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41.
42.
Gianluca Bianchi Fasani Francesca Bozzano Michele Cercato 《Bulletin of Engineering Geology and the Environment》2011,70(4):533-542
There are many abandoned underground mines beneath the city of Rome, created in the Pleistocene pyroclastic deposits over
thousands of years. These pose a serious public safety risk hence the study was undertaken to better assess the stability
of the underground workings. The Villa de Sanctis public park was selected as a suitable test site, as in this area the cavity
network can be inspected and the different steps of the progressive migration of voids toward the surface can be identified.
In addition to an underground geological survey, geophysical investigations were undertaken to elucidate some key characteristics
of the involved lithological units, including elastic stiffness and layer thickness. Recommendations are made for further
studies of the accessible and inaccessible areas. 相似文献
43.
Gianluca Paravati Andrea Sanna Fabrizio Lamberti Luigi Ciminiera 《Mobile Networks and Applications》2011,16(3):385-393
Wireless communication advances have enabled emerging video streaming applications to mobile handheld devices. For example,
it is possible to display and interact with complex 3D virtual environments on mobile devices that don’t have enough computational
and storage capabilities (e.g. smart phones, PDAs) through remote rendering techniques, where a server renders 3D data and
streams the corresponding image flow to the client. However, due to fluctuations in bandwidth characteristics and limited
mobile device CPU capabilities, it is extremely challenging to design effective systems for streaming interactive multimedia
over wireless networks. This paper presents a novel approach based on a controller that can automatically adjust streaming
parameters basing on feedback measures from the client device. Experimental results prove the effectiveness of the proposed
solution in coping with bandwidth changes, thus providing high Quality of Service (QoS) in remote visualizations. 相似文献
44.
45.
Paola Bonizzoni Gianluca Della Vedova Riccardo Dondi Giancarlo Mauri 《Algorithmica》2010,58(2):282-303
The problem of clustering fingerprint vectors with missing values is an interesting problem in Computational Biology that
has been proposed in Figueroa et al. (J. Comput. Biol. 11(5):887–901, 2004). In this paper we show some improvements in closing the gaps between the known lower bounds and upper bounds on the approximability
of variants of the biological problem. Moreover, we have studied two additional variants of the original problem proposed
in Figueroa et al. (Proc. 11th Computing: The Australasian Theory Symposium (CATS), CRPIT, vol. 41, pp. 57–60, 2005). We prove that all such problems are APX-hard even when each fingerprint contains only two unknown positions and we present
a greedy algorithm that has constant approximation factors for these variants. Despite the hardness of these restricted versions
of the problem, we show that the general clustering problem on an unbounded number of missing values such that they occur
for every fixed position of an input vector in at most one fingerprint is polynomial time solvable. 相似文献
46.
Fair exchange constitutes a fundamental mechanism for electronic commerce. Fair exchange assumes that it is possible to verify
the correctness of the digital items to be exchanged. However, when an item is indescribable , i.e., it cannot be formally specified, its verification becomes difficult, if not impossible. This hinders a practical deployment
of fair exchange.
We propose a methodology for the verification of indescribable digital items. The methodology allows a participant in a fair
exchange protocol to personally verify the indescribable item without giving him any practical advantage over the other participant, and therefore without
violating the fairness imposed by the protocol. 相似文献
47.
Cesare Celozzi Gianluca Paravati Andrea Sanna 《International journal of human-computer interaction》2013,29(8):549-561
Existing tracking methods designed for interacting with projection-based displays generally require visible artifacts to be introduced in the environment in order to guarantee effective stability and accuracy. For instance, in optical-oriented approaches, either the camera sensor or the reference pattern used for tracking are often located within the user's sight (or interfere with it), thus occluding portions of the scene or altering the perception of the virtual environment. Several ways to tackle these issues have been recently explored. Proposed approaches basically aim at making the presence of tracking references in the virtual space transparent to the user. However, such solutions introduce possibly critical constraints on required hardware or environment configuration. In this work, a novel tracking approach based on imperceptible fiducial markers is proposed. The approach relies on a hiding technique that allows digital images to be embedded in (and retrieved from) a projected scene by exploiting the properties of light polarization and additive color mixing. In particular, the virtual scene is obtained by overlapping the light beams of two projectors and by dealing with markers’ hiding via color compensation. A prototype setup has been deployed, where interaction with a flat surface projection environment has been evaluated in terms of tracking accuracy and artifacts avoidance performance by using a consumer camera equipped with a polarizing filter. Although the performed tests presented in this article represent only a preliminary and a partial evaluation of the proposed approach, they provided encouraging results indicating that the proposed technique could be possibly applied in more complex interaction scenarios still with limited hardware requirements. 相似文献
48.
Terenzio Bertuzzi Silvia Rastelli Annalisa Mulazzi Gianluca Donadini Amedeo Pietri 《Food Control》2011,22(12):2059-2064
The occurrence of ochratoxin A, trichothecenes, fumonisins and aflatoxins in a sample of 106 beers produced in several European countries, was investigated. The analyses were conducted using high-performance liquid chromatography with fluorimetric detection for ochratoxin A and aflatoxins, gas-chromatography and high-performance liquid chromatography, both coupled with mass spectrometer, for trichothecenes and fumonisins, respectively. Aflatoxins were not detected in any samples, whereas ochratoxin A, deoxynivalenol and fumonisins were found in a relatively high number of samples. Their presence was at low levels in all samples; however, some differences were observed between the European countries. As regards ochratoxin A, beer samples from southern Europe showed levels always lower than 0.040 μg l?1, while the samples from other European countries showed significantly higher values, up to 0.189 μg l?1 (P < 0.001). For fumonisins, the levels of Italian beers were significantly higher compared to the samples from other countries (P = 0.006). 相似文献
49.
50.
This paper deals with the identification of concrete fracture parameters through indirect methods based on size effect experiments. These methods utilize the size effect curve (structural strength versus structural size), associated with a certain specimen geometry, to identify the tensile strength and the initial fracture energy. These two parameters, in turn, are typically used to characterize the peak and the initial post-peak slope of the cohesive crack law. In the literature, two different approaches can be found for the calculation of the size effect curve: (a) an approach based on the polynomial interpolation of numerically calculated structural strengths of geometrically similar specimens of different sizes, and (b) the classical approach based on equivalent elastic fracture mechanics, which gives rise to the well-known Bažant’s size effect law (SEL). In this paper, the two approaches are first reviewed, the relationship between them is investigated, and a new procedure to identify the tensile strength using the SEL is proposed. Then several sets of experimental results, recently performed at the Politecnico di Milano, are analyzed with both approaches in order to assess their range of applicability and accuracy in the identification of the two fracture parameters specified above. 相似文献