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81.
Cocaine use is a significant problem among methadone maintenance clients. Contingency management (CM) is a reinforcement-based approach with demonstrated efficacy for reducing cocaine use. This study examines whether the efficacy of CM treatment for cocaine-dependent individuals receiving methadone maintenance for opioid dependence differs by ethnicity. Participants were 191 African American, Hispanic, and White cocaine-dependent methadone maintenance clients, randomly assigned to standard methadone treatment or standard methadone treatment plus CM for 12 weeks. Hispanic participants were younger, less educated, and reported fewer years of cocaine use than did African American and White participants and reported fewer years of heroin use than did African American participants. African American participants were less likely to report a history of psychiatric symptoms or treatment in comparison with Hispanic and White participants. While CM was associated with longer duration of continuous cocaine abstinence and a greater proportion of submitted urine samples negative for cocaine, ethnicity was not related to treatment outcomes, and there was no significant interaction between treatment and ethnicity. CM appears to be an efficacious treatment for cocaine dependence among methadone maintenance clients, regardless of ethnicity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
82.
The effects of thermal exposure on the strengths of Nextel™ 550 and 720 tows, bare and coated with carbon, were determined by room-temperature tensile testing of single filaments extracted from tows that had been exposed to different thermal environments (i.e., air or vacuum) at temperatures from 550° to 1400°C. The results help define the allowable composite processing conditions when using these tows. A 28% drop in the strength of Nextel 550 filaments occurred after a thermal exposure at 1100°C for 2 h in air. After an exposure of 1300°C/2 h/air, a strength degradation of ∼47% resulted. Filaments exposed above 1100°C under vacuum showed more severe strength degradation than filaments exposed in air. The observed strength degradation may stem from a combination of phase transformations of the alumina, the onset of mullite crystallization, and/or exaggerated mullite grain growth. Strength after heat treatment under vacuum at 1050° and 1150°C did not deteriorate as rapidly as after heat treatment under vacuum between 950° and 1050°C or between 1150° and 1250°C. This may be a result of the competition between healing of flaws by the amorphous silica and its evaporation (leading to an increase in its viscosity or loss) and/or densification of the filaments. Nextel 720 filaments exhibited about 9% strength loss after an exposure at 1100°C/2 h/air. The filaments maintained 75% of their strength after a 1300°C/2 h/air heat treatment. The observed strength degradation may stem from thermal grooving, grain growth, and/or annealing of the mullite subgrain boundaries. Thermal exposure of >10 h at 1300°C was required to produce measurable grain growth. Strength loss between 1200° and 1300°C (air heat treatment) was not as great as between 1100° and 1200°C or 1300° and 1400°C.  相似文献   
83.
Starches isolated from wheat (Rapoport's variety) at different stages of maturation and from completely maturated rye (Viatka‐2 variety) were investigated in excess of water and in 0.6 M KCl using high sensitivity differential scanning microcalorimetry (HSDSC). Applying some physico‐chemical approaches, the starch polymorphous structure, the thickness of the crystalline lamellae and the thermodynamic parameters characterizing their surface faces were determined. It has been established that wheat and rye starches belong to the A‐type starches. It is suggested that during biosynthesis of granules the formation of the A‐type structure is accompanied by an accumulation of crystal defects. This process leads to a decrease in the melting temperature of starches.  相似文献   
84.
This paper concerns the modeling of imprecision, vagueness, and uncertainty in databases through an extension of the relational model of data: the fuzzy rough relational database, an approach which uses both fuzzy set and rough set theories for knowledge representation of imprecise data in a relational database model. The fuzzy rough relational database is formally defined, along with a fuzzy rough relational algebra for querying. Comparisons of theoretical properties of operators in this model with those in the standard relational model are discussed. An example application is used to illustrate other aspects of this model, including a fuzzy entity–relationship type diagram for database design, a fuzzy rough data definition language, and an SQL‐like query language supportive of the fuzzy rough relational database model. This example also illustrates the ease of use of the fuzzy rough relational database, which often produces results that are better than those of conventional databases since it more accurately models the uncertainty of real‐world enterprises than do conventional databases through the use of indiscernibility and fuzzy membership values. ©2000 John Wiley & Sons, Inc.  相似文献   
85.
A new approach for analyzing the similarity of dynamical systems is presented, with applications to speech analysis. This approach is based on a temporal fuzzy set representation of the trajectories of the dynamical system. The similarity between segments of the speech signal is determined via similarity measures of the corresponding temporal fuzzy sets. We present an application of the method to vowel recognition in the samples (amplitude–time) space. © 2000 John Wiley & Sons, Inc.  相似文献   
86.
The behaviour of monosulfonated telechelic polystyrene with various molar masses and different counterions has been investigated using static and dynamic light scattering. For concentrations above the critical micelle concentration, free unimers associate to form well‐defined star‐shaped micelles. The number of polystyrene chains per micelle (nag) is independent of the concentration and the type of counterion; nag decreases with decreasing molar mass of the polystyrene and increasing polarity of the solvent. The micelles behave like covalently bonded star polystyrene from a structural, dynamic and thermodynamic point of view. © 2000 Society of Chemical Industry  相似文献   
87.
The high wet fibrillation tendency of Lyocell fibres forms the background to this investigation. The wet abrasion behaviour can be improved by crosslinking reactions. Substances containing sulfato ethyl sulfonyl groups but different bridging groups were synthesised and optimised regarding to their application. The wet fibrillation tendency can be reduced clearly with these selected substances. If the concentration of the crosslinking agent on the fibre is the basis of comparisons the different structures have a similar effect on the fibrillation tendency. So the swollen Lyocell fibre permits a crosslinking reaction with curing agents of different size.  相似文献   
88.
The macroscopic symptoms of the high crystallinity of solvent-spun cellulosic fibres appear as a specific tendency to fibrillation, if the swollen fibres are exposed to mechanical stress. The method of proving such fibrillations is the wet abrasion. An increase of the binding forces between the fibril structural elements of the solvent-spun cellulosic fibres results in a reduction of fibrillation. The reinforced bonds are also reflected in increased wet abrasion numbers. By reaction with solvent-spun cellulosic fibres, mono- as well as bi(poly)functional reactive dyestuffs can increase the wet abrasion number. This fact could indicate crosslinking processes between cellulosic chains. The effect of monofunctional reactive dyestuffs with two reactive centres in one reactive group is imaginable as a partial crosslinking realised by covalent and hydrogen bridge bonds. Essentially higher wet abrasion numbers can be achieved with bifunctional reactive dyestuffs. By means of the wet abrasion test it was found that there is a relation between the structural characteristics of the dyestuff and its ability to form crosslinking bridges. In this case the arrangement of the reactive groups on the chromophore and the constitution of the chromophore play an important role. Furthermore, the wet abrasion number is influenced by the concentration of the reactive dyestuff and by the dyeing conditions, for example electrolyte quantity, pH-value and dyeing temperature.  相似文献   
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