全文获取类型
收费全文 | 468篇 |
免费 | 36篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 137篇 |
金属工艺 | 1篇 |
机械仪表 | 2篇 |
建筑科学 | 20篇 |
能源动力 | 6篇 |
轻工业 | 187篇 |
水利工程 | 1篇 |
石油天然气 | 3篇 |
无线电 | 12篇 |
一般工业技术 | 48篇 |
冶金工业 | 32篇 |
自动化技术 | 52篇 |
出版年
2024年 | 6篇 |
2023年 | 5篇 |
2022年 | 13篇 |
2021年 | 12篇 |
2020年 | 11篇 |
2019年 | 13篇 |
2018年 | 13篇 |
2017年 | 20篇 |
2016年 | 17篇 |
2015年 | 14篇 |
2014年 | 15篇 |
2013年 | 35篇 |
2012年 | 34篇 |
2011年 | 39篇 |
2010年 | 29篇 |
2009年 | 26篇 |
2008年 | 32篇 |
2007年 | 28篇 |
2006年 | 20篇 |
2005年 | 12篇 |
2004年 | 13篇 |
2003年 | 14篇 |
2002年 | 15篇 |
2001年 | 5篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 12篇 |
1997年 | 10篇 |
1996年 | 9篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
排序方式: 共有504条查询结果,搜索用时 15 毫秒
1.
Montserrat Bóo Francisco Argüello Javier D. Bruguera Emilio L. Zapata 《The Journal of VLSI Signal Processing》1997,17(1):57-73
A rate 1/n binary generic convolutional encoder is a shift-register circuit where the inputs are information bits and the outputs are blocks of n bits generated as linear combinations on the appropriate shift register contents. The decoding of the outputs of a convolutional encoder can be carried out by the well-known Viterbi algorithm. The communication pattern of the Viterbi Algorithm is given as a graph, called trellis, associated to the state diagram of the corresponding encoder. In this paper we present a methodology that permits the efficient mapping of the Viterbi algorithm onto a column of an arbitrary number of processors. This is done through the representation of the data flow by using mathematical operators which present an inmediate hardware projection. A single operator string has been obtained to represent a generic encoder through the study of the data flow of free-forward encoders and feed-back encoders. The formal model developed is employed for the partitioning of the computations among an arbitrary number of processors in such a way that the data are recirculated opimizing the use of the processors and the communications. As a result, we obtain a highly regular and modular architecture suitable for VLSI implementation. 相似文献
2.
O Parra N García-Esclasans JM Montserrat L García Eroles J Ruíz JA López JM Guerra JJ Sope?a 《Canadian Metallurgical Quarterly》1997,10(8):1720-1724
The purpose of this study was to analyse the validity and the economic efficiency of a portable monitor of respiratory parameters (PMRP), used in a home setting for the diagnosis of sleep apnoea/hypopnoea syndrome (SAHS). Eighty nine patients with suspected SAHS were studied in two settings: in the sleep laboratory using full-polysomnography (full-PSG); and at the patient's home using a PMRP. In the home setting, 50 patients were assisted by a technician and 39 set up the equipment themselves. SAHS (apnoea/hypopnoea index (AHI) >10 events x h(-1) by means of full-PSG) was diagnosed in 75 of the 89 patients. An acceptable agreement was obtained between the AHI measured by full-PSG and PMRP, according to the Bland and Altman method of concordance (mean bias 2.56; 95% confidence interval 3.25). Sensitivity and specificity of PMRP were adequate for diagnostic purposes; however, their values rely on the prior PMRP-AHI cut-off point selected with reference to full-PSG-AHI >10. The clinical therapeutic decision taken after PMRP agreed with that taken with full-PSG in 79 patients (89%). Although 10% of the studies with an individual set-up needed repetition, both of the domiciliary modalities (with and without a technician's intervention) were, economically, about three times more efficient than full-PSG. In conclusion, we believe that patients with a suspected sleep apnoea/hypopnoea syndrome should initially be studied in a home setting with a portable monitor of respiratory parameters, since it is a reliable method with an acceptable cost-effective profile. 相似文献
3.
Single crystals of nylon 7 prepared by crystallization from glycerine were studied by both X-rays and electron microscopy. Electron diffraction proved that they consist of a twinned layered-structure with hydrogen bonds running parallel to their long dimension. Polyethylene decoration of such crystals showed that they are subdivided in folding domains so that both chain folding and hydrogen bonding take place along the same crystallographical planes. 相似文献
4.
