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排序方式: 共有87条查询结果,搜索用时 15 毫秒
1.
In this study, polyvinyl alcohol/organically modified montmorillonite (HDA/MMT; organoclay) composite was prepared for the intercalation processes. Firstly, the rheological behavior of aqueous montmorillonite dispersions was investigated as a function of solid content. Hexadecylamine (HDA) was added to the montmorillonite dispersion (2%, w/w) in different concentrations in the range of 5 × 10?4 – 9 × 10?3 mmol/L. The basal spacing of the organoclay (OMMT) was studied by X‐ray diffraction. The FTIR spectra are obtained from the modified montmorillonite products, which revealed the characteristic absorbencies after treatment with HDA. HDA/MMT/PVA composite, which was produced by the reaction of 1 wt % PVA solution with organoclay complex, is characterized by the rheology, electrokinetic, XRD, FTIR, and SEM techniques. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:2315–2323, 2006 相似文献
2.
C. Yürdü S. Işçi C. Ünlü O. Atici Ö. I. Ece N. Güngör 《Bulletin of Materials Science》2005,28(6):623-628
In this study, the rheologic and colloidal characterizations of sodium montmorillonite (NaMMT) were examined. Hexadecylamine
(CH3(CH2)15NH2, HDA) was added to the bentonite water dispersion (2%, w/w) in different concentrations in the range 5.6 × 10−4−9.4 × 10−3 mmol/l. The rheological and electrokinetic behaviour of aqueous montmorillonite dispersions was investigated as a function
of solid content and HDA concentration. The basal spacings of the HDA/NaMMT composites were studied by X-ray diffraction.
The FTIR spectra were obtained from the modified bentonite products, which revealed the characteristic absorbances after treatment
with HDA. 相似文献
3.
Ece Sogut 《应用聚合物科学杂志》2020,137(30):48902
The aim of this study was to prepare nanocomposite films composed of whey protein isolate (W) and carrageenan (C) with nanocellulose (N) for food packaging applications. Response surface methodology was applied to investigate the effect of W concentration (v/v, 0–100%), glycerol/sorbitol (G/S) ratio (0–1), and N concentration (w/w, 0–5%) on the physicomechanical properties of film samples. Higher W and N contents and lower G/S ratios showed positive effect on rigidity of film samples, while introducing high concentration of N increased the water vapor permeability values with increasing plasticizer and C concentration. The highest water uptake values were observed in C based films, while a higher C content resulted in lower opacity values. The addition of nanocellulose into whey protein and carrageenan blend films in the presence of a plasticizer mixture improved the suitability of selected biopolymers for food packaging applications when compared to their neat films. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48902. 相似文献
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Allan Provins David Pearce Ece Ozdemiroglu Susana Mourato Sian Morse-Jones 《Progress in Planning》2008
In this paper we consider the question, ‘What is the the scope for using results of economic valuation studies in the appraisal and assessment of heritage-related projects and programmes?’ This entails assessing the potential role and scope of ‘value transfer’, which is an approach to economic valuation that uses results of previous valuation studies (for example, travel cost or stated preference studies) in the appraisal of projects and programmes. A distinct appeal of value transfer is its expediency and value for money properties in relation to commissioning original valuation studies, which can enable greater use of economic values within decision making. Its potential role in the appraisal of heritage assets depends on whether it is deemed a reliable approach to economic valuation, and whether there is a sufficient body of economic valuation literature concerning the heritage sector. Correspondingly, we examine: (i) the applicability of economic valuation to the historic environment; (ii) the basis for value transfer; and (iii) the literature pertaining to the valuation of the historic environment. We also develop a case study, which demonstrates the use of value transfer in a heritage context. Overall there currently appears to be limited scope for value transfer applications in heritage-related appraisal and evaluation exercises. This is in part due to the heterogeneity and complexity of heritage assets. However, a more fundamental constraining factor is the current extent of heritage valuation literature; only 30 valuation studies were identified relating to the historic environment. We recommend that future work focuses on developing a database of valuation studies relating to the heritage sector, and on establishing a broader base of high-quality original heritage-related economic valuation studies. Moreover, where value transfer is applied in an appraisal and evaluation context to heritage assets, much emphasis should be placed on satisfying the criteria for identifying suitable valuation evidence from existing studies. 相似文献
7.
Use of microalgal biomass for renewable energy production has gained considerable attention in the world due to increasing global energy demand and negative environmental impacts of nonrenewable fossil fuels. Anaerobic digestion is one of the renewable technologies that microalgal biomass is converted into biogas by anaerobic archea. One of the main drawbacks of using microalgal biomass for biogas production is that certain types of microalgae has rigid cell wall characteristics, which limits accessibility of anaerobic archea to microalgal intracellular organic matter during hydrolysis phase. This limitation lowers efficiency of biogas production from microalgal biomass. However, introducing pretreatment methods prior to anaerobic digestion provides disruption of rigid microalgal cell wall and improve biogas yields from microalgal biomass. The objective of this paper was to review current knowledge related to pretreatment methods applied prior to anaerobic digestion of microalgal biomass. Efficiency and applicability of pretreatment methods mainly depend on type of microalgae, cell wall characteristics, and cost and energy requirements during pretreatment process. In this review, various type of pretreatment methods applied to microalgal biomass was discussed in detail with background knowledge and literature studies in their potential on maximization of biogas yields and their cost effectiveness, which is important for large‐scale applications. In the view of current knowledge, it was concluded that each pretreatment method has a relative contribution to improvement in biogas production depending on the type of microalgae. However, energy and cost requirements are the main limitations for pretreatment. So, further studies should focus on reduction of cost and energy demand by introducing combined methods, novel chemicals, and on‐site or immobilized enzymes in pretreatment to increase feasibility of pretreatment prior to anaerobic digestion in industrial scale. 相似文献
8.
Summary Vibration and buckling of in-plane loaded simply supported double-walled carbon nanotubes were investigated using the nonlocal
Timoshenko-beam theory. The influence of in-plane loads on the natural frequencies was determined. The results show that while
the natural frequencies decrease with increasing compressive in-plane loads, an increase in frequencies is observed for tension
type of in-plane loads. Effects of in-plane loads are more pronounced for lower modes, and some mode changes are observed
at critical in-plane loads. A comparison of nonlocal elasticity solutions with local elasticity solutions indicates that the
nonlocal effects should be considered for higher modes of vibration of double-walled carbon nanotubes. 相似文献
9.
In this paper, a method for the representation of hysteresis and power losses in the laminations of power transformers is proposed. The developed model is based on data supplied from steel manufacturer and able to predict hysteresis and eddy current losses. 相似文献
10.
Abstract Due to substantial clean-up efforts, water quality in the River Thames in London has steadily improved over the last three decades. However, London's Victorian sewage system still discharges untreated sewage into the Thames, at times of moderate to heavy rainfall. This happens approximately 60 times every year, creating adverse environmental and amenity impacts on the river. Major and costly engineering works will be required to solve the sewage overflow problem. This paper reports the results of a stated preference study designed to value the multiple non-market benefits—eductions in sewage litter, risk to human health, and risk to fish populations—associated with a range of potential engineering solutions. Our findings indicate that household willingness to pay for these benefits is likely to be significantly greater than the projected costs per household of, at least, some potential technical solutions. Although arguably justifiable on economic grounds, the final decision on whether to proceed with such a large infrastructure project is unlikely to depend wholly on cost-benefit thinking, but involve complex trade-offs with other socially desirable criteria. 相似文献