全文获取类型
收费全文 | 42954篇 |
免费 | 2664篇 |
国内免费 | 54篇 |
学科分类
工业技术 | 45672篇 |
出版年
2024年 | 67篇 |
2023年 | 364篇 |
2022年 | 472篇 |
2021年 | 1283篇 |
2020年 | 952篇 |
2019年 | 1061篇 |
2018年 | 1563篇 |
2017年 | 1558篇 |
2016年 | 1680篇 |
2015年 | 1326篇 |
2014年 | 1645篇 |
2013年 | 3282篇 |
2012年 | 2585篇 |
2011年 | 2775篇 |
2010年 | 2155篇 |
2009年 | 2032篇 |
2008年 | 1927篇 |
2007年 | 1698篇 |
2006年 | 1286篇 |
2005年 | 1123篇 |
2004年 | 1043篇 |
2003年 | 947篇 |
2002年 | 841篇 |
2001年 | 611篇 |
2000年 | 567篇 |
1999年 | 631篇 |
1998年 | 2780篇 |
1997年 | 1779篇 |
1996年 | 1200篇 |
1995年 | 660篇 |
1994年 | 547篇 |
1993年 | 550篇 |
1992年 | 184篇 |
1991年 | 176篇 |
1990年 | 130篇 |
1989年 | 154篇 |
1988年 | 157篇 |
1987年 | 146篇 |
1986年 | 114篇 |
1985年 | 151篇 |
1984年 | 114篇 |
1983年 | 77篇 |
1982年 | 87篇 |
1981年 | 106篇 |
1980年 | 108篇 |
1978年 | 53篇 |
1977年 | 185篇 |
1976年 | 368篇 |
1975年 | 57篇 |
1973年 | 61篇 |
排序方式: 共有10000条查询结果,搜索用时 593 毫秒
991.
Soledad Escolar Díaz Florin Isaila Alejandro Calderón Mateos Luis Miguel Sanchez García David E. Singh 《The Journal of supercomputing》2010,51(1):76-93
In the last years the Wireless Sensor Networks’ (WSN) technology has been increasingly employed in various application domains.
The extensive use of WSN posed new challenges in terms of both scalability and reliability. This paper proposes Sensor Node
File System (SENFIS), a novel file system for sensor nodes, which addresses both scalability and reliability concerns. SENFIS
can be mainly used in two broad scenarios. First, it can transparently be employed as a permanent storage for distributed
TinyDB queries, in order to increase the reliability and scalability. Second, it can be directly used by a WSN application
for permanent storage of data on the WSN nodes. The experimental section shows that SENFIS implementation makes an efficient
use of resources in terms of energy consumption, memory footprint, flash wear levelling, while achieving execution times similarly
with existing WSN file systems. 相似文献
992.
Lower bounds on lengths of checking sequences 总被引:1,自引:0,他引:1
Guy-Vincent Jourdan Hasan Ural Hüsnü Yenigün Ji Chao Zhang 《Formal Aspects of Computing》2010,22(6):667-679
Lower bounds on the lengths of checking sequences constructed for testing from Finite State Machine-based specifications are
established. These bounds consider the case where a distinguishing sequence is used in forming state recognition and transition
verification subsequences and identify the effects of overlapping among such subsequences. Empirical results show that the
existing methods for construction of checking sequences provide checking sequences with lengths that are within acceptable
distance to these lower bounds. 相似文献
993.
An adaptive, real-time, traffic monitoring system 总被引:1,自引:0,他引:1
In this paper we describe a computer vision-based traffic monitoring system able to detect individual vehicles in real-time.
Our fully integrated system first obtains the main traffic variables: counting, speed and category; and then computes a complete
set of statistical variables. The objective is to investigate some of the difficulties impeding existing traffic systems to
achieve balanced accuracy in every condition; i.e. day and night transitions, shadows, heavy vehicles, occlusions, slow traffic
and congestions. The system we present is autonomous, works for long periods of time without human intervention and adapts
automatically to the changing environmental conditions. Several innovations, designed to deal with the above circumstances,
are proposed in the paper: an integrated calibration and image rectification step, differentiated methods for day and night,
an adaptive segmentation algorithm, a multistage shadow detection method and special considerations for heavy vehicle identification
and treatment of slow traffic. A specific methodology has been developed to benchmark the accuracy of the different methods
proposed. 相似文献
994.
