全文获取类型
收费全文 | 964篇 |
免费 | 85篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 15篇 |
综合类 | 3篇 |
化学工业 | 242篇 |
金属工艺 | 21篇 |
机械仪表 | 48篇 |
建筑科学 | 24篇 |
矿业工程 | 3篇 |
能源动力 | 41篇 |
轻工业 | 129篇 |
水利工程 | 12篇 |
石油天然气 | 11篇 |
无线电 | 78篇 |
一般工业技术 | 181篇 |
冶金工业 | 119篇 |
原子能技术 | 8篇 |
自动化技术 | 118篇 |
出版年
2024年 | 5篇 |
2023年 | 5篇 |
2022年 | 16篇 |
2021年 | 46篇 |
2020年 | 38篇 |
2019年 | 42篇 |
2018年 | 43篇 |
2017年 | 46篇 |
2016年 | 49篇 |
2015年 | 30篇 |
2014年 | 42篇 |
2013年 | 83篇 |
2012年 | 45篇 |
2011年 | 65篇 |
2010年 | 53篇 |
2009年 | 45篇 |
2008年 | 45篇 |
2007年 | 32篇 |
2006年 | 26篇 |
2005年 | 25篇 |
2004年 | 24篇 |
2003年 | 22篇 |
2002年 | 13篇 |
2001年 | 18篇 |
2000年 | 16篇 |
1999年 | 16篇 |
1998年 | 30篇 |
1997年 | 16篇 |
1996年 | 19篇 |
1995年 | 21篇 |
1994年 | 17篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 7篇 |
1975年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有1053条查询结果,搜索用时 134 毫秒
71.
S. S. M. Tavares J. R. Teodósio J. M. Neto M. R. Da Silva 《Journal of Materials Science》1999,34(18):4545-4550
A Fe-20Mo-5Ni-0.075C (wt%) alloy for magnets was prepared by induction melting under vacuum. The material was hot rolled, solution treated and aged at 610°C for different periods of time. The magnetic properties (Hc, Br, Bs and (BH)max) were measured and compared with some commercial alloys containing cobalt. The precipitation of Mo-rich phases and the decrease of the ferrite lattice parameter during ageing were detected by X-ray diffraction. The thermomagnetic analysis (TMA) was carried out in the solution treated samples and aged samples. The behaviour of TMA curves was explained with the help of X-ray analysis. 相似文献
72.
Rodrigo Scherer Paula Rossini Augusti Vivian Caetano Bochi Camila Steffens Leadir Lucy Martins Fries Ana Paula Daniel Ernesto Hashime Kubota João Radünz Neto Tatiana Emanuelli 《Food chemistry》2006,99(1):136-142
The effect of two slaughter methods (immersion in ice-water slurry and electrical stunning followed by ice slurry asphyxiation) on chemical and microbiological parameters of grass carp (Ctenopharyngodon idella) stored in ice for 20 days was evaluated. No differences in total volatile basic nitrogen (TVB-N), pH, carbohydrate or protein content of mucus were observed between the slaughter methods. Ice-slaughtered fish had lower bacteria counts at the beginning of storage, but higher counts than fish slaughtered by electricity at the end of storage (p < 0.05). However, no significant differences in the shelf life were observed between the slaughter methods evaluated (limit of acceptability – counts > 3 × 106 CFU g−1 – attained after 13–16 days). Results indicated that the chemical parameters evaluated have a limited applicability to assess the shelf life of grass carp stored in ice, since pH limit (6.8) was exceeded after 4 days, while TVB-N limit (30 mg%) was not attained after 20 days of storage. 相似文献
73.
The authors present a linearized error analysis and a gross error identification procedure for a power system linear programming state estimator. This type of estimator uses the weighted sum of the estimation residuals as its performance criterion and has the property of automatic gross error rejection in most situations likely to occur in practice. Numerical results which illustrate the practical application of the proposed technique to some power systems are presented 相似文献
74.
Evaluation and optimization of chromium removal from tannery effluent by microemulsion in the Morris extractor 总被引:2,自引:0,他引:2
Dantas Neto AA de Castro Dantas TN Alencar Moura MC 《Journal of hazardous materials》2004,111(1-3):115-122
A multidisciplinary Road Accident Analysis Group with the objective of conducting in-depth investigations of specific types of accidents has existed in Denmark for some years. The group has analysed head-on collisions, left-turn accidents, truck accidents and single vehicle accidents. The data collection included police reports, the group's investigation of accident sites and vehicles involved, and interviews with the involved road users and witnesses. The main accident factors in the head-on collisions and in the single vehicle accidents were excessive speed, drunk driving and driving under the influence of illegal drugs. The primary accident factors in left-turn accidents were attention errors or misjudging the amount of time available to complete the left turn. In the truck accidents insufficient searching for visual information as well as speeding were major factors. For all the accident themes the primary injury factor was failure to wear seat- belts. The multidisciplinary approach has provided a rather precise knowledge of the contributing factors leading up to the accident. The method requires a lot of resources, which is a limiting factor for the number of accidents to be analysed in this way. However, the method is suitable for analysis of common occurring or very serious types of accidents. 相似文献
75.
