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排序方式: 共有193条查询结果,搜索用时 296 毫秒
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We have developed a simple new method to control the diameter of carbon nanotubes (CNTs) using catalytic nanoparticle arrays fabricated by filling the pores of well-ordered porous anodic aluminum oxide (AAO) templates with a metal ion solution. Fe ion solution was used to fill the pores in which Co had been deposited electrochemically, and then the template was dried naturally on a magnet. After this process, the pores were widened in NaOH solution. Well-graphitized multi-walled CNTs were grown from almost all the pores and were very long in length and homogeneous in diameter. We were able to control the diameter of CNTs, simply, by changing the concentration of iron ion solution. For example, the average outer diameters of the CNTs are 7 ± 1.5, 13 ± 1, and 17 ± 1 nm when the concentrations of Fe ion in their mother solutions were 1.0 × 10−3, 3.0 × 10−3, and 6.0 × 10−3 M, respectively. The inner diameters of these CNTs corresponded to the calculated diameters of Fe nanoparticles by assuming that all Fe ions contained in each pore are reduced to a single nanoparticle. This means that homogeneous nanoparticles are made in each pore. Our new method could be used to fabricate homogeneous nanoparticles from most metal ion solutions. 相似文献
3.
Seonho Kim Ho Kyun Jung Puji Lestari Handayani Taehoon Kim Byung Mun Jung U Hyeok Choi 《Advanced functional materials》2023,33(13):2210916
For the development of all-solid-state lithium metal batteries (LMBs), a high-porous silica aerogel (SA)-reinforced single-Li+ conducting nanocomposite polymer electrolyte (NPE) is prepared via two-step selective functionalization. The mesoporous SA is introduced as a mechanical framework for NPE as well as a channel for fast lithium cation migration. Two types of monomers containing weak-binding imide anions and Li+ cations are synthesized and used to prepare NPEs, where these monomers are grafted in SA to produce SA-based NPEs (SANPEs) as ionomer-in-framework. This hybrid SANPE exhibits high ionic conductivities (≈10−3 S cm−1), high modulus (≈105 Pa), high lithium transference number (0.84), and wide electrochemical window (>4.8 V). The resultant SANPE in the lithium symmetric cell possesses long-term cyclic stability without short-circuiting over 800 h under 0.2 mA cm−2. Furthermore, the LiFePO4|SANPE|Li solid-state batteries present a high discharge capacity of 167 mAh g−1 at 0.1 C, good rate capability up to 1 C, wide operating temperatures (from −10 to 40 °C), and a stable cycling performance with 97% capacity retention and 100% coulombic efficiency after 75 cycles at 1 C and 25 °C. The SANPE demonstrates a new design principle for solid-state electrolytes, allowing for a perfect complex between inorganic silica and organic polymer, for high-energy-density LMBs. 相似文献
4.
Online game is the most popular entertainment application in the virtual world and online gamers demonstrate high attachment to playing online games. Previous studies have linked to the numerous negative outcomes in playing online games. The factors contribute to the negative consequences on using online game have been relatively neglected. The purpose of this study is to explore the impact of perceived risk, intangibility, gender and age (adolescent/adult) difference on online game playing consequences and intentions. Past usage frequency is also made to look into the influence additional purchase intention. A total of 1418 useful questionnaires (including 1018 from public interview and 400 from online questionnaire feedback) were collected for final data analysis. The results demonstrated the important roles that time risk, psychological risk, financial risk, physical intangibility, mental intangibility and generality play on the negative consequences associated with online game playing. The results also indicated that male and adolescent individuals spent much more time on online game and intented to act the entertainment more than females and adults did. Finally, past online game playing frequency was showed to be a positive predictor of future online game playing intention. 相似文献
5.
The knowledge economy offers opportunity to a broad and diverse community of information systems users to efficiently gain
information and know-how for improving qualifications and enhancing productivity in the work place. Such demand will continue
and users will frequently require optimised and personalised information content. The advancement of information technology
and the wide dissemination of information endorse individual users when constructing new knowledge from their experience in
the real-world context. However, a design of personalised information provision is challenging because users’ requirements
and information provision specifications are complex in their representation. The existing methods are not able to effectively
support this analysis process. This paper presents a mechanism which can holistically facilitate customisation of information
provision based on individual users’ goals, level of knowledge and cognitive styles preferences. An ontology model with embedded
norms represents the domain knowledge of information provision in a specific context where users’ needs can be articulated
and represented in a user profile. These formal requirements can then be transformed onto information provision specifications
which are used to discover suitable information content from repositories and pedagogically organise the selected content
to meet the users’ needs. The method is provided with adaptability which enables an appropriate response to changes in users’
requirements during the process of acquiring knowledge and skills. 相似文献
6.
