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   2686篇
  免费   214篇
  国内免费   9篇
电工技术   59篇
综合类   1篇
化学工业   773篇
金属工艺   34篇
机械仪表   66篇
建筑科学   73篇
矿业工程   3篇
能源动力   101篇
轻工业   320篇
水利工程   10篇
石油天然气   1篇
无线电   208篇
一般工业技术   437篇
冶金工业   43篇
原子能技术   34篇
自动化技术   746篇
  2024年   4篇
  2023年   35篇
  2022年   129篇
  2021年   206篇
  2020年   80篇
  2019年   98篇
  2018年   117篇
  2017年   92篇
  2016年   138篇
  2015年   117篇
  2014年   152篇
  2013年   225篇
  2012年   172篇
  2011年   201篇
  2010年   138篇
  2009年   170篇
  2008年   141篇
  2007年   100篇
  2006年   99篇
  2005年   97篇
  2004年   67篇
  2003年   52篇
  2002年   44篇
  2001年   30篇
  2000年   27篇
  1999年   18篇
  1998年   27篇
  1997年   21篇
  1996年   24篇
  1995年   14篇
  1994年   5篇
  1993年   8篇
  1992年   7篇
  1991年   7篇
  1990年   2篇
  1989年   5篇
  1988年   2篇
  1987年   5篇
  1985年   2篇
  1984年   4篇
  1983年   4篇
  1982年   4篇
  1980年   3篇
  1979年   2篇
  1978年   2篇
  1977年   4篇
  1976年   2篇
  1975年   3篇
  1974年   1篇
  1973年   1篇
排序方式: 共有2909条查询结果,搜索用时 312 毫秒
181.
Development of robust dynamical systems and networks such as autonomous aircraft systems capable of accomplishing complex missions faces challenges due to the dynamically evolving uncertainties coming from model uncertainties, necessity to operate in a hostile cluttered urban environment, and the distributed and dynamic nature of the communication and computation resources. Model-based robust design is difficult because of the complexity of the hybrid dynamic models including continuous vehicle dynamics, the discrete models of computations and communications, and the size of the problem. We will overview recent advances in methodology and tools to model, analyze, and design robust autonomous aerospace systems operating in uncertain environment, with stress on efficient uncertainty quantification and robust design using the case studies of the mission including model-based target tracking and search, and trajectory planning in uncertain urban environment. To show that the methodology is generally applicable to uncertain dynamical systems, we will also show examples of application of the new methods to efficient uncertainty quantification of energy usage in buildings, and stability assessment of interconnected power networks.  相似文献   
182.
183.
We report on the deposition of soft matter thin films by Matrix Assisted Pulsed Laser Evaporation (MAPLE). In particular, thin layers of biological material (Bovine Serum Albumin) and polymers (polyfluorene) for medical and optoelectronic applications, were realized by laser irradiating a frozen solution containing a low amount of material diluted in a laser absorbing volatile solvent. The depositions were carried out varying different parameters as solvent–solute concentration, solvent nature, laser fluencies, etc. The optical, morphological, structural and spectroscopical properties were detected by means of different analyses as FTIR, photoluminescence, AFM and SDS.  相似文献   
184.
Vinylene-linked donor–acceptor–donor semiconducting polymers have been prepared by electropolymerization of the new monomers 2,6-bis[(E)-2-(1-methylpyrrol-2-yl)vinyl]pyridine and 2,5-bis[(E)-2-(1-methylpyrrol-2-yl)vinyl]pyridine. The monomers, consisting of two pyrrole donor units and a central pyridine acceptor ring spaced by vinylene links, differ by the substitution pattern around the central pyridine core (2,6 vs. 2,5-substitution). The electropolymerization process is more efficient on the 2,5-derivative. The new polymers show reversible electrochemistry dominated by a strong charge trapping effect. Poly(2,5-bis[(E)-2-(1-methylpyrrol-2-yl)vinyl]pyridine) energy levels closely match those of design rules for optimized polymers in combination with fullerene derivatives in bulk heterojunction solar cells.  相似文献   
185.
In this work, the hydration process of durum wheat–based functional bread loaded with yellow pepper flour was optimised. In particular, the investigated vegetable flour and durum wheat semolina were mixed after they were separately hydrated. Three different amounts of water added to the yellow pepper flour were studied for assessing the effect of vegetable flour hydration level on the dough development and overall quality of bread. The bread formulation investigated in a previous work, based on 25% of yellow pepper and 2% of guar seed as structuring agent where the vegetable flour was directly added to the hydrated durum wheat semolina dough, was chosen as control sample. Results highlighted that dough samples with yellow pepper flour hydrated at highest water content showed a rheological behaviour similar to the durum wheat dough. Moreover, creep analysis showed that the sample added with no‐hydrated yellow pepper flour recorded the greatest resistance to deformation. Same results were obtained for the dough tensile and bread compression tests. The use of the hydrated yellow pepper flour also improved all sensorial attributes.  相似文献   
186.
187.
Quercetin shows interesting pharmacological effects, but its use in topical applications is limited by its low skin permeability and solubility. In this work, the synthesis of highly lipophilic quercetin esters with oleic, linoleic and linolenic acid useful as topical quercetin prodrugs is reported. Partial OH esterification is advisable to maintain the antioxidant activity of these compounds; tetraesters and triesters can be achieved by modulating the reaction conditions utilized for the total esterification of quercetin. The chemical structures of the esters were proven by spectroscopic techniques; quantum chemical NMR calculation were mandatory to unequivocally assign the free position in triesters. Finally, the antioxidant activity of all the synthesized compounds was determined by the 2,2-diphenyl-1-picryl-hydrazyl method and by 2,2-azinobis(3-ethyl-benzothiazoline-6-sulfonic acid) assay.  相似文献   
188.
This paper explores the use of manufacturing-type constraints, in particular pattern gradation and repetition, in the context of building layout optimization. By placing constraints on the design domain in terms of number and variable size of repeating patterns along any direction, the conceptual design for buildings is facilitated. To substantiate the potential future applications of this work, examples within the context of high-rise building design are presented. Successful development of such ideas can contribute to practical engineering solutions, especially during the building design process. Examples are given to illustrate the ideas developed both in two-dimensional and three-dimensional building configurations.  相似文献   
189.
International Journal of Control, Automation and Systems - In the framework of the Future Internet, the aim of the Quality of Experience (QoE) Control functionalities is to track the personalized...  相似文献   
190.
Convex piecewise-linear fitting   总被引:1,自引:1,他引:0  
We consider the problem of fitting a convex piecewise-linear function, with some specified form, to given multi-dimensional data. Except for a few special cases, this problem is hard to solve exactly, so we focus on heuristic methods that find locally optimal fits. The method we describe, which is a variation on the K-means algorithm for clustering, seems to work well in practice, at least on data that can be fit well by a convex function. We focus on the simplest function form, a maximum of a fixed number of affine functions, and then show how the methods extend to a more general form.  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