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21.
Diego Q. Leite Julio C. Duarte Luiz P. Neves Jauvane C. de Oliveira Gilson A. Giraldi 《Multimedia Tools and Applications》2017,76(20):20423-20455
This paper presents a real-time framework that combines depth data and infrared laser speckle pattern (ILSP) images, captured from a Kinect device, for static hand gesture recognition to interact with CAVE applications. At the startup of the system, background removal and hand position detection are performed using only the depth map. After that, tracking is started using the hand positions of the previous frames in order to seek for the hand centroid of the current one. The obtained point is used as a seed for a region growing algorithm to perform hand segmentation in the depth map. The result is a mask that will be used for hand segmentation in the ILSP frame sequence. Next, we apply motion restrictions for gesture spotting in order to mark each image as a ‘Gesture’ or ‘Non-Gesture’. The ILSP counterparts of the frames labeled as “Gesture” are enhanced by using mask subtraction, contrast stretching, median filter, and histogram equalization. The result is used as the input for the feature extraction using a scale invariant feature transform algorithm (SIFT), bag-of-visual-words construction and classification through a multi-class support vector machine (SVM) classifier. Finally, we build a grammar based on the hand gesture classes to convert the classification results in control commands for the CAVE application. The performed tests and comparisons show that the implemented plugin is an efficient solution. We achieve state-of-the-art recognition accuracy as well as efficient object manipulation in a virtual scene visualized in the CAVE. 相似文献
22.
Jorge Lopez-Moreno Jorge JimenezSunil Hadap Ken AnjyoErik Reinhard Diego Gutierrez 《Computers & Graphics》2011,35(1):99-111
Recent works in image editing are opening up new possibilities to manipulate and enhance input images. Within this context, we leverage well-known characteristics of human perception along with a simple depth approximation algorithm to generate non-photorealistic renditions that would be difficult to achieve with existing methods. Once a perceptually plausible depth map is obtained from the input image, we show how simple algorithms yield powerful new depictions of such an image. Additionally, we show how artistic manipulation of depth maps can be used to create novel non-photorealistic versions, for which we provide the user with an intuitive interface. Our real-time implementation on graphics hardware allows the user to efficiently explore artistic possibilities for each image. We show results produced with six different styles proving the versatility of our approach, and validate our assumptions and simplifications by means of a user study. 相似文献
23.
TinyPBC: Pairings for authenticated identity-based non-interactive key distribution in sensor networks 总被引:2,自引:0,他引:2
Key distribution in Wireless Sensor Networks (WSNs) is challenging. Symmetric cryptosystems can perform it efficiently, but they often do not provide a perfect trade-off between resilience and storage. Further, even though conventional public key and elliptic curve cryptosystems are computationally feasible on sensor nodes, protocols based on them are not, as they require the exchange and storage of large keys and certificates, which is expensive.Using Pairing-Based Cryptography (PBC) protocols parties can agree on keys without any interaction. In this work, we (i) show how security in WSNs can be bootstrapped using an authenticated identity-based non-interactive protocol and (ii) present TinyPBC, to our knowledge, the most efficient implementation of PBC primitives for 8, 16 and 32-bit processors commonly found in sensor nodes. TinyPBC is able to compute pairings, the most expensive primitive of PBC, in 1.90 s on ATmega128L, 1.27 s on MSP430 and 0.14 s on PXA27x. 相似文献
24.
Garzón-Alvarado DA Martinez AM Segrera DL 《Computer methods and programs in biomedicine》2011,104(3):489-497
The cerebral cortex is a gray lamina formed by bodies of neurons covering the cerebral hemispheres, varying in thickness from 1.25 mm in the occipital lobe to 4 mm in the anterior lobe. The brain's surface is about 30 times greater that of the skull because of its many folds; such folds form the gyri, sulci and fissures and mark out areas having specific functions, divided into five lobes. Convolution formation may vary between individuals and is an important feature of brain formation; such patterns can be mathematically represented as Turing patterns. This article describes how a phenomenological model was developed by describing the formation pattern for the gyri occurring in the cerebral cortex by reaction diffusion equations with Turing space parameters. Numerical examples for simplified geometries of a brain were solved to study pattern formation. The finite element method was used for the numerical solution, in conjunction with the Newton–Raphson method. The numerical examples showed that the model can represent cerebral cortex fold formation and reproduce pathologies related to gyri formation, such as polymicrogyria and lissencephaly. 相似文献
25.
Yannis Ioannidis Diego Milano Hans-Jörg Schek Heiko Schuldt 《International Journal on Digital Libraries》2008,9(2):101-114
DelosDLMS is a novel digital library management system (DLMS) that has been developed as an integration effort within the
DELOS Network of Excellence, a European Commission initiative funded under its fifth and sixth framework programs. In this
paper, we describe DelosDLMS that takes into account the recommendations of several activities that were initiated by DELOS
including the DELOS vision for digital libraries (DLs). A key aspect of DelosDLMS is its novel generic infrastructure that
allows the generation of digital library systems out of a set of basic system services and DL services in a modular and extensible
way. DL services like feature extraction, visualization, intelligent browsing, media-type-specific indexing, support for multilinguality,
relevance feedback and many others can easily be incorporated or replaced. A further key aspect of DelosDLMS is its robustness
against failures and its scalability for large collections and many parallel user requests. We discuss the current status
of an effort to build DelosDLMS, a Digital Library Management System that integrates in various ways several components developed
by DELOS members and showcases a great variety of functionality that is outlined as part of the DELOS vision. 相似文献
26.
Daniel Roggen Diego Federici Dario Floreano 《Genetic Programming and Evolvable Machines》2007,8(1):61-96
With a gene required for each phenotypic trait, direct genetic encodings may show poor scalability to increasing phenotype
length. Developmental systems may alleviate this problem by providing more efficient indirect genotype to phenotype mappings.
