全文获取类型
收费全文 | 50366篇 |
免费 | 2781篇 |
国内免费 | 155篇 |
专业分类
电工技术 | 713篇 |
综合类 | 68篇 |
化学工业 | 10895篇 |
金属工艺 | 2158篇 |
机械仪表 | 3273篇 |
建筑科学 | 1120篇 |
矿业工程 | 25篇 |
能源动力 | 2131篇 |
轻工业 | 4095篇 |
水利工程 | 274篇 |
石油天然气 | 89篇 |
武器工业 | 2篇 |
无线电 | 7939篇 |
一般工业技术 | 10836篇 |
冶金工业 | 3924篇 |
原子能技术 | 662篇 |
自动化技术 | 5098篇 |
出版年
2024年 | 50篇 |
2023年 | 581篇 |
2022年 | 897篇 |
2021年 | 1520篇 |
2020年 | 1097篇 |
2019年 | 1200篇 |
2018年 | 1475篇 |
2017年 | 1447篇 |
2016年 | 1795篇 |
2015年 | 1326篇 |
2014年 | 2143篇 |
2013年 | 3072篇 |
2012年 | 3335篇 |
2011年 | 3978篇 |
2010年 | 2888篇 |
2009年 | 2985篇 |
2008年 | 2862篇 |
2007年 | 2230篇 |
2006年 | 2062篇 |
2005年 | 1759篇 |
2004年 | 1601篇 |
2003年 | 1538篇 |
2002年 | 1344篇 |
2001年 | 1143篇 |
2000年 | 1004篇 |
1999年 | 932篇 |
1998年 | 1566篇 |
1997年 | 1002篇 |
1996年 | 809篇 |
1995年 | 563篇 |
1994年 | 466篇 |
1993年 | 408篇 |
1992年 | 296篇 |
1991年 | 277篇 |
1990年 | 259篇 |
1989年 | 243篇 |
1988年 | 207篇 |
1987年 | 169篇 |
1986年 | 120篇 |
1985年 | 115篇 |
1984年 | 93篇 |
1983年 | 63篇 |
1982年 | 39篇 |
1981年 | 39篇 |
1980年 | 30篇 |
1979年 | 31篇 |
1978年 | 30篇 |
1977年 | 38篇 |
1976年 | 61篇 |
1973年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Incremental Linear Discriminant Analysis Using Sufficient Spanning Sets and Its Applications 总被引:1,自引:0,他引:1
Tae-Kyun Kim Björn Stenger Josef Kittler Roberto Cipolla 《International Journal of Computer Vision》2011,91(2):216-232
This paper presents an incremental learning solution for Linear Discriminant Analysis (LDA) and its applications to object
recognition problems. We apply the sufficient spanning set approximation in three steps i.e. update for the total scatter matrix, between-class scatter matrix and the projected data
matrix, which leads an online solution which closely agrees with the batch solution in accuracy while significantly reducing
the computational complexity. The algorithm yields an efficient solution to incremental LDA even when the number of classes
as well as the set size is large. The incremental LDA method has been also shown useful for semi-supervised online learning.
Label propagation is done by integrating the incremental LDA into an EM framework. The method has been demonstrated in the
task of merging large datasets which were collected during MPEG standardization for face image retrieval, face authentication
using the BANCA dataset, and object categorisation using the Caltech101 dataset. 相似文献
992.
Multicore architectures are evolving with the promise of extreme performance for the classes of applications that require
high performance and large bandwidth of memory. Irregular reduction is one of important computation patterns for many complex
scientific applications, and it typically requires high performance and large bandwidth of memory. In this article, we propose
region-based parallelization techniques for irregular reductions on multicore architectures with explicitly managed memory
hierarchies. Managing memory hierarchy in software requires a lot of programming efforts and tends to be error-prone. The
difficulties are even worse for applications with irregular data access patterns. To relieve the burden of memory management
from programmers, we develop abstractions, particularly targeted to irregular reduction, for structuring parallel tasks, mapping
the parallel tasks to processing units and scheduling data transfers between the memory hierarchies. Our framework employs
iteration reordering based on regions of data along with dynamic scheduling of parallel tasks. We experimentally evaluate
the effectiveness of our techniques for irregular reduction kernels on the Cell processor embedded in a Sony PlayStation3.
Experimental results show the speedups of 8 to 14 on the six available SPEs. 相似文献
993.
This paper presents the design, fabrication, and characterization of a contactless radio frequency (RF) microelectromechanical system (MEMS) switch, composed of two surface-micromachined piezoelectric tunable capacitors and two bonded-wire inductors. The measured insertion loss and power isolation of the fabricated switch are 2.2 and 10.1 dB, respectively, with a capacitance variation of 4:1 over a narrow bandwidth near 2.2 GHz. This novel approach of using inductors eases the deflection requirement for the deformable bridge of the variable capacitor, and allows piezoelectric ZnO film to be used to deflect the capacitor bridge to vary the air gap, thus yielding a contactless RF switch. 相似文献
994.
