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1.
Inclined surfaces, where both the lifter and load are on the slope, may be encountered in a jobsite situation. The purpose of this study was to determine if facing up or down a sloped surface (10 degrees and 20 degrees ) would affect maximal acceptable weights of lift (MAWL) using a 10 min psychophysical approach with symmetric freestyle technique at 4 lifts/min. Seventeen healthy men and 18 women determined floor to knuckle height MAWL while facing uphill, downhill, and on a level surface. Motion capture was also performed to examine sagittal plane joint angles and foot placement relative to a milk crate. Slope did not alter MAWL (p>0.05) with the men lifting more than the women in every condition (p<0.001) (25 kg vs. 15 kg, respectively). Foot placement relative to the box was altered by slope such that both horizontal position behind and vertical position below the box increased as slope changed from the downhill to uphill conditions (both p<0.001). Forward torso lean as well as hip, knee, and ankle (plantar) flexion generally decreased as slope changed from the downhill to uphill conditions (all p<0.001). Torso and knee motion appeared to be protected compared to the other joints, changing the least. Though trends were the same in both sexes, interactions did exist in vertical foot position and hip angle (both p0.001). In conclusion, the body is highly adaptive to floor slope, maintaining MAWL at least in the short term. However, while slight technique differences exist between men and women, care should be taken by all when facing uphill due to the tendency to stand further from the load horizontally and when facing downhill due to increased torso lean. 相似文献
2.
Roldão Luis de Charette Raoul Verroust-Blondet Anne 《International Journal of Computer Vision》2022,130(8):1978-2005
International Journal of Computer Vision - Semantic scene completion (SSC) aims to jointly estimate the complete geometry and semantics of a scene, assuming partial sparse input. In the last years... 相似文献
3.
Corrosion of steel in reinforced concrete structures is a recurrent problem affecting civil engineering structures and costing the world billions of dollars per year. This physical phenomenon mainly results from chloride ingress or concrete carbonation. Corrosion can be diagnosed through a nondestructive method such as half-cell potential measurements. The present paper studies this method on a reinforced concrete wall containing eighteen unconnected steel bars and subjected to chloride-induced macrocell corrosion. Three corrosion systems with different configurations of connections between the steel bars are generated, involving three different anode-to-cathode surface ratios. Then, half-cell potential variations are observed versus macrocell corrosion current. The results lead to a critical discussion regarding the physical relevance of the usual potential threshold method to detect corroding rebars in reinforced concrete structures. In addition, the experiments demonstrate that electrical continuity between reinforcing steel bars is not necessary to get meaningful information about the macrocell corrosion system. At last, the paper show that the electric field (potential gradient) relative to a macrocell corrosion system may be measured by connecting the measurement system (reference electrode?+?voltmeter) to any electrochemical system in electrolytic contact with the concrete. 相似文献
4.
Klara Nahrstedt Zhenyu Yang Wanmin Wu Ahsan Arefin Raoul Rivas 《Multimedia Tools and Applications》2011,51(2):593-623
In the recent past we have seen a boom of distributed interactive multimedia environments which use multiple correlated media
sensors, multi-view displays, and advanced haptic-audio-visual user interfaces for teleimmersive gaming, business meetings
and other collaborative activities. However, when we investigate the emerging teleimmersive environments closer, we realize
that their overall session management, including end-to-end session setup, establishment and run-time management are not appropriate
for the new demands that these environments present. These environments are cyber-physical rooms that demand (a) large scale of multi-sensory devices across geographically-distributed locations and (b) interaction with each other in synchronous and real-time manner. To deal with the new teleimmersive demands, we present a new session management design with (a) session initiation protocol(s) that understand media correlations, (b) view-based multi-stream topology establishment among multiple parties, (c) efficient, light-weight and distributed session monitoring with querying and debugging capabilities, (d) flexible view-based session adaptation with efficient topology adjustments, and (e) light-weighted and consistent session tear-down protocols. The presented design of the next generation session management protocols, services, algorithms and data structures is based
on our extensive experiences with building 3D teleimmersive interactive systems, experimenting with high impact teleimmersive
applications and deploying such environments at various venues. 相似文献
5.
