全文获取类型
收费全文 | 35409篇 |
免费 | 3258篇 |
国内免费 | 2024篇 |
专业分类
电工技术 | 2118篇 |
综合类 | 2306篇 |
化学工业 | 7010篇 |
金属工艺 | 2056篇 |
机械仪表 | 3515篇 |
建筑科学 | 1391篇 |
矿业工程 | 742篇 |
能源动力 | 2821篇 |
轻工业 | 826篇 |
水利工程 | 557篇 |
石油天然气 | 1554篇 |
武器工业 | 343篇 |
无线电 | 2151篇 |
一般工业技术 | 3561篇 |
冶金工业 | 956篇 |
原子能技术 | 159篇 |
自动化技术 | 8625篇 |
出版年
2024年 | 117篇 |
2023年 | 546篇 |
2022年 | 861篇 |
2021年 | 1141篇 |
2020年 | 1117篇 |
2019年 | 990篇 |
2018年 | 1003篇 |
2017年 | 1192篇 |
2016年 | 1323篇 |
2015年 | 1430篇 |
2014年 | 2142篇 |
2013年 | 2226篇 |
2012年 | 2127篇 |
2011年 | 3205篇 |
2010年 | 2249篇 |
2009年 | 2498篇 |
2008年 | 2397篇 |
2007年 | 2609篇 |
2006年 | 2126篇 |
2005年 | 1777篇 |
2004年 | 1493篇 |
2003年 | 1309篇 |
2002年 | 1073篇 |
2001年 | 783篇 |
2000年 | 661篇 |
1999年 | 481篇 |
1998年 | 368篇 |
1997年 | 280篇 |
1996年 | 213篇 |
1995年 | 184篇 |
1994年 | 152篇 |
1993年 | 131篇 |
1992年 | 113篇 |
1991年 | 87篇 |
1990年 | 68篇 |
1989年 | 60篇 |
1988年 | 28篇 |
1987年 | 20篇 |
1986年 | 23篇 |
1985年 | 25篇 |
1984年 | 16篇 |
1983年 | 4篇 |
1982年 | 9篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1975年 | 3篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
E. P. M. Leiva C. Vázquez M. I. Rojas M. M. Mariscal 《Journal of Applied Electrochemistry》2008,38(8):1065-1073
In this work, the structural and energetic properties of two typical catalytic surfaces, Na/Pt(111) and O/Pt(111), are studied
by means of quantum mechanical calculations and Monte Carlo Grand Canonical simulations. The simulations were performed with
electrostatic potentials at different truncation schemes. In order to elucidate the modification of catalyst surfaces produced
by the backspillover of ionic species onto Pt(111), the electrostatic field at the interface due to the electric double layer
was also analyzed. 相似文献
72.
Reda Karoum Antonio de Lucas-Consuegra Fernando Dorado Jose Luis Valverde Alain Billard Philippe Vernoux 《Journal of Applied Electrochemistry》2008,38(8):1083-1088
The electrochemical promotion of catalysis (EPOC) of propene combustion was investigated using Pt sputtered thin film on an
O2− conductor, 8 mol% Y2O3-stabilized-ZrO2 (YSZ). In order to separate the influence of the thermal migration of the O2− oxide ions from the electrolyte to the catalyst surface and the impact of an electrical polarization on the catalytic activity,
several light-off experiments (cool down and heat up procedures) were successively performed under different polarizations,
i.e. OCV, +2 and −2 V. These experiments have clearly shown that the presence of O2− (thermally or electrochemically induced) inhibits the catalytic activity of the platinum for the propene deep oxidation.
These results demonstrate the importance to define a normalized rate enhancement ratio, ρ
n
, from a reference value of the catalytic rate corresponding to a Pt surface state free of O2− ions. 相似文献
73.
N. Ilayaraja A. Manivel D. Velayutham M. Noel 《Journal of Applied Electrochemistry》2008,38(2):175-186
Electrochemical perfluorination (ECPF) of n-hexanoyl, n-heptanoyl, n-octanoyl, n-nonanoyl and n-decanoyl chlorides was carried out under identical experimental conditions in liquid HF. The product distribution among perfluorinated
carboxylic acids, perfluoro ethers, perfluoroalkanes, isomerised and fragmented products containing less number of carbon
atoms was identified using 19F NMR. The selectivity of C6–C10 perfluoro carboxylic acid varied between 29 and 36%. The alkali insoluble perfluoro cyclic ether and perfluoro alkane fractions
increased with increasing chain length. The increase of perfluoroalkane fractions is mainly due to decarboxylation. Cyclic
ether fractions also decreased slightly with increase in chain length. Among the cyclic ethers α substituted oxolanes were
the predominant products. Six membered cyclic ethers were always found to contain β substitution. The possible pathways for
these products are also indicated.
