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   1477篇
  免费   113篇
电工技术   5篇
综合类   6篇
化学工业   466篇
金属工艺   16篇
机械仪表   15篇
建筑科学   122篇
矿业工程   1篇
能源动力   26篇
轻工业   280篇
水利工程   24篇
石油天然气   4篇
无线电   60篇
一般工业技术   235篇
冶金工业   178篇
原子能技术   3篇
自动化技术   149篇
  2024年   4篇
  2023年   23篇
  2022年   48篇
  2021年   81篇
  2020年   42篇
  2019年   58篇
  2018年   56篇
  2017年   48篇
  2016年   54篇
  2015年   52篇
  2014年   77篇
  2013年   119篇
  2012年   99篇
  2011年   133篇
  2010年   105篇
  2009年   78篇
  2008年   70篇
  2007年   68篇
  2006年   50篇
  2005年   53篇
  2004年   42篇
  2003年   41篇
  2002年   27篇
  2001年   16篇
  2000年   19篇
  1999年   10篇
  1998年   9篇
  1997年   10篇
  1996年   7篇
  1995年   10篇
  1994年   3篇
  1993年   10篇
  1992年   6篇
  1990年   4篇
  1989年   5篇
  1988年   4篇
  1987年   5篇
  1986年   3篇
  1985年   3篇
  1984年   7篇
  1982年   4篇
  1981年   4篇
  1980年   3篇
  1977年   2篇
  1976年   3篇
  1975年   4篇
  1974年   3篇
  1972年   4篇
  1964年   1篇
  1959年   1篇
排序方式: 共有1590条查询结果,搜索用时 15 毫秒
101.
102.
103.
People often coordinate their actions with sequences that exhibit temporal variability and unfold at multiple periodicities. We compared oscillator- and timekeeper-based accounts of temporal coordination by examining musicians' coordination of rhythmic musical sequences with a metronome that gradually changed rate at the end of a musical phrase (Experiment 1) or at the beginning of a phrase (Experiment 2). The rhythms contained events that occurred at the same periodic rate as the metronome and at half the period. Rate change consisted of a linear increase or decrease in intervals between metronome onsets. Musicians coordinated their performances better with a metronome that decreased than increased in tempo (as predicted by an oscillator model), at both beginnings and ends of musical phrases. Model performance was tested with an oscillator period or timekeeper interval set to the same period as the metronome (1:1 coordination) or half the metronome period (2:1 coordination). Only the oscillator model was able to predict musicians' coordination at both periods. These findings suggest that coordination is based on internal neural oscillations that entrain to external sequences. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
104.
In the present work, a monolithic solution approach for thermo‐structure interaction problems motivated by the challenging application of the behaviour of rocket nozzles is proposed. Structural and thermal fields are independently discretised via finite elements. The resulting system of equations is solved via a monolithic thermo‐structure interaction scheme, which is constructed by a block Gauss–Seidel preconditioner in combination with algebraic multigrid methods. The proposed method is tested for four numerical examples, the second Danilovskaya problem, a simplified rocket nozzle configuration, an internally loaded hollow sphere, and a fully three‐dimensional nozzle configuration of a subscale thrust chamber. Good agreement of the numerical results with results from the literature is observed. Furthermore, it is shown that the monolithic solution algorithm can handle the complete range of the parameter spectrum, whereas partitioned algorithms are limited to a certain parameter range only. Moreover, the monolithic algorithm exhibits improved efficiency and robustness compared to partitioned algorithms. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
105.
A thermodynamic study was carried out in order to quantify the stability of yttrium silicates under different atmospheres (argon, air, moisture), and to predict their behaviour as an EBC. For this purpose, the partial pressures of gaseous species formed during the reactive vaporization in equilibrium with yttrium silicates were evaluated and compared to those over each oxide taken separately. The partial pressures of silicon and rare earth hydroxides at the equilibrium over rare earth silicates are lower than those over each single oxide. Thus yttrium silicates appear to be sufficiently stable to be promising materials to be used as environmental barrier coatings.  相似文献   
106.
