全文获取类型
收费全文 | 265篇 |
免费 | 19篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 82篇 |
金属工艺 | 10篇 |
机械仪表 | 4篇 |
建筑科学 | 15篇 |
能源动力 | 9篇 |
轻工业 | 46篇 |
水利工程 | 2篇 |
无线电 | 14篇 |
一般工业技术 | 40篇 |
冶金工业 | 22篇 |
原子能技术 | 2篇 |
自动化技术 | 35篇 |
出版年
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 15篇 |
2020年 | 7篇 |
2019年 | 10篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 14篇 |
2014年 | 7篇 |
2013年 | 21篇 |
2012年 | 27篇 |
2011年 | 24篇 |
2010年 | 18篇 |
2009年 | 12篇 |
2008年 | 22篇 |
2007年 | 15篇 |
2006年 | 9篇 |
2005年 | 14篇 |
2004年 | 8篇 |
2003年 | 6篇 |
2002年 | 4篇 |
2001年 | 5篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1995年 | 4篇 |
1993年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有284条查询结果,搜索用时 15 毫秒
1.
Stefanie Vanbecelaere Katrien Van den Berghe Frederik Cornillie Delphine Sasanguie Bert Reynvoet Fien Depaepe 《Journal of Computer Assisted Learning》2020,36(4):502-513
For the training of academic skills, digital educational games with integrated adaptivity are promising. Adaptive games are considered superior to non-adaptive games, because they constantly assess children's performance, and accordingly adapt the difficulty of the tasks corresponding to the children's individual level. However, empirical evidence with regard to the effectivity of adaptive compared to non-adaptive games is limited. A study was conducted with 191 children from the third year of Kinder garten who were enrolled in one of three conditions, that is, playing an adaptive version of the reading game (RG), a non-adaptive version of the RG or training with pen-and-paper exercises. In all three conditions, children trained emergent reading (phonological awareness and letter knowledge) once a week for 30 min over a period of 5 weeks. Children's performance on cognitive (phonological awareness, letter knowledge, reading fluency) and non-cognitive (motivation, self-concept) factors was assessed. Results revealed a significant improvement in phonological awareness and letter knowledge in all conditions. However, no differences between the conditions were observed with respect to children's improvement on phonological awareness and letter knowledge or on their post-test scores for reading fluency. With regard to motivation and self-concept, again, no differences in these non-cognitive factors were observed across conditions. 相似文献
2.
This paper presents a control design for the one‐phase Stefan problem under actuator delay via a backstepping method. The Stefan problem represents a liquid‐solid phase change phenomenon which describes the time evolution of a material's temperature profile and the interface position. The actuator delay is modeled by a first‐order hyperbolic partial differential equation (PDE), resulting in a cascaded transport‐diffusion PDE system defined on a time‐varying spatial domain described by an ordinary differential equation (ODE). Two nonlinear backstepping transformations are utilized for the control design. The setpoint restriction is given to guarantee a physical constraint on the proposed controller for the melting process. This constraint ensures the exponential convergence of the moving interface to a setpoint and the exponential stability of the temperature equilibrium profile and the delayed controller in the norm. Furthermore, robustness analysis with respect to the delay mismatch between the plant and the controller is studied, which provides analogous results to the exact compensation by restricting the control gain. 相似文献
3.
Wyatt L. Brown Douglas A. Day Harald Stark Demetrios Pagonis Jordan E. Krechmer Xiaoxi Liu Derek J. Price Erin F. Katz Peter F. DeCarlo Catherine G. Masoud Dongyu S. Wang Lea Hildebrandt Ruiz Caleb Arata David M. Lunderberg Allen H. Goldstein Delphine K. Farmer Marina E. Vance Jose L. Jimenez 《Indoor air》2021,31(1):141-155
Understanding the sources and composition of organic aerosol (OA) in indoor environments requires rapid measurements, since many emissions and processes have short timescales. However, real-time molecular-level OA measurements have not been reported indoors. Here, we present quantitative measurements, at a time resolution of five seconds, of molecular ions corresponding to diverse aerosol-phase species, by applying extractive electrospray ionization mass spectrometry (EESI-MS) to indoor air analysis for the first time, as part of the highly instrumented HOMEChem field study. We demonstrate how the complex spectra of EESI-MS are screened in order to extract chemical information and investigate the possibility of interference from gas-phase semivolatile species. During experiments that simulated the Thanksgiving US holiday meal preparation, EESI-MS quantified multiple species, including fatty acids, carbohydrates, siloxanes, and phthalates. Intercomparisons with Aerosol Mass Spectrometer (AMS) and Scanning Mobility Particle Sizer suggest that EESI-MS quantified a large fraction of OA. Comparisons with FIGAERO-CIMS shows similar signal levels and good correlation, with a range of 100 for the relative sensitivities. Comparisons with SV-TAG for phthalates and with SV-TAG and AMS for total siloxanes also show strong correlation. EESI-MS observations can be used with gas-phase measurements to identify co-emitted gas- and aerosol-phase species, and this is demonstrated using complementary gas-phase PTR-MS observations. 相似文献
4.
