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1.
J. H. Elder S. J. D. Prince Y. Hou M. Sizintsev E. Olevskiy 《International Journal of Computer Vision》2007,72(1):47-66
We address the problem of localizing and obtaining high-resolution footage of the people present in a scene. We propose a
biologically-inspired solution combining pre-attentive, low-resolution sensing for detection with shiftable, high-resolution,
attentive sensing for confirmation and further analysis.
The detection problem is made difficult by the unconstrained nature of realistic environments and human behaviour, and the
low resolution of pre-attentive sensing. Analysis of human peripheral vision suggests a solution based on integration of relatively
simple but complementary cues. We develop a Bayesian approach involving layered probabilistic modeling and spatial integration
using a flexible norm that maximizes the statistical power of both dense and sparse cues. We compare the statistical power
of several cues and demonstrate the advantage of cue integration. We evaluate the Bayesian cue integration method for human
detection on a labelled surveillance database and find that it outperforms several competing methods based on conjunctive
combinations of classifiers (e.g., Adaboost). We have developed a real-time version of our pre-attentive human activity sensor
that generates saccadic targets for an attentive foveated vision system. Output from high-resolution attentive detection algorithms
and gaze state parameters are fed back as statistical priors and combined with pre-attentive cues to determine saccadic behaviour.
The result is a closed-loop system that fixates faces over a 130 deg field of view, allowing high-resolution capture of facial
video over a large dynamic scene. 相似文献
2.
Measurements in the CROCUS reactor at EPFL, Lausanne, are reported for the critical water level and the inverse reactor period for several different sets of delayed supercritical conditions. The experimental configurations were also calculated by four different calculation methods. For each of the supercritical configurations, the absolute reactivity value has been determined in two different ways, viz.: (i) through direct comparison of the multiplication factor obtained employing a given calculation method with the corresponding value for the critical case (calculated reactivity: ρcalc); (ii) by application of the inhour equation using the kinetic parameters obtained for the critical configuration and the measured inverse reactor period (measured reactivity: ρmeas). The calculated multiplication factors for the reference critical configuration, as well as ρcalc for the supercritical cases, are found to be in good agreement. However, the values of ρmeas produced by two of the applied calculation methods differ appreciably from the corresponding ρcalc values, clearly indicating deficiencies in the kinetic parameters obtained from these methods. 相似文献
3.
Prosthetic feet having new keel configurations were specially designed to store deformation energy during early and midstance and release it at push-off. These prosthetic components display longitudinal symmetry favoring good energy storage/release capability in the sagittal plane. The need for inverters/everters either as independent components or within the foot structure has long been recognized. This article documents the walking and slow jogging performances of six young adults wearing below-knee prostheses fitted with the Space Foot, a flexible foot prosthesis that provides medio-lateral control at heel-strike and lateral and forward propulsion at push-off. Results indicate that the Space Foot behaves as a flexible keel foot prosthesis. Its gait performances are also good for fast walking; however, the Space Foot's actual design should be modified if used in sporting activities involving running. 相似文献
4.
5.
Many of the targeted applications for powder-metallurgy materials, particularly in the automotive industry, undergo cyclic
loading. It is, therefore, essential to examine the fatigue mechanisms in these materials. The mechanisms of fatigue-crack
initiation and propagation in ferrous powder-metallurgy components have been investigated. The fatigue mechanisms are controlled
primarily by the inherent porosity present in these materials. Since most, if not all, fatigue cracks initiate and propagate
at the specimen surface, surface replication was used to determine the role of surface porosity in relation to fatigue behavior.
Surface replication provides detailed information on both initiation sites and on the propagation path of fatigue cracks.
The effect of microstructural features such as pore size and pore shape, as well as the heterogeneous microstructure on crack
deflection, was examined and is discussed. Fracture surfaces were examined to elucidate a mechanistic understanding of fatigue
processes in these materials. 相似文献
6.
Two new modeling and simulation approaches for Simultaneous Switching Noise (SSN) are described and compared to “brute force”
simulation by SPICE. Both simulation accuracy and simulation run-time are considered. The two new approaches are: 1) the “effective
inductance” method, in which an approximate, very efficient method of extracting an SSN L
eff
is utilized; and 2) the “macromodel” method, in which the complex inductance network responsible for SSN is represented by
only a few dominant poles in the frequency domain and the time domain response is obtained by an efficient convolution algorithm.
Both approaches are shown to be accurate and fast, but only the effective inductance algorithm is robust in numerical convergence.
Received: 19 March 1997 / Accepted: 25 March 1997 相似文献
7.
R.I.R. Blyth S.S. Dhesi P.A. Gravil K. Newstead R. Cosso R.J. Cole A.J. Patchett T. Mitrelias N.P. Prince S.D. Barrett 《Journal of Alloys and Compounds》1992,180(1-2):259-263
Angle-resolved UV photoemission has been used to investigate the electronic structure of the (0001) surfaces of scandium, yttrium, praseodymium and gadolinium. Off-normal emission spectra were recorded with high angular resolution, enabling detailed mapping of the dispersion of valence band features. Yttrium and gadolinium show similar results to published data from Ho(0001), suggesting minimal 4f influence in the lanthanide bandstructures. Differences seen on praseodymium and scandium may be due to 4f derived states and surface states respectively. 相似文献
8.
A review is provided of the use of analytical models and two dimensional (2D) and three dimensional (3D) microstructure based
FEM models to accurately predict the properties of particle reinforced composite materials. It is shown that analytical models
do not account for the microstructural factors that influence the mechanical behavior of the material. 2D models do capture
the anisotropy in deformation behavior induced by anisotropy in particle orientation. The experimentally-observed dependence
of Young's modulus and tensile strength is confirmed by the 2D microstructure-based numerical model. However, because of the
2D stress state, a realistic comparison to actual experimental values is not possible. A serial sectioning process can be
used to reproduce and visualize the 3D microstructure of particle reinforced metal matrix composites. The 3D microstructure-based
FEM accurately represents the alignment, aspect ratio, and distribution of the particles. Comparison with single particle
and multiparticle models of simple shape (spherical and ellipsoidal) shows that the 3D microstructure-based approach is more
accurate in simulating and understanding material behavior. 相似文献
9.
George M. Prince 《Creativity & Innovation Management》2003,12(4):240-246
Independently of the creativity movement, others have demonstrated the benefits of creating positive fields. I have reviewed a number of cases involving field below and added some from my own creativity experiences. I then explore the psychological explanation of why such fields are effective and go on to the findings of recent brain research, which not only reinforce the benefits of positive fields but also throw light on the difficulty of creating them. Finally, I offer some suggestions from my own experience of what can be done to create positive fields. I believe that this should now be the focus of our efforts: to the extent that we are successful, we should get the creativity and innovation we need as a by‐product. 相似文献
10.