This study investigates the influence of carboxylic monomers, such as itaconic acid (IA), on the colloidal properties of the latexes made by semi-continuous emulsion copolymerization of styrene (STy) with n-butyl acrylate (BA). A number of copolymerization runs were carried out with different IA concentrations. The effect of functional monomer on the overall conversion, the colloidal properties of the latexes, and the distribution of the carboxylic groups (buried, particle surface and aqueous phase) were examined. The carboxylic groups present in the latexes were analyzed using conductimetric and potentiometric titrations. The behavior of the IA on the wet scrub resistance of highly pigmented paints for architectural coatings was examined and correlated with the distribution of the carboxylic groups. The results obtained showed that the properties of highly pigmented paints are greatly dependent on the amount and distribution of the carboxylic groups. The carboxylic acid distributed in the aqueous phase has a strong influence on the wet scrub resistance and on the characteristics of the final products.  相似文献   
107.
Native milk fat globules of various mean diameters, ranging from d43 = 2.3 µm to 8.0 µm, were obtained using microfiltration of raw whole milk. After milk fat globule washing, the milk fat globule membrane (MFGM) was separated by manual churning. After total lipid extraction and separation of polar lipids, their phospholipid (PL) and sterol composition was measured using thin‐layer chromatography, methyl ester analyses by gas chromatography, and gas chromatography coupled to mass spectrometry. The main PL species were phosphatidylethanolamine, phosphatidylcholine and sphingomyelin. The respective fatty acid composition of each PL species was measured. Many different minor bioactive sterols were detected in the MFGM, e.g. lanosterol, lathosterol, desmosterol, stigmasterol and β‐sitosterol. No significant differences in the PL and sterol profile were found between MFGM extracted from small and large milk fat globule fractions.  相似文献   
108.
Recent research has focused on preventing copper oxidation for direct wiring applications. In this study, a novel coating method was developed for nano-sized copper powders using vapor self-assembled monolayer (VSAM). The surfaces of oxidized and non-oxidized copper powders were studied to determine whether they can be coated with a vapor form of octanethiol. It was found that non-oxidized copper powders were successfully coated with the vapor form of octanethiol according to X-ray photoelectron spectroscopy (XPS) analysis. However, due to the partial coating of self-assembled monolayer (SAM) on a copper surface, a very small amount of copper oxide was detected when the coating mechanism was verified using Atomic Force Microscopy (AFM). Overall, the vapor form of octanethiol successfully adhered to the surface of nanosized copper powders, constituting the novel method of preventing oxidation. A complete coating method for the nano-sized copper powders must be developed in future research.  相似文献   
109.
110.
Highest quality synthetic voices remain scarce in both parametric synthesis systems and in concatenative ones. Much synthetic speech lacks naturalness, pleasantness and flexibility. While great strides have been made over the past few years in the quality of synthetic speech, there is still much work that needs to be done. Now the major challenges facing developers are how to provide optimal size, performance, extensibility, and flexibility, together with developing improved signal processing techniques. This paper focuses on issues of performance and flexibility against a background containing a brief evolution of speech synthesis; some acoustic, phonetic and linguistic issues; and the merits and demerits of two commonly used synthesis techniques: parametric and concatenative. Shortcomings of both techniques are reviewed. Methodological developments in the variable size, selection and specification of the speech units used in concatenative systems are explored and shown to provide a more positive outlook for more natural, bearable synthetic speech. Differentiating considerations in making and improving concatenative systems are explored and evaluated. Acoustic and sociophonetic criteria are reviewed for the improvement of variable synthetic voices, and a ranking of their relative importance is suggested. Future rewards are weighed against current technical and developmental challenges. The conclusion indicates some of the current and future applications of TTS.  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