Magnuson James S.; Tanenhaus Michael K.; Aslin Richard N.; Dahan Delphine 《Canadian Metallurgical Quarterly》2003,132(2):202
The time course of spoken word recognition depends largely on the frequencies of a word and its competitors, or neighbors (similar-sounding words). However, variability in natural lexicons makes systematic analysis of frequency and neighbor similarity difficult. Artificial lexicons were used to achieve precise control over word frequency and phonological similarity. Eye tracking provided time course measures of lexical activation and competition (during spoken instructions to perform visually guided tasks) both during and after word learning, as a function of word frequency, neighbor type, and neighbor frequency. Apparent shifts from holistic to incremental competitor effects were observed in adults and neural network simulations, suggesting such shifts reflect general properties of learning rather than changes in the nature of lexical representations. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
Delphine Patriarche Emmanuel Ledoux Rgine Simon-Coinon Jean-Luc Michelot Justo Cabrera 《Applied Clay Science》2004,26(1-4):109
Argillites are one of the geological formations studied by IRSN for their confining properties for isolation of radioactive wastes. One of the main objectives is the study of water transport through rocks with very low water content and very low hydraulic conductivity by modeling of natural tracer profiles. This paper presents the protocol developed for and applied to the acquisition of data for chloride content in interstitial water of the Toarcian argillites at the Tournemire site (Southern France). This protocol is based on laboratory diffusion experiments and on modeling. Experimental data obtained during the transient and steady-state parts of diffusion experiments enable, respectively, the assessment of the diffusion coefficient and the determination of Cl concentration in pore water. Using this protocol, profiles with depth for both of these data sets have been acquired along the geological sequence. Taking into account the present knowledge of the geological and hydrogeological history of the Tournemire massif, a conceptual model granting the main role for mass transport to diffusion has been proposed. According to this conceptual model, a one-dimensional numerical model was built for simulating the mass transport of chloride through the sedimentary column, over 53 Ma. The good agreement between experimental data and calculated values for both diffusion coefficients and concentrations of chloride confirms that diffusion is likely the main process for mass transport in the massif. This model was also tested with the deuterium content of interstitial water, applying variable concentrations at the aquifer system boundaries for reflecting the thermal dependency of isotopic composition in precipitation. These simulations also reveal the likely important role of heterogeneities, such as fractures, in the variability of tracer concentrations with regards to a simple diffusion profile. 相似文献
6.
Pflieger D Gonnet F de la Fuente van Bentem S Hirt H de la Fuente A 《Mass spectrometry reviews》2011,30(2):268-297
Proteomes are intricate. Typically, thousands of proteins interact through physical association and post-translational modifications (PTMs) to give rise to the emergent functions of cells. Understanding these functions requires one to study proteomes as "systems" rather than collections of individual protein molecules. The abstraction of the interacting proteome to "protein networks" has recently gained much attention, as networks are effective representations, that lose specific molecular details, but provide the ability to see the proteome as a whole. Mostly two aspects of the proteome have been represented by network models: proteome-wide physical protein-protein-binding interactions organized into Protein Interaction Networks (PINs), and proteome-wide PTM relations organized into Protein Signaling Networks (PSNs). Mass spectrometry (MS) techniques have been shown to be essential to reveal both of these aspects on a proteome-wide scale. Techniques such as affinity purification followed by MS have been used to elucidate protein-protein interactions, and MS-based quantitative phosphoproteomics is critical to understand the structure and dynamics of signaling through the proteome. We here review the current state-of-the-art MS-based analytical pipelines for the purpose to characterize proteome-scale networks. 相似文献
7.