The production of crude palm oil and palm kernel is a complex problem due to the influence of processing variables and environmental factors. These processing variables influence the amount of crude palm oil and palm kernel losses during processing. Instead of mathematical model, fuzzy logic approach provides a simpler and easier mechanism to describe the relationships between the processing variables and the amount of crude palm oil and palm kernel losses. In this study, four fuzzy expert system models were developed for each palm oil processing station. An approximation of centre of gravity method for defuzzification is also proposed to enable the development of the model using Microsoft®Excel. For comparison purpose, the models were also developed using MATLAB®. Results obtained from the Excel model are found to be very close to the results from MATLAB. 相似文献
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8.
Mark T. Greiner Lily Chai Michael G. Helander Wing‐Man Tang Zheng‐Hong Lu 《Advanced functional materials》2012,22(21):4557-4568
Transition metal oxides are capable of a wide range of work functions. This quality allows them to be used in many applications that involve charge transfer with adsorbed molecules, for example as heterogeneous catalysts, as charge‐injection layers in organic electronics, and as electrodes in fuel cells. Chemical and structural factors can alter transition‐metal oxide work functions, often making their work functions difficult to control. Little is known about the effects of the cation oxidation state and point defects on the oxide work function. It is necessary to understand how such chemical and structural factors affect work functions in order to controllably tune transition metal oxides for desired applications. Here, a correlation between the oxide work function and cation oxidation state is demonstrated. This correlation is attributed to the change in cation electronegativity with oxidation state. A model is presented that relates the work function to the oxygen deficiency for d0 oxides in the limit of dilute oxygen vacancies. It is proposed that the rapid initial decrease in work function, observed for d0 oxides, is caused by an increase in the density of donor‐like defect states. It is also shown that oxides tend to have decreased work functions near a metal/metal‐oxide interface as a consequence of the relationship between defects and work function. These insights provide guidelines for tuning transition metal oxide work functions. 相似文献
9.
Prof. Aaron R. Van Dyke Lily S. Etemad Michael J. Vessicchio George A. Naclerio Victoria Jedson 《Chembiochem : a European journal of chemical biology》2016,17(17):1602-1605
A strategy for labeling native enzymes in a manner that preserves their activity is reported: capture–tag–release (CTR). Key to this approach is the small molecule CTR probe that contains an enzyme inhibitor, benzophenone crosslinker, and aryl phosphine ester. After UV‐derived capture of the enzyme, addition of an azide‐containing tag triggers a Staudinger ligation that labels the enzyme. A further consequence of the Staudinger ligation is fragmentation of the CTR probe, thus releasing the inhibitor and restoring enzymatic activity. As a proof‐of‐principle, the CTR strategy was applied to the hydrolase β‐galactosidase. The enzyme was efficiently labeled with biotin, and the kinetic data for the biotinylated enzyme were comparable to those for unlabeled β‐galactosidase. The CTR probe exhibits excellent targeting specificity, as it selectively labeled β‐galactosidase in a complex protein mixture. 相似文献
10.
Continuous flow characterization of solid biomass in a reciprocating/rotating scraper tube: An experimental study
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Kamelia V. K. Boodhoo Lily Smith Juan Pedro Solano Mark Gronnow James Clark 《American Institute of Chemical Engineers》2014,60(11):3732-3738
The performance of reciprocating/rotating scrapers has been assessed in a visualization study of the continuous flow hydrodynamics of air‐fluidized solid biomass under varying conditions of air flow rate and scraping velocities. A combination of low air flow rates and high scraping velocities results in more uniform flow of both types of biomass investigated. Power consumed by the reciprocating action of the scrapers increases with the scraping velocity but typically represents no more than 20% of the overall power consumption at the highest air flow rate applied. We also demonstrate that rotation of the scrapers superimposed on their reciprocating action gives higher flow rate of biomass and better mixing within the bulk solid compared to reciprocating action alone. The application of the reciprocating/rotating scraper technology described in this study represents a viable step forward in developing a continuous, large‐scale process for the microwave‐assisted decomposition of solid biomass to produce bio‐oils. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3732–3738, 2014 相似文献