首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   296篇
  免费   9篇
电工技术   2篇
综合类   1篇
化学工业   64篇
金属工艺   2篇
机械仪表   10篇
建筑科学   10篇
能源动力   8篇
轻工业   39篇
水利工程   2篇
石油天然气   1篇
无线电   11篇
一般工业技术   49篇
冶金工业   7篇
原子能技术   3篇
自动化技术   96篇
  2023年   3篇
  2022年   5篇
  2021年   27篇
  2020年   8篇
  2019年   13篇
  2018年   18篇
  2017年   14篇
  2016年   11篇
  2015年   10篇
  2014年   17篇
  2013年   40篇
  2012年   22篇
  2011年   26篇
  2010年   20篇
  2009年   11篇
  2008年   11篇
  2007年   6篇
  2006年   8篇
  2005年   4篇
  2004年   2篇
  2003年   2篇
  2002年   5篇
  2001年   3篇
  2000年   4篇
  1999年   3篇
  1998年   4篇
  1997年   2篇
  1996年   1篇
  1994年   1篇
  1991年   1篇
  1990年   1篇
  1968年   2篇
排序方式: 共有305条查询结果,搜索用时 15 毫秒
71.
72.
Molecular imprinting method is widely used to recognize various templates. Recognition of bisphenol A (BPA) as a harmful template is important. Herein a novel BPA molecular imprinted polymer nanoparticles (BMIPN) is reported by core-shell surface molecular imprinting technology. In this process, BPA was imprinted by polymerizing methacrylic acid (MAA) as functional monomer, in presence of ethylene glycol dimethacrylate (EGDMA) as a cross-linker and goethite nanorods (GNR) functionalized with fumaric acid. The formation of different materials in different steps was confirmed by Fourier transform infrared spectroscopy (FT-IR), the size and surface morphological of material was observed by field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM). The BMIPN structure was characterized by X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). The important effective factors on adsorption process such as pH, contact time, amount of GNR, initial concentration of BPA, release and reusability and selectivity of BMIPN were studied. The excellent selectivity behavior of BMIPN was evaluated in the presence of phenol (Ph), 4, 4′-biphenol (BPh), hydroquinone (HQ) and 2, 2′-Bis(4-hydroxyphenyl)butane (BPB), as interferences. Based on the isotherm and kinetic studies, the experimental data obey Langmuir isotherm and the pseudo-second-order kinetic models. The results showed that BMIPN had excellent properties for adsorbing BPA in a short time even in the presence of analogous.  相似文献   
73.
Slicing is a program analysis technique which can be used for reducing the size of the model and avoid state space explosion in model checking. In this work a static slicing technique is proposed for reducing Rebeca models with respect to a property. For applying the actor-based slicing techniques, the Rebeca control flow graph (RCFG) and the Rebeca dependence graph (RDG) are introduced. We propose two different approaches for constructing the RDG, where each approach can be more effective under certain conditions. As the static slicing usually produces large slices, two other slicing-based reduction techniques, step-wise slicing and bounded slicing, are proposed as simple novel ideas. Step-wise slicing first generates slices that overapproximate the behavior of the original model and then refines it, and bounded slicing is based on the semantics of nondeterministic assignments in Rebeca. We also propose a static slicing algorithm for deadlock detection (in absence of any particular property). The efficiency of these techniques is checked by applying them to several case studies which are included in this paper. Similar techniques can be applied on the other actor-based languages.  相似文献   
74.
In this study, changes in the vibro-mechanical properties of fungi-treated wood, during sorption and desorption at different humidity levels, were investigated. Norway spruce resonance wood (with uniform narrow annual rings and high tonal quality for musical instrument craftsmanship) was incubated with Physisporinus vitreus for 36 weeks. Stiffness, internal friction, and tonal performance indices of control (untreated) and fungi-treated wood were compared after exposure to a stepwise variation of relative humidity. It was demonstrated that fungal treatment increased the internal friction and decreased the specific modulus of elasticity, during reduction of wood density. Internal friction of both control and fungi-treated wood significantly increased during dynamic sorption, especially during early stages (hours) of each humidity change step. Both specific modulus of elasticity and internal friction showed a hysteretic behavior during humidity variation cycles. Hysteresis was smaller in fungi-treated wood. Also, tonal performance indices were improved after fungal treatment and showed a reduced variation at different relative humidity conditions. Dynamic vapor sorption tests and FT-IR microscopy studies revealed changes in hygroscopicity and the supramolecular structure of wood, which may explain the observed vibrational behavior. Less dependency of wood vibrational properties to the variation of the ambient humidity is important for the acoustic performance of string instruments.  相似文献   
75.
