全文获取类型
收费全文 | 470篇 |
免费 | 16篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 40篇 |
化学工业 | 99篇 |
金属工艺 | 8篇 |
机械仪表 | 9篇 |
建筑科学 | 11篇 |
矿业工程 | 1篇 |
能源动力 | 25篇 |
轻工业 | 17篇 |
水利工程 | 4篇 |
石油天然气 | 2篇 |
无线电 | 45篇 |
一般工业技术 | 89篇 |
冶金工业 | 73篇 |
原子能技术 | 4篇 |
自动化技术 | 60篇 |
出版年
2023年 | 12篇 |
2022年 | 14篇 |
2021年 | 18篇 |
2020年 | 11篇 |
2019年 | 12篇 |
2018年 | 17篇 |
2017年 | 9篇 |
2016年 | 14篇 |
2015年 | 8篇 |
2014年 | 11篇 |
2013年 | 33篇 |
2012年 | 21篇 |
2011年 | 31篇 |
2010年 | 16篇 |
2009年 | 11篇 |
2008年 | 14篇 |
2007年 | 21篇 |
2006年 | 14篇 |
2005年 | 7篇 |
2004年 | 12篇 |
2003年 | 9篇 |
2002年 | 10篇 |
2001年 | 6篇 |
2000年 | 10篇 |
1999年 | 10篇 |
1998年 | 16篇 |
1997年 | 17篇 |
1996年 | 11篇 |
1995年 | 4篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 9篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1969年 | 2篇 |
1967年 | 2篇 |
1946年 | 1篇 |
1945年 | 1篇 |
1944年 | 1篇 |
1942年 | 1篇 |
排序方式: 共有487条查询结果,搜索用时 15 毫秒
81.
In P. A. van der Helm and E. L. J. Leeuwenberg (see record 1996-01780-002), the authors presented a representation model for the goodness, or detectability, of visual regularities such as mirror symmetry and repetition. J. Wagemans (see record 1999-03499-009) acknowledged that this holographic goodness model has considerable explanatory power, but he also argued that it is not good enough yet. He challenged van der Helm and Leeuwenberg to qualify some open ends of their representation model, in particular those concerning its process assumptions. He also questioned the authors' assessment of previous goodness accounts such as S. E. Palmer's (1982, 1983) transformational approach and his own bootstrap model. He concluded that it is expedient to aim at a synthesis of useful aspects of diverse accounts of goodness, but he did not establish such a synthesis. Van der Helm and Leeuwenberg agree with his conclusion that such a synthesis is a worthy cause, but they disagree with his evaluation of the issues involved. This article is a reply with an alternative evaluation of these issues, advancing the discussion to a process-representation synthesis called holographic bootstrapping. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
82.
83.
Francesca Tinti Siraye E. Debebe Wendimagegn Mammo Teketel Yohannes Nadia Camaioni 《Synthetic Metals》2011,161(9-10):794-798
Transport of holes in thin films of a low-bandgap alternating polyfluorene copolymer, APFO-Green5, was investigated by means of admittance spectroscopy as a function of field and temperature. The values of hole mobility were evaluated from the position of the maxima in the plots of the negative differential susceptance as a function of frequency. Hole mobility was found to be strongly field- and temperature-dependent. The charge transport parameters were extracted by analyzing the mobility data by the uncorrelated and the correlated Gaussian Disorder Models. 相似文献
84.
Mass spectrometric imaging (MSI) has emerged as a powerful technique to obtain spatial arrangement of individual molecular ions in animal tissues. Ambient desorption electrospray ionization (DESI) technique is uniquely suited for such imaging experiments, as it can be performed on animal tissues in their native environment without prior treatments. Although MSI has become a rapid growing technique for localization of proteins, lipids, drugs, and endogenous compounds in different tissues, quantification of imaged targets has not been explored extensively. Here we present a novel MSI approach for localization and quantification of drugs in animal thin tissue sections. DESI-MSI using an Orbitrap mass analyzer in full scan mode was performed on 6 μm coronal brain sections from rats that were administered 2.5 mg/kg clozapine. Clozapine was localized and quantified in individual brain sections 45 min postdose. External calibration curves were prepared by micropipetting standards with internal standard (IS) on top of the tissues, and average response factors were calculated for the scans in which both clozapine and IS were detected. All response factors were normalized to area units. Quantifications from DESI-MSI revealed 0.2-1.2 ng of clozapine in individual brain sections, results that were further confirmed by extraction and liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis. 相似文献
85.
