全文获取类型
收费全文 | 656篇 |
免费 | 21篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 180篇 |
金属工艺 | 7篇 |
机械仪表 | 11篇 |
建筑科学 | 11篇 |
矿业工程 | 1篇 |
能源动力 | 14篇 |
轻工业 | 46篇 |
水利工程 | 15篇 |
无线电 | 62篇 |
一般工业技术 | 105篇 |
冶金工业 | 141篇 |
原子能技术 | 10篇 |
自动化技术 | 70篇 |
出版年
2022年 | 14篇 |
2021年 | 27篇 |
2020年 | 14篇 |
2019年 | 26篇 |
2018年 | 22篇 |
2017年 | 12篇 |
2016年 | 17篇 |
2015年 | 16篇 |
2014年 | 27篇 |
2013年 | 31篇 |
2012年 | 37篇 |
2011年 | 27篇 |
2010年 | 17篇 |
2009年 | 20篇 |
2008年 | 22篇 |
2007年 | 27篇 |
2006年 | 13篇 |
2005年 | 14篇 |
2004年 | 17篇 |
2003年 | 15篇 |
2002年 | 8篇 |
2001年 | 8篇 |
2000年 | 12篇 |
1999年 | 10篇 |
1998年 | 39篇 |
1997年 | 24篇 |
1996年 | 25篇 |
1995年 | 18篇 |
1994年 | 12篇 |
1993年 | 14篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1973年 | 4篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有677条查询结果,搜索用时 15 毫秒
31.
Giordano Bruno L.; Rocchesso Davide; McAdams Stephen 《Canadian Metallurgical Quarterly》2010,36(2):462
Sound sources are perceived by integrating information from multiple acoustical features. The factors influencing the integration of information are largely unknown. We measured how the perceptual weighting of different features varies with the accuracy of information and with a listener’s ability to exploit it. Participants judged the hardness of two objects whose interaction generates an impact sound: a hammer and a sounding object. In a first discrimination experiment, trained listeners focused on the most accurate information, although with greater difficulty when perceiving the hammer. We inferred a limited exploitability for the most accurate hammer-hardness information. In a second rating experiment, listeners focused on the most accurate information only when estimating sounding-object hardness. In a third rating experiment, we synthesized sounds by independently manipulating source properties that covaried in Experiments 1 and 2: sounding-object hardness and impact properties. Sounding-object hardness perception relied on the most accurate acoustical information, whereas impact-properties influenced more strongly hammer hardness perception. Overall, perceptual weight increased with the accuracy of acoustical information, although information that was not easily exploited was perceptually secondary, even if accurate. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
32.
Rubiola E Groslambert J Brunet M Giordano V 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2000,47(2):361-368
Frequency flicker of quartz resonators can be derived from the measurement of S(phi) (f), i.e., the power spectrum density of phase fluctuations phi. The interferometric method appears to be the best choice to measure the phase fluctuations of the quartz resonators because of its high sensitivity in the low power conditions, which is required for this type of resonator. Combining these two ideas, we built an instrument suitable to measure the frequency flicker floor of the quartz resonators, and we measured the stability of some 10-MHB high performance resonators as a function of the dissipated power. The stability limit of our instrument, described in terms of Allan deviation sigma(y)(tau), is of some 10(-14). 相似文献
33.
P Giordano M Galli GC Del Vecchio M Altomare F Norbis L Ruggeri M Petronelli D de Mattia 《Canadian Metallurgical Quarterly》1998,102(4):903-906
Anticardiolipin antibodies (ACA) and lupus anticoagulant (LA) have been detected in patients with hepatitis C virus (HCV) infection and have been associated in autoimmune diseases (i.e. systemic lupus erythematosus) with an increased risk of thromboembolic events. Because of the high prevalence of HCV infection and the thrombotic risk described in thalassaemia we decided to investigate the prevalence of ACA and LA in a cohort of 68 thalassaemia patients. We found a high prevalence (34%) of beta2-glycoprotein I independent ACA in our thalassaemia patients which was related to HCV infection. None of patients developed any complications related to antiphospholipid antibodies (APL); therefore the clinical significance of positivity for APL in patients with HCV infection is at present unclear. In conclusion, the results of our study indicate that ACA in the serum of HCV-infected thalassaemic patients exhibit the characteristics of natural autoantibodies rather than those of the pathogenic autoantibodies that are found in patients with systemic lupus erythematosus. 相似文献
34.
An acoustic-emission characterization of the failure modes in polymer-composite materials 总被引:3,自引:0,他引:3
M Giordano A Calabro C Esposito A D'Amore L Nicolais 《Composites Science and Technology》1998,58(12):1923-1928
A new methodology for the analysis of failure modes in composite materials by means of acoustic emission techniques has been developed. A single-carbon-fiber composite based on a polyester matrix, has been used as a simple model. The occurrence of fiber-breakage during tensile loading tests has been observed by a polarized light microscope and concurrently detected by a resonant acoustic probe. The resonant probe has been used as a trigger for the reading of fiber failure events. Single acoustic emission events from a wide-band probe has been recorded for FFT Analysis. The single-fiber specimen, having a unique failure mode, has advantages for the standardization of AE techniques for the quantitative analysis of failures in polymer-composite materials.