A novel classification of multi-cellular developmental systems in evolvable hardware is introduced. It shows a category of
developmental systems that up to now has rarely been explored. We argue that this category is where most of the benefits of
developmental systems lie (e.g. speed, scalability, robustness, inter-cellular and environmental interactions that allow fault-tolerance
or adaptivity). This article describes a very simple genetic encoding and developmental system designed for multi-cellular
circuits that belongs to this category. We refer to it as the morphogenetic system. The morphogenetic system is inspired by gene expression and cellular differentiation. It focuses on low computational requirements
which allows fast execution and a compact hardware implementation. The morphogenetic system shows better scalability compared
to a direct genetic encoding in the evolution of structures of differentiated cells, and its dynamics provides fault-tolerance
up to high fault rates. It outperforms a direct genetic encoding when evolving spiking neural networks for pattern recognition
and robot navigation. The results obtained with the morphogenetic system indicate that this “minimalist” approach to developmental
systems merits further study.
相似文献
Dario FloreanoEmail: |
27.
Sergio Orts Jose Garcia-Rodriguez Diego Viejo Miguel Cazorla Vicente Morell 《Journal of Parallel and Distributed Computing》2012
Self-organising neural models have the ability to provide a good representation of the input space. In particular the Growing Neural Gas (GNG) is a suitable model because of its flexibility, rapid adaptation and excellent quality of representation. However, this type of learning is time-consuming, especially for high-dimensional input data. Since real applications often work under time constraints, it is necessary to adapt the learning process in order to complete it in a predefined time. This paper proposes a Graphics Processing Unit (GPU) parallel implementation of the GNG with Compute Unified Device Architecture (CUDA). In contrast to existing algorithms, the proposed GPU implementation allows the acceleration of the learning process keeping a good quality of representation. Comparative experiments using iterative, parallel and hybrid implementations are carried out to demonstrate the effectiveness of CUDA implementation. The results show that GNG learning with the proposed implementation achieves a speed-up of 6× compared with the single-threaded CPU implementation. GPU implementation has also been applied to a real application with time constraints: acceleration of 3D scene reconstruction for egomotion, in order to validate the proposal. 相似文献
28.
Diego Perez-Palacin Raffaela Mirandola José Merseguer 《Journal of Systems and Software》2012,85(12):2796-2811
Energy use is becoming a key design consideration in computing infrastructures and services. In this paper we focus on service-based applications and we propose an adaptation framework that can be used to reduce power consumption according to the observed workload. The adaptation guarantees a trade-off between energy consumption and system performance. The approach is based on the principle of proportional energy consumption obtained by scaling down energy for unused resources, considering both the number of servers switched on and their operating frequencies. Stochastic Petri nets are proposed for the modeling of the framework concerns, their analyses give results about the trade-offs. The application of the approach to a simple case study shows its usefulness and practical applicability. Finally, different types of workloads are analyzed with validation purposes. 相似文献
29.
Elena Garces Adolfo Munoz Jorge Lopez‐Moreno Diego Gutierrez 《Computer Graphics Forum》2012,31(4):1415-1424
Decomposing an input image into its intrinsic shading and reflectance components is a long‐standing ill‐posed problem. We present a novel algorithm that requires no user strokes and works on a single image. Based on simple assumptions about its reflectance and luminance, we first find clusters of similar reflectance in the image, and build a linear system describing the connections and relations between them. Our assumptions are less restrictive than widely‐adopted Retinex‐based approaches, and can be further relaxed in conflicting situations. The resulting system is robust even in the presence of areas where our assumptions do not hold. We show a wide variety of results, including natural images, objects from the MIT dataset and texture images, along with several applications, proving the versatility of our method. 相似文献
30.
Given a text T[1..u] over an alphabet of size σ, the full-text search problem consists in finding the occ occurrences of a given pattern P[1..m] in T. In indexed text searching we build an index on T to improve the search time, yet increasing the space requirement. The current trend in indexed text searching is that of compressed full-text self-indices, which replace the text with a more space-efficient representation of it, at the same time providing indexed access to the text. Thus, we can provide efficient access within compressed space. The Lempel-Ziv index (LZ-index) of Navarro is a compressed full-text self-index able to represent T using 4uH k (T)+o(ulog?σ) bits of space, where H k (T) denotes the k-th order empirical entropy of T, for any k=o(log? σ u). This space is about four times the compressed text size. The index can locate all the occ occurrences of a pattern P in T in O(m 3log?σ+(m+occ)log?u) worst-case time. Although this index has proven very competitive in practice, the O(m 3log?σ) term can be excessive for long patterns. Also, the factor 4 in its space complexity makes it larger than other state-of-the-art alternatives. In this paper we present stronger Lempel-Ziv based indices (LZ-indices), improving the overall performance of the original LZ-index. We achieve indices requiring (2+ε)uH k (T)+o(ulog?σ) bits of space, for any constant ε>0, which makes them the smallest existing LZ-indices. We simultaneously improve the search time to O(m 2+(m+occ)log?u), which makes our indices very competitive with state-of-the-art alternatives. Our indices support displaying any text substring of length ? in optimal O(?/log? σ u) time. In addition, we show how the space can be squeezed to (1+ε)uH k (T)+o(ulog?σ) to obtain a structure with O(m 2) average search time for m≥2log? σ u. Alternatively, the search time of LZ-indices can be improved to O((m+occ)log?u) with (3+ε)uH k (T)+o(ulog?σ) bits of space, which is much less than the space needed by other Lempel-Ziv-based indices achieving the same search time. Overall our indices stand out as a very attractive alternative for space-efficient indexed text searching. 相似文献