全文获取类型
收费全文 | 1510篇 |
免费 | 95篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 21篇 |
综合类 | 1篇 |
化学工业 | 393篇 |
金属工艺 | 22篇 |
机械仪表 | 32篇 |
建筑科学 | 50篇 |
矿业工程 | 3篇 |
能源动力 | 48篇 |
轻工业 | 129篇 |
水利工程 | 13篇 |
石油天然气 | 10篇 |
无线电 | 126篇 |
一般工业技术 | 287篇 |
冶金工业 | 177篇 |
原子能技术 | 22篇 |
自动化技术 | 273篇 |
出版年
2023年 | 15篇 |
2022年 | 12篇 |
2021年 | 58篇 |
2020年 | 40篇 |
2019年 | 51篇 |
2018年 | 50篇 |
2017年 | 51篇 |
2016年 | 65篇 |
2015年 | 48篇 |
2014年 | 57篇 |
2013年 | 121篇 |
2012年 | 92篇 |
2011年 | 100篇 |
2010年 | 62篇 |
2009年 | 81篇 |
2008年 | 73篇 |
2007年 | 56篇 |
2006年 | 51篇 |
2005年 | 49篇 |
2004年 | 35篇 |
2003年 | 32篇 |
2002年 | 33篇 |
2001年 | 23篇 |
2000年 | 14篇 |
1999年 | 13篇 |
1998年 | 29篇 |
1997年 | 16篇 |
1996年 | 21篇 |
1995年 | 17篇 |
1994年 | 18篇 |
1993年 | 11篇 |
1992年 | 10篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 8篇 |
1984年 | 8篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1977年 | 7篇 |
1976年 | 10篇 |
1975年 | 8篇 |
1974年 | 10篇 |
1973年 | 6篇 |
1971年 | 9篇 |
1970年 | 8篇 |
1968年 | 6篇 |
1967年 | 6篇 |
1966年 | 15篇 |
排序方式: 共有1607条查询结果,搜索用时 21 毫秒
71.
Anton A. Kiss Costin Sorin Bildea 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(7):861-879
Biodiesel is a biodegradable and renewable fuel, emerging as a viable alternative to petroleum diesel. Conventional biodiesel processes still suffer from problems associated with the use of homogeneous catalysts and the limitations imposed by the chemical reaction equilibrium, thus leading to severe economic and environmental penalties. This work provides a detailed review—illustrated with relevant examples—of novel reactive separation technologies used in biodiesel production: reactive distillation/absorption/extraction, and membrane reactors. Reactive separation offers new and exciting opportunities for manufacturing the fatty acid alkyl esters involved in the industrial production of biodiesel and specialty chemicals. The integration of reaction and separation into one operating unit overcomes equilibrium limitations and provides major benefits such as low capital investment and operating costs. These reactive separation processes can be further enhanced by heat‐integration and powered by heterogeneous catalysts, to eliminate all conventional catalyst related operations, using efficiently the raw materials and the reaction volume, while offering higher conversion and selectivity, as well as significant energy savings compared with conventional biodiesel processes. Remarkable, in spite of the high degree of integration, such integrated reactive‐separation processes are still very well controllable as illustrated by the included examples. Copyright © 2012 Society of Chemical Industry 相似文献
72.
In this paper, we study the response to external disturbances of a double integrator with a saturating feedback. For a class of disturbances that have bounded integrals over all intervals, we show that a linear static feedback law can always be designed to ensure boundedness of the states. Moreover, boundedness can be preserved if the disturbance is biased by a small DC signal. In the special case that the disturbance is made up of a finite number of sinusoids and a small bias, any linear static feedback ensures boundedness of the states. These results are an extension of previous results by Wen, Roy, and Saberi (2008). 相似文献
73.
Anton Chuvakin 《EDPACS》2013,47(4):8-12
Abstract. This article covers the importance of employing a cross-platform and cross-application log management approach rather than a siloed approach to collecting and reviewing logs for simplifying security and operational monitoring as well as compliance initiatives. 相似文献
74.
In this paper, we study control of a chain of integrators under actuator saturation and non‐additive disturbances. We shall show that boundedness of the states can be ensured if the disturbances are matched and integral‐bounded, misaligned and magnitude‐bounded, or a combination of the two, using either a static or a dynamic low‐gain state feedback. This result is an extension of our earlier work on double integrator. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
75.
Jay Sagin Anton Sizo Howard Wheater Timothy D. Jardine 《International journal of remote sensing》2013,34(3):764-781
Tracking surface water coverage changes is a complicated task for many regions of the world. It is, however, essential to monitor the associated biological changes and bioproductivity. We present a methodology to track contemporary water coverage changes using optical remote sensing and use it to estimate historical summer water coverage in a large river delta. We used a geographical information system automated routine, based on the modified normalized difference water index, to extract the surface water coverage area (SWCA) from optical satellite data sets using the surface water extraction coverage area tool (SWECAT). It was applied to measure SWCA during drought and flood peaks in the Saskatchewan River Delta in Canada, from Landsat, SPOT and RapidEye images. Landsat results compared favourably with Canadian National Hydro Network (CNHN) GeoBase data, with deviations between SWCA classifications and the base CNHN GeoBase shapefile of ~2%. Difference levels between the extracted SWCA layer from Landsat and the higher resolution commercial satellites (SPOT and RapidEye) were also less than 2%. SWCA was tightly linked to discharge and level measurements from in-channel gauges (r2 > 0.70). Using the SWCA versus discharge relationship for the gauge with the longest record, we show that peak summer SWCA has declined by half over the last century, from 13% of our study area to 6%, with likely implications for fish and wildlife production. 相似文献
76.
