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31.
Fabien Tâche François Pomerleau Gilles Caprari Roland Siegwart Michael Bosse Roland Moser 《野外机器人技术杂志》2011,28(2):180-203
The MagneBike inspection robot is a climbing robot equipped with magnetic wheels. The robot is designed to drive on three‐dimensional (3D) complexly shaped pipe structures; therefore it is necessary to provide 3D visualization tools for the user, who remotely controls the robot out of sight. The localization system is required to provide a 3D map of the unknown environment and the 3D location of the robot in the environment's map. The localization strategy proposed in this paper consists of combining 3D odometry with 3D scan registration. The odometry model is based on wheel encoders and a three‐axis accelerometer. Odometry enables the tracking of the robot trajectory between consecutive 3D scans and is used as a prior for the scan matching algorithm. The 3D scan registration facilitates the construction of a 3D map of the environment and refines the robot position computed with odometry. This paper describes in detail the implementation of the localization concept. It presents the lightweight, small‐sized 3D range finder that has been developed for the MagneBike. It also proposes an innovative 3D odometry model that estimates the local surface curvature to compensate for the absence of angular velocity inputs. The different tools are characterized in detail based on laboratory and field experiments. They show that the localization concepts reliably track the robot moving in the specific application environment. We also describe various techniques to optimize the 3D scanning process, which is time consuming, and to compensate for the identified limitations. These techniques are useful inputs for the future automatization of the robot's control and optimization of its localization process. © 2010 Wiley Periodicals, Inc. 相似文献
32.
Dissipative particle dynamics simulations for fibre suspensions in newtonian and viscoelastic fluids
Duc Duong-Hong Nhan Phan-Thien Khoon Seng Yeo Gilles Ausias 《Computer Methods in Applied Mechanics and Engineering》2010,199(23-24):1593-1602
A versatile model of fibre suspensions in Newtonian and viscoelastic fluids has been developed using dissipative particle dynamics method. The viscoelastic fluid is modelled by linear chains with linear connector spring force (the Oldroyd-B model), which is known to be a reasonable model for the so-called Boger fluid (a dilute suspension of polymer in a highly viscous solvent). The numerical results are in excellent agreement with the analytical results of the Oldroyd-B model in simple shear flow. An effective meso-scale model of fibre in DPD is proposed and then incorporated with simple Newtonian fluid and our Boger fluid to enable entirely study rheological properties of fibre suspensions in both Newtonian and viscoelastic solvents. The numerical results are well compared with available experimental data and other numerical models. 相似文献
33.
34.
This paper describes a process for mashing heterogeneous data sources based on the Multi-data source Fusion Approach (MFA) (Nachouki and Quafafou, 2008 [52]). The aim of MFA is to facilitate the fusion of heterogeneous data sources in dynamic contexts such as the Web. Data sources are either static or active: static data sources can be structured or semi-structured (e.g. XML documents or databases), whereas active sources are services (e.g. Web services). Our main objective is to combine (Web) data sources with a minimal effort required from the user. This objective is crucial because the mashing process implies easy and fast integration of data sources. We suppose that the user is not expert in this field but he/she understands the meaning of data being integrated. In this paper, we consider two important aspects of the Web mashing process. The first one concerns the information extraction from the Web. The results of this process are the static data sources that are used later together with services in order to create a new result/application. The second one concerns the problem of semantic reconciliation of data sources. This step consists to generate the Conflicts data source in order to improve the problem of rewriting semantic queries into sub-queries (not addressed in this paper) over data sources. We give the design of our system MDSManager. We show this process through a real-life application. 相似文献
35.
The last generation of infrared imaging aircraft seekers and trackers uses pattern recognition algorithms to find and keep
a lock on an aircraft in the presence of decoy flares. These algorithms identify targets, based on the features of the various
objects in the missile’s field of view. Because modern both aircrafts and missiles fly faster than sound, speed of operation
of the target identifier is critical. In this article, we propose a target recognition system that respects this time constraint.
It is based on an artificial neural network implemented in hardware, as a set of parallel processors on a commercially available
silicon chip called a ZISC, for zero instruction set computer. This chip would be integrated in the infrared missile seeker
and tracker. We describe the characteristics of the images that the image processing module of this seeker and tracker extracts
from the infrared video frames and show how to construct from these translation and rotation invariant features that can be
used as input to the neural network. We determine the individual discriminating power of these features by constructing their
histograms, which allows us to eliminate some as not being useful for our purpose. Finally, by testing our system on real
data, we show that it has a 90% success rate in aircraft-flare identification, and a processing time that during this time,
the aircrafts and missiles will have traveled only a few millimeters. Most of the images on which the neural network makes
its mistakes are seen to be hard to recognize even by a human expert. 相似文献
36.
