全文获取类型
收费全文 | 1033篇 |
免费 | 73篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 11篇 |
化学工业 | 283篇 |
金属工艺 | 15篇 |
机械仪表 | 16篇 |
建筑科学 | 19篇 |
能源动力 | 42篇 |
轻工业 | 203篇 |
水利工程 | 3篇 |
石油天然气 | 3篇 |
无线电 | 96篇 |
一般工业技术 | 163篇 |
冶金工业 | 92篇 |
原子能技术 | 3篇 |
自动化技术 | 159篇 |
出版年
2023年 | 10篇 |
2022年 | 39篇 |
2021年 | 35篇 |
2020年 | 21篇 |
2019年 | 39篇 |
2018年 | 34篇 |
2017年 | 36篇 |
2016年 | 37篇 |
2015年 | 39篇 |
2014年 | 41篇 |
2013年 | 73篇 |
2012年 | 56篇 |
2011年 | 78篇 |
2010年 | 48篇 |
2009年 | 57篇 |
2008年 | 65篇 |
2007年 | 35篇 |
2006年 | 53篇 |
2005年 | 40篇 |
2004年 | 38篇 |
2003年 | 28篇 |
2002年 | 23篇 |
2001年 | 22篇 |
2000年 | 10篇 |
1999年 | 14篇 |
1998年 | 26篇 |
1997年 | 18篇 |
1996年 | 15篇 |
1995年 | 13篇 |
1994年 | 9篇 |
1993年 | 9篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 9篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有1108条查询结果,搜索用时 15 毫秒
101.
Partially filled skutterudites were investigated by ultrafast spectroscopy using a femtosecond laser system, which excites resonant oscillations due to the host–guest interactions. To investigate the effect of individual guest elements on phonon-mediated thermal transport, four skutterudite samples were studied: three samples partially filled with Ba, Yb, and La, respectively, and a fourth with a combination of these three elements. The spectrum of the oscillations in the transient thermoreflectance signal was analyzed by Fourier transformation. Comparison with the Raman spectra shows that different guest elements cause resonant oscillations with different frequencies, which can scatter phonons in different spectrum spans. This further demonstrates that multiple guest elements can scatter a wider spectrum of phonons than a single guest element at similar filling fractions, which results in lower lattice thermal conductivity (κ L) in skutterudites. These findings are consistent with thermal conductivity measurements reported previously. 相似文献
102.
The continuously growth of learning resources available in on-line repositories has raised the concern for the development of automated methods for quality assessment. The current existence of on-line evaluations in such repositories has opened the possibility of searching for statistical profiles of highly-rated resources that can be used as priori indicators of quality. In this paper, we analyzed 35 metrics in learning objects refereed inside the MERLOT repository and elaborated profiles for these resources regarding the different categories of disciplines and material types available. We found that some of the intrinsic metrics presented significant differences between highly rated and poorly-rated resources and that those differences are dependent on the category of discipline to which the resource belongs and on the type of the resource. Moreover, we found that different profiles should be identified according to the type of rating (peer-review or user) under evaluation. At last, we developed an initial model using linear discriminant analysis to evaluate the strength of relevant metrics when performing an automated quality classification task. The initial results of this work are promising and will be used as the foundations for the further development of an automated tool for contextualized quality assessment of learning objects inside repositories. 相似文献
103.
Low fat dry fermented sausages were manufactured using controlled ripening conditions and a slow fermented process. The effect of fat content and ripening time on the chemical, colour, texture parameters and sensory acceptability was studied. The fat reduction in slow fermented sausages produced an increase in the pH decline during the first stage of the process that was favoured by the higher water content of the low fat sausages. Fat reduction did not affect the external appearance and there was an absence of defects but lower fat content resulted in lower sausage lightness. The sausage texture in low fat sausages caused an increase in chewiness and at longer ripening times, an increase in hardness. The sensory acceptability of the fermented sausages analyzed by internal preference mapping depended on the different preference patterns of consumers. A group of consumers preferred sausages with high and medium fat content and high ripening time. The second group of consumers preferred sausages with low ripening time regardless of fat content except for the appearance, for which these consumers preferred sausages of high ripening time. Finally, the limit to produce high acceptability low fat fermented sausages was 16% fat content in the raw mixture that is half the usual content of dry fermented sausages. 相似文献
104.
105.
Crystalline powder samples belonging to the pseudoternary system SrO·6M2 O3 (M = Fe, Al, Cr) were synthesized in air. The limit of the magnetoplumbite-type (M-type) phase solid solution is governed by the presence of Cr3+ in the structure and is accompanied by the formation of a chromate and a sesquioxide. The extension of the solid solution in the Cr-containing pseudobinaries depends to a large extent on the crystallographic site preference of the host cation. The extension of the M-type solid solution is also narrowed at a lower temperature. 相似文献
106.
Maria José Ocio Pablo Salvador Fernandez Miguel Rodrigo Paula Periago A. Martinez 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1997,205(4):325-328
A time temperature integrator (TTI) was developed by immobilizing Bacillus stearothermophilus spores in a cylindrical particle consisting of an alginate-starch-mushroom purée. The particle showed homogeneous spore distribution,
and when heated over a temperature range of 121 – 130° C negligible spore leakage was observed after the thermal process.
The experimental data on spore survivor levels obtained for each temperature-time combination were compared with theoretical
predictions using a mathematical model. The results showed a good correlation between the experimental and theoretical data.
All these results provide evidence that this artificial particle could be a very reliable TTI for monitoring the thermal impact
on micro-organisms during validating sterilization processes in continuous aseptic systems.
Received: 25 February 1997 相似文献
107.
Teresa Lana Villarreal Peter Bogdanoff Pedro Salvador N.Nicols Alonso-Vante 《Solar Energy Materials & Solar Cells》2004,83(4):347-362
Surface mesoscopic titanium dioxide (P25) films deposited onto conducting glass plates (SnO2:F) were modified by colloidal RuxSey nanoparticles (2 nm diameter). A decrease of the photocurrent was found upon modification of TiO2 films. However, interfacial electron transfer kinetics to oxygen was favored. The increase of the catalyst surface concentration onto TiO2, shifts the onset of the photocurrent under UV-illumination, to 0.6 V/RHE in presence of oxygen dissolved in the electrolyte. Concomitant to this, the cathodic current becomes important and shifts to more positive potentials. This phenomenon allows the system to work catalytically under open circuit conditions. On non-modified TiO2, the application of a 0.3 V/RHE potential leads to an enhancement of the photooxidation of formic acid. Photocurrent images revealed a non-homogeneous distribution of the catalyst on the titanium dioxide films. 相似文献
108.
109.
A study was made of the interfacial properties of Poly(pyrrole) (PP) deposited electrochemically onto single crystal p-Si
surfaces. The interfacial properties are dependent upon the counterions. The formation of “Quasi-Ohmic” and “non-Ohmic” contacts,
respectively, of PP(C1O4) and PP films doped with other counterions (BF4 and para-toluene sulfonate) with p-Si, are explained in-terms of the conductivity of these films and the flat band potential,V
fb, of PP relative to that ofp-Si. The PP film seems to passivate or block intrinsic surface states present on thep-Si surface. The differences in the impedance behavior of para-toluene sulfonate doped and C1O4 doped PP are compared. 相似文献
110.