全文获取类型
收费全文 | 3684篇 |
免费 | 258篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 112篇 |
综合类 | 4篇 |
化学工业 | 873篇 |
金属工艺 | 73篇 |
机械仪表 | 116篇 |
建筑科学 | 123篇 |
矿业工程 | 8篇 |
能源动力 | 137篇 |
轻工业 | 527篇 |
水利工程 | 17篇 |
石油天然气 | 13篇 |
无线电 | 293篇 |
一般工业技术 | 909篇 |
冶金工业 | 64篇 |
原子能技术 | 11篇 |
自动化技术 | 664篇 |
出版年
2023年 | 28篇 |
2022年 | 43篇 |
2021年 | 102篇 |
2020年 | 89篇 |
2019年 | 99篇 |
2018年 | 143篇 |
2017年 | 127篇 |
2016年 | 168篇 |
2015年 | 119篇 |
2014年 | 185篇 |
2013年 | 379篇 |
2012年 | 263篇 |
2011年 | 278篇 |
2010年 | 217篇 |
2009年 | 176篇 |
2008年 | 180篇 |
2007年 | 156篇 |
2006年 | 124篇 |
2005年 | 85篇 |
2004年 | 59篇 |
2003年 | 68篇 |
2002年 | 52篇 |
2001年 | 39篇 |
2000年 | 40篇 |
1999年 | 41篇 |
1998年 | 38篇 |
1997年 | 18篇 |
1996年 | 37篇 |
1995年 | 25篇 |
1994年 | 33篇 |
1993年 | 25篇 |
1992年 | 25篇 |
1991年 | 20篇 |
1990年 | 21篇 |
1989年 | 20篇 |
1988年 | 15篇 |
1985年 | 37篇 |
1984年 | 35篇 |
1983年 | 28篇 |
1982年 | 25篇 |
1981年 | 38篇 |
1980年 | 33篇 |
1979年 | 26篇 |
1978年 | 24篇 |
1977年 | 18篇 |
1976年 | 20篇 |
1975年 | 13篇 |
1974年 | 12篇 |
1973年 | 15篇 |
1972年 | 14篇 |
排序方式: 共有3944条查询结果,搜索用时 31 毫秒
61.
The interaction spaces between instructors and learners in the traditional face-to-face classroom environment are being changed by the diffusion and adoption of many forms of computer-based pedagogy. An integrated understanding of these evolving interaction spaces together with how they interconnect and leverage learning are needed to develop meaningful strategies for effective teaching and learning. The 18i collaborative interaction spaces model was designed based on constructivist principles, and describes 18 mixed instructor–learner spaces contextualized at a finer operational scale that makes explicit a wider range of interactions. The model was implemented during the life cycle of an undergraduate GIS-based multimedia cartography course. One output was the generation of a repository of rule-based trajectory plans for rapid planning and problem solving. The model provides an integrated workflow to manage course contents, products, interactions, individuality, and learning styles in blended environments. 相似文献
62.
Cecilia Laschi Gioel Asuni Eugenio Guglielmelli Giancarlo Teti Roland Johansson Hitoshi Konosu Zbigniew Wasik Maria Chiara Carrozza Paolo Dario 《Autonomous Robots》2008,25(1-2):85-101
This paper presents a sensory-motor coordination scheme for a robot hand-arm-head system that provides the robot with the capability to reach an object while pre-shaping the fingers to the required grasp configuration and while predicting the tactile image that will be perceived after grasping. A model for sensory-motor coordination derived from studies in humans inspired the development of this scheme. A peculiar feature of this model is the prediction of the tactile image. The implementation of the proposed scheme is based on a neuro-fuzzy module that, after a learning phase, starting from visual data, calculates the position and orientation of the hand for reaching, selects the best-suited hand configuration, and predicts the tactile feedback. The implementation of the scheme on a humanoid robot allowed experimental validation of its effectiveness in robotics and provided perspectives on applications of sensory predictions in robot motor control. 相似文献
63.
Caleb Krouse Aaron A. Jennings Dario Gasparini 《Environmental Modelling & Software》2009,24(4):557-568
Consumer batteries littered on urban pavements release metals of environmental significance (Ag, Cd, Cr, Cu, Hg, Li, Mn, Ni, Pd, Ti, Zn) to stormwater runoff. Predicting the mass loading of any one metal is difficult because of the random composition of battery litter. However, when littering is modeled as a conditional filtered Poisson process, bounds may be estimated for the mean and variance of site mass loading for any metal if the site litter rate and battery product contributions are known. Site-specific data on the battery brand distribution in litter can improve load estimates, but statistics computed from 5500 littered batteries collected in the Cleveland area may be used to approximate the brand distribution. Zinc load calculations based on battery litter size, type and brand discretizations are implemented in a model titled BLML and illustrated for a case-study location. Results indicate that, at some urban sites, zinc released from battery litter can be the largest source of zinc in urban pavement runoff. 相似文献
64.