Graft copolymerization of vinyl acetate (VA) and methyl acrylate (MA) on cotton cellulose was initiated by the Ce (IV) ion, and ungrafted vinylic polymer was separated from the graft copolymer by acetone extraction. The influence of the ratio aqueous initiator solution volume/monomeric volume (Vaq/Vmon), vinyl acetate volume/methyl acrylate volume (VVA/VMA), and the cellulose crystallinity index (CI) on the grafting reaction were studied. To modify the crystallinity of cellulose, native cotton was treated with NaOH in the concentrations 10, 15, and 20% (mercerized). The viscosimetric average molecular weight (Mv), the polymerization degree (PD), and the crystallinity index proposed by Nelson and O'Connor (CI) were determined for native and NaOH-treated cotton. The polymeric side chains grafted were separated from the cellulose backbone by acid hydrolysis in 72% H2SO4. The viscosimetric average molecular weight (Mv) was determined, and the number of vinylic chains per cellulosic chain (graft frequency, GF) were calculated. The grafting percentage, %G, was higher for most amorphous cellulose and for a higher methyl acrylate percentage (%MA) in monomeric reaction mixtures (VA-MA). The Vaq/Vmon ratio that yields the highest %G was 70/30. The increase of the %G with the %MA in the VA–MA monomeric mixture seems to be due to both an increase in the length of vinylic grafted chains (as shown by its Mv) and the number of grafted chains (GF). The increase in the %G when the crystallinity index (CI) of the cellulosic substrate decreases seems to be due to an increase in the length of the vinylic grafted chains, but not to an increase in the number of grafted chains, since the Mv increases and GF decreases when the CI of cellulose decreases. 相似文献
5.
The viscoelastic response of some vinylic copolymers of cellulose prepared with vinyl acetatemethyl acrylate mixtures and with Ce(IV) ion as initiator, and native cellulose, were studied at 110 Hz in a range of temperatures from ?120–100°C. The viscoelastic spectrum of cellulose shows the β-relaxation that is not shown in its vinylic copolymers. We observed the same effect in the dielectric β-relaxation. For the vinylic copolymers of cellulose, one viscoelastic relaxation attributed to the α-relaxation of the grafted vinylic chains is observed. Some differences in the characteristics of this relaxation may be related to the composition of PVA/PMA vinylic side chains and to the ratio of cellulose in the copolymer. The plots of the Argand diagrams give us a better understanding of the viscoelastic behaviour of these materials. The results seem to indicate that the cellulose hinders the large-scale motions of the vinylic chains grafted onto it. The glass transition temperature (Tg) determined by differential scanning calorimetry (DSC) also shows the same fact: the Tg of the vinylic copolymers of cellulose are higher than both the Tg of polyvinyl acetate–polymethyl acrylate copolymers (PVA–PMA) without cellulose and the Tg of some blends of cellulose and the PVA–PMA whose composition was as similar as possible to the cellulosic copolymers. The importance of the covalent bonds between cellulose and the vinylic side chains in the structural transitions are revealed. The present results are compared with the dielectric α-relaxation that we described elsewhere. © 1993 John Wiley & Sons, Inc. 相似文献
6.
This paper introduces a novel solution for the multi‐input multi‐output (MIMO) quantitative feedback theory control design problem with tracking error specifications. Looking for a minimum controller overdesign, the technique finds new controller quantitative feedback theory bounds based on necessary and sufficient conditions for the existence of suitable associated prefilter matrix elements. It improves previous approaches to the subject and includes (i) the possibility of a free selection of the nominal plant, (ii) a less conservative application of the Schwartz inequality to decisively reduce the potential controller overdesign, (iii) a methodology to design independently the elements of the prefilter matrix, and (iv) a scope of application to both sequential and nonsequential MIMO controller design methods. The benefits of the new control design technique are illustrated by means of two examples. The first one, a standard 2 × 2 MIMO problem, is provided for comparison purposes with previous approaches. The second example, included as a major control challenge, deals with a well‐known demanding distillation column benchmark problem. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
7.