Joong-Tae Park Jae-Bok Song Se-Jin Lee Munsang Kim 《Journal of Intelligent and Robotic Systems》2011,63(3-4):465-480
This paper describes a sonar sensor-based exploration method. To build an accurate map in an unknown environment during exploration, a simultaneous localization and mapping problem must be solved. Therefore, a new type of sonar feature called a ??sonar salient feature?? (SS-feature), is proposed for robust data association. The key concept of an SS-feature is to extract circle feature clouds on salient convex objects from environments by associating sets of sonar data. The SS-feature is used as an observation in the extended Kalman filter (EKF)-based SLAM framework. A suitable strategy is needed to efficiently explore the environment. We used utilities of driving cost, expected information about an unknown area, and localization quality. Through this strategy, the exploration method can greatly reduce behavior that leads a robot to explore a previously visited place, and thus shorten the exploration distance. A robot can select a favorable path for localization by localization gain during exploration. Thus, the robot can estimate its pose more robustly than other methods that do not consider localizability during exploration. This proposed exploration method was verified by various experiments, and it ensures that a robot can build an accurate map fully autonomously with sonar sensors in various home environments. 相似文献
995.
Heung-Nam Kim Abdulmajeed Alkhaldi Abdulmotaleb El Saddik Geun-Sik Jo 《Expert systems with applications》2011,38(7):8488-8496
With the popularity of social media services, the sheer amount of content is increasing exponentially on the Social Web that leads to attract considerable attention to recommender systems. Recommender systems provide users with recommendations of items suited to their needs. To provide proper recommendations to users, recommender systems require an accurate user model that can reflect a user’s characteristics, preferences and needs. In this study, by leveraging user-generated tags as preference indicators, we propose a new collaborative approach to user modeling that can be exploited to recommender systems. Our approach first discovers relevant and irrelevant topics for users, and then enriches an individual user model with collaboration from other similar users. In order to evaluate the performance of our model, we compare experimental results with a user model based on collaborative filtering approaches and a vector space model. The experimental results have shown the proposed model provides a better representation in user interests and achieves better recommendation results in terms of accuracy and ranking. 相似文献
996.
Jeongsoo Lee Janghyeok Yoon Wonchul Seo Kwangsoo Kim Cheol-Han Kim 《Expert systems with applications》2011,38(10):12281-12292
Modern business environment emphasizes the role of knowledge-intensive business services (KIBS). As well as the enterprises in any other kinds of industries, business process management (BPM) can be a source of core competency for the enterprises in KIBS industry. However, most of the business processes in KIBS are human processes which are collaborative, innovative, and dynamic, which cannot be supported well by current BPM technologies. Human interaction management (HIM) has emerged as an alternative theory to deal with human processes in KIBS. But, the current ways of process modeling and management in HIM have a problem of complexity, especially in terms of realizing its principle of ‘supportive activity management’. This research adopts fact-oriented ontological approach to address this problem. Based on fact-oriented approach, human-friendly condition modeling and state management during supportive activity management can be achieved. 相似文献
997.
Quay cranes (QCs) are the most important equipment for vessel operation in container terminals. It is important to efficiently
schedule the operations of QCs so that a high productivity may be achieved in terminals. Because the storage yard is shared
by multiple vessels, where the congestion of yard cranes and yard trucks must be considered, the operations of QCs for multiple
vessels must be simultaneously considered for QC scheduling. The objective terms include the QC make-span, the total traveling
distance of QCs, the expected delay time from interference, and the uniformity of workload among blocks. This study suggests
a heuristic algorithm based on a meta-heuristic search algorithm. Finally, a numerical experiment is carried out to test the
performance of the algorithm. 相似文献
998.
Firms that have implemented knowledge management initiatives are now interested in nurturing voluntary knowledge sharing organizations, called communities of practice (CoPs). Adopting the Triandis model on attitude formation, we identified and validated a set of organizational factors that was anticipated to have effects on knowledge sharing by CoP members such as perceived consequences, affect, social factors and facilitating conditions. One hundred and seventy-nine members from 70 CoPs of a large multinational electronics firm participated in this survey. Based on the PLS analysis, perceived consequences, affect, social factors, and facilitating conditions were found to significantly affect knowledge sharing in CoPs. 相似文献
999.
In this paper, a new weighted approach on Lagrangian support vector machine for imbalanced data classification problem is proposed. The weight parameters are embedded in the Lagrangian SVM formulation. The training method for weighted Lagrangian SVM is presented and its convergence is proven. The weighted Lagrangian SVM classifier is tested and compared with some other SVMs using synthetic and real data to show its effectiveness and feasibility. 相似文献
1000.
Jeoungkun Kim Soongeun Hong Jinyoung Min Heeseok Lee 《Expert systems with applications》2011,38(8):9530-9542
Although ASP (Application Service Provider) has the potential to fundamentally change the manner in which IT services are provided for user firms, current ASPs often fail to provide good results in accumulating and retaining customers. To fill the gap between the expected benefits of application service and its disappointing results in the real world, we present a conceptual model including three quality measures – System Quality, Information Quality, and Service Quality. To extend the horizons of ASP acceptance, this study sharpens the model that these quality measures regulate Satisfaction and Trust, which lead to Continuance Intention. We test the research model and hypotheses through the use of the data from 203 small and medium enterprises with application service experience. Data analysis results using LISREL reveal that Satisfaction and Trust have significant effects on a client firm’s Continuance Intention. Trust is found to be the most salient determinant while previous studies mainly focused on the role of Satisfaction. Furthermore, an empirical support is found for the direct effect of Service Quality on Continuance Intention as well as its mediating effects. 相似文献