Pablo Quintía Roberto Iglesias Miguel A. Rodríguez Carlos V. Regueiro 《Robotics and Autonomous Systems》2010,58(12):1306-1315
One of the main problems of robots is the lack of adaptability and the need for adjustment every time the robot changes its working place. To solve this, we propose a learning approach for mobile robots using a reinforcement-based strategy and a dynamic sensor-state mapping. This strategy, practically parameterless, minimises the adjustments needed when the robot operates in a different environment or performs a different task.Our system will simultaneously learn the state space and the action to execute on each state. The learning algorithm will attempt to maximise the time before a robot failure in order to obtain a control policy suited to the desired behaviour, thus providing a more interpretable learning process. The state representation will be created dynamically, starting with an empty state space and adding new states as the robot finds new situations that has not seen before. A dynamic creation of the state representation will avoid the classic, error-prone and cyclic process of designing and testing an ad hoc representation. We performed an exhaustive study of our approach, comparing it with other classic strategies. Unexpectedly, learning both perception and action does not increase the learning time. 相似文献
995.
Glauston R. Teixeira de Lima José Demísio S. Silva Osamu Saotome 《Neural computing & applications》2010,19(3):421-436
In this paper, we report results obtained with a Madaline neural network trained to classify inductive signatures of two vehicles classes: trucks with one rear axle and trucks with double rear axle. In order to train the Madaline, the inductive signatures were pre-processed and both classes, named C2 and C3, were subdivided into four subclasses. Thus, the initial classification task was split into four smaller tasks (theoretically) easier to be performed. The heuristic adopted in the training attempts to minimize the effects of the input space non-linearity on the classifier performance by uncoupling the learning of the classes and, for this, we induce output Adalines to specialize in learning one of the classes. The percentages of correct classifications presented concern patterns which were not submitted to the neural network in the training process, and, therefore, they indicate the neural network generalization ability. The results are good and stimulate the maintenance of this research on the use of Madaline networks in vehicle classification tasks using not linearly separable inductive signatures. 相似文献
996.
Inés González-Rodríguez Camino R. Vela Jorge Puente 《Journal of Intelligent Manufacturing》2010,21(1):65-73
In this work we consider a multiobjective job shop problem with uncertain durations and crisp due dates. Ill-known durations
are modelled as fuzzy numbers. We take a fuzzy goal programming approach to propose a generic multiobjective model based on
lexicographical minimisation of expected values. To solve the resulting problem, we propose a genetic algorithm searching
in the space of possibly active schedules. Experimental results are presented for several problem instances, solved by the
GA according to the proposed model, considering three objectives: makespan, tardiness and idleness. The results illustrate
the potential of the proposed multiobjective model and genetic algorithm. 相似文献
997.
N. Ruiz Reyes P. Vera Candeas S. García Galán J.E. Muñoz 《Engineering Applications of Artificial Intelligence》2010,23(2):151-159
Automatic discrimination of speech and music is an important tool in many multimedia applications. The paper presents a robust and effective approach for speech/music discrimination, which relies on a two-stage cascaded classification scheme. The cascaded classification scheme is composed of a statistical pattern recognition classifier followed by a genetic fuzzy system. For the first stage of the classification scheme, other widely used classifiers, such as neural networks and support vector machines, have also been considered in order to assess the robustness of the proposed classification scheme. Comparison with well-proven signal features is also performed. In this work, the most commonly used genetic learning algorithms (Michigan and Pittsburgh) have been evaluated in the proposed two-stage classification scheme. The genetic fuzzy system gives rise to an improvement of about 4% in the classification accuracy rate. Experimental results show the good performance of the proposed approach with a classification accuracy rate of about 97% for the best trial. 相似文献
998.
999.
Rubén Fuentes-Fernández Iván García-Magariño Alma María Gómez-Rodríguez Juan Carlos González-Moreno 《Engineering Applications of Artificial Intelligence》2010,23(3):432-444
The formalization of engineering processes is necessary for guaranteeing the quality and cost of the products involved. Agent-oriented engineering has already proposed development processes that still need to be further formalized to be applicable by non-researchers. This paper proposes a technique to instantiate processes for specific agent-oriented methodologies. This technique is based on three orthogonal views that are respectively related with lifecycles, disciplines and guidances. In addition, processes are modeled with a tool, which is automatically generated from a process metamodel inspired by the software & systems process engineering metamodel. Accordingly, engineers can choose the methodology–process pair best-suited for the characteristics of their project. The paper illustrates the approach based on the unified development process and the scrum process for the INGENIAS methodology and compares the results with other existing alternatives. 相似文献
1000.
A methodology is proposed for designing a robust nonlinear model predictive controller based on a Volterra series model with uncertain coefficients. A key benefit of using the Volterra series model is that it can be split into a nominal and an uncertainty model thus permitting the application of robust analysis tools. The controller is based on the on-line solution of a robust performance test based on a Structured Singular Value norm. The cost function of the controller can be formulated to account for manipulated variable movement weighting, manipulated variable constraints and a terminal condition. Finally, the proposed methodology is applied to a single-input–single-output continuous stirred tank reactor problem and to a multiple-input–multiple-output pH neutralization process. 相似文献