全文获取类型
收费全文 | 15380篇 |
免费 | 1317篇 |
国内免费 | 621篇 |
学科分类
工业技术 | 17318篇 |
出版年
2024年 | 34篇 |
2023年 | 305篇 |
2022年 | 425篇 |
2021年 | 664篇 |
2020年 | 533篇 |
2019年 | 449篇 |
2018年 | 518篇 |
2017年 | 521篇 |
2016年 | 445篇 |
2015年 | 608篇 |
2014年 | 783篇 |
2013年 | 850篇 |
2012年 | 959篇 |
2011年 | 1027篇 |
2010年 | 900篇 |
2009年 | 869篇 |
2008年 | 883篇 |
2007年 | 759篇 |
2006年 | 803篇 |
2005年 | 657篇 |
2004年 | 537篇 |
2003年 | 451篇 |
2002年 | 437篇 |
2001年 | 366篇 |
2000年 | 346篇 |
1999年 | 406篇 |
1998年 | 303篇 |
1997年 | 285篇 |
1996年 | 252篇 |
1995年 | 220篇 |
1994年 | 182篇 |
1993年 | 128篇 |
1992年 | 106篇 |
1991年 | 67篇 |
1990年 | 64篇 |
1989年 | 47篇 |
1988年 | 29篇 |
1987年 | 28篇 |
1986年 | 20篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1970年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
45.
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
46.
In this article, a new algorithm based on an artificial potential field and hierarchical cell decomposition technique is developed to solve the find-path problem for a mobile robot. The complete map of the workspace including obstacle locations is assumed to be known a priori. The basic cell structure used for decomposition is a hexagon. The artificial potential field is based on an attractive force from the goal position and repelling forces from the obstacles. Computer simulations of the algorithm for various obstacle scenarios are also presented. © 1994 John Wiley & Sons, Inc. 相似文献
47.
Two free and one silylated (silane-substituted) photochromic spirooxazines are doped into organically modified ceramics (Ormocer) coatings by sol-gel processing and the thermal decoloration kinetics of these coatings are investigated and compared with the corresponding ethanol solutions and PMMA coatings. The decoloration behaviour of the two free dyes (SO-1 and SO-2) in the Ormocer coatings is similar to that in ethanol solutions, obeying a first-order mechanism and possessing almost the same decoloration rates as in ethanol. This suggests that the dye molecules encapsulated within the pores of the solid matrix are as free as those in ethanol solutions. The silylated dye (SO-3) in the Ormocer coatings, however, exhibits a considerably lower decoloration rate than the corresponding free dye (SO-1) and evident deviation from the first-order mechanism. This indicates apparently that the degree of freedom of the dye molecules is reduced by the silylation. These results are discussed on the basis of solvent polarity, porous structure of the Ormocer coating, and the dye-to-matrix connectivity. 相似文献
48.
本文用三维弹性动力学理论研究圆柱体在两端简支约束下的轴对称自由振动问题。给出位移振型和应力振型的解析表达式,求得固有频率的精确解。研究结果表明:在圆柱体的径向还存在着不同的半波数的位移振型,这种性质在初等理论中是无法反映的 相似文献
49.
非致冷焦平面热成象技术及其应用 总被引:12,自引:6,他引:6
90年代以后,非致冷红外焦平面技术的实用化成为红外热成象技术中最引入注目的突破之一,基估军事和民用领域的广泛应用前景受到国内外的普遍重视。本文综述了非致冷红外焦平面技术的两大技术途径及其特点、发展趋势和应用情况,并了发展我国非致冷红外焦平面技术的途径。 相似文献
50.
M. S. Han S. R. Hahn H. C. Kwon Y. Bin T. W. Kang J. H. Leem Y. B. Hou H. C. Jeon J. K. Hyun Y. T. Jeoung H. K. Kim J. M. Kim T. W. Kim 《Journal of Electronic Materials》1998,27(6):680-683
Double-crystal x-ray rocking curve (DCRC) and secondary-ion mass-spectroscopy (SIMS) measurements have been performed to investigate the effect of rapid thermal annealing on the interdiffusion behavior of Hg in HgTe/CdTe superlattices grown on Cd0.96Zn0.04Te (211)B substrates by molecular beam epitaxy. The sharp satellite peaks of the DCRC measurements on a 100-period HgTe/CdTe (100Å/100Å) superlattice show a periodic arrangement of the superlattice with high-quality interfaces. The negative direction of the entropy change obtained from the diffusion coefficients as a function of the reciprocal of the temperature after RTA indicates that the Hg diffusion for the annealed HgTe/CdTe superlattice is caused by an interstitial mechanism. The Cd and the Hg concentration profiles near the annealed HgTe/CdTe superlattice interfaces, as measured by SIMS, show a nonlinear behavior for Hg, originating from the interstitial diffusion mechanism of the Hg composition. These results indicate that a nonlinear interdiffusion behavior is dominant for HgTe/CdTe superlattices annealed at 190°C and that the rectangular shape of HgTe/CdTe superlattices may change to a parabolic shape because of the intermixing of Hg and Cd due to the thermal treatment. 相似文献