全文获取类型
收费全文 | 606篇 |
免费 | 31篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 164篇 |
金属工艺 | 11篇 |
机械仪表 | 15篇 |
建筑科学 | 17篇 |
能源动力 | 21篇 |
轻工业 | 60篇 |
水利工程 | 5篇 |
石油天然气 | 2篇 |
无线电 | 46篇 |
一般工业技术 | 168篇 |
冶金工业 | 25篇 |
原子能技术 | 3篇 |
自动化技术 | 94篇 |
出版年
2023年 | 5篇 |
2022年 | 21篇 |
2021年 | 37篇 |
2020年 | 18篇 |
2019年 | 10篇 |
2018年 | 24篇 |
2017年 | 17篇 |
2016年 | 17篇 |
2015年 | 11篇 |
2014年 | 32篇 |
2013年 | 44篇 |
2012年 | 49篇 |
2011年 | 53篇 |
2010年 | 34篇 |
2009年 | 34篇 |
2008年 | 29篇 |
2007年 | 29篇 |
2006年 | 20篇 |
2005年 | 26篇 |
2004年 | 15篇 |
2003年 | 14篇 |
2002年 | 16篇 |
2001年 | 9篇 |
2000年 | 4篇 |
1999年 | 9篇 |
1998年 | 11篇 |
1997年 | 8篇 |
1996年 | 9篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有638条查询结果,搜索用时 15 毫秒
91.
Eduardo N. Dvorkin Eugenio Onte Javier Oliver 《International journal for numerical methods in engineering》1988,26(7):1597-1613
An incremental Total Lagrangian Formulation for curved beam elements that includes the effect of large rotation increments is developed. A complete and symmetric tangent stiffness matrix is obtained and the numerical results show, in general, an improvement over the standard formulation where the assumption of infinitesimal rotation increments is made in the derivation of the tangent stiffness matrix. 相似文献
92.
The treatment of sulfate-rich wastewater using an anaerobic sequencing batch biofilm pilot-scale reactor 总被引:1,自引:0,他引:1
This paper presents the results from 92 cycles of an anaerobic sequencing batch biofilm reactor containing biomass immobilized on inert support (mineral coal) applied for the treatment of an industrial wastewater containing high sulfate concentration. The pilot-scale reactor, with a total volume of 1.2 m3, was operated at sulfate loading rates ranging from 0.15 to 1.90 kgSO42−/cycle (48 h — cycle) corresponding to sulfate concentrations of 0.25 to 3.0 gSO42− l− 1. Domestic sewage and ethanol were utilized as electron donors for sulfate reduction. Influent sulfate concentrations were increased in order to evaluate the minimum COD/sulfate ratio at which high reactor performance could be maintained. The mean sulfate removal efficiency remained between the range of 88 to 92% at several sulfate concentrations. Temporal profiles along the 48 h cycles were carried out under stable operation at sulfate concentrations of 1.0, 2.0 and 3.0 gSO42− l− 1. Sulfate removal reached 99% for cycle times of 15, 25, and 30 h, and the effluents sulfate concentrations were lower than 8 mgSO42− l− 1. The results demonstrate the potential applicability of the anaerobic configuration for the biological treatment of sulfate-rich wastewaters. 相似文献
93.
T.L.R. Hewer S. Surez J.M. Coronado R. Portela P. Avila B. Sanchez 《Catalysis Today》2009,143(3-4):302
Hybrid photocatalysts based on an adsorbent SiMgOx and a photocatalyst TiO2 were developed in a plate shape. The ceramic surface was coated with TiO2 by the slip-casting technique. The effect of the support in the photocatalytic degradation of trichloroethylene (TCE) was analyzed by modifying TiO2 loading and the layer thickness. Photocatalysts were characterised by N2 adsorption–desorption, mercury intrusion porosimetry, SEM, UV–vis spectroscopy and XRD. A direct relationship between the TiO2 content and the photocatalytic activity was observed up to three layers of TiO2 (0.66 wt.%). Our results indicate that intermediate species generated on the TiO2 layer can migrate through relatively long distances to react with the OH− surface groups of the support. By increasing the TiO2 loading of the photocatalyst two effects were observed: trichloroethylene conversion is enhanced, while the efficiency of the oxidation process is decreased at expenses of increasing the selectivity to COCl2 and dichloroacetylchloride (DCAC). The results are discussed in terms of the layer thickness, TiO2 amount, TCE conversion and CO2, and COCl2 selectivity. 相似文献
94.