This paper presents a new, two-level, model-driven engineering approach to industrial process control software. The first level (infrastructure engineering) is concerned with the following: the definition of the development process and guidelines, the definition of a domain-specific modeling language, the specification of the model transformations, and the development of a tool suite. This tool suite enables modeling of the process control software and the automatic code generation for programmable logic controllers. In the second level (application engineering), the process control software is engineered using the results of the infrastructure level. The approach is demonstrated on excerpts from an industrial project.  相似文献   
76.
Software agents in e-commerce systems are assigned to the participants. Buyer and supplier agents into multi-agent system architecture of the e-commerce system negotiate with others through an automated negotiation mechanism. In this study, an automated negotiation to interact between buyer and supplier and attain agreement for both is presented. A fuzzy inference system was used to automate negotiation process and consider two effective factors in the negotiation process: requirements and preferences. Requirements are qualitative or quantitative values which the participants assign to the issues of negotiation. Preferences of the participants are priorities assigned by them to issues. These values express an importance measure of issues from a participant perspective. Proposed model applies different fuzzy inference system (FIS) schemes for qualitative and quantitative negotiation issues to enhance the satisfaction level of the buyer and supplier. The FISs infer based on the preferences and requirements of both parties. Additionally, analytic hierarchy process was used to get preferences of the issues. In this proposal, mediator uses issue trade-offs strategy in which multiple issues are traded-offs against one another. The model applies a fuzzy system approach to make trade-offs.  相似文献   
77.
An unsupervised incremental algorithm for grammar inference and its application to domain-specific language development are described. Grammatical inference is the process of learning a grammar from the set of positive and optionally negative sentences. Learning general context-free grammars is still considered a hard problem in machine learning and is not completely solved yet. The main contribution of the paper is a newly developed memetic algorithm, which is a population-based evolutionary algorithm enhanced with local search and a generalization process. The learning process is incremental since a new grammar is obtained from the current grammar and false negative samples, which are not parsed by the current grammar. Despite being incremental, the learning process is not sensitive to the order of samples. All important parts of this algorithm are explained and discussed. Finally, a case study of a domain specific language for rendering graphical objects is used to show the applicability of this approach.  相似文献   
78.
The adsorption of methylene blue dye (MBD) from aqueous solutions was investigated using a new composite made up of shrimp waste chitosan and zeolite as adsorbent. Response surface methodology (RSM) was used to optimize the effects of process variables, such as contact time, pH, adsorbent dose and initial MBD concentration on dye removal. The results showed that optimum conditions for removal of MBD were adsorbent dose of 2.5 g/L and pH of 9.0, and initial MBD concentration of 43.75 mg/L and contact time of 138.65 min. The initial concentration of dye had the greatest influence on MBD adsorption among other variables. The experimental data were well fitted by the pseudo-second order kinetic model, while the Freundlich isotherm model indicated a good ability for describing equilibrium data. According to this isotherm model, maximum adsorption capacity of the composite was 24.5 mg/g. Desorption studies showed that the desorption process is favored at low pH under acidic conditions.  相似文献   
79.
80.
Non-destructive neutron radiography is used to study the different processes of liquid transport in Scots pine sapwood and heartwood. The spatial and temporal changes in moisture content and saturation degree, measured at high resolution, are provided for water uptake in longitudinal, radial and tangential directions. Liquid uptake in sapwood, compared to in heartwood, is found to be faster and more homogeneous. Latewood cells are the preferential pathways for longitudinal and tangential uptake in both sapwood and heartwood resulting in strongly non-uniform water fronts. In radial uptake, water accumulates first in the border between growth layers. While the moisture content profiles vary strongly between earlywood and latewood layers, the corresponding swelling strain profiles change smoothly due to the mechanical interaction between the different layers. Long term experiments in laboratory show three phases of uptake: a first fast phase, a second slower phase and a third phase reaching capillary saturation. The main difference between sapwood and heartwood uptake takes place in the first phase when liquid is mainly transported in the lumen, until moisture reaches the top of the sample. After that, both wood types behave similarly, uptake is followed by a slower adsorption in the wood cell walls and liquid redistribution in perpendicular to the uptake direction until the sample is almost totally saturated. These findings are of interest for future studies on durability and treatability of pine sapwood and hardwood.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号