全文获取类型
收费全文 | 4447篇 |
免费 | 268篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 56篇 |
综合类 | 2篇 |
化学工业 | 948篇 |
金属工艺 | 60篇 |
机械仪表 | 97篇 |
建筑科学 | 161篇 |
矿业工程 | 4篇 |
能源动力 | 130篇 |
轻工业 | 650篇 |
水利工程 | 35篇 |
石油天然气 | 8篇 |
无线电 | 358篇 |
一般工业技术 | 636篇 |
冶金工业 | 638篇 |
原子能技术 | 32篇 |
自动化技术 | 905篇 |
出版年
2024年 | 6篇 |
2023年 | 49篇 |
2022年 | 46篇 |
2021年 | 222篇 |
2020年 | 100篇 |
2019年 | 100篇 |
2018年 | 160篇 |
2017年 | 100篇 |
2016年 | 184篇 |
2015年 | 140篇 |
2014年 | 195篇 |
2013年 | 292篇 |
2012年 | 263篇 |
2011年 | 336篇 |
2010年 | 202篇 |
2009年 | 230篇 |
2008年 | 213篇 |
2007年 | 191篇 |
2006年 | 169篇 |
2005年 | 123篇 |
2004年 | 103篇 |
2003年 | 107篇 |
2002年 | 85篇 |
2001年 | 55篇 |
2000年 | 65篇 |
1999年 | 72篇 |
1998年 | 224篇 |
1997年 | 150篇 |
1996年 | 113篇 |
1995年 | 71篇 |
1994年 | 67篇 |
1993年 | 44篇 |
1992年 | 21篇 |
1991年 | 17篇 |
1990年 | 11篇 |
1989年 | 20篇 |
1988年 | 13篇 |
1987年 | 10篇 |
1986年 | 13篇 |
1985年 | 10篇 |
1984年 | 10篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1981年 | 13篇 |
1980年 | 14篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 15篇 |
1976年 | 18篇 |
1973年 | 3篇 |
排序方式: 共有4720条查询结果,搜索用时 296 毫秒
81.
82.
Claudio Baecchi Tiberio Uricchio Marco Bertini Alberto Del Bimbo 《Multimedia Tools and Applications》2016,75(5):2507-2525
In this paper we investigate the use of a multimodal feature learning approach, using neural network based models such as Skip-gram and Denoising Autoencoders, to address sentiment analysis of micro-blogging content, such as Twitter short messages, that are composed by a short text and, possibly, an image. The approach used in this work is motivated by the recent advances in: i) training language models based on neural networks that have proved to be extremely efficient when dealing with web-scale text corpora, and have shown very good performances when dealing with syntactic and semantic word similarities; ii) unsupervised learning, with neural networks, of robust visual features, that are recoverable from partial observations that may be due to occlusions or noisy and heavily modified images. We propose a novel architecture that incorporates these neural networks, testing it on several standard Twitter datasets, and showing that the approach is efficient and obtains good classification results. 相似文献
83.
Richard O. Sinnott Christopher Bayliss Andrew Bromage Gerson Galang Yikai Gong Philip Greenwood Glenn Jayaputera Davis Marques Luca Morandini Ghazal Nogoorani Hossein Pursultani Muhammad Sarwar William Voorsluys Ivo Widjaja 《Journal of Grid Computing》2016,14(4):603-618
Big data technologies and a range of Government open data initiatives provide the basis for discovering new insights into cities; how they are planned, how they managed and the day-to-day challenges they face in health, transport and changing population profiles. The Australian Urban Research Infrastructure Network (AURIN – www.aurin.org.au) project is one example of such a big data initiative that is currently running across Australia. AURIN provides a single gateway providing online (live) programmatic access to over 2000 data sets from over 70 major and typically definitive data-driven organizations across federal and State government, across industry and across academia. However whilst open (public) data is useful to bring data-driven intelligence to cities, more often than not, it is the data that is not-publicly accessible that is essential to understand city challenges and needs. Such sensitive (unit-level) data has unique requirements on access and usage to meet the privacy and confidentiality demands of the associated organizations. In this paper we highlight a novel geo-privacy supporting solution implemented as part of the AURIN project that provides seamless and secure access to individual (unit-level) data from the Department of Health in Victoria. We illustrate this solution across a range of typical city challenges in localized contexts around Melbourne. We show how unit level data can be combined with other data in a privacy-protecting manner. Unlike other secure data access and usage solutions that have been developed/deployed, the AURIN solution allows any researcher to access and use the data in a manner that meets all of the associated privacy and confidentiality concerns, without obliging them to obtain ethical approval or any other hurdles that are normally put in place on access to and use of sensitive data. This provides a paradigm shift in secure access to sensitive data with geospatial content. 相似文献
84.