The same procedure can be exploited to investigate other failure modes namely, fiber matrix solidus debonding and matrix cracking. 相似文献
35.
In this paper we present various logical characterizations of justification-based (nonmonotonic) truth maintenance systems (JTMS). These characterizations, which are proved to be equivalent, aim at describing dependency-directed backtracking (DDB) (i.e., the process of resolving conflicts which can arise when nogoods are allowed in the set of justifications), mainly relying on the intuitive idea that a contrapositrve use of justifications is needed to resolve inconsistencies. The idea is first formalized by means of the notion of three-valued labeling and then through a transformation which explicitly adds all contrapositives of the justifications. An abductive characterization of the JTMS is provided through a further transformation which converts a set of nonmonotonic justifications to a corresponding abduction framework. This approach provides a unifying framework, based on the notion of abduction, for describing both JTMSs and assumption-based TMSs (ATMSs). 相似文献
36.
The nitrate ion oxidation at platinum electrodes from AgNO3 in acetonitrile solutions has been studied under a wide range of experimental conditions. LiClO4 0·4 M was used as supporting electrolyte. Coulommetry, steady state polarization curves in unstirred solutions, rotating disk electrode and chronopotentiometry were employed as electrochemical techniques to analyse the electrode reaction.During the electrolysis Ag2+ ions were detected. Ag2+ is obtained through a nitrate catalytic reaction pathway according to: The heterogeneous catalytic behaviour of the electrode reaction was confirmed by chronopotentiometry and rde results.The diffusion coefficient of the reacting species and the heterogeneous catalytic constant were calculated. Both techniques give coherent results. 相似文献
37.
Rosso F Barbarisi A Barbarisi M Giordano A Ambrosio L 《Journal of materials science. Materials in medicine》2004,15(6):679-686
Copolymerisation of charged and neutral monomers is a well-known methodology to introduce charged moieties in a polymeric chain to obtain polyelectrolytes. New polyelectrolyte complexes have been synthesised by radical copolymerisation of neutral methacrylic monomer 2-hydroxyethyl methacrylate (HEMA) with cationic 2-methacryloyloxyethyltrimethyl ammonium chloride and anionic 2-acrylamido-2-methylpropane-sulphonic acid monomers in 10:1:1 and 10:1:2 stechiometric ratio. Chemical structure of the synthesised terpolymers was confirmed by FT-IR spectroscopy, moreover, X-ray photoelectron spectroscopy showed the presence of a cationic charge excess on the 10:1:2 terpolymer surface with respect to 10:1:1 terpolymer. Swelling studies for 10:1:2 terpolymers showed a high water content in the swollen state and a "smart behaviour" upon changes in external stimuli such as pH, while, 10:1:1 terpolymer presented the behaviour of a neutral polymer. Mechanical and differential scanning calorimetry analysis confirmed that terpolymer networks were stabilised by ionic co-operative interactions. Infact, the inclusion of oppositely ionic charges in the polymeric network of p(HEMA) represent a way to achieve higher elastic modulus as they stabilise the terpolymer networks. Cytotoxicity and cytocompatibility studies demonstrated that all materials were not toxic, moreover, the presence of a cationic charge excess on 10:1:2 terpolymer surface was able to promote fibroblast adhesion. 相似文献
38.
Scott M. Giordano 《Information Systems Frontiers》2004,6(2):161-174
Today, documents and data are likely to be encountered in electronic form. This creates a challenge for the legal system since its rules of evidence evolved to deal with tangible (physical) evidence. Digital evidence differs from tangible evidence in various respects, which raise important issues as to how digital evidence is to be authenticated, ascertained to be reliable and determined to be admissible in criminal or civil proceedings. This article explains how digital evidence differs from traditional physical evidence and reviews the current state of the law with regard to the processes of authentication, reliability and admissibility. 相似文献
39.
40.
Co-adsorption of nitromethane at Pt electrodes, and its influence on HCOOH electrocatalytic oxidation were investigated by cyclic voltammetry and potentiostatic quasi-steady state polarization curves. Potentiodynamic I/E curves in the presence of nitromethane show a considerable current increase in the low potential region (0.2–0.5 V). This effect is maintained under quasi-steady state conditions.Electrosorption studies performed with nitromethane indicated that partially reduced species are adsorbed on the electrode surface. These species could be responsible for the observed promoting effect.The results obtained with nitromethane addition are compared with acetonitrile and dimethylsulfoixide. Competition for adsorption sites and modifications of surface adsorption energy produced by additive adsorption, account for their specific influence on the HCOOH oxidation rate. 相似文献