全文获取类型
收费全文 | 1683篇 |
免费 | 116篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 11篇 |
综合类 | 3篇 |
化学工业 | 482篇 |
金属工艺 | 18篇 |
机械仪表 | 31篇 |
建筑科学 | 90篇 |
矿业工程 | 2篇 |
能源动力 | 20篇 |
轻工业 | 335篇 |
水利工程 | 21篇 |
石油天然气 | 4篇 |
无线电 | 61篇 |
一般工业技术 | 284篇 |
冶金工业 | 255篇 |
原子能技术 | 3篇 |
自动化技术 | 181篇 |
出版年
2024年 | 2篇 |
2023年 | 11篇 |
2022年 | 15篇 |
2021年 | 126篇 |
2020年 | 43篇 |
2019年 | 54篇 |
2018年 | 57篇 |
2017年 | 47篇 |
2016年 | 47篇 |
2015年 | 45篇 |
2014年 | 71篇 |
2013年 | 116篇 |
2012年 | 107篇 |
2011年 | 134篇 |
2010年 | 100篇 |
2009年 | 97篇 |
2008年 | 105篇 |
2007年 | 92篇 |
2006年 | 75篇 |
2005年 | 62篇 |
2004年 | 53篇 |
2003年 | 46篇 |
2002年 | 43篇 |
2001年 | 22篇 |
2000年 | 19篇 |
1999年 | 21篇 |
1998年 | 12篇 |
1997年 | 25篇 |
1996年 | 15篇 |
1995年 | 12篇 |
1994年 | 10篇 |
1993年 | 15篇 |
1992年 | 6篇 |
1991年 | 8篇 |
1990年 | 10篇 |
1989年 | 9篇 |
1988年 | 8篇 |
1987年 | 12篇 |
1986年 | 7篇 |
1985年 | 9篇 |
1984年 | 4篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1980年 | 6篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1972年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有1801条查询结果,搜索用时 343 毫秒
61.
Silvia Gillermina Ceballos-Maga?a Jose Marcos Jurado Roberto Mu?iz-Valencia Angela Alcázar Fernado de Pablos María Jesus Martín 《Food Analytical Methods》2012,5(2):260-265
The elemental profile of tequila samples from the three main production areas of the State of Jalisco, namely Amatitlan, Guadalajara,
and Tequila, was used to carry out their geographical characterization. With this aim, the concentration of Al, Ba, Ca, Cu,
Fe, K, Mg, Mn, Na, S, Sr, and Zn was determined by inductively coupled plasma atomic emission spectroscopy. Principal component
analysis was addressed to visualize data trends. The number of input variables was reduced by means of backward stepwise linear
discriminant analysis and support vector machines were used to construct an adequate classification model. The best classification
performance was obtained by a linear support vector machine model with 100% of prediction ability. 相似文献
62.
Antonella Ilenia Alfano Prof. Elisabetta Buommino Prof. Maria Grazia Ferraro Prof. Carlo Irace Prof. Angela Zampella Prof. Heiko Lange Prof. Margherita Brindisi 《ChemMedChem》2021,16(24):3795-3809
The generation of peptidomimetic substructures for medicinal chemistry purposes requires effective and divergent synthetic methods. We present in this work an efficient flow process that allows quick modulation of reagents for Joullié-Ugi multicomponent reaction, using spiroindolenines as core motifs. This sterically hindered imine equivalent could successfully be diversified using various isocyanides and amino acids in generally good space-time yields. A telescoped flow process combining interrupted Fischer reaction for spiroindolenine synthesis and subsequent Joullié-Ugi-type modification resulted in product formation in very good overall yield in less than 2 hours compared to 48 hours required in batch mode. The developed protocol can be seen as a general tool for rapid and facile generation of peptidomimetic compounds. We also showcase preliminary biological assessments for the prepared compounds. 相似文献
63.
This paper provides an introduction and an editorial to this special issue of River Research and Applications by documenting the contributions made by Professor Geoffrey Petts to our interdisciplinary understanding of the functioning of rivers and their floodplains and their sustainable management. We outline Geoff's career, which framed not only his research but its communication through his inspirational teaching but also included very high level and innovative contributions to the management and development of several UK universities. We then explain how and why Geoff was an outstanding interdisciplinary river scientist and how he communicated his science through both integrative books and book chapters and also research papers that developed eight complementary research themes. Lastly, we introduce the papers in this special issue and show how they provide inputs to Geoff's areas of research interest. 相似文献
64.