Moritz Emanuel Beber Christoph Fretter Shubham Jain Nikolaus Sonnenschein Matthias Müller-Hannemann Marc-Thorsten Hütt 《Journal of the Royal Society Interface》2012,9(77):3426-3435
Few-node subgraphs are the smallest collective units in a network that can be investigated. They are beyond the scale of individual nodes but more local than, for example, communities. When statistically over- or under-represented, they are called network motifs. Network motifs have been interpreted as building blocks that shape the dynamic behaviour of networks. It is this promise of potentially explaining emergent properties of complex systems with relatively simple structures that led to an interest in network motifs in an ever-growing number of studies and across disciplines. Here, we discuss artefacts in the analysis of network motifs arising from discrepancies between the network under investigation and the pool of random graphs serving as a null model. Our aim was to provide a clear and accessible catalogue of such incongruities and their effect on the motif signature. As a case study, we explore the metabolic network of Escherichia coli and show that only by excluding ever more artefacts from the motif signature a strong and plausible correlation with the essentiality profile of metabolic reactions emerges. 相似文献
86.
One-dimensional templates, such as the U.S. Air Force resolution target or the circular spoke target, are commonly used for the characterization of imaging systems via the modulation transfer function response. It is shown in this paper that one needs a new family of templates for a true characterization of imaging systems that acquire two-dimensional (2D) high-density images or handle 2D information, such as 2D bar code detection and identification. The contrast provided by the newly defined 2D templates is the "true" contrast of the acquired image that the electronic processors are challenged with. 相似文献
87.
Biodegradation of triclosan by a wastewater microorganism 总被引:1,自引:0,他引:1
Triclosan, a synthetic antimicrobial agent, has been considered as an emerging environmental contaminant. Here we reported a triclosan-degrading wastewater bacterial isolate, Sphingopyxis strain KCY1, capable of dechlorinating triclosan with a stoichiometric release of chloride. The stain can degrade diphenyl ether but not 2,4,4′-tribromodiphenyl ether and 2,2′,4,4′-tetrabromodiphenyl ether, despite all these three compounds are structurally similar to triclosan. While strain KCY1 was unable to grow on triclosan and catechol, it could grow with glucose, sodium succinate, sodium acetate, and phenol. When grown with complex nutrient medium containing a trace amount of triclosan (as low as 5 μg/L), the strain could retain its degradation ability toward triclosan. The maximum-specific triclosan degradation rate (qm) and the half-velocity constant (Km) are 0.13 mg-triclosan/mg-protein/day and 2.8 mg-triclosan/L, respectively. As triclosan degradation progressed, five metabolites were identified and these metabolites continue to transform into non-chlorinated end products, which was supported by a sharp drop in androgenic potential. The activity of catechol 2,3-dioxygenase in the cell extract was detected. No triclosan degradation was observed in the presence of 3-fluorocatechol, an inhibitor of meta-cleavage enzyme, suggesting that triclosan degradation proceed via meta-cleavage pathway. Based on all the observations, a degradation pathway for triclosan by strain KCY1 was proposed. 相似文献
88.
Maria Luísa Braga FARINHA José Vieira de LEMOS Emanuel MARANHA DAS NEVES 《Frontiers of Architecture and Civil Engineering in China》2012,(1)
This paper presents the application of a methodology which can be used to assess arch dam foundation stability,using the discrete element method (DEM) and the code 3DEC.A global three-dimensional model... 相似文献
89.
Alain Geiser Bin Fan Hadjar Benmansour Fernando Castro Jakob Heier Beat Keller Karl Emanuel Mayerhofer Frank Nüesch Roland Hany 《Solar Energy Materials & Solar Cells》2008,92(4):464-473
The performance of heterojunction organic solar cells is critically dependent on the morphology of the donor and acceptor components in the active film. We report results of photovoltaic devices consisting of bilayers and bulk heterojunctions using poly(3-hexylthiophene) (P3HT) and Buckminsterfullerene C60. White light power efficiencies of η2.2% (bulk heterojunction) and 2.6% (bilayer) were measured after a thermal annealing step on completed devices. Optical and structural investigations on non-annealed bilayer thin films indicated a distinct porosity of the spin-coated polymer, which allows C60 to penetrate the P3HT layer and to touch the anode. This resulted for these bilayer solar cells in the experimental observation that electrons were collected predominantly at the cathode after photo-excitation of P3HT, but predominantly at the anode after C60 excitation. A morphological model to explain the ambipolar charge collection phenomenon is proposed. 相似文献
90.
Emanuel Parzen 《技术计量学》2013,55(4):473-474
Residuals from fit are often examined in regression analysis. A test suggested by Ellenberg [5] and Prescott [7] for the largest residual being an outlier is implemented through table development. Tables of critical valltes for tests at levels (α ≤ 0.10, 00.5, and 0.01 are included. 相似文献