases emissions and CO2 footprint reduction as key objectives and information and communications technologies as key enabler technologies, a novel and revolutionary electric grid paradigm, the so-called Smart Grid, is emerging, in which energy efficiency and renewable generation play a central role. This paper presents an overview on the main requirements and features of Smart Grids to integrate energy efficiency, on the work done and to be done, on the enabler technologies, as well as on the expected impacts and the main benefits Smart Grids will bring. 相似文献