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排序方式: 共有199条查询结果,搜索用时 9 毫秒
191.
Delignification rate expressions for neutral sulfite semichemical (NSSC) and neutral sulfite semichemical anthraquinone (NSSC-AQ) pulping of black spruce have been developed. The rates take into account the effects of temperature and reaction times on the rates of delignification.

NSSC in this study is defined by an alkali ratio [sodium sulfite/(sodium sulfite + sodium carbonate)] of 0.60 (expressed as sodium oxide) giving a final pulp yield between 55 and 60%. NSSC-AQ is identical to NSSC with the addition of anthraquinone.

Reaction temperature and pulping chemical concentrations were held essentially constant in all kinetic experiments. Isothermal experiments were conducted in the temperature range between 165 and 180°C. A concentration of 150 g/L sodium sulfite with a liquor to wood ratio 62 were used.  相似文献   
192.
The effects of different laser treatments on some mechanical properties of acrylic resin and soft liner were investigated. A total of 60 test specimens were fabricated according to test requirements. The specimens were roughened with Potassium-ticanyl-Phosphate (KTP), Er:YAG, and Nd:YAG lasers before application of soft liner. The flexural, peel, and tensile bond strengths were measured using a universal testing machine. Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) spectra of surfaces were also obtained to evaluate changes on the lased surfaces. No significant difference was apparent between the tensile bond strength values of the groups. Although peel strength values obtained for each of the laser types were lower than those of the control group, flexural strength values were higher than those of the control specimens. The spectra of specimens showed that lasing led to some chemical changes on the resin surfaces. Physical changes on the treated surfaces were visualized by scanning electron microscopy (SEM) analysis. Results of this study suggest that such treatments may be warranted because of the increase in flexural strength.  相似文献   
193.
This study evaluated the effect of argon plasma treatment on tensile bonding of heat-cured and auto-polymerized acrylic resins prior to the processing of a silicone soft liner. Both types of polymethylmethacrylate (PMMA) resins were treated with argon plasma for 1 min or 10 min (n = 5). A control group, including untreated resin specimens, was also formed. After processing of the soft liner, the specimens were deflasked and stored dry for 24 h, and they were then subjected to tensile bond strength testing. In order to see the plasma effect on the resin surface chemistry, representative specimens were analysed by XPS. Highest tensile bond strengths were observed in the 1-min exposure group for each resin, and 10-min exposure yielded the lowest bond strength likely due to the damaging effect of the plasma treatment. XPS analysis showed that the O/C ratios increased greatly in treated samples and that the binding energy values were not significantly changed.  相似文献   
194.
This paper introduces two different current differencing buffered amplifier (CDBA)‐based synthetic floating inductance circuits. Both configurations use a grounded capacitor. They are fully integrable and provide the advantages of electronic tuning.  相似文献   
195.
This paper presents a cascadable current-mode (CM) multifunction biquadratic filter. The proposed circuit realizes all five different filter transfer functions employing only two current differencing buffered amplifiers (CDBAs), while previously reported CM multifunction filters require more CDBAs and more passive component count for the same number of filter transfer function realizations. Examples for different filter transfer functions are given along with the results of circuit simulations. It is shown that theoretical and simulation results are in good agreement.  相似文献   
196.
Electrical conductivity and Hall-effect measurements on undoped and Sb-doped SnO2 thin films prepared by the sol–gel technique were carried out as a function of temperature (55 K to 300 K). Structural characterizations of the films were performed by atomic force microscopy (AFM) and x-ray diffraction (XRD). A doping-induced metal–insulator transition (MIT) was observed. On the metallic side of the transition, the experimental data were interpreted in terms of electron–electron interactions (EEI). The existence of EEI was confirmed by excellent agreement between theoretical and experimental data. The experimental data on the insulator side of the transition were analyzed in terms of variable-range hopping (VRH) conduction. A complete set of parameters describing the properties of the localized electrons, including hopping energy, hopping distance, and the value of the density of states at the Fermi level, was determined.  相似文献   
197.
Transactive memory system in new product development teams   总被引:1,自引:0,他引:1  
With the increasing popularity of collective memory in the group behavior literature, the transactive memory system (TMS) attracts many researchers and practitioners from different fields, in particular, small group research. Nevertheless, the application of the theory of TMS on new product development teams is surprisingly scant. We argue that the TMS leverages the notion of project-team memory, which is mostly equated with mechanistic memory or electronic documents and databases, by facilitating an interpersonal awareness of who knows what and who has appropriate and adequate skills and expertise, and then receiving information from that person. We then empirically test the effects of TMS on new product development outcomes including mediating and moderating factors, i.e., the collective mind and environmental turbulence, respectively. By investigating 79 Turkish new product development project teams, we found that: 1) the TMS has a positive impact on team learning and speed-to-market; 2) the collective mind (i.e., team members' attention to interrelating actions) mediates relations between the TMS, team learning, and speed-to-market; and 3) team learning and speed-to-market mediates relations between the TMS and new product success. Further, the moderating effect of environmental turbulence is investigated between the TMS, and team learning and speed-to-market. We found that the impact of the TMS on: 1) speed-to-market is negative when market and technology turbulence associated with the environment is high and 2) team learning changes quadratically with respect to the market and technology turbulence. Theoretical and managerial implications of the study findings are discussed.  相似文献   
198.
Decision-making techniques are used to help evaluate the current suppliers’ aim at classifying performance of individual suppliers against desired levels of performance, so as to design suitable plans to increase the performance and capabilities of suppliers. In this study, an integrated model is introduced and proposed for increasing the supplier selection and evaluation quality. The methodology is composed of two steps. The first stage is fuzzy decision-making trial and evaluation laboratory method in which the interactions between the evaluation criteria and the criteria weight have been computed. At the second stage, performances of suppliers are assessed using both the criteria weights obtained at the first stage and fuzzy c-means clustering algorithm by classifying the vendors according to their performances. Obtained results show that the proposed model is very well suited as a decision-making tool for supplier selection decisions.  相似文献   
199.
A probability-based method is proposed for calculating the concentration of chloride at specified points of deterministic and random heterogeneous microstructures. The method, referred to as local method, is used to calculate effective diffusion coefficients of composite media. The effective diffusion coefficient of a heterogeneous material specimen is defined as the diffusion coefficient of a fictitious homogeneous specimen with the same global properties as those of the original specimen. The local method is based on properties of diffusion processes and Itô’s formula; it is simple to code, always stable, accurate and suitable for parallel computing. We use the method to calculate effective diffusion coefficients of a material specimen with a deterministic diffusivity field and a random heterogeneous mortar specimen calibrated to an experiment reported in Ref. Caré (2003) [11].  相似文献   
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