Alberto Abad Anna Pompili Angela Costa Isabel Trancoso José Fonseca Gabriela Leal Luisa Farrajota Isabel P. Martins 《Computer Speech and Language》2013,27(6):1235-1248
One of the most common effects among aphasia patients is the difficulty to recall names or words. Typically, word retrieval problems can be treated through word naming therapeutic exercises. In fact, the frequency and the intensity of speech therapy are key factors in the recovery of lost communication functionalities. In this sense, speech and language technology can have a relevant contribution in the development of automatic therapy methods. In this work, we present an on-line system designed to behave as a virtual therapist incorporating automatic speech recognition technology that permits aphasia patients to perform word naming training exercises. We focus on the study of the automatic word naming detector module and on its utility for both global evaluation and treatment. For that purpose, a database consisting of word naming therapy sessions of aphasic Portuguese native speakers has been collected. In spite of the different patient characteristics and speech quality conditions of the collected data, encouraging results have been obtained thanks to a calibration method that makes use of the patients’ word naming ability to automatically adapt to the patients’ speech particularities. 相似文献
65.
Angela Xia Liu Yinglei Wang Xi Chen Xuping Jiang 《Information Systems and E-Business Management》2014,12(2):239-258
While the sales of mobile digital content have been growing exponentially, the understanding of its diffusion remains limited in the literature. In this study, we set out to enrich this understanding using a growth curve modelling approach. We applied four widely used growth curve models of innovation diffusion and compared their performance in explaining the diffusion of mobile digital content empirically. Analysis based on the data collected on a product adopted by nearly 30 million mobile phone users over a 149-week period in 31 regions in China revealed that the Gompertz model was the most effective model in depicting the diffusion process, with more than 99 % of the variance explained. Moreover, we found that population, urbanization, education level, and mobile technology usage were significant determinants of various parameters such as the diffusion rate and inflection point of the diffusion process, respectively. Implications for both researchers and practitioners are discussed. 相似文献
66.
67.
68.
Angela Sester Katrin Stüer-Patowsky Prof. Dr. Wolf Hiller Dr. Florian Kloss Prof. Dr. Stephan Lütz Prof. Dr. Markus Nett 《Chembiochem : a European journal of chemical biology》2020,21(16):2268-2273
Enzyme promiscuity has important implications in the field of biocatalysis. In some cases, structural analogues of simple metabolic building blocks can be processed through entire pathways to give natural product derivatives that are not readily accessible by chemical means. In this study, we explored the plasticity of the aurachin biosynthesis pathway with regard to using fluoro- and chloroanthranilic acids, which are not abundant in the bacterial producers of these quinolone antibiotics. The incorporation rates of the tested precursor molecules disclosed a regiopreference for halogen substitution as well as steric limitations of enzymatic substrate tolerance. Three previously undescribed fluorinated aurachin derivatives were produced in preparative amounts by fermentation and structurally characterized. Furthermore, their antibacterial activities were evaluated in comparison to their natural congener aurachin D. 相似文献
69.
Charles Weir Ingolf Becker James Noble Lynne Blair M. Angela Sasse Awais Rashid 《Software》2020,50(3):275-298
Though some software development teams are highly effective at delivering security, others either do not care or do not have access to security experts to teach them how. Unfortunately, these latter teams are still responsible for the security of the systems they build: systems that are ever more important to ever more people. We propose that a series of lightweight interventions, six hours of facilitated workshops delivered over three months, can improve a team's motivation to consider security and awareness of assurance techniques, changing its security culture even when no security experts are involved. The interventions were developed after an Appreciative Inquiry and Grounded Theory survey of security professionals to find out what approaches work best. We tested the interventions in a participatory action research field study where we delivered the workshops to three software development organizations and evaluated their effectiveness through interviews beforehand, immediately afterwards, and after twelve months. We found that the interventions can be effective with teams with limited or no security experience and that improvement is long-lasting. This approach and the learning points arising from the work here have the potential to be applied in many development teams, improving the security of software worldwide. 相似文献
70.
Natalie Williams Portal A. W. M. van Schijndel Angela Sasic Kalagasidis 《Building Simulation》2014,7(3):217-227
The basic structure of historic sites and their associated interior artefacts can be damaged or even destroyed by climate change. The evaluation of combined heat and moisture induced stress and strain (HMSS) can predict possible damage-related processes. In this paper, the development of one- and two-dimensional HMSS models of building materials and artefacts in COMSOL Multiphysics Version 4, a commercial finite element software, is presented. The validation of the numerical models is revealed using analytical, numerical and experimental solutions. As a result, the HMSS model was shown to be an adequate predictive tool to determine possible damage-related processes in building assemblies and artefacts. 相似文献