全文获取类型
收费全文 | 363篇 |
免费 | 7篇 |
专业分类
化学工业 | 123篇 |
金属工艺 | 12篇 |
机械仪表 | 5篇 |
建筑科学 | 6篇 |
矿业工程 | 1篇 |
能源动力 | 17篇 |
轻工业 | 58篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 29篇 |
一般工业技术 | 58篇 |
冶金工业 | 20篇 |
原子能技术 | 2篇 |
自动化技术 | 36篇 |
出版年
2023年 | 3篇 |
2022年 | 11篇 |
2021年 | 7篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 8篇 |
2017年 | 10篇 |
2016年 | 11篇 |
2015年 | 10篇 |
2014年 | 13篇 |
2013年 | 32篇 |
2012年 | 13篇 |
2011年 | 26篇 |
2010年 | 14篇 |
2009年 | 28篇 |
2008年 | 15篇 |
2007年 | 9篇 |
2006年 | 10篇 |
2005年 | 8篇 |
2004年 | 16篇 |
2003年 | 10篇 |
2002年 | 7篇 |
2001年 | 4篇 |
2000年 | 7篇 |
1999年 | 3篇 |
1998年 | 9篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1988年 | 4篇 |
1986年 | 3篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 5篇 |
1972年 | 2篇 |
1971年 | 4篇 |
1966年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有370条查询结果,搜索用时 15 毫秒
61.
Compagnone G Campanella F Domenichelli S Lo Meo S Bonelli M delle Canne S Isoardi P Marinaro M Ursetta M Curini R 《Radiation protection dosimetry》2012,150(3):316-324
Interventional cardiology procedures are increasing because they offer many advantages to patients compared with other techniques: therefore the Italian National Institution for Insurance against Accidents at Work decided to start a survey for monitoring the state-of-the-art regarding the professionals involved in those procedures. The survey covered six cardiology and medical physics Italian departments. Each centre was asked to record 10 examinations for five types of procedures: coronary angiography (CA), electrophysiology studies (ES), pacemaker implantation (PI), percutaneous transluminal coronary angioplasty (PTCA) and radiofrequency catheter ablation (RA). For each examination all the centres were requested to fill in a questionnaire containing information regarding the operator performing the examination, the patient and the procedure. A total of 290 examinations were recorded: 103 CA, 14 ES, 68 PI, 79 PTCA and 26 RA. As occupational doses are strongly related to patient doses, both patients and operators radiation dose data are reported. Ratios of maximum to minimum mean patient doses across the hospitals surveyed were 2.0, 3.9, 7.0, 1.8 and 1.4 for CA, ES, PI, PTCA and RA, respectively. The calculated rounded mean dose-area product values across all participating hospitals were comparable with other values reported in the literature. In general, specific radiation protection tools were used by all operators performing different procedures in all hospitals. A major issue in this survey was the absence of information about correlation between staff and patient doses in a single procedure: future studies could be more aimed to prospective goals where occupational exposures per procedure are monitored specifically. 相似文献
62.
Giuseppe BattistoniFrancesco Broggi Markus BruggerMauro Campanella Massimo CarboniAnton Empl Alberto FassòEttore Gadioli Francesco CeruttiAlfredo Ferrari Anna FerrariMatthias Lantz Andrea MairaniM. Margiotta Cristina MoroneSilvia Muraro Katia ParodiVincenzo Patera Mauricio PelliccioniLarry Pinsky Johannes RanftStefan Roesler Sofia RolletPaola R. Sala Mario SantanaLucia Sarchiapone Massimiliano SioliGeorge Smirnov Florian SommererChristian Theis Stefania TrovatiR. Villari Heinz VinckeHelmut Vincke Vasilis Vlachoudis Joachim VollaireNeil Zapp 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2011,269(24):2850-2856
63.
Gang Chen Imran Mahmood Khan Wensen He Yongxin Li Peng Jin Osvaldo H. Campanella Haihua Zhang Yanrong Huo Yang Chen Huqing Yang Ming Miao 《Comprehensive Reviews in Food Science and Food Safety》2022,21(3):2688-2714
The applications of lipases in esterification, amidation, and transesterification have broadened their potential in the production of fine compounds with high cumulative values. Mostly, the catalytic triad of lipases is covered by either one or two mobile peptides called the “lid” that control the substrate channel to the catalytic center. The lid holds unique conformational allostery via interfacial activation to regulate the dynamics and catalytic functions of lipases, thereby highlighting its importance in redesigning these enzymes for industrial applications. The structural characteristic of lipase, the dynamics of lids, and the roles of lid in lipase catalysis were summarized, providing opportunities for rebuilding lid region by biotechniques (e.g., metagenomic technology and protein engineering) and enzyme immobilization. The review focused on the advantages and disadvantages of strategies rebuilding the lid region. The main shortcomings of biotechnologies on lid rebuilding were discussed such as negative effects on lipase (e.g., a decrease of activity). Additionally, the main shortcomings (e.g., enzyme desorption at high temperatre) in immobilization on hydrophobic supports via interfacial action were presented. Solutions to the mentioned problems were proposed by combinations of computational design with biotechnologies, and improvements of lipase immobilization (e.g., immobilization protocols and support design). Finally, the review provides future perspectives about designing hyperfunctional lipases as biocatalysts in the food industry based on lid conformation and dynamics. 相似文献
64.
A new technique, named impulse viscoelasticity, was introduced and applied to investigate the rheological properties of dough. Specifically, the effects of mixing and fermentation times on the extensional properties of dough were characterized under small extensional strains of short duration. From the stress and strain responses measured, the tensile storage and loss moduli of dough were obtained as a function of mixing and fermentation times. There were significant changes in the tensile moduli of the dough samples over mixing times and in general high extensional properties were measured for the optimally-mixed dough. Fermentation caused the reduction of both tensile storage/loss moduli with a greater decrease in the storage moduli, clearly showing the loss of elasticity of the fermenting dough. The results showed that the short duration of the applied strain allows the impulse viscoelastic technique to be appropriately used in characterizing the rheology of foods which can vary during processing. 相似文献
65.