In analogy to cyclic codes, we study linear codes over finite fields obtained from left ideals in a quotient ring of a (non-commutative) skew polynomial ring. The paper shows how existence and properties of such codes are linked to arithmetic properties of skew polynomials. This class of codes is a generalization of the θ-cyclic codes discussed in [Boucher, D., Geiselmann, W., Ulmer, F., 2007. Skew cyclic codes. Applied Algebra in Engineering, Communication and Computing 18, 379–389]. However θ-cyclic codes are powerful representatives of this family and we show that the dual of a θ-cyclic code is still θ-cyclic. Using Groebner bases, we compute all Euclidean and Hermitian self-dual θ-cyclic codes over of length less than 40, including a [36,18,11] Euclidean self-dual θ-cyclic code which improves the previously best known self-dual code of length 36 over . 相似文献
8.
Molybdenum dichalcogenides are semiconductors with layered type structure, which can act as efficient electrodes in the realization of photoelectrochemical solar cells. The main advantage of this molybdenum diselenide (MoSe2) semiconductor is the prevention of electrolyte corrosion because of the phototransitions involving non-bonding d-d orbital of the Mo atoms. Polycrystalline molybdenum diselenide thin films are prepared by pulsed electrodeposition on conducting glass and titanium substrates in galvanostatic mode from an ammoniacal solution of H2MoO4 and SeO2. The growth kinetics of the film was studied and the deposition parameters such as electrolyte bath concentration, bath temperature, time of deposition, deposition current, pH of the electrolyte and duty cycle of the current are optimized. X-ray diffraction analysis of the as deposited and annealed films showed the presence of highly textured MoSe2 films with polycrystalline nature. EDAX spectrum of the surface composition confirms the nearly stoichiometric MoSe2 nature of the film. Surface morphology studies by scanning electron microscope (SEM) shows that the films are pinhole free and of device quality nature. The optical absorption spectra show an indirect band gap value of 1.16 eV. Conductivity measurements were carried out at different temperatures and electrical constants such as activation energy, trapped energy state and barrier height were calculated. 相似文献
9.
Pieter Geiregat Carmelita Rodá Ivo Tanghe Shalini Singh Alessio Di Giacomo Delphine Lebrun Gianluca Grimaldi Jorick Maes Dries Van Thourhout Iwan Moreels Arjan J.Houtepen Zeger Hens 《光:科学与应用(英文版)》2021,10(6):1122-1132
2D materials are considered for applications that require strong light-matter interaction because of the apparently giant oscillator strength of the exciton tra... 相似文献
10.
Yilin Tian Caleb Arata Erin Boedicker David M. Lunderberg Sameer Patel Sumit Sankhyan Kasper Kristensen Pawel K. Misztal Delphine K. Farmer Marina Vance Atila Novoselac William W. Nazaroff Allen H. Goldstein 《Indoor air》2021,31(1):88-98
Inhalation of particulate matter is associated with adverse health outcomes. The fluorescent portion of supermicron particulate matter has been used as a proxy for bioaerosols. The sources and emission rates of fluorescent particles in residential environments are not well-understood. Using an ultraviolet aerodynamic particle sizer (UVAPS), emissions of total and fluorescent supermicron particles from common human activities were investigated during the HOMEChem campaign, a test-house investigation of the chemistry of indoor environments. Human occupancy and activities, including cooking and mopping, were found to be considerable sources of indoor supermicron fluorescent particles, which enhanced the indoor particle concentrations by two orders of magnitude above baseline levels. The estimated total (fluorescent) mass emission rates for the activities tested were in the range of 4-30 (1-11) mg per person meal for cooking and 0.1-4.9 (0.05-4.7) mg/h for occupancy and mopping. Model calculations indicate that, once released, the dominant fate of coarse particles (2.5-10 micrometer in diameter) was deposition onto indoor surfaces, allowing for the possibility of subsequent resuspension and consequent exposures over durations much longer than the ventilation time scale. Indoor coarse particle deposition would also contribute to soiling of indoor surfaces. 相似文献