Mancić A Fuchs J Antici P Gaillard SA Audebert P 《The Review of scientific instruments》2008,79(7):073301
In this paper, the absolute calibration of photostimulable image plates (IPs) used as proton detectors is presented. The calibration is performed in a wide range of proton energies (0.5-20 MeV) by exposing simultaneously the IP and calibrated detectors (radiochromic films and solid state detector CR39) to a source of broadband laser-accelerated protons, which are spectrally resolved. The final result is a calibration curve that enables retrieving the proton number from the IP signal. 相似文献
65.
One of the key time-domain closed-loop performance requirements is the closed-loop response decay ratio. In this paper, the decay ratios of the disturbance-rejection magnitude optimum (DRMO) tuning method [Vranci? D, Strmcnik S, Kocijan J. Improving disturbance rejection of PI controllers by means of the magnitude optimum method. ISA Trans 2004; 43: 73-84; Vranci? D, Strmcnik S. Achieving optimal disturbance rejection by using the magnitude optimum method. In: Pre-prints of the CSCC'99 conference. 1999. p. 3401-6] are analyzed and compared to decay ratios of two other modern tuning methods, i.e. the Kappa-Tau tuning method (based on time-domain step-response characteristics) [Astr?m KJ, H?gglund T. PID controllers: Theory, design, and tuning. 2nd ed. Instrument Society of America; 1995] and the non-convex optimization tuning method (based on frequency response) [Panagopoulos H, Astr?m KJ, H?gglund T. Design of PI controllers based on non-convex optimization. Automatica 1998; 34: 585-601; Panagopoulos H, Astr?m KJ, H?gglund T. Design of PID controllers based on constrained optimisation. IEE Proc Control Theory Appl 2002; 149 (1): 32-40]. It is shown that the DRMO method results in such a closed-loop response that the decay ratio is within a relatively narrow interval when compared to the other two methods. 相似文献
66.
The experimentally determined chromaticities and reflectance spectra of films consisting of uniform ellipsoidal or spherical colloidal hematite particles are compared with calculated values and are found to be in good agreement. The theoretical treatment of the light-scattering problem involves the Mie theory for the spheres and the T-matrix method for the ellipsoids. The reflectance spectra for the pigment films are calculated through the use of the Kubelka-Munk analysis. 相似文献
67.
The analysis of statistical parameters of computer-generated therfial images by a line-scanning technique indicates an approach to efficient image transmission. 相似文献
68.
Algorithm for the determination of intrinsic optical constants of metal films: application to aluminum 总被引:2,自引:0,他引:2
Rakić AD 《Applied optics》1995,34(22):4755-4767
Optical and electron-energy-loss data for evaporated-aluminum films have been critically analyzed and used in an iterative, self-consistent algorithm that represents a combination of the Kramers-Kronig analysis and the semiquantum-model application. The novel values of the intrinsic optical functions of aluminum have been determined in a wide spectral range from 200 μm (6.2 meV) to 0.12 nm (10 keV). These functions are in accordance with recent calculations by Lee and Chang [Phys. Rev. B 49, 2362 (1994)], with dc conductivity measurements, and are in good agreement with both peak positions and line widths obtained from electron-energy-loss experiments. The results are examined for internal consistency by inertial and f-sum rules. 相似文献
69.
B. Kaluderović 《Journal of Materials Science》1995,30(7):1839-1844
Carbon-carbon composites were prepared with commercially available carbonized and graphitized fibres, with a mixture of pitch and phenolic resin as a binder and pitch as an impregnant. The contents of pitch in mixtures were: 0, 10, 20 and 30 wt %. The influence of pitch content in the mixture and fibre type on mass loss, shrinkage and mechanical properties of the composites was examined. With an increase of pitch content mass loss and shrinkage increased, while mechanical properties decreased. After three densification cycles, flexural strength increased with increasing pitch content in the binder, especially for composites with graphitized fibres. 相似文献
70.
Foehn Philipp Brescianini Dario Kaufmann Elia Cieslewski Titus Gehrig Mathias Muglikar Manasi Scaramuzza Davide 《Autonomous Robots》2022,46(1):307-320
Autonomous Robots - This paper presents a novel system for autonomous, vision-based drone racing combining learned data abstraction, nonlinear filtering, and time-optimal trajectory planning. The... 相似文献