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141.
Jonas Unger Joel Kronander Per Larsson Stefan Gustavson Joakim Löw Anders Ynnerman 《Computers & Graphics》2013,37(7):923-934
Illumination is one of the key components in the creation of realistic renderings of scenes containing virtual objects. In this paper, we present a set of novel algorithms and data structures for visualization, processing and rendering with real world lighting conditions captured using High Dynamic Range (HDR) video. The presented algorithms enable rapid construction of general and editable representations of the lighting environment, as well as extraction and fitting of sampled reflectance to parametric BRDF models. For efficient representation and rendering of the sampled lighting environment function, we consider an adaptive (2D/4D) data structure for storage of light field data on proxy geometry describing the scene. To demonstrate the usefulness of the algorithms, they are presented in the context of a fully integrated framework for spatially varying image based lighting. We show reconstructions of example scenes and resulting production quality renderings of virtual furniture with spatially varying real world illumination including occlusions. 相似文献
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143.
An improved thermodynamic modeling of the Fe-Cr system down to zero kelvin coupled with key experiments 总被引:1,自引:0,他引:1
Wei Xiong Peter HedströmMalin Selleby Joakim OdqvistMattias Thuvander Qing Chen 《Calphad》2011,35(3):355-366
A thermodynamic modeling of the Fe-Cr system down to 0 K is performed on the basis of our recent comprehensive review of this binary system [W. Xiong, M. Selleby, Q. Chen, J. Odqvist, Y. Du, Evaluation of phase equilibria and thermochemical properties in the Fe-Cr system, Crit. Rev. Solid State Mater. Sci. 35 (2010) 125-152]. The model predicts a sign change for the magnetic ordering energy of mixing rather than the enthalpy of mixing in the bcc phase at 0 K. Designed key experiments are performed not only to check the validity of the present modeling but also to assist in understanding the mechanism for spinodal decomposition of the Fe-Cr alloy. Heat capacities and Curie temperatures of several Fe-rich alloys are determined between 320 and 1093 K by employing differential scanning calorimetry. The measured heat capacities are found to be in remarkable agreement with the prediction based on the present modeling. Microstructural patterns and frequency distribution diagrams of Cr are studied in alloys containing 26.65, 31.95, and 37.76 at.% Cr by using atom probe tomography. The observed phase separation results correspond well with our model-predicted boundary for the spinodal decomposition. Interestingly, a horn on the Cr-rich spinodal boundary is predicted below 200 K for the first time. This work demonstrates a way to bridge the ab initio calculations and CALPHAD approach. 相似文献
144.
Class Refinement as Semantics of Correct Object Substitutability 总被引:2,自引:0,他引:2
Subtype polymorphism, based on syntactic conformance of objects' methods and used for substituting subtype objects for supertype
objects, is a characteristic feature of the object-oriented programming style. While certainly very useful, typechecking of
syntactic conformance of subtype objects to supertype objects is insufficient to guarantee correctness of object substitutability.
In addition, the behaviour of subtype objects must be constrained to achieve correctness. In class-based systems classes specify
the behaviour of the objects they instantiate. In this paper we define the class refinement relation which captures the semantic
constraints that must be imposed on classes to guarantee correctness of substitutability in all clients of the objects these
classes instantiate. Clients of class instances are modelled as programs making an iterative choice over invocation of class
methods, and we formally prove that when a class C′ refines a class C, substituting instances of C′ for instances of C is refinement for the clients.
Received May 1999 / Accepted in revised form March 2000 相似文献
145.
Encoding, Decoding and Data Refinement 总被引:1,自引:1,他引:0
Data refinement is the systematic replacement of a data structure with another one in program development. Data refinement
between program statements can on an abstract level be described as a commutativity property where the abstraction relationship
between the data structures involved is represented by an abstract statement (a decoding). We generalise the traditional notion of data refinement by defining an encoding operator that describes the least (most abstract) data refinement with respect to a given abstraction. We investigate the categorical
and algebraic properties of encoding and describe a number of special cases, which include traditional notions of data refinement.
The dual operator of encoding is decoding, which we investigate and give an intuitive interpretation to. Finally we show a number of applications of encoding and decoding.
Received May 1999 / Accepted in revised form November 2000 相似文献
146.
An electrochromic prototype with WO3 and NiO as electrochromic layers was analysed in an absolute spectrophotometer. The electrochromic glazing was measured in combination with a clear float glass and a low-e glass in order to simulate a ‘real’ window. Similar measurements were performed on a commercial electrochromic product, i.e., a Gentex Night Vision Safety™ (NVS®) mirror from Gentex Corporation, and the results were compared. The spectral transmittance was measured, in bleached and coloured state, over the solar wavelength range at the angles of incidence, φ=0, 40, 60 and 70°. The direct solar transmittance, Tsol, the visual transmittance, Tvis, and the angular dependence for these parameters were calculated. 相似文献
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150.
Stabilizing Active Edge Sites in Semicrystalline Molybdenum Sulfide by Anchorage on Nitrogen‐Doped Carbon Nanotubes for Hydrogen Evolution Reaction 下载免费PDF全文
Joakim Ekspong Tiva Sharifi Andrey Shchukarev Alexey Klechikov Thomas Wågberg Eduardo Gracia‐Espino 《Advanced functional materials》2016,26(37):6766-6776
Finding an abundant and cost‐effective electrocatalyst for the hydrogen evolution reaction (HER) is crucial for a global production of hydrogen from water electrolysis. This work reports an exceptionally large surface area hybrid catalyst electrode comprising semicrystalline molybdenum sulfide (MoS2+x) catalyst attached on a substrate based on nitrogen‐doped carbon nanotubes (N‐CNTs), which are directly grown on carbon fiber paper (CP). It is shown here that nitrogen‐doping of the carbon nanotubes improves the anchoring of MoS2+x catalyst compared to undoped carbon nanotubes and concurrently stabilizes a semicrystalline structure of MoS2+x with a high exposure of active sites for HER. The well‐connected constituents of the hybrid catalyst are shown to facilitate electron transport and as a result of the good attributes, the MoS2+x/N‐CNT/CP electrode exhibits an onset potential of ?135 mV for HER in 0.5 m H2SO4, a Tafel slope of 36 mV dec?1, and high stability at a current density of ?10 mA cm?2. 相似文献