全文获取类型
收费全文 | 7717篇 |
免费 | 438篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 58篇 |
综合类 | 6篇 |
化学工业 | 2093篇 |
金属工艺 | 80篇 |
机械仪表 | 130篇 |
建筑科学 | 283篇 |
矿业工程 | 17篇 |
能源动力 | 297篇 |
轻工业 | 1481篇 |
水利工程 | 76篇 |
石油天然气 | 24篇 |
无线电 | 485篇 |
一般工业技术 | 1129篇 |
冶金工业 | 227篇 |
原子能技术 | 48篇 |
自动化技术 | 1729篇 |
出版年
2024年 | 10篇 |
2023年 | 96篇 |
2022年 | 292篇 |
2021年 | 392篇 |
2020年 | 232篇 |
2019年 | 287篇 |
2018年 | 312篇 |
2017年 | 291篇 |
2016年 | 338篇 |
2015年 | 246篇 |
2014年 | 397篇 |
2013年 | 645篇 |
2012年 | 579篇 |
2011年 | 630篇 |
2010年 | 457篇 |
2009年 | 433篇 |
2008年 | 407篇 |
2007年 | 383篇 |
2006年 | 236篇 |
2005年 | 225篇 |
2004年 | 183篇 |
2003年 | 177篇 |
2002年 | 136篇 |
2001年 | 80篇 |
2000年 | 75篇 |
1999年 | 79篇 |
1998年 | 96篇 |
1997年 | 72篇 |
1996年 | 59篇 |
1995年 | 55篇 |
1994年 | 38篇 |
1993年 | 37篇 |
1992年 | 29篇 |
1991年 | 25篇 |
1990年 | 21篇 |
1989年 | 24篇 |
1988年 | 8篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 11篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1978年 | 8篇 |
1977年 | 7篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1973年 | 2篇 |
排序方式: 共有8163条查询结果,搜索用时 0 毫秒
71.
Pawe Kuakowski Javier Vales-Alonso Esteban Egea-Lpez Wiesaw Ludwin Joan García-Haro 《Computers & Electrical Engineering》2010,36(6):1181-1186
Among the large number of contributions concerning the localization techniques for wireless sensor networks (WSNs), there is still no simple, energy and cost efficient solution suitable in outdoor scenarios. In this paper, a technique based on antenna arrays and angle-of-arrival (AoA) measurements is carefully discussed. While the AoA algorithms are rarely considered for WSNs due to the large dimensions of directional antennas, some system configurations are investigated that can be easily incorporated in pocket-size wireless devices.A heuristic weighting function that enables decreasing the location errors is introduced. Also, the detailed performance analysis of the presented system is provided. The localization accuracy is validated through realistic Monte-Carlo simulations that take into account the specificity of propagation conditions in WSNs as well as the radio noise effects. Finally, trade-offs between the accuracy, localization time and the number of anchors in a network are addressed. 相似文献
72.
We present and analyze an unsupervised method for Word Sense Disambiguation (WSD). Our work is based on the method presented
by McCarthy et al. in 2004 for finding the predominant sense of each word in the entire corpus. Their maximization algorithm allows weighted
terms (similar words) from a distributional thesaurus to accumulate a score for each ambiguous word sense, i.e., the sense
with the highest score is chosen based on votes from a weighted list of terms related to the ambiguous word. This list is
obtained using the distributional similarity method proposed by Lin Dekang to obtain a thesaurus. In the method of McCarthy
et al., every occurrence of the ambiguous word uses the same thesaurus, regardless of the context where the ambiguous word occurs.
Our method accounts for the context of a word when determining the sense of an ambiguous word by building the list of distributed
similar words based on the syntactic context of the ambiguous word. We obtain a top precision of 77.54% of accuracy versus
67.10% of the original method tested on SemCor. We also analyze the effect of the number of weighted terms in the tasks of
finding the Most Frecuent Sense (MFS) and WSD, and experiment with several corpora for building the Word Space Model. 相似文献
73.
Artur J. Lemonte Francisco Cribari-Neto 《Computational statistics & data analysis》2010,54(5):1307-718
The Birnbaum-Saunders regression model is commonly used in reliability studies. We address the issue of performing inference in this class of models when the number of observations is small. Our simulation results suggest that the likelihood ratio test tends to be liberal when the sample size is small. We obtain a correction factor which reduces the size distortion of the test. Also, we consider a parametric bootstrap scheme to obtain improved critical values and improved p-values for the likelihood ratio test. The numerical results show that the modified tests are more reliable in finite samples than the usual likelihood ratio test. We also present an empirical application. 相似文献
74.
Francisco J. Pino Author Vitae Oscar Pedreira Author Vitae 《Journal of Systems and Software》2010,83(10):1662-1677
For software process improvement - SPI - there are few small organizations using models that guide the management and deployment of their improvement initiatives. This is largely because a lot of these models do not consider the special characteristics of small businesses, nor the appropriate strategies for deploying an SPI initiative in this type of organization. It should also be noted that the models which direct improvement implementation for small settings do not present an explicit process with which to organize and guide the internal work of the employees involved in the implementation of the improvement opportunities. In this paper we propose a lightweight process, which takes into account appropriate strategies for this type of organization. Our proposal, known as a “Lightweight process to incorporate improvements”, uses the philosophy of the Scrum agile method, aiming to give detailed guidelines for supporting the management and performance of the incorporation of improvement opportunities within processes and their putting into practice in small companies. We have applied the proposed process in two small companies by means of the case study research method, and from the initial results, we have observed that it is indeed suitable for small businesses. 相似文献
75.
