全文获取类型
收费全文 | 918篇 |
免费 | 40篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 17篇 |
综合类 | 1篇 |
化学工业 | 241篇 |
金属工艺 | 38篇 |
机械仪表 | 15篇 |
建筑科学 | 19篇 |
矿业工程 | 3篇 |
能源动力 | 64篇 |
轻工业 | 68篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 97篇 |
一般工业技术 | 249篇 |
冶金工业 | 82篇 |
原子能技术 | 6篇 |
自动化技术 | 58篇 |
出版年
2023年 | 14篇 |
2022年 | 23篇 |
2021年 | 39篇 |
2020年 | 28篇 |
2019年 | 23篇 |
2018年 | 35篇 |
2017年 | 25篇 |
2016年 | 23篇 |
2015年 | 23篇 |
2014年 | 26篇 |
2013年 | 50篇 |
2012年 | 38篇 |
2011年 | 48篇 |
2010年 | 33篇 |
2009年 | 30篇 |
2008年 | 43篇 |
2007年 | 40篇 |
2006年 | 17篇 |
2005年 | 24篇 |
2004年 | 23篇 |
2003年 | 18篇 |
2002年 | 14篇 |
2001年 | 21篇 |
2000年 | 14篇 |
1999年 | 16篇 |
1998年 | 26篇 |
1997年 | 20篇 |
1996年 | 21篇 |
1995年 | 19篇 |
1994年 | 13篇 |
1993年 | 21篇 |
1992年 | 15篇 |
1991年 | 17篇 |
1990年 | 9篇 |
1989年 | 10篇 |
1988年 | 10篇 |
1987年 | 14篇 |
1986年 | 11篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1973年 | 2篇 |
1972年 | 2篇 |
排序方式: 共有962条查询结果,搜索用时 78 毫秒
1.
Rahul Sasidharan Pillai Matteo Frasnelli Vincenzo M. Sglavo 《Ceramics International》2018,44(2):1328-1333
The present work focuses on the fabrication of βTCP (β-tricalcium phosphate) and HA/βTCP (hydroxyapatite/β-tricalcium phosphate) composite coatings by plasma spraying. The starting powders were produced via solid-state method using 2 wt% MgO to stabilize βTCP phase. The synthesized powders were preliminarily granulated to be used by the plasma spray process. Coatings obtained on titanium substrates are uniform and well adherent but due to the high temperature and cooling rate typical for plasma spraying process, βTCP phase is almost totally transformed into the α allotrope. Thermal treatment at 800 °C allows the reconversion of the phase αTCP→ βTCP. It is therefore possible to produce coatings with tuneable dissolution properties by selecting the proper initial powder mixture and the specific thermal treatment. 相似文献
2.
Carin L. Felsen L.B. Kralj D.R. Oh H.S. Lee W.C. Unnikrishna Pillai S. 《Antennas and Propagation, IEEE Transactions on》1997,45(4):592-600
Phase-space data processing is receiving increased attention because or its potential for furnishing new discriminants relating to classification and identification of targets and other scattering environments. Primary emphasis has been on time-frequency processing because of its impact on transient, especially wideband, short-pulse excitations. Here, we investigate the windowed Fourier transform, the wavelet transform, and model based superresolution algorithms within the context of a fully quantified and calibrated