David Sachez Montserrat Batet Aida Valls 《International Journal of Software and Informatics》2010,4(1):39-52
Computation of semantic similarity between concepts is a very common problem
in many language related tasks and knowledge domains. In the biomedical field, several approaches have been developed to deal with this issue by exploiting the structured knowledge
available in domain ontologies (such as SNOMED-CT or MeSH) and specific, closed and
reliable corpora (such as clinical data). However, in recent years, the enormous growth of
the Web has motivated researchers to start using it as the corpus to assist semantic analysis
of language. This paper proposes and evaluates the use of the Web as background corpus for
measuring the similarity of biomedical concepts. Several ontology-based similarity measures
have been studied and tested, using a benchmark composed by biomedical terms, comparing
the results obtained when applying them to the Web against approaches in which specific
clinical data were used. Results show that the similarity values obtained from the Web for
ontology-based measures are at least and even more reliable than those obtained from specific
clinical data, showing the suitability of the Web as information corpus for the biomedical
domain. 相似文献
8.
Montserrat Marimon 《Language Resources and Evaluation》2013,47(2):371-397
In this article we present a Spanish grammar implemented in the Linguistic Knowledge Builder system and grounded in the theoretical framework of Head-driven Phrase Structure Grammar. The grammar is being developed in an international multilingual context, the DELPH-IN Initiative, contributing to an open-source repository of software and linguistic resources for various Natural Language Processing applications. We will show how we have refined and extended a core grammar, derived from the LinGO Grammar Matrix, to achieve a broad-coverage grammar. The Spanish DELPH-IN grammar is the most comprehensive grammar for Spanish deep processing, and it is being deployed in the construction of a treebank for Spanish of 60,000 sentences based in a technical corpus in the framework of the European project METANET4U (Enhancing the European Linguistic Infrastructure, GA 270893GA; http://www.meta-net.eu/projects/METANET4U/.) and a smaller treebank of about 15,000 sentences based in a corpus from the press. 相似文献
9.
Raúl Tauro Montserrat Serrano-Medrano Omar Masera 《Clean Technologies and Environmental Policy》2018,20(7):1527-1539
Bioenergy is the largest renewable energy source in Mexico with an estimated 4–9% of total current energy demand. There are large uncertainties and contrasting estimates regarding its current extent and end-uses, particularly with traditional uses. However, a large potential exists to improve the efficiency of existing uses and, at the same time, to diversify the use of SBF in the industrial and power sectors. This paper aims at: providing the first updated and comprehensive estimate of current SBF demand in Mexico including traditional and modern uses; providing a consistent estimate of actual SBF supply potential; estimating the total potential substitution of fossil fuels that could be achieved by SBF considering an integrated “modernization scenario”; and finally describing the main barriers limiting SBF to fully triggering its potential. Results show that current SBF consumption reached 481 PJ/yr in 2015; SBF supply potential reaches 3622 PJ/yr, out of which 883 PJ/yr could be used to substitute up to 29% of current demand of FF, mitigating 66 MtCO2e/yr of greenhouse gas (GHG) emissions, or near 88 MtCO2e/yr if mitigation from traditional uses is added. 相似文献
10.
Ontology-driven web-based semantic similarity 总被引:1,自引:0,他引:1
David Sánchez Montserrat Batet Aida Valls Karina Gibert 《Journal of Intelligent Information Systems》2010,35(3):383-413
Estimation of the degree of semantic similarity/distance between concepts is a very common problem in research areas such
as natural language processing, knowledge acquisition, information retrieval or data mining. In the past, many similarity
measures have been proposed, exploiting explicit knowledge—such as the structure of a taxonomy—or implicit knowledge—such
as information distribution. In the former case, taxonomies and/or ontologies are used to introduce additional semantics;
in the latter case, frequencies of term appearances in a corpus are considered. Classical measures based on those premises
suffer from some problems: in the first case, their excessive dependency of the taxonomical/ontological structure; in the
second case, the lack of semantics of a pure statistical analysis of occurrences and/or the ambiguity of estimating concept
statistical distribution from term appearances. Measures based on Information Content (IC) of taxonomical concepts combine
both approaches. However, they heavily depend on a properly pre-tagged and disambiguated corpus according to the ontological
entities in order to compute accurate concept appearance probabilities. This limits the applicability of those measures to
other ontologies –like specific domain ontologies- and massive corpus –like the Web-. In this paper, several of the presented
issues are analyzed. Modifications of classical similarity measures are also proposed. They are based on a contextualized
and scalable version of IC computation in the Web by exploiting taxonomical knowledge. The goal is to avoid the measures’
dependency on the corpus pre-processing to achieve reliable results and minimize language ambiguity. Our proposals are able
to outperform classical approaches when using the Web for estimating concept probabilities. 相似文献