77.
Zbyšek Pavlík Anton Trník Martin Keppert Milena Pavlíková Jaromír Žumár Robert Černý 《International Journal of Thermophysics》2014,35(3-4):767-782
Experimental analysis of a wide range of properties of a lightweight plaster which should enhance the heat-storage capacity of building envelopes is presented. The basic physical characteristics, namely, the bulk density, matrix density, total open porosity, and pore-size distribution are measured at first. Then, the compressive strength is determined for an assessment of mechanical performance of the plaster. The thermal conductivity and thermal diffusivity are studied using an impulse technique. Differential scanning calorimetry measurements are performed as well, in order to identify the temperature range and latent heat of the phase change and to determine the specific heat capacity as a function of temperature. Durability properties are assessed using the measurement of the water absorption coefficient and sorption and desorption isotherms. The experimental results indicate a good capability of the designed plaster to moderate effectively the interior climate of buildings. 相似文献
78.
Univ.-Doz. Mag. Dr. Anton Köck Livia Chitu Stefan Defregger Elke Kraker Günther Maier Stephan Steinhauer Robert Wimmer-Teubenbacher 《BHM Berg- und Hüttenm?nnische Monatshefte》2014,159(9):385-389
We report on the synthesis of SnO2 and CuO nanowires and their application as gas sensing components. The fabrication of SnO2 and CuO single nanowire devices by optical and electron beam lithography is described, and sensing performance to the toxic gas carbon monoxide is demonstrated. We briefly present the development of CMOS fabricated micro-hotplates as platforms for gas sensors and show our approach for nanowire implementation. Finally, we demonstrate a fully CMOS integrated CuO multi nanowire device and present our roadmap for a fully integrated multi-parameter smart sensor device which could be implemented as safety feature in smart phones. 相似文献
79.
Reshef Tenne Ronit Popovitz-Biro Anton Twersky Yaron Rosenfeld Hacohen 《Israel journal of chemistry》2001,41(1):7-14
Nanoparticles of various layered compounds having a closed cage or nanotubular structure, designated also inorganic fullerene-like (IF) materials, have been reported in the past. In this work IF-CdCl2 nanoparticles were synthesized by two methods. In one technique, a high temperature evaporation and subsequent condensation of dried cadmium chloride powder was used. In the other method, electron beam irradiation of the source powder led to its recrystallization into closed nanoparticles with a nonhollow core. The two methods are shown to produce nanoparticles of different topologies. While mostly spherical nested structures are obtained from the high temperature process, polyhedra with hexagonal or elongated rectangular characters are obtained by the electron beam induced process. The analysis also shows that, while the source (dried) powder is orthorhombic cadmium chloride monohydrate, the crystallized IF cage consists of the anhydrous 3R polytype which is not stable as bulk material in ambient atmosphere. Consistent with previous observations, this study shows that the seamless structure of the IF materials can stabilize phases, which are otherwise unstable in ambient conditions. 相似文献
80.
Metallopolymers based on a polyazomethine ligand containing rigid oxadiazole and flexible tetramethyldisiloxane units 下载免费PDF全文
Mirela‐Fernanda Zaltariov Maria Cazacu Carmen Racles Valentina Musteata Angelica Vlad Anton Airinei 《应用聚合物科学杂志》2015,132(11)
Soluble, easily processable polymer–metal complexes with improved optical and dielectric properties for optoelectronic functional materials were obtained. For this, a new polyazomethine (PAZ2) was prepared by the reaction of a siloxane dialdehyde and bis(formyl‐p‐phenoxymethyl) tetramethyldisiloxane with 2,5‐bis(p‐aminophenyl)‐1,3,4‐oxadiazole, and it was used as a ligand for Cu(II), Co(II), and Zn(II) ions on the basis of the presence of the electron‐donor nitrogen atoms from the azomethine group and oxadiazole ring. The structure of the PAZ2 was determined by spectral [Fourier transform infrared (FTIR) and 1H‐NMR spectroscopy] techniques. The metal complexation was proven by FTIR spectroscopy, and the silicon‐to‐metal ratios in the complexes were established by energy‐dispersive X‐ray fluorescence. The new materials were characterized by gel permeation chromatography, thermogravimetric analysis, and differential scanning calorimetry. The optical properties of PAZ2 and the derived metal complexes were studied by ultraviolet–visible and fluorescence spectroscopies. PAZ2 shows fluorescence emission, and it was significantly enhanced by metal complexation. The emission was enhanced by protonation; this behavior is useful, especially for sensors. The electrical properties were investigated by dielectric spectroscopy at various frequencies and temperatures, and this emphasized the existence of dipolar relaxations. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41631. 相似文献