全文获取类型
收费全文 | 505篇 |
免费 | 40篇 |
专业分类
电工技术 | 8篇 |
综合类 | 1篇 |
化学工业 | 173篇 |
金属工艺 | 4篇 |
机械仪表 | 3篇 |
建筑科学 | 25篇 |
矿业工程 | 2篇 |
能源动力 | 6篇 |
轻工业 | 99篇 |
水利工程 | 2篇 |
无线电 | 41篇 |
一般工业技术 | 79篇 |
冶金工业 | 49篇 |
原子能技术 | 3篇 |
自动化技术 | 50篇 |
出版年
2023年 | 4篇 |
2022年 | 32篇 |
2021年 | 51篇 |
2020年 | 22篇 |
2019年 | 13篇 |
2018年 | 14篇 |
2017年 | 18篇 |
2016年 | 21篇 |
2015年 | 25篇 |
2014年 | 24篇 |
2013年 | 28篇 |
2012年 | 25篇 |
2011年 | 31篇 |
2010年 | 24篇 |
2009年 | 14篇 |
2008年 | 21篇 |
2007年 | 18篇 |
2006年 | 16篇 |
2005年 | 14篇 |
2004年 | 3篇 |
2003年 | 8篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 7篇 |
1994年 | 12篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1984年 | 2篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 7篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有545条查询结果,搜索用时 234 毫秒
31.
An Integrative Model of Mobile Phone Appropriation 总被引:1,自引:0,他引:1
Werner Wirth Thilo von Pape Veronika Karnowski 《Journal of Computer-Mediated Communication》2008,13(3):593-617
The evolution of mobile communication devices and services has taken up a dynamic that makes any prognosis in the field almost impossible. Whereas part of this dynamic may remain inscrutable, we believe that a much higher degree of explanation can be achieved by systematically paying closer attention to the process of appropriation. To seize upon this potential, we present an integrative model to analyze mobile phone appropriation (the "MPA model").
The model is based on existing theoretical approaches of the quantitative "adoption" paradigm (namely, Innovation Diffusion Theory and Theory of Planned Behavior) as well as the mostly qualitative research paradigm devoted to "appropriation" (Cultural studies and Frame Analysis), with the Uses-and-Gratifications approach playing a role on both sides. The model has been developed, operationalized and empirically applied in the context of mobile phone appropriation; however, with certain modifications it can be adapted to other information and communications technology (ICT) innovations. 相似文献
The model is based on existing theoretical approaches of the quantitative "adoption" paradigm (namely, Innovation Diffusion Theory and Theory of Planned Behavior) as well as the mostly qualitative research paradigm devoted to "appropriation" (Cultural studies and Frame Analysis), with the Uses-and-Gratifications approach playing a role on both sides. The model has been developed, operationalized and empirically applied in the context of mobile phone appropriation; however, with certain modifications it can be adapted to other information and communications technology (ICT) innovations. 相似文献
32.
Harald Rohm und Veronika Veits 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1989,189(6):538-543
Zusammenfassung Die in den USA entwickelte sensorische Texturprofilanalyse stellt die aussagestärkste Methode zur quantitativen und qualitativen Bewertung der Texturunterschiede von Lebensmitteln dar. Vor der Anwendung in Regionen mit anderen Konsumgewohnheiten bedarf sie jedoch einer entsprechenden Adaptierung. Mitteilung 1 berichtet über modifizierte standardisierte Intensitätsskalen zur quantitativen Einstufung der mechanischen Textureigenschaften Festigkeit, Brüchigkeit, Kaubarkeit, weichelastisches Verhalten, Viskosität und Adhäsivität. Die Anpassung an das österreichische Lebensmittelspektrum erfolgte mittels rheologischer Vorprüfungen potentieller Standardpunkte und anschließender Fixierung der Normskalen durch ein geschultes Prüferpanel unter guter Korrelation zwischen instrumentellen und sensorischen Prüfungen.
Adaption of sensory texture profile analysis 1. Scaling of mechanical properties
Summary Texture profile analysis, originally developed in the United States, represents the most complete system of both quantitative and qualitative sensory texture measurements of foodstuffs. Due to regionally varying habits of consumption, an adequate adaptation is necessary prior to application. This paper deals with the evaluation of the mechanical properties firmness, brittleness, chewiness, gumminess, viscosity and adhesiveness. Modifications of standard rating scales for typical Austrian food materials are reported. Rheological examination of commodities was followed by final establishment of standard scales with a trained panel. Good correlation between instrumental and sensory results was obtained.相似文献
33.
