全文获取类型
收费全文 | 1667篇 |
免费 | 153篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 13篇 |
综合类 | 2篇 |
化学工业 | 483篇 |
金属工艺 | 20篇 |
机械仪表 | 57篇 |
建筑科学 | 45篇 |
矿业工程 | 3篇 |
能源动力 | 56篇 |
轻工业 | 471篇 |
水利工程 | 10篇 |
石油天然气 | 15篇 |
无线电 | 94篇 |
一般工业技术 | 262篇 |
冶金工业 | 116篇 |
原子能技术 | 10篇 |
自动化技术 | 167篇 |
出版年
2024年 | 4篇 |
2023年 | 16篇 |
2022年 | 36篇 |
2021年 | 77篇 |
2020年 | 48篇 |
2019年 | 80篇 |
2018年 | 73篇 |
2017年 | 78篇 |
2016年 | 76篇 |
2015年 | 60篇 |
2014年 | 85篇 |
2013年 | 122篇 |
2012年 | 112篇 |
2011年 | 136篇 |
2010年 | 85篇 |
2009年 | 86篇 |
2008年 | 89篇 |
2007年 | 81篇 |
2006年 | 65篇 |
2005年 | 52篇 |
2004年 | 38篇 |
2003年 | 45篇 |
2002年 | 35篇 |
2001年 | 33篇 |
2000年 | 14篇 |
1999年 | 19篇 |
1998年 | 38篇 |
1997年 | 19篇 |
1996年 | 22篇 |
1995年 | 20篇 |
1994年 | 16篇 |
1993年 | 10篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 2篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 6篇 |
1975年 | 2篇 |
1973年 | 3篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有1824条查询结果,搜索用时 15 毫秒
91.
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
92.
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
93.
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
94.
95.
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
96.
Susana?Tejadillos Carmen?Armero Paula M.?Periago Antonio?MartínezEmail author 《European Food Research and Technology》2003,216(6):535-538
A new microbiological predictive model was developed, relating pH, NaCl concentration and temperature (T) with the decimal reduction coefficient D as dependent variable, using data previously reported by [1]. The model was obtained by multiple linear regression using only three predictor variables (T 2, pH2 and NaCl), easily computed from the basic variables pH, NaCl concentration and temperature (T). The fitted model is robust, stable and satisfies all the basic hypotheses of the regression models. It also provides simplicity when compared with previously published models based on multiple linear regression tools. 相似文献
97.
Rogelio?RodríguezEmail author Miriam?Estevez Susana?Vargas M.?Antonieta?Mondragón 《Materials Research Innovations》2003,7(2):80-84
The synthesis and characterization of a hybrid ceramic-polymer coating with high wearing resistance and designed to cover
wood surfaces, are reported in this work. This hybrid material provides a high wearing resistance (400% higher than a conventional
commercial product typically used to protect these surfaces); additionally it has a high UV resistance and high transparency
and gloss. The wood surfaces were previously treated either with a primer coating or with a special coupling agent, before
the hybrid coating was applied; in both cases, good adhesion with the substrate was obtained.
Electronic Publication 相似文献
98.
Agustin?de?la Isla Witold?BrostowEmail author Bernard?Bujard Miriam?Estevez J.?Rogelio?Rodriguez Susana?Vargas Victor?M.?Casta?o 《Materials Research Innovations》2003,7(2):110-114
We cover teeth surfaces with nanohybrid coatings containing an inorganic ceramic and an organic copolymer constituents. We
report the first ever values of scratch penetration depth and scratch recovery for bare and coated teeth. We find that uncoated
teeth undergo viscoelastic recovery (healing) after microscratching – the first manifestation of bone viscoelasticity in tribology.
The coatings fill "valleys" in teeth surfaces. In each case a large improvement in the scratch resistance as compared to uncoated
teeth is seen. The extent of the improvement depends on the inorganic/organic component ratios in the nanohybrids.
Electronic Publication 相似文献
99.
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
100.
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