全文获取类型
收费全文 | 1837篇 |
免费 | 191篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 39篇 |
综合类 | 11篇 |
化学工业 | 466篇 |
金属工艺 | 55篇 |
机械仪表 | 32篇 |
建筑科学 | 152篇 |
矿业工程 | 2篇 |
能源动力 | 51篇 |
轻工业 | 66篇 |
水利工程 | 6篇 |
无线电 | 189篇 |
一般工业技术 | 412篇 |
冶金工业 | 100篇 |
原子能技术 | 9篇 |
自动化技术 | 444篇 |
出版年
2024年 | 6篇 |
2023年 | 51篇 |
2022年 | 63篇 |
2021年 | 101篇 |
2020年 | 86篇 |
2019年 | 79篇 |
2018年 | 85篇 |
2017年 | 70篇 |
2016年 | 99篇 |
2015年 | 98篇 |
2014年 | 115篇 |
2013年 | 132篇 |
2012年 | 145篇 |
2011年 | 160篇 |
2010年 | 134篇 |
2009年 | 93篇 |
2008年 | 98篇 |
2007年 | 88篇 |
2006年 | 75篇 |
2005年 | 50篇 |
2004年 | 29篇 |
2003年 | 14篇 |
2002年 | 19篇 |
2001年 | 15篇 |
2000年 | 8篇 |
1999年 | 12篇 |
1998年 | 23篇 |
1997年 | 15篇 |
1996年 | 9篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1991年 | 4篇 |
1987年 | 1篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有2034条查询结果,搜索用时 15 毫秒
991.
Dynamic mechanical, thermal, and morphological study of ABS/textile fiber composites 总被引:1,自引:1,他引:0
Johnny N. Martins Tobias G. Klohn Otavio Bianchi Rudinei Fiorio Estevão Freire 《Polymer Bulletin》2010,64(5):497-510
In this work, acrylonitrile–butadiene–styrene ABS terpolymer was mixed with acrylic fiber, cotton fiber, and waste textile
fiber (WTF) (50/50 wt% cotton/acrylic fiber) with 10 and 30 wt% of fiber content in a batch mixer. The composites with 30 wt%
of acrylic fiber showed the highest stabilized torque, while the compositions with 30 wt% of cotton were situated at the lowest
values in torque rheometry. The fiber addition up to 30 wt% did not have effect on the degradation behavior of ABS matrix.
The composites with 30% textile fiber showed a higher degradation step, which is related to fiber degradation. The fiber content
resulted in a considerable increase in stiffness at all temperatures as can be observed on the dynamic mechanical thermal
properties (DMTA). The reinforcing effect was higher in the region above the glass transition temperature, T
g, of the matrix, this is primarily due to the larger difference in mechanical properties between the filler and the matrix
as it goes from the glassy to the rubbery state. 相似文献
992.
Martin Iggland Henrik Leion Tobias Mattisson Anders Lyngfelt 《Chemical engineering science》2010,65(22):5841-5851
Chemical looping combustion (CLC) uses an oxygen carrier circulating between an air and a fuel reactor to replace direct burning of fuels in air. The very low energy penalty for CO2 separation in CLC gives it the potential to become an important technology on the way to a CO2 neutral energy supply. In this work, the influence of the particle size of coal on the rate of reaction of the coal was investigated in a bed of oxygen carrier. In order to do this, a method to quench the reaction of coal with oxygen carriers at a specified time and measure the particle size distribution of the remaining coal was developed. Three size fractions of coal were used in the experiments: 90–125, 180–212 and 250–355 μm. Particle size distributions of the fuel show a decrease in particle size with time. The influence of devolatilisation of the coal on the coal particle size was measured, showing that coal particles do not break in the fluidized bed reactor used for the experiments. Reaction rates based on measurements of gas phase concentrations of CO2, CO and CH4 showed that the reaction rate is independent of the particle size. These results are in line with literature findings, as studies have shown that carbon gasification is size-independent at conditions similar to those in the performed CLC experiments. 相似文献
993.