Dr. Kornelia Hardes Dr. Gero L. Becker Dr. Yinghui Lu Dr. Sven O. Dahms Susanne Köhler Dr. Wolfgang Beyer Prof. Kirsten Sandvig Dr. Hiroyuki Yamamoto Prof. Iris Lindberg Lisa Walz Dr. Veronika von Messling Dr. Manuel E. Than Prof. Wolfgang Garten Prof. Torsten Steinmetzer 《ChemMedChem》2015,10(7):1218-1231
New peptidomimetic furin inhibitors with unnatural amino acid residues in the P3 position were synthesized. The most potent compound 4‐guanidinomethyl‐phenylacteyl‐Arg‐Tle‐Arg‐4‐amidinobenzylamide (MI‐1148) inhibits furin with a Ki value of 5.5 pM . The derivatives also strongly inhibit PC1/3, whereas PC2 is less affected. Selected inhibitors were tested in cell culture for antibacterial and antiviral activity against infectious agents known to be dependent on furin activity. A significant protective effect against anthrax and diphtheria toxin was observed in the presence of the furin inhibitors. Furthermore, the spread of the highly pathogenic H5N1 and H7N1 avian influenza viruses and propagation of canine distemper virus was strongly inhibited. Inhibitor MI‐1148 was crystallized in complex with human furin. Its N‐terminal guanidinomethyl group in the para position of the P5 phenyl ring occupies the same position as that found previously for a structurally related inhibitor containing this substitution in the meta position, thereby maintaining all of the important P5 interactions. Our results confirm that the inhibition of furin is a promising strategy for a short‐term treatment of acute infectious diseases. 相似文献
34.
Gtz Hüsken Stephan Pirskawetz Dietmar Meinel Veronika Babski Hans‐Carsten Kühne 《Bautechnik》2016,93(10):711-716
Methods for analyzing the fracture behavior of high‐strength steel fiber‐reinforced concretes High‐strength and ultra‐high strength fiber‐reinforced concretes are most suitable for applications with extreme mechanical loads. These extreme conditions require a ductile behavior under tensile loading, which is obtained solely by the addition of steel fibers and their working mechanism. Profound know ledge on the working mechanism of the steel fibers is necessary for optimizing this material. Usually, this knowledge is obtained by means of classical measuring techniques of destructive tests. Adopting measuring techniques from non‐destructive material testing helps to analyze and to identify the different stages of the fracture mechanism of high‐strength and ultra‐high strength fiber‐reinforced concretes in detail. The application of different non‐destructive measuring techniques is shown exemplary on tensile tests conducted on an ultra‐high strength fiber‐reinforced concrete and its applicability for analyzing the fracture behavior is discussed. The main focus is on the characterization of the relevant failure modes under tensile loading by the different measuring techniques and the comparison with classical measuring techniques (e. g. extensometer). The tensile tests have been analyzed by optical deformation measurements using digital image correlation (DIC), acoustic emission analysis (AE), and 3D computed tomography (CT). 相似文献
35.
Jiri Pikula Hana Bandouchova Klara Hilscherova Veronika Paskova Jana Sedlackova Ondrej Adamovsky Zora Knotkova Jiri Machat Ladislav Novotny Frantisek Vitula 《The Science of the total environment》2010,408(21):4984-4992
Under environmental conditions, wild birds can be exposed to multiple stressors including natural toxins, anthropogenic pollutants and infectious agents at the same time.This experimental study was successful in testing the hypothesis that adverse effects of cyanotoxins, heavy metals and a non-pathogenic immunological challenge combine to enhance avian toxicity. Mortality occurred in combined exposures to naturally occurring cyanobacterial biomass and lead shots, lead shots and Newcastle vaccination as well as in single lead shot exposure. Mostly acute effects around day 10 were observed. On day 30 of exposure, there were no differences in the liver accumulation of lead in single and combined exposure groups. Interestingly, liver microcystin levels were elevated in birds co-exposed to cyanobacterial biomass together with lead or lead and the Newcastle virus. Significant differences in body weights between all Pb-exposed and Pb-non-exposed birds were found on days 10 and 20. Single exposure to cyanobacterial biomass resulted in hepatic vacuolar dystrophy, whereas co-exposure with lead led to more severe granular dystrophy. Haematological changes were associated with lead exposure, in particular. Biochemical analysis revealed a decrease in glucose and an increase in lactate dehydrogenase in single and combined cyanobacterial and lead exposures, which also showed a decreased antibody response to vaccination.The combined exposure of experimental birds to sub-lethal doses of individual stressors is ecologically realistic. It brings together new pieces of knowledge on avian health. In light of this study, investigators of wild bird die-offs should be circumspect when evaluating findings of low concentrations of contaminants that would not result in mortality on a separate basis. As such it has implications for wildlife biologists, veterinarians and conservationists of avian biodiversity. 相似文献
36.
37.
