全文获取类型
收费全文 | 224篇 |
免费 | 11篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 20篇 |
金属工艺 | 1篇 |
机械仪表 | 4篇 |
建筑科学 | 1篇 |
能源动力 | 12篇 |
轻工业 | 9篇 |
无线电 | 32篇 |
一般工业技术 | 27篇 |
冶金工业 | 45篇 |
原子能技术 | 1篇 |
自动化技术 | 79篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 1篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 9篇 |
2017年 | 8篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 8篇 |
2013年 | 15篇 |
2012年 | 8篇 |
2011年 | 13篇 |
2010年 | 12篇 |
2009年 | 14篇 |
2008年 | 18篇 |
2007年 | 15篇 |
2006年 | 6篇 |
2005年 | 5篇 |
2004年 | 8篇 |
2003年 | 5篇 |
2002年 | 6篇 |
2001年 | 7篇 |
2000年 | 2篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 7篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1916年 | 1篇 |
1913年 | 2篇 |
排序方式: 共有235条查询结果,搜索用时 31 毫秒
21.
22.
Coolstreaming: Design, Theory, and Practice 总被引:6,自引:0,他引:6
Peer-to-peer (P2P) technology has found much success in applications like file distributions and VoIP yet, its adoption in live video streaming remains as an elusive goal. Our recent success in Coolstreaming system brings promises in this direction; however, it also reveals that there exist many practical engineering problems in real live streaming systems over the Internet. Our focus in this paper is on a nonoptimal real working system, in which we illustrate a set of existing practical problems and how they could be handled. We believe this is essential in providing the basic understanding of P2P streaming systems. This paper uses a set of real traces and attempts to develop some theoretical basis to demonstrate that a random peer partnership selection with a hybrid pull-push scheme has the potentially to scale. Specifically, first, we describe the fundamental system design tradeoffs and key changes in the design of a Coolstreaming system including substreaming, buffer management, scheduling and the adopt of a hybrid pull-push mechanism over the original pull-based content delivery approach; second, we examine the overlay topology and its convergence; third, using a combination of real traces and analysis, we quantitatively provide the insights on how the buffering technique resolves the problems associated with dynamics and heterogeneity; fourth, we show how substream and path diversity can help to alleviate the impact from congestion and churns; fifth, we discuss the system scalability and limitations. 相似文献
23.
Natural gas is normally transported through a vast network of pipelines. A pipeline network is generally established either
to transmit gas at high pressure from coastal supplies to regional demand points (transmission network) or to distribute gas
to consumers at low pressure from the regional demand points (distribution network). In this study, the distribution network
is considered. The distribution network differs from the transmission one in a number of ways. Pipes involved in a distribution
network are often much smaller and the network is simpler, having no valves, compressors or nozzles. In this paper, we propose
the problem of minimizing the cost of pipelines incurred by driving the gas in a distribute non-linear network under steady-state
assumptions. In particular, the decision variables include the length of the pipes’ diameter, pressure drops at each node
of the network, and mass flow rate at each pipeline leg. We establish a mathematical optimization model of this problem, and
then present a global approach, which is based on the GOP primal-relaxed dual decomposition method presented by Visweswaran
and Floudas (Global optimization in engineering design. Kluwer book series in nonconvex optimization and its applications.
Kluwer, Netherlands, 1996), to the optimization model. Finally, results from application of the approach to data from gas company are presented. 相似文献
24.
25.
Peter C. Guschl Joshua U. Otaigbe Chun‐Keung Loong 《Polymer Engineering and Science》2004,44(9):1692-1701
The phase behavior of novel, binary organic‐inorganic hybrids consisting of an ultra‐low Tg tin‐based phosphate glass (Pglass) and polystyrene (PS) was investigated. Dynamic mechanical analysis (DMA) revealed that the glass transition peaks of the PS changed slightly with Pglass volume fraction, leading to a broad peak at the phase inversion point. The phase inversion and degree of phase continuity of the hybrid were studied through solvent extraction, optical/scanning electron microscopy, and dynamic rheology. The Jordhamo and Utracki viscosity ratio models provided reliable estimates of the inversion point. Torque rheometry revealed a trend toward linear additivity within the temperature range 200°C–230°C. Small‐angle neutron scattering experiments gave further evidence of the hybrid phase incompatibility. The results of this study point to a promising new class of blend materials with the potential to present a unique combination of properties impossible to achieve with classical polymer blends. Polym. Eng. Sci. 44:1692–1701, 2004. © 2004 Society of Plastics Engineers. 相似文献
26.
Evaluating performance of individual features of WiMAX technology is a topic of widespread discussion. Currently, there is no quantitative way of measuring WiMAX technology so that wireless operators can meet their design objectives. This paper outlines a set of design criteria for WiMAX and provides a decision-making aid that ranks the importance of criteria using Analytic Hierarchy Process (AHP). This ranking should sufficiently reflect market expectations of the relative importance of various design criteria. A model integrating AHP priorities with enhanced Data Envelopment Analysis (DEA) is the basis for formulating a technological value in simple,comparable format. A case study is provided to show how this technological value is used to evaluate a three year network deployment plan. In the future, this model could be extended to WiMAX equipment suppliers for the purpose of validating performance targets of individual criteria, and enhancing supplier roadmaps for future network development. 相似文献
27.
In this paper, an improved EMD meta-learning rate-based model for gold price forecasting is proposed. First, we adopt the EMD method to divide the time series data into different subsets. Second, a back-propagation neural network model (BPNN) is used to function as the prediction model in our system. We update the online learning rate of BPNN instantly as well as the weight matrix. Finally, a rating method is used to identify the most suitable BPNN model for further prediction. The experiment results show that our system has a good forecasting performance. 相似文献
28.
29.
Discovering useful concept prototypes for classification based on filtering and abstraction 总被引:2,自引:0,他引:2
Wai Lam Chi-Kin Keung Danyu Liu 《IEEE transactions on pattern analysis and machine intelligence》2002,24(8):1075-1090
The nearest-neighbor algorithm and its derivatives have been shown to perform well for pattern classification. Despite their high classification accuracy, they suffer from high storage requirement, computational cost, and sensitivity to noise. We develop anew framework, called ICPL (Integrated Concept Prototype Learner), which integrates instance-filtering and instance-abstraction techniques by maintaining a balance of different kinds of concept prototypes according to instance locality. The abstraction component, based on typicality, employed in our ICPL framework is specially designed for concept integration. We have conducted experiments on a total of 50 real-world benchmark data sets. We find that our ICPL framework maintains or achieves better classification accuracy and gains a significant improvement in data reduction compared with existing filtering and abstraction techniques as well as some existing techniques. 相似文献
30.
Manne Sharon L.; Ostroff Jamie; Winkel Gary; Grana Generosa; Fox Kevin 《Canadian Metallurgical Quarterly》2005,24(6):635
This 18-month longitudinal study examined the associations among partner unsupportive behavior, avoidant coping, and distress experienced by 219 women with early stage breast cancer. The role of patient and partner ratings of unsupportive behavior were evaluated. Results indicated that patient and partner ratings of unsupportive behavior were highly correlated. Growth curve modeling suggested that unsupportive behavior, from both patient and partner perspectives, predicted more avoidant coping and distress. When partner and patient perceptions were placed in the same model, patient perceptions mediated the association between partners' ratings of their unsupportive behavior and patient distress. Avoidance also mediated the association between unsupportive behavior and distress, extending prior cross-sectional findings. Results highlight the long-term detrimental effects of partners' unsupportive behavior on the quality of life of women with early stage breast cancer. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献