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71.
Takaaki Nagaoka Cihangir Duran Toshihiro Isobe Yuji Hotta Koji Watari 《Journal of the American Ceramic Society》2007,90(12):3998-4001
The present work describes the effect of hydraulic alumina (HA) as a new inorganic binder on extrusion of alumina ceramics. The addition of a small amount of HA imparted significant flowability and rigidity to the extruded alumina. Under optimum processing conditions such as amounts of HA and water, and curing period, alumina rods and tubes were successfully extruded using a single screw extruder. Sintered specimens have achieved a relative density of 97% after sintering at 1600°C for 2 h. Dense alumina samples prepared using organic and inorganic binders had similar mechanical properties, that is, Young's modulus >380 GPa and H v >2000. These results suggest that HA is a new kind of inorganic binder applicable to the extrusion of ceramics. 相似文献
72.
73.
M. Duran Toksarı Ertan Güner 《The International Journal of Advanced Manufacturing Technology》2008,38(7-8):801-808
In this study, we introduce a mixed nonlinear integer programming formulation for parallel machine earliness/tardiness (ET) scheduling with simultaneous effects of learning and linear deterioration, sequence-dependent setups, and a common due-date for all jobs. By the effects of learning and linear deterioration, we propose that the processing time of a job is defined by increasing function of its execution start time and position in the sequence. The developed model allows sequence-dependent setups and sequence-dependent early/tardy penalties. The model can easily provide the optimal solution to problems involving about eleven jobs and two machines. 相似文献
74.
Gallardo S. Barrero F.J. Martinez-Torres M.R. Toral S.L. Duran M.J. 《Education, IEEE Transactions on》2007,50(2):129-136
This paper proposes and details a course organization methodology based on learner satisfaction achievement. The approach follows the prevailing tendency in modern university reforms which are primarily concerned about "how people learn." As a consequence, the learner has been placed as the main actor of the teaching-learning process. Nevertheless, the current learning literature has not addressed the measurement of learner satisfaction within laboratory and practical subjects. This study develops a general and comprehensive methodology for learner satisfaction measurement in practical subjects. As a case example, the proposed methodology has been applied to an electronic instrumentation and measurement course, confirming the variables with a significant influence on learner satisfaction and becoming the starting point for curriculum redesign based on the learner satisfaction approach. To assess the improvement of the proposed course organization methodology, a comparison with previous academic years has been performed showing the students' rated score evolution. Results fully confirm the validity of the technique and the novel course organization 相似文献
75.
This research paper shows the application of the mathematical tool “wavelet's” to be used in the interpretation and analysis of electrochemical noise signals. The Fast Fourier Transformation (FFT) is one of the most commonly used techniques for analyzing electrochemical noise. But the application of this methodology to the analysis of stochastic signals does not allow their interpretation in a suitable way. The wavelet's methodology carries out the analysis by means of the construction of finite base functions. In several studies, it has been found out that the function that is closest to the electrochemical oscillations is the one called “coiflets,” which presents a similar geometry to what it is observed when an ionic–electronic interchange occurs during an electrochemical interphase. The analysis that appears here was implemented using the toolbox “LabView?.” 相似文献
76.
Parallel machine scheduling problem to minimize the earliness/tardiness costs with learning effect and deteriorating jobs 总被引:1,自引:0,他引:1
The focus of this work is to analyze parallel machine earliness/tardiness (ET) scheduling problem with simultaneous effects
of learning and linear deterioration, sequence-dependent setups, and a common due-date for all jobs. By the effects of learning
and linear deterioration, we mean that the processing time of a job is defined by an increasing function of its starting time
and a decreasing function of the position in the sequence. We develop a mixed integer programming formulation for the problem
and show that the optimal sequence is V-shaped: all jobs scheduled before the shortest jobs and all jobs scheduled after the
shortest job are in a non-increasing and non-decreasing order of processing times, respectively. The developed model allows
sequence-dependent setups and sequence-dependent early/tardy penalties. The illustrative example with 11 jobs for 2 machines
and 3 machines shows that the model can easily provide the optimal solution, which is V-shaped, for problem. 相似文献
77.
Acrylamide (AAm)/acrylic acid (AAc) hydrogels in the cylindirical form were prepared by γ‐irradiating binary systems of AAm/AAc with 2.6–20.0 kGy γ‐rays. The effect of the dose and relative amounts of AAc and pH on the swelling properties, diffusion behavior of water, diffusion coefficients, and network properties of hydrogel systems was investigated. The swelling capacities of AAm/AAc hydrogels were in the range of 1000–3000%, while poly(acrylamide) (PAAm) hydrogels swelled in the range of 450–700%. Water diffusion into hydrogels was found to be non‐Fickian‐type diffusion. Diffusion coefficients of AAm/AAc hydrogels were found between 0.79 × 10?5 and 2.78 × 10?5 cm2 min?1. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3570–3580, 2002 相似文献
78.
79.
Seasonal and diel distributions of denitrifying and bacterial communities in a hypersaline microbial mat (Camargue, France) 总被引:1,自引:0,他引:1
Desnues C Michotey VD Wieland A Zhizang C Fourçans A Duran R Bonin PC 《Water research》2007,41(15):3407-3419
Changes in spatio-temporal distribution of bacterial and denitrifying communities were qualitatively studied in a microbial mat from Camargue (France). During a diel and a seasonal cycle, patterns of 16S rRNA and nitrite reductase genes (nirS and nirK) were compared by denaturing gradient gel electrophoresis (DGGE). Statistical analysis of DGGE profiles showed a significant seasonal shift in the community structure of the nirS-containing bacteria with a winter superficial population that extended in summer, whereas the nirK-containing bacteria seemed more affected by vertical gradients rather than by month-to month-changes. Denitrifying activities remained stable during these sampling times. The bacterial community at the surface of the mat also changed according to season, but appeared stable over a day. Finally, during a diel cycle nirK populations were localized in zones with large fluctuations of environmental parameters (oxygen, pH, and sulfur levels) while nirS populations seemed more restricted to the permanent anoxic layer of the microbial mat. 相似文献
80.
J. Esteban Duran Madjid Mohseni Fariborz Taghipour 《Chemical engineering science》2010,65(3):1201-1211
A CFD-based model for predicting the performance of annular reactors with surface reaction was developed. The capability of several hydrodynamic models to predict successfully the kinetic behavior of the reactor under diffusion limiting conditions was assessed against experimental data. The evaluation included five models: laminar, standard k–ε, realizable k–ε, Reynolds stress (RSM), and Abe–Kondoh–Nagano (AKN). The catalytic decomposition of hydrogen peroxide over a Mn/Al oxide catalyst coated on the reactor surface was used as a model reaction. The reactor was tested within a range of flow rates corresponding to 530<Re<11,000 and intrinsic reaction rate constants of 5×10?5 to 1 m/s. The results demonstrated that the performance of the hydrodynamic models is associated with their capability to predict external mass transfer and ultimately, the level of mass transfer limitation present in the reacting system. For laminar flow conditions, the laminar model is capable of predicting the experimental behavior of the system. For transient and turbulent flow regimes, all the analyzed turbulence models provided good predictions of the system when the process was controlled by surface reaction. When the system presented some degree of mass transfer limitation, AKN and RSM exhibited better performance. 相似文献