In a 2008 paper, Walmsley argued that the explanations employed in the dynamical approach to cognitive science, as exemplified
by the Haken, Kelso and Bunz model of rhythmic finger movement, and the model of infant preservative reaching developed by
Esther Thelen and her colleagues, conform to Carl Hempel and Paul Oppenheim’s deductive-nomological model of explanation (also
known as the covering law model). Although we think Walmsley’s approach is methodologically sound in that it starts with an
analysis of scientific practice rather than a general philosophical framework, we nevertheless feel that there are two problems
with his paper. First, he focuses only on the deductivenomological model and so neglects the important fact that explanations
are causal. Second, the explanations offered by the dynamical approach do not take the deductive-nomological format, because
they do not deduce the explananda from exceptionless laws. Because of these two points, Walmsley makes the dynamical explanations
in cognitive science appear problematic, while in fact they are not. 相似文献
6.
7.
This paper proposes a model of the mechanical behaviour of corroded reinforced concrete members subjected to bending under
service load. The model is based on the formulation of a macro-element to be used in FEM analysis, having a length equal to
the distance between two consecutive flexural cracks and a cross-section equal to the member cross-section. The mechanical
formulation is directly written in generalized variables (bending moment and curvature) and is based on the concept of the
transfer length necessary for the transmission of tensile load from re-bar to tensile concrete thanks to the bond. It is thus
possible to take into account the effect of reinforcement corrosion on the bond between re-bar and concrete, by increasing
the transfer length versus intensity of corrosion. The variation of the transfer length versus corrosion is expressed using
a scalar damage parameter. A first experimental validation is performed on a 17-year-old beam kept in a chloride environment
under its service load. 相似文献
8.
The Use of the Concept of Ecological Networks in Nature Conservation Policies and Planning Practices
The concept of Ecological Networks is popular in nature conservation policies. This paper reflects on advantages and disadvantages of using this concept in planning and realizing ecological ambitions. It focuses on how the concept is variously interpreted and used by different people. A case study on the Ecological Network and its users in the province of Gelderland in the Netherlands shows that concepts can be useful for promoting ideas and uniting people. However, the use of a concept can also lead to misleading consensus and hidden responsibilities, which can frustrate the implementation of the Ecological Networks. 相似文献
9.
Huizenga HM de Munck JC Waldorp LJ Grasman RP 《IEEE transactions on bio-medical engineering》2002,49(6):533-539
A method is described to incorporate the spatiotemporal noise covariance matrix into a spatiotemporal source analysis. The essential feature is that the estimation problem is split into two parts. First, a model is fitted to the observed noise covariance matrix. This model is a Kronecker product of a spatial and a temporal matrix. The spatial matrix models the spatial covariances by a function dependent on sensor distance. The temporal matrix models the temporal covariances as lag dependent. In the second part, sources are estimated given this noise model, which can be done very efficiently due to the Kronecker formulation. An application to real electroencephalogram (EEG) data shows that the noise model fits the data very well. Simulation results show that the resulting source estimates are more precise than those obtained from a standard analysis neglecting the noise covariance. In addition, the estimated standard errors of the source parameter estimates are far more precise than those obtained from a standard analysis. Finally, the source parameter standard errors are used to investigate the effects of temporal sampling. It is shown that increasing the sampling by a factor x, decreases the standard errors of all source parameters with the square root of x. 相似文献
10.
D. Zhuang Z. G. Herro R. Schlesser B. Raghothamachar M. Dudley Z. Sitar 《Journal of Electronic Materials》2006,35(7):1513-1517
Seeded growth of AlN single crystals was demonstrated in an induction-heated, high-temperature reactor via a physical vapor
transport (PVT) process. AlN seeds were prepared from a self-seeded boule containing large single-crystalline grains. Seeded
growth was interrupted several times in order to refill the AlN powder source, and a dedicated process scheme was used to
ensure epitaxial growth on the seed surface, after prior exposure to air. The growth temperatures were in the range of 2200–2300°C,
and the reactor pressure was in the range of 500–900 torr of UHP-grade nitrogen during each growth run. Under these growth
conditions, a seed (10 mm diameter) expanded at an angle of 45°, and a larger single crystal up to 18 mm in diameter was obtained.
The as-grown surface had three facets, of which facet (1120) was smooth and featureless while the other two, (4150) and (2570),
showed serrated morphologies. The double-crystal x-ray rocking curve and glow discharge mass spectroscopy analysis confirmed
that the grown crystal was of high crystalline quality with low impurity incorporation. 相似文献