Marli L. Moraes Nara C. de Souza Caio O. Hayasaka Marystela Ferreira Ubirajara P. Rodrigues Filho Antonio Riul Valtencir Zucolotto Osvaldo N. Oliveira 《Materials science & engineering. C, Materials for biological applications》2009,29(2):442-447
The preserved activity of immobilized biomolecules in layer-by-layer (LbL) films can be exploited in various applications, including biosensing. In this study, cholesterol oxidase (COX) layers were alternated with layers of poly(allylamine hydrochloride) (PAH) in LbL films whose morphology was investigated with atomic force microscopy (AFM). The adsorption kinetics of COX layers comprised two regimes, a fast, first-order kinetics process followed by a slow process fitted with a Johnson–Mehl–Avrami (JMA) function, with exponent ~ 2 characteristic of aggregates growing as disks. The concept based on the use of sensor arrays to increase sensitivity, widely employed in electronic tongues, was extended to biosensing with impedance spectroscopy measurements. Using three sensing units, made of LbL films of PAH/COX and PAH/PVS (polyvinyl sulfonic acid) and a bare gold interdigitated electrode, we were able to detect cholesterol in aqueous solutions down to the 10? 6 M level. This high sensitivity is attributed to the molecular-recognition interaction between COX and cholesterol, and opens the way for clinical tests to be made with low cost, fast experimental procedures. 相似文献
66.
Mariaelena Tagliabue Osvaldo Da PosAndrea Spoto Giulio Vidotto 《Accident; analysis and prevention》2013
Riding a moped, like many other everyday activities, is a complex behavior in which attention plays a crucial role. This study aims to investigate the role of attention in enhancing the skills required to ride a moped simulator. Two experiments were conducted with 207 and 60 students (14–15 years old), respectively, using a moped simulator to ride on 12 different tracks. The assignment was to ride safely and avoid hazards. In experiment 1, we divided the hazard scenes of the tracks on the basis of the fact that a shift in attention was required to escape the danger. We showed that during the riding training, when no attentional shift was required, the ability to avoid hazards was constantly higher. In experiment 2, participants were asked to cope with the same basic experimental setting but with an additional attentive task. The results showed that they performed in such a way that not only did the attentive task not impair their performance, but it also produced an improvement in the ability to shift attentional focus, preserving performance efficiency. On the basis of these data, it can be claimed that, primarily, attentional shift plays a prominent role in accounting for accident circumstances. Secondarily, it can be claimed that attentional training contributes to improved processing efficiency so as to prevent mishaps. 相似文献
67.
Chayene G. Anchieta Daniela Sallet Edson L. Foletto Syllos S. da Silva Osvaldo Chiavone-Filho Claudio A.O. do Nascimento 《Ceramics International》2014
Ternary zinc spinel oxides such as Zn2SnO4, ZnAl2O4 and ZnFe2O4 were synthesized and characterized, and their activities in the photodegradation of phenol molecules were investigated. Zn2SnO4, ZnAl2O4 and ZnFe2O4 powders were synthesized by hydrothermal, metal–chitosan complexation and solvothermal routes, respectively. The face-centered cubic spinel structure of each material was confirmed by powder X-ray diffractometry (XRD) and its porous structure by N2 adsorption–desorption isotherms. The characterization of spinels was complemented with Fourier transform infrared spectroscopy (FTIR) and X-rays fluorescence (XRF), revealing the formation of spinel structures with high purity. The photocatalytic activity in the degradation of phenol was observed only with Zn2SnO4 oxide. Mineralization degree of phenol molecules by Zn2SnO4 photocatalyst determined by total organic carbon analysis (TOC) reached 80% at 360 min under sunlight. 相似文献
68.
This article proposes an analytical algorithm for predicting errors in lock-in amplifiers (LIAs) working with time-varying reference frequency. Furthermore, a simple method for correcting such errors is presented. The reference frequency can be swept in order to measure the frequency response of a system within a given spectrum. The continuous variation of the reference frequency produces a measurement error that depends on three factors: the sweep speed, the LIA low-pass filters, and the frequency response of the measured system. The proposed error prediction algorithm is based on the final value theorem of the Laplace transform. The correction method uses a double-sweep measurement. A mathematical analysis is presented and validated with computational simulations and experimental measurements. 相似文献
69.
Sergio R. de Miguel Osvaldo A. Scelza Alberto A. Castro Javier Soria 《Topics in Catalysis》1994,1(1-2):87-94
The influence of alkali metals on the Lewis acid sites of gamma-alumina has been studied with NMR and IR of adsorbed CO. The physical properties of the alumina are slightly changed by the addition of low alkali metal concentrations. Li and K are adsorbed selectively on tetrahedral Lewis Al3+ sites of the alumina surface. These effects on the tetrahedral cations are more marked with increasing molar concentration and ionic radius of the alkali metal added to alumina. Results demonstrate that the influence of the alkali metals is not only due to steric factors but also to possible electronic modifications.This work was supported by a grant from CONICET, Argentina. 相似文献
70.
△ 《中国化学工程学报》1998,6(3):271-276
1 INTRODUCTIONSelective hydrogenatioll of small amounts of butynes and butadiene is industrially employedfor obtaining high purity butene-l used as co-monomer in the production of linear low-densitypolyethyene.For this purpose,the content of vinylacetylene.butyne-l and 1,3-butadiene presentin the process stream should be reduced to a few tens of ppm. 相似文献