The purpose of this study was to investigate the implications of selected chemopreventive parameters and metabolic conversion of resveratrol in vivo. In two 8-week long feeding experiments with rats, a low-resveratrol diet containing 50 mg resveratrol per kg body weight (bw) and day and a high-resveratrol diet with 300 mg per kg bw and day were administered. For chemopreventive evaluation selected phase I and phase II enzymes of the biotransformation system, the total antioxidant activity, and the vitamin E status of the animals were determined. The level of resveratrol and its metabolites in the feces, urine, plasma, liver, and kidneys was identified and quantitated by high-performance liquid chromatography-diode array detection (HPLC-DAD) using synthesized resveratrol conjugate standards. Feeding of different dosages of resveratrol revealed no effect on the different chemopreventive parameters, except for the total antioxidant activity, which was elevated in plasma by 19% after feeding 50 mg resveratrol per kg bw and day. The formation of trans-resveratrol-3-sulfate, trans-resveratrol-4'-sulfate, trans-resveratrol-3,5-disulfate, trans-resveratrol-3,4'-disulfate, trans-resveratrol-3,4',5-trisulfate, trans-resveratrol-3-O-beta-D-glucuronide, and resveratrol aglycone was detected by HPLC analysis, depending on the biological material. Total resveratrol recovery in urine and feces of rats fed on 50 mg resveratrol per kg bw and day was 15% and 13%, respectively. For rats fed the higher dosage of 300 mg resveratrol per kg bw and day recovery was 54% and 17%, respectively. This is the first study performed with synthesized standards of relevant resveratrol conjugates. The lack of effect on the chemopreventive parameters is probably due to the formation of various resveratrol conjugates reducing its bioavailability in the rat. 相似文献
38.
Frantisek Rybnikar Martina Kaszonyiova Roman Cermak Veronika Habrova Martin Obadal 《应用聚合物科学杂志》2013,128(3):1665-1672
This study focuses on the structure, morphology, and properties of linear polyethylene (PE) profiles manufactured by continuous extrusion. High level of chain orientation was achieved using specific flow and processing conditions. An extrusion die with semihyperbolic convergency was used to generate high percentage of elongational flow and chain extension. Simultaneously, high extrusion pressure and relatively low melt temperature led to flow‐induced crystallization of PE extended chains. The structure of PE tapes consists of crystal aggregates with different level of orientation and crystallinity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
39.
K. Petritsch J. J. Dittmer E. A. Marseglia R. H. Friend A. Lux G. G. Rozenberg S. C. Moratti A. B. Holmes 《Solar Energy Materials & Solar Cells》2000,61(1)
We have fabricated organic donor/acceptor solar cells with three different architectures using soluble derivatives (dyes) of the molecular semiconductors phthalocyanine as electron donor (D), i.e. hole transport material and perylene as electron acceptor (A), i.e. electron transport material. These architectures comprise a blend and a double layer structure as well as the only recently reported laminated-device structure. The organic semiconducting films were deposited at room temperature via spin coating from solution. Current–voltage (I/V) characteristics and external quantum efficiency spectra will be discussed. The measured quantum efficiencies reach values between 0.3% and 1.1% with a photoresponse covering the entire spectrum of visible light. Our results show that together with insoluble small molecules (pigments) and conjugated polymers, dye molecules represent a new class of organic semiconducting materials that can be used to manufacture D/A solar cells. 相似文献
40.
The Dama de Elche (4th–5th century B.C.), an emblematic piece of the ancient Iberian culture, was first sculpted in fossiliferous limestone of Tertiary
Age. In this first systematic study, two classic pigments have been identified: Egyptian blue, prepared with a potassium flux,
and natural vermilion applied over a preparation layer of gypsum, mixed with calcium carbonate, that migrated and recrystallized
on the polychrome surface of the bust, process favoured by the change suffered after its disinterment. No anachronisms have
been found on the identified polychromy, the existing coating surface nor any other element that might suggest it to be a
modern forgery.
Editorial note The “Eduardo Torroja” Institute (CSIC) is a RILEM Titular Member. Dra. M.P. de Luxán participates in RILEM TCs CUA ‘Concrete use of additions’ and RHM, ‘Repair mortars for historic buildings’. Dr. F. Dorrego also participates in RILEM TC RHM. 相似文献
Résumé La Dama de Eleche, sculpture emblématique de la culture ibère, fut taillée en pierre calcaire avec des fossiles de l'ère tertiaire. Dans cette première investigation systématique, on a identifié deux pigments classiques: le bleu égyptien, préparé avec un fondant potassique, et le vermillon naturel, appliqués sur une couche de préparation en platre, mélangé avec de la chaux, qui a migré et a recristallisé sur la surface polychrome du buste. Ce procédé a été aidé pour les changements subis après son déterrement. On n'a pas trouvé d'anachronisme en ce qui concerne les pigments et la couche de préparation. Aucun élément ne permet, de déduire que la sculpture puisse être un faux moderne.
Editorial note The “Eduardo Torroja” Institute (CSIC) is a RILEM Titular Member. Dra. M.P. de Luxán participates in RILEM TCs CUA ‘Concrete use of additions’ and RHM, ‘Repair mortars for historic buildings’. Dr. F. Dorrego also participates in RILEM TC RHM. 相似文献