Region merging methods consist of improving an initial segmentation by merging some pairs of neighboring regions. In a graph,
merging two regions, separated by a set of vertices, is not straightforward. The perfect fusion graphs defined in J. Cousty
et al. (J. Math. Imaging Vis. 30:(1):87–104, 2008) verify all the basic properties required by region merging algorithms as used in image segmentation. Unfortunately, the
graphs which are the most frequently used in image analysis (namely, those induced by the direct and the indirect adjacency
relations) are not perfect fusion graphs. The perfect fusion grid, introduced in the above mentioned reference, is an adjacency
relation on ℤ
d
which can be used in image analysis, which indeed induces perfect fusion graphs and which is “between” the graphs induced
by the direct and the indirect adjacencies. One of the main results of this paper is that the perfect fusion grid is the only
such graph whatever the dimension d.
相似文献
Gilles BertrandEmail: |
37.
Tegawendé F. Bissyandé Laurent Réveillère Julia L. Lawall Gilles Muller 《Automated Software Engineering》2016,23(1):3-41
The Linux kernel does not export a stable, well-defined kernel interface, complicating the development of kernel-level services, such as device drivers and file systems. While there does exist a set of functions that are exported to external modules, this set of functions frequently changes, and the functions have implicit, ill-documented preconditions. No specific debugging support is provided. We present Diagnosys, an approach to automatically constructing a debugging interface for the Linux kernel. First, a designated kernel maintainer uses Diagnosys to identify constraints on the use of the exported functions. Based on this information, developers of kernel services can then use Diagnosys to generate a debugging interface specialized to their code. When a service including this interface is tested, it records information about potential problems. This information is preserved following a kernel crash or hang. Our experiments show that the generated debugging interface provides useful log information and incurs a low performance penalty. 相似文献
38.
Transfer of learning in virtual environments: a new challenge? 总被引:1,自引:0,他引:1
The aim of all education is to apply what we learn in different contexts and to recognise and extend this learning to new
situations. Virtual learning environments can be used to build skills. Recent research in cognitive psychology and education
has shown that acquisitions are linked to the initial context. This provides a challenge for virtual reality in education
or training. A brief overview of transfer issues highlights five main ideas: (1) the type of transfer enables the virtual
environment (VE) to be classified according to what is learned; (2) the transfer process can create conditions within the
VE to facilitate transfer of learning; (3) specific features of VR must match and comply with transfer of learning; (4) transfer
can be used to assess a VE’s effectiveness; and (5) future research on transfer of learning must examine the singular context
of learning. This paper discusses how new perspectives in cognitive psychology influence and promote transfer of learning
through the use of VEs. 相似文献
39.
This paper describes a new approach of heterogeneous data source fusion. Data sources are either static or active: static data sources can be structured or semi-structured, whereas active sources are services. In order to develop data sources fusion systems in dynamic contexts, we need to study all issues raised by the matching paradigms. This challenging problem becomes crucial with the dominating role of the internet. Classical approaches of data integration, based on schemas mediation, are not suitable to the World Wide Web (WWW) environment where data is frequently modified or deleted. Therefore, we develop a loosely integrated approach that takes into consideration both conflict management and semantic rules which must be enriched in order to integrate new data sources. Moreover, we introduce an XML-based Multi-data source Fusion Language (MFL) that aims to define and retrieve conflicting data from multiple data sources. The system, which is developed according to this approach, is called MDSManager (Multi-Data Source Manager). The benefit of the proposed framework is shown through a real world application based on web data sources fusion which is dedicated to online markets indices tracking. Finally, we give an evaluation of our MFL language. The results show that our language improves significantly the XQuery language especially considering its expressiveness power and its performances. 相似文献
40.
Improving security and performance of an Ad Hoc network through a multipath routing strategy 总被引:1,自引:0,他引:1
Hervé Aiache François Haettel Laure Lebrun Cédric Tavernier 《Journal in Computer Virology》2008,4(4):267-278
Privacy and security solutions require today the protection of personal information so that it may not be disclosed to unauthorized
participant for illegal purposes. It is a challenge to address these issues in networks with strong constraints such as Ad
Hoc network. The security increase is often obtained with a quality of service (QoS) decrease. We propose in this paper a
solution that provides at the anonymity, security to Ad Hoc network with a limited impact on QoS. This method could be efficient
against some viral attacks. We also give some security proofs of our solution for Ad Hoc networks.
The work of Hervé Aiache and Cédric Tavernier was supported by DISCREET, IST project no. 027679, funded in part by the European
Commission’s Information Society Technology 6th Framework Programme. 相似文献