Luis de-Marcos José Ramón Hilera Roberto Barchino Lourdes Jiménez José Javier Martínez José Antonio Gutiérrez José María Gutiérrez Salvador Otón 《Computers & Education》2010
Mobile learning is considered an evolution of e-learning that embraces the ubiquitous nature of current computational systems in order to improve teaching and learning. Within this context it is possible to develop mobile applications oriented to learning, but it is also important to assess to what extent such applications actually work. In this paper we present a new tool designed to reinforce students’ knowledge by means of self-assessment. Improvement in student achievement was evaluated and an attitudinal survey was also carried out to measure student attitudes towards this new tool. Three different experimental groups were selected for this research, with students aged from 14 to 21 years old, including high-school and university students. Results show that this kind of tool improves student achievement, especially amongst younger learners, with a relatively low impact on current teaching activities and methodology. 相似文献
76.
Humanitarian Non-Governmental Organisations (NGOs) play a growing role in the response to natural disasters, but despite being largely demanded, there is no available decision support system (DSS) specifically designed to address their problem. In this paper we present a decision support system (DSS) to aid those Humanitarian NGOs concerned with the response to natural disasters. Such a DSS has been designed avoiding sophisticated methodologies that may exceed the infrastructural requirements and constraints of emergency management by NGOs. A data-based, two-level knowledge methodology which allows damage assessment of multiple disaster scenarios is presented in order to address that problem. Validation results show viability of our approach. 相似文献
77.
Véronique Souchère Laurent Millair Javier Echeverria François Bousquet Christophe Le Page Michel Etienne 《Environmental Modelling & Software》2010,25(11):1359-1370
Erosive runoff is a recurring problem and is a source of sometimes deadly muddy floods in the Pays de Caux (France). The risk results from a conjunction of natural factors and human activity. Efficient actions against runoff in agricultural watersheds are well known. However they are still difficult to implement as they require co-operation between stakeholders. Local actors thus need tools to help them understand the collective consequences of their individual decisions and help to initiate a process of negotiation between them. We decided to use a participatory approach called companion modelling (ComMod), and, in close collaboration with one of the first group of local stakeholders, to create a role-playing game (RPG) to facilitate negotiations on the future management of erosive runoff. This paper describes and discusses the development of the RPG and its use with other groups of local stakeholders within the framework of two game sessions organized by two different watershed management committees. During the joint construction step, stakeholders shared their viewpoints about the environment, agents, rules, and how to model runoff in preparation for the creation of the RPG. During the RPG sessions, two groups of eight players, including farmers, mayors and watershed advisors, were confronted with disastrous runoff in a fictive agricultural watershed. Results showed that they managed to reduce runoff by 20–50% by engaging a dialogue about grass strips, storage ponds and management of the intercrop period. However, further progress is still needed to better control runoff through the implementation of better agricultural practices because, during the RPG sessions, the watershed advisors did not encourage farmers to do so. Because of the complexity of management problems, results of jointly constructing the game and the RPG sessions showed that modelling and simulation can be a very useful way of accompanying the collective learning process. This new way of working was welcomed by the participants who expressed their interest in organizing further RPG sessions. 相似文献
78.
In this paper we present adaptive algorithms for solving the uniform continuous piecewise affine approximation problem (UCPA)
in the case of Lipschitz or convex functions. The algorithms are based on the tree approximation (adaptive splitting) procedure.
The uniform convergence is achieved by means of global optimization techniques for obtaining tight upper bounds of the local
error estimate (splitting criterion). We give numerical results in the case of the function distance to 2D and 3D geometric
bodies. The resulting trees can retrieve the values of the target function in a fast way. 相似文献
79.
A new fast prototype selection method based on clustering 总被引:2,自引:1,他引:1
J. Arturo Olvera-López J. Ariel Carrasco-Ochoa J. Francisco Martínez-Trinidad 《Pattern Analysis & Applications》2010,13(2):131-141
In supervised classification, a training set T is given to a classifier for classifying new prototypes. In practice, not all information in T is useful for classifiers, therefore, it is convenient to discard irrelevant prototypes from T. This process is known as prototype selection, which is an important task for classifiers since through this process the
time for classification or training could be reduced. In this work, we propose a new fast prototype selection method for large
datasets, based on clustering, which selects border prototypes and some interior prototypes. Experimental results showing
the performance of our method and comparing accuracy and runtimes against other prototype selection methods are reported. 相似文献
80.
Francisco J. Rubio Francisco J. Valero Jose Luis Suñer Vicente Mata 《Asian journal of control》2010,12(4):468-479
This paper addresses the solution of smooth trajectory planning for industrial robots in environments with obstacles using a direct method, creating the trajectory gradually as the robot moves. The presented method deals with the uncertainties associated with the lack of knowledge of kinematic properties of intermediate via‐points since they are generated as the algorithm evolves looking for the solution. Several cost functions are also proposed, which use the time that has been calculated to guide the robot motion. The method has been applied successfully to a PUMA 560 robot and four operational parameters (execution time, computational time, distance travelled and number of configurations) have been computed to study the properties and influence of each cost function on the trajectory obtained. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society 相似文献