An erratum to this article can be found at 相似文献
74.
Michael Rabinovich Kate L. Olsavsky Burr Leach Mauricio Cabrera‐Ríos José M. Castro 《应用聚合物科学杂志》2008,109(4):2465-2471
Sheet molding compound (SMC) is a fiber‐reinforced polymeric composite. It is often used in automotive, marine, and industrial applications over other materials because of its high strength to density ratio, resistance to corrosion, and low cost. There is a demand in the SMC industry to be able to characterize SMC processability. This is particularly true for heavy truck body panels, one of the fastest growing applications of SMC. Because of their large size and high strength requirement, the molding forces have a major influence in the molding cycle. Also because of the long flow paths involved, the ability of the paste to carry glass needs to be properly characterized when developing new SMC materials. In this article, we demonstrate the benefits of using spiral flow as a processability tester. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
75.
T.S. Gates G.M. Odegard S.J.V. Frankland T.C. Clancy 《Composites Science and Technology》2005,65(15-16):2416
The paper provides details on the current approach to multi-scale modeling and simulation of advanced materials for structural applications. Examples are given that illustrate the suggested approaches to predicting the behavior and influencing the design of nanostructured materials such as high-performance polymers, composites, and nanotube-reinforced polymers. Primary simulation and measurement methods applicable to multi-scale modeling are outlined. Key challenges including verification and validation are highlighted and discussed. 相似文献
76.
Wei Wei Craig A. BennettRyuzo Tanaka Gang HouMichael T. Klein Jr. Michael T. Klein 《Fuel Processing Technology》2008
The complexity of many chemical and refining reaction systems and the thus-derived tedious and time-consuming process of building the associated kinetic models have been major obstacles in the use of fundamental kinetics in the solution of chemical engineering problems. This review summarizes work aimed at removing theses obstacles. Our recent work that has led to the enhancement of the Kinetic Modeler's Toolbox (KMT) and the development of the Kinetic Model Editor (KME) presents an end-to-end solution to the kinetic modeling process, including automated feedstock modeling, reaction network construction, kinetic rate estimation, model programming, process system configurations, model customizations, compilations, model execution and results analysis. 相似文献
77.
78.
In this study, analytical modeling of the tensile strength of hot-mix asphalt (HMA) mixtures at low temperatures was developed. To do this, HMA mixtures were treated as a two-phase composite material with aggregates (coarse and fine) dispersed in an asphalt mastic matrix. A two-phase composite model, which was similar to Papanicolaou and Bakos's [J. Reinforced Plast. Compos. 11 (1992) 104] model with a particle embedded in an infinite matrix, was proposed. Unlike Papanicolaou and Bakos's model, an axial stress was introduced to the fiber end to consider the load transferred from the asphalt mastic the aggregate. Efforts were also made to consider the effect of aggregate gradation, asphalt mastic degradation, and interfacial damage between the aggregates and asphalt mastic matrix on the tensile strength of the HMA mixtures. Experimental investigations were conducted to validate the developed theoretical relations. A reasonable agreement was found between the predicted tensile strength and the experimental results at low temperatures. Parameters affecting the tensile strength of asphalt mixtures were discussed based on the calculated results. 相似文献
79.
We report here a non-enzymatic detecting electrode strip for fast monitoring of uric acid in human whole blood. A single-use amperometric uric acid sensor strip, incorporating a three-electrode configuration, has been fabricated on a polypropylene substrate using low cost screen-printing (thick-film) technology. Both the working and counter electrodes were prepared by screen-printing commercial carbon ink. The integration on the same support of pseudo-reference electrode was obtained by screen-printing a commercial silver ink and subsequent electrochemical pretreatment. Simply by placing a 20 μl human whole blood drop on the strip is enough for uric acid analysis by square-wave voltammetry. Real human whole blood samples were analyzed by this method and compared to the phosphotungstic acid clinical test procedure with satisfactory results. 相似文献
80.
亚齐示范屋与生态技术 总被引:1,自引:1,他引:0
亚齐示范屋是在传承印度尼西亚当地住宅传统的基础上,海啸灾区重建的示范性建筑。从当地传统的传承、设计理念及生态技术方面对该示范屋进行了分析、研究,结合我国的情况得出我国生态建筑的发展策略。 相似文献