The catalytic activation of carbon-carbon single bonds represents a major challenge in organometallic chemistry. Strained ring substrates occupy in this respect a privileged role as their inherent ring strain facilitates the desired metal insertion. Employing symmetrically substituted tert-cyclobutanols, an enantioselective rhodium(I)-catalyzed beta-carbon elimination creates alkyl-rhodium species bearing all-carbon quaternary stereogenic centers. Downstream reactions enable access to a wide range of synthetically versatile products such as substituted cyclohexenones, lactones and indanols with excellent enantioselectivities of up to 99% ee. 相似文献
994.
995.
996.
Lobell M Hendrix M Hinzen B Keldenich J Meier H Schmeck C Schohe-Loop R Wunberg T Hillisch A 《ChemMedChem》2006,1(11):1229-1236
The need for in silico characterization of HTS hit structures as part of a data-driven hit-selection process is demonstrated. A solution is described in the form of an in silico ADMET traffic light and PhysChem scoring system. This has been extensively validated with in-house data at Bayer, published data, and a collection of launched small-molecule oral drugs. 相似文献
997.
Plasmonic dimer nanoantennas are characterized by a strong enhancement of the optical field, leading to large nonlinear effects. The third harmonic emission spectrum thus depends strongly on the antenna shape and size as well as on its gap size. Despite the complex shape of the nanostructure, we find that for a large range of different geometries the nonlinear spectral properties are fully determined by the linear response of the antenna. We find excellent agreement between the measured spectra and predictions from a simple nonlinear oscillator model. We extract the oscillator parameters from the linear spectrum and use the amplitude of the nonlinear perturbation only as scaling parameter of the third harmonic spectra. Deviations from the model only occur for gap sizes below 20 nm, indicating that only for these small distances the antenna hot spot contributes noticeable to the third harmonic generation. Because of its simplicity and intuitiveness, our model allows for the rational design of efficient plasmonic nonlinear light sources and is thus crucial for the design of future plasmonic devices that give substantial enhancement of nonlinear processes such as higher harmonics generation as well as difference frequency mixing for plasmonically enhanced terahertz generation. 相似文献
998.
T Schuh T Miyamachi S Gerstl M Geilhufe M Hoffmann S Ostanin W Hergert A Ernst W Wulfhekel 《Nano letters》2012,12(9):4805-4809
Magnetic anisotropy and magnetization dynamics of rare earth Gd atoms and dimers on Pt(111) and Cu(111) were investigated with inelastic tunneling spectroscopy. The spin excitation spectra reveal that giant magnetic anisotropies and lifetimes of the excited states of Gd are nearly independent of the supporting surfaces and the cluster size. In combination with theoretical calculations, we argue that the observed features are caused by strongly localized character of 4f electrons in Gd atoms and clusters. 相似文献
999.
Noble gas and metal atoms form minimum-energy clusters. Here, we present analogous agglomerates of gold nanoparticles formed in oil-in-water emulsions. We exclude interfacial templating and nucleation-and-growth as formation mechanisms of these supraparticles. Similar to atomic clusters, the supraparticles form when a mobile precursor state can reconfigure until the nanoparticles' interactions with each other and with the liquid-liquid interface are maximized. This formation mechanism is in striking contrast to that previously reported for microparticle clusters. 相似文献
1000.
Because of its high spatial resolution, energy-filtering transmission electron microscopy (EFTEM) has become widely used for the analysis of the chemical composition of nanostructures. To obtain the best spatial resolution, the precise correction of instrumental influences and the optimization of the data acquisition procedure are very important. In this publication, we discuss a modified image acquisition procedure that optimizes the acquisition process of the EFTEM images, especially for long exposure times and measurements that are affected by large spatial drift. To alleviate the blurring of the image caused by the spatial drift, we propose to take several EFTEM images with a shorter exposure time (sub-images) and merge these sub-images afterwards. To correct for the drift between these sub-images, elastically filtered images are acquired between two subsequent sub-images. These elastically filtered images are highly suitable for spatial drift correction based on the cross-correlation method. The use of the drift information between two elastically filtered images permits to merge the drift-corrected sub-images automatically and with high accuracy, resulting in sharper edges and an improved signal intensity in the final EFTEM image. Artefacts that are caused by prominent noise-peaks in the dark reference image have been suppressed by calculating the dark reference image from three images. Furthermore, using the information given by the elastically filtered images, it is possible to drift-correct a set of EFTEM images already during the acquisition. This simplifies the post-processing for elemental mapping and offers the possibility for active drift correction using the image shift function of the microscope, leading to an increased field of view. 相似文献