María D. Hernndez-Alonso Isabel Tejedor-Tejedor Juan M. Coronado Marc A. Anderson Javier Soria 《Catalysis Today》2009,143(3-4):364
Operando FTIR spectroscopy has been used to study the photocatalytic oxidation of acetone vapors over semiconductors films containing TiO2 and ZrO2. Preparation of these coatings was carried out by dipping a silicon wafer in stable sols containing particles of TiO2, Ti1−xZrxO2, or a mixture of ZrO2 and TiO2. These differences in chemical composition and phase homogeneity were selected in order to determine their effect on the photocatalytic performance. A transmission cell specifically designed for in situ studies of photocatalytic coatings was utilized for the FTIR experiments under reaction conditions. In contrast with investigations with powdered photocatalysts, the use of thin films guarantees that the whole semiconductor is irradiated, and for that reason purely photochemical reactions are monitored. Acetone adsorption takes place molecularly and is higher on the Ti1−xZrxO2 coating. This fact is very likely related to the higher specific surface of the samples containing Zr. However, the maximum photocatalytic rate for acetone degradation corresponds to the films composed by a binary mixture of TiO2 and ZrO2. On the other hand, remarkable differences on the type and concentration of intermediates appearing as a result of the photocatalytic oxidation of acetone are found for the coatings studied. A simple kinetic model was applied to analyze the evolution of both gas phase and surface species. The parameters obtained indicate that each specific surface process is affected in a different way by the variation in the composition of the photoactive films. 相似文献
95.
Manuel Acosta Daniel Coronado Esther Ferrándiz M. Dolores León Pedro J. Moreno 《Scientometrics》2017,112(1):215-240
This paper contributes to the literature on the factors explaining the regional university production of science and its quality in the field of Food Science and Technology (FS&T). We hypothesized that the regional quantity of science generated by universities is shaped not only by the amount of research and development (R&D) funds, as the main mainstream literature suggests, but also by the demand for science at the regional level. Furthermore, given the evolutionary nature of knowledge production, we suggest that the number of publications has a significant effect on the quality of scientific research at the regional level. Drawing on a sample of 48,207 scientific papers in FS&T over the period 1998–2010, we first map and examine the regional distribution of science and its quality across Europe-15. Second, we address our hypotheses by specifying several econometric models to identify the factors affecting the quantity and quality of scientific production. Our results show that the regional demand for FS&T—captured by the regional employment in the food and beverage industry—matters for the generation of science. Additionally, our findings support the hypothesis of a positive and significant effect of the production of papers on the scientific quality at the regional level. 相似文献
96.
Aleixandre-Benavent Rafael Sapena Antonia Ferrer Ferrer Silvia Coronado Peset Fernanda García Alicia García 《Scientometrics》2019,118(2):439-451
Scientometrics - Sharing research data is an increasingly necessary requirement for the advancement of science. The goal of this paper is twofold. First, to analyze the policies on openness in... 相似文献
97.
98.
Vaz Isabela C. F. Macchi Carlos Eugenio Somoza Alberto Rocha Leandro S. R. Longo Elson Cabral Luis da Silva Edison Z. Simões Alexandre Zirpoli Zonta Giulia Malagù Cesare Desimone P. Mariela Ponce Miguel Adolfo Moura Francisco 《Journal of Materials Science: Materials in Electronics》2022,33(15):11632-11649
Journal of Materials Science: Materials in Electronics - This study reports the electrical properties of Nd-doped cerium oxide (CeO2) films synthesized by microwave assisted hydrothermal using a... 相似文献
99.
Jillian Aurisano Abhinav Kumar Abeer Alsaiari Barbara Di Eugenio Andrew Johnson 《Computer Graphics Forum》2020,39(3):229-240
This paper describes results from an observational, exploratory study of visual data exploration in a large, multi-view, flexible canvas environment. Participants were provided with a set of data exploration sub-tasks associated with a local crime dataset and were instructed to pose questions to a remote mediator who would respond by generating and organizing visualizations on the large display. We observed that participants frequently posed requests to cast a net around one or several subsets of the data or a set of data attributes. They accomplished this directly and by utilizing existing views in unique ways, including by requesting to copy and pivot a group of views collectively and posing a set of parallel requests on target views expressed in one command. These observed actions depart from multi-view flexible canvas environments that typically provide interfaces in support of generating one view at a time or actions that operate on one view at a time. We describe how participants used these ‘cast-a-net’ requests for tasks that spanned more than one view and describe design considerations for multi-view environments that would support the observed multi-view generation actions. 相似文献
100.
Uzma Choudry Dr. Derren J. Heyes Dr. Samantha J. O. Hardman Michiyo Sakuma Dr. Igor V. Sazanovich Joyce Woodhouse Dr. Eugenio De La Mora Dr. Martin N. Pedersen Dr. Michael Wulff Dr. Martin Weik Dr. Giorgio Schirò Prof. Nigel S. Scrutton 《Chembiochem : a European journal of chemical biology》2018,19(10):1036-1043
Phytochromes are bilin‐containing photoreceptors that are typically sensitive to the red/far‐red region of the visible spectrum. Recently, phytochromes from certain eukaryotic algae have become attractive targets for optogenetic applications because of their unique ability to respond to multiple wavelengths of light. Herein, a combination of time‐resolved spectroscopy and structural approaches across picosecond to second timescales have been used to map photochemical mechanisms and structural changes in this atypical group of phytochromes. The photochemistry of an orange/far‐red light‐sensitive algal phytochrome from Dolihomastix tenuilepis has been investigated by using a combination of visible, IR and X‐ray scattering probes. The entire photocycle, correlated with accompanying structural changes in the cofactor/protein, are reported. This study identifies a complex photocycle for this atypical phytochrome. It also highlights a need to combine outcomes from a range of biophysical approaches to unravel complex photochemical and macromolecular processes in multi‐domain photoreceptor proteins that are the basis of biological light‐mediated signalling. 相似文献