Most of the literature on innovation management highlights the fundamental role played by people in the innovation process and the need to fully develop the creative and innovative potential of organizations' members. This article offers the result of extensive research carried out among some of the most innovative companies in the Basque Country, a highly innovative region located in the north of Spain. It draws interesting conclusions about how these innovative companies combine strong leadership, human resource practices, and an organizational culture that enhances innovation capabilities among the company's employees. More specifically, it answers questions such as the following: Are human resources policies, leadership, and innovation culture implemented equally in Basque innovative companies? Do companies make the same effort in deploying these elements or routines and practices related to them? Can we see a pattern in the use of these elements among innovative firms? © 2012 Wiley Periodicals, Inc. 相似文献
85.
Elena Baralis Andrea Bianco Tania Cerquitelli Luca Chiaraviglio Marco Mellia 《Computer Networks》2013,57(17):3300-3315
Internet measured data collected via passive measurement are analyzed to obtain localization information on nodes by clustering (i.e., grouping together) nodes that exhibit similar network path properties. Since traditional clustering algorithms fail to correctly identify clusters of homogeneous nodes, we propose the NetCluster novel framework, suited to analyze Internet measurement datasets. We show that the proposed framework correctly analyzes synthetically generated traces. Finally, we apply it to real traces collected at the access link of Politecnico di Torino campus LAN and discuss the network characteristics as seen at the vantage point. 相似文献
86.
Weiwei Fang Xiangmin Liang Shengxin Li Luca Chiaraviglio Naixue Xiong 《Computer Networks》2013,57(1):179-196
In recent years, the power costs of cloud data centers have become a practical concern and have attracted significant attention from both industry and academia. Most of the early works on data center energy efficiency have focused on the biggest power consumers (i.e., computer servers and cooling systems), yet without taking the networking part into consideration. However, recent studies have revealed that the network elements consume 10–20% of the total power in the data center, which poses a great challenge to effectively reducing network power cost without adversely affecting overall network performance. Based on the analysis on topology characteristics and traffic patterns of data centers, this paper presents a novel approach, called VMPlanner, for network power reduction in the virtualization-based data centers. The basic idea of VMPlanner is to optimize both virtual machine placement and traffic flow routing so as to turn off as many unneeded network elements as possible for power saving. We formulate the optimization problem, analyze its hardness, and solve it by designing VMPlanner as a stepwise optimization approach with three approximation algorithms. VMPlanner is implemented and evaluated in a simulated environment with traffic traces collected from a data center test-bed, and the experiment results illustrate the efficacy and efficiency of this approach. 相似文献
87.
A challenge in cloud resource management is to design self-adaptable solutions capable to react to unpredictable workload fluctuations and changing utility principles. This paper analyzes the problem from the perspective of an Application Service Provider (ASP) that uses a cloud infrastructure to achieve scalable provisioning of its services in the respect of QoS constraints.First we draw a taxonomy of IaaS provider and use the identified features to drive the design of four autonomic service management architectures differing on the degree of control an ASP have on the system. We implemented two of this solutions and related mechanism to test five different resource provisioning policies. The implemented testbed has been evaluated under a realistic workload based on Wikipedia access traces on Amazon EC2 platform.The experimental evaluation performed confirms that: the proposed policies are capable to properly dimension the system resources making the whole system self-adaptable respect to the workload fluctuation. Moreover, having full control over the resource management plan allow to save up to the 32% of resource allocation cost always in the respect of SLA constraints. 相似文献
88.