76.
Maria?Augusta?Neto Jorge?A.?C.?Ambr’osioEmail author Rog’erio?Pereira?Leal 《Multibody System Dynamics》2004,12(4):385-405
The use of a multibody methodology to describe the large motion of complex systems that experience structural deformations enables to represent the complete system motion, the relative kinematics between the components involved, the deformation of the structural members and the inertia coupling between the large rigid body motion and the system elastodynamics. In this work, the flexible multibody dynamics formulations of complex models are extended to include elastic components made of composite materials, which may be laminated and anisotropic. The deformation of any structural member must be elastic and linear, when described in a coordinate frame fixed to one or more material points of its domain, regardless of the complexity of its geometry. To achieve the proposed flexible multibody formulation, a finite element model for each flexible body is used. For the beam composite material elements, the sections properties are found using an asymptotic procedure that involves a two-dimensional finite element analysis of their cross-section. The equations of motion of the flexible multibody system are solved using an augmented Lagrangian formulation and the accelerations and velocities are integrated in time using a multi-step multi-order integration algorithm based on the Gear method. 相似文献
77.
Removal of chromium from aqueous solutions by diatomite treated with microemulsion 总被引:10,自引:0,他引:10
In order to evaluate the sorption of heavy metals, a crude diatomite was impregnated with a microemulsion which showed remarkable increase in chromium sorption capacity as compared to untreated diatomite. Samples with two different granulometries were investigated, both yielding practically complete adsorption. The adsorption process is pH dependent and the best results for the initial Cr (III) concentration of 1.5 g/L were obtained at pH 2.95. The effect of the concentration of the chromium synthetic solution was also investigated. The adsorption isotherms were obtained (30. 40 and 50 degrees C) and the Freundlich and Langmuir models were used to determine the adsorption capacity of the adsorbent. Following the adsorption step, a desorption process was carried out using several eluant solutions. The best results were obtained using hydrochloric acid (100%) as eluant. 相似文献
78.
Neto A. Llombart N. Gerini G. Bonnedal D.M. de Maagt P. 《Antennas and Propagation, IEEE Transactions on》2007,55(8):2185-2193
We describe the use of electromagnetic bandgap (EBG) super-layers to improve the shape of reflectors illumination function. Following an investigation of the leaky wave pole singularities of the EBG Green's function, the shape of the radiation patterns of small apertures in ground planes are optimized. The maximization of the reflector aperture efficiency can be obtained by properly tuning the super layers geometrical parameters. A prototype of such feed has been designed, manufactured and tested. The results indicate that the inclusion of the EBG, increases the aperture efficiency of the feed+reflector system to values higher than 80%, over a 10% bandwidth. These low profile feeds are compatible with printed circuit board and/or integrated technology. 相似文献
79.
J. M. Pardal S. S. M. Tavares M. P. Cindra Fonseca M. R. da Silva J. M. Neto H. F. G. Abreu 《Journal of Materials Science》2007,42(7):2276-2281
The magnetic properties and hardness of a Ni–Co–Mo–Ti maraging steel 300 grade were measured as function of aging temperature.
The austenite and martensite phase quantifications in the different heat treatment conditions were carried out by X-ray diffraction
using direct comparison method. The behavior of the hardening, magnetization saturation and coercive force against aging temperature
and time were explained taking into account the variation of austenite volume fraction with aging time and temperature. 相似文献
80.
Ramón Fernandez Astudillo Dorothea Kolossa Alberto Abad Steffen Zeiler Rahim Saeidi Pejman Mowlaee João Paulo da Silva Neto Rainer Martin 《Computer Speech and Language》2013,27(3):837-850
This paper presents a new approach for increasing the robustness of multi-channel automatic speech recognition in noisy and reverberant multi-source environments. The proposed method uses uncertainty propagation techniques to dynamically compensate the speech features and the acoustic models for the observation uncertainty determined at the beamforming stage. We present and analyze two methods that allow integrating classical multi-channel signal processing approaches like delay and sum beamformers or Zelinski-type Wiener filters, with uncertainty-of-observation techniques like uncertainty decoding or modified imputation. An analysis of the results on the PASCAL-CHiME task shows that this approach consistently outperforms conventional beamformers with a minimal increase in computational complexity. The use of dynamic compensation based on observation uncertainty also outperforms conventional static adaptation with no need of adaptation data. 相似文献