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81.
Effects of environmental factors on seasonal and spatial changes in surface zooplankton in Golden Horn Estuary (Istanbul,Turkey) 下载免费PDF全文
The abundance and spatial distribution of zooplankton at monthly intervals were studied in polluted Golden Horn Estuary (Istanbul, Turkey), from July 2006 to December 2007. Selected water quality parameters also were measured. The zooplankton community was characterized by the presence of freshwater, estuarine and marine species, with a total of 59 taxa. Rotifers were the most important fraction of the total zooplankton, comprising 36.52% of all the samples. The zooplankton exhibited seasonal patterns, with the highest abundance occurring in the summer (979 ind. L?1) and the lowest in the spring (856 ind. L?1). Rotifera was the most abundant group in the upper and middle estuary, whereas Copepoda usually reaches the maximum densities in the higher salinity waters in the lower estuary. The study results indicated that both the sampling time (seasons) and sampling sites jointly had significant effects on the zooplankton densities (manova P < 0.05), and horizontal patterns were related to electrical conductivity, water temperature, dissolved oxygen, suspended particulate matter, pH and chlorophyll a measured in the estuary. 相似文献
82.
Zeynep Serinyel Olivier HerbinetOphélie Frottier Patricia DirrenbergerValérie Warth Pierre Alexandre GlaudeFrédérique Battin-Leclerc 《Combustion and Flame》2013
The experimental study of the oxidation of cyclohexane has been performed in a jet-stirred reactor at temperatures ranging from 500 to 1100 K (low- and intermediate temperature zones including the negative temperature-coefficient area), at a residence time of 2 s and for dilute mixtures with equivalence ratios of 0.5, 1, and 2. Experiments were carried out at quasi-atmospheric pressure (1.07 bar). The fuel and reaction product mole fractions were measured using online gas chromatography. A total of 34 reaction products have been detected and quantified in this study. Typical reaction products formed in the low-temperature oxidation of cyclohexane include cyclic ethers (1,2-epoxycyclohexane and 1,4-epoxycyclohexane), 5-hexenal (formed from the rapid decomposition of 1,3-epoxycyclohexane), cyclohexanone, and cyclohexene, as well as benzene and phenol. Cyclohexane displays high low-temperature reactivity with well-marked negative temperature-coefficient (NTC) behavior at equivalence ratios 0.5 and 1. The fuel-rich system (? = 2) is much less reactive in the same region and exhibits no NTC. To the best of our knowledge, this is the first jet-stirred reactor study to report NTC in cyclohexane oxidation. Laminar burning velocities were also measured by the heated burner method at initial gas temperatures of 298, 358, and 398 K and at 1 atm. The laminar burning velocity values peak at ? = 1.1 and are measured as 40 and 63.1 cm/s for Ti = 298 and 398 K, respectively. An updated detailed chemical kinetic model including low-temperature pathways was used to simulate the present (jet-stirred reactor and laminar burning velocity) and literature experimental (laminar burning velocity, rapid compression machine, and shock tube ignition delay times) data. Reasonable agreement is observed with most of the products observed in our reactor, as well as the literature experimental data considered in this paper. 相似文献
83.
Mustafa Tuzen Yunus Emre Unsal Mustafa Soylak Zeynep Akkirman Baki Hazer 《International Journal of Food Science & Technology》2013,48(11):2384-2390
A separation and preconcentration procedure based on solid‐phase extraction of Cu(II) and Pb(II) as their Sudan III chelates on polyhydroxybutyrate‐b‐polydimethyl siloxane (PHB‐b‐PDMS) block copolymer disc has been established. Various analytical parameters including pH, amount of Sudan III, eluent type and volume, sample volume, flow rates were optimised. The effects of concomitant ions on the retentions of the analyte ions on PHB‐b‐PDMS disc were also examined. The detection limits for Cu(II) and Pb(II) were found to be 2.3 and 4.9 μgL?1, respectively. Preconcentration factor was found to be sixty. Relative standard deviation was found to be 5%. The accuracy of the method was confirmed by analysing certified reference materials (TMDA 54.4 fortified lake water and NIST 1515 Apple leaves). Optimised method was applied to determine the analyte ions in various water and food samples from Turkey. 相似文献
84.
Although there is a growing literature on the factors associated with the length of interorganizational relationships, there seem to be few empirical studies related to the subject in project-based industries such as construction. In this study we looked for correlations among the length of the relationship between main and specialist trade contractors, control methods and the number of rival speciality contractors in the Turkish construction industry, drawing on the data provided by a study of 27 specialist trade contractors. Correlation analysis was used to investigate the relationship. The results demonstrate that the length of the relationship between main and speciality contractors is inversely related to the number of rival specialist trade contractors, but directly related to the flexibility of control exercised by the main contractor. 相似文献
85.
Mehmet Kılıç Zeynep Güven Özdemir Ümit Alkan Yaşar Karabul Orhan İçelli 《应用聚合物科学杂志》2019,136(18):47414
In this study, we investigated the effects of high-dose γ-ray irradiation on the mechanical and dielectric properties of polypropylene (PP)–basalt thick films. PP–basalt thick-film composites with various basalt contents from 0.5 to 10.0% were prepared by a hot-press method. The samples were exposed to γ radiation at different doses in the range 3–25 kGy. The mechanical properties of the samples, such as the Young's modulus, tensile strength, percentage strain at break, and energy at break, were examined in the context of the γ-irradiation process. Although the maximum elasticity was obtained for the unirradiated 0.5% basalt-added composite, the 6 kGy γ-irradiated PP–1.0% basalt sample exhibited the highest elasticity properties among all of the composites. The best mechanical properties, including the ultimate tensile strength and energy at break values, were achieved for the 12 kGy γ-irradiated neat PP. The dielectric properties of the PP–basalt composites were also investigated in the 100 Hz to 15 MHz frequency region at room temperature. According to the analysis of the dielectric properties, the 3 kGy γ-irradiated neat PP may have potential for microelectronic device applications that require low dielectric constant and dielectric loss materials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47414. 相似文献
86.
Yakup Say Bunyamin Aksakal Zeynep A. Sinirlioglu 《International Journal of Applied Ceramic Technology》2022,19(5):2701-2712
The effects of silver (Ag), selenium (Se), and chitosan (Cht) additives on the antibacterial activity and cell viability of NiTi were investigated. Three different hydroxyapatite (HA)-based bioceramic coatings to improve the antibacterial activity and cell viability of NiTi; HA, HA/Ag, and HA/Se–Cht were applied to NiTi substrates by a sol–gel method. The coated samples were characterized by scanning electron microscopy–electron-dispersive spectroscopy and X-ray diffraction and surface hardnesses were measured. The antimicrobial efficiency of the coatings and uncoated surfaces were tested against Escherichia coli-JM 103 and Staphylococcus aureus-ATCC29293. In vitro cell–material interactions using Saos-2 osteoblast cells were characterized by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (mitochondrial activity test) assay for cell viability. A homogeneous, crack-free, and porous surface morphology is achieved in coatings. It has been shown that the Se–Cht additives did not have a significant effect on the surface hardness of the HA coating, but the Ag additive increased the hardness. Through in vitro antibacterial activity and cell viability tests, it was shown that Ag additive to bioceramic coatings significantly increased (p < .05) antibacterial properties but caused a decrease in cell viability. However, although Se–Cht additives did not have a significant effect on antibacterial properties (p < .05), it was observed that they increased cell viability. 相似文献
87.
In the digital economy, the volume, variety and availability of data produced in myriad forms from a diversity of sources has become an important resource for competitive advantage, innovation opportunity as well as source of new management challenges. Building on the theoretical and empirical foundations of the traditional manufacturing Supply Chain (SC), which describes the flow of physical artefacts as raw materials through to consumption, we propose the Data Supply Chain (DSC) along which data are the primary artefact flowing. The purpose of this paper is to outline the characteristics and bring conceptual distinctiveness to the context around DSC as well as to explore the associated and emergent management challenges and innovation opportunities. To achieve this, we adopt the systematic review methodology drawing on the operations management and supply chain literature and, in particular, taking a framework synthetic approach which allows us to build the DSC concept from the pre-existing SC template. We conclude the paper by developing a set of propositions and outlining an agenda for future research that the DSC concept implies. 相似文献
88.
The facility layout problem is typically solved in what is referred to as a “top-down approach” of block layout design followed by detailed layout determination. However, a number of research efforts recently have challenged this approach, producing a reformulated bottom-up approach to the facility layout problem. In this paper we consider the bottom-up approach, applying a tighter formulation than prior efforts and investigating the solvability limits of the new model. Empirical testing of the new bottom-up layout model indicates that although this model produces more usable output, as judged by industry experts, it is approximately three times harder to solve. Valid inequalities and special cases are identified to help improve the formulation's solvability. 相似文献
89.
With the rapid development of the software industry, improving the quality of software development has gained increasing importance.
Software manufacturers have recently applied quality improvement techniques to software development to respond to the needs
for software quality. Software quality function deployment (SQFD), as a technique for improving the quality of the software
development process to create products responsive to customer expectations, is used to maximize customer satisfaction. This
paper presents a fuzzy regression and optimization approach to determine target levels in SQFD. The inherent fuzziness of
relationships in SQFD modeling justifies the use of fuzzy regression. Fuzzy regression is used to identify the functional
relationships between customer requirements and technical attributes, and among technical attributes. Then, a mathematical
programming model is developed to determine target levels of technical attributes using the functional relationships obtained
by fuzzy regression. A search engine quality improvement problem is presented to illustrate the application of the proposed
approach. 相似文献
90.
Video game goals are important features of video games. Player’s interaction with goals can not only shape the gaming experience by evoking cognitive and affective reactions in players, but also lead to learning outcomes. However, there are few empirical studies on the effects of interacting with game goals, and no previous research has manipulated goal setting. In two experimental studies, participants were randomly assigned to one of the following five conditions: self-set goal repetitive play, assigned goal repetitive play, no-set goal repetitive play, no-set goal single play, and no play. Results show that playing earthquake preparedness video games generates significant learning outcomes; playing repeatedly with self-set goals yields greater learning compared to playing once with no-set goals or not playing; and cognitive reactions mediates the relation between goal interaction and learning. Implications of the results for the design and evaluation of future video games for learning are explored. 相似文献