Arregui-Dalmases C Del Pozo E Stacey S Kindig M Lessley D Lopez-Valdes F Forman J Kent R 《Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine》2011,225(7):688-695
While rupture of the aorta is a leading cause of sudden death following motor vehicle crashes, the specific mechanism that causes this injury is not currently well understood. Aortic ruptures occurring in the field are likely due to a complex combination of contributing factors such as acceleration, compression of the chest, and increased pressure within the aorta. The objective of the current study was to investigate one of these factors in more detail than has been done previously; specifically, to investigate the in situ intra-aortic pressure generated during isolated belt loading to the abdomen. Ten juvenile swine were subjected to dynamic belt loads applied to the abdomen. Intraaortic pressure was measured at multiple locations to assess the magnitude and propagation of the resulting blood pressure wave. The greatest average peak pressure (113.6 +/- 43.5 kPa) was measured in the abdominal aorta. Pressures measured in the thoracic aorta and aortic arch were 70 per cent and 50 per cent, respectively, that measured in the abdominal aorta. No macroscopic aortic trauma was observed. To the authors' knowledge the present study is the first one to document the presence, propagation, and attenuation of a transient pressure wave in the aorta generated by abdominal belt loading. The superiorly moving wave is sufficient to generate hydrostatic and intimal shear stress in the aorta, possibly contributing to the hypothesized mechanisms of traumatic aortic rupture. 相似文献
89.
Di Luca GA Mufarrege MM Sánchez GC Hadad HR Maine MA 《Water science and technology》2011,63(10):2374-2380
The aim of this work was to study the accumulation and fractionation of P in the inlet and outlet sediment of a constructed wetland for the wastewater treatment of a metallurgic plant in Argentina. It was important to predict whether P could be released into the water again by changing environmental conditions or retained over time. P-fractionation was performed using a sequential extraction method. Sediment cores were sliced at depths of: 0-3; 3-7 and 7-10 cm. Sediment showed high pH values and anoxic conditions. In the inlet area, P was principally bound to the carbonate fraction, whereas in the outlet area, it was mainly bound in the residual fraction. This behavior was justified by the effluent composition, which is rich in Ca2+ and Fe3+ and presents high values of pH and conductivity. These conditions favor CaCO3 and Fe(OOH)n precipitation and the subsequent sorption of P to their surface. The sediment active layer involved in the exchange reactions was the superficial one (0-3 cm). The wetland is highly efficient in P retention. P was retained by sediment in fractions that will not release it to the water while chemical and environmental conditions of the system are maintained. 相似文献
90.
Daniel Dominguez Gouvêa Cyro de A. Assis D. Muniz Gilson A. Pinto Alberto Avritzer Rosa Maria Meri Leão Edmundo de Souza e Silva Morganna Carmem Diniz Vittorio Cortellessa Luca Berardinelli Julius C. B. Leite Daniel Mossé Yuanfang Cai Michael Dalton Lucia Happe Anne Koziolek 《Software and Systems Modeling》2013,12(4):765-787
In this paper, we report on our experience with the application of validated models to assess performance, reliability, and adaptability of a complex mission critical system that is being developed to dynamically monitor and control the position of an oil-drilling platform. We present real-time modeling results that show that all tasks are schedulable. We performed stochastic analysis of the distribution of task execution time as a function of the number of system interfaces. We report on the variability of task execution times for the expected system configurations. In addition, we have executed a system library for an important task inside the performance model simulator. We report on the measured algorithm convergence as a function of the number of vessel thrusters. We have also studied the system architecture adaptability by comparing the documented system architecture and the implemented source code. We report on the adaptability findings and the recommendations we were able to provide to the system’s architect. Finally, we have developed models of hardware and software reliability. We report on hardware and software reliability results based on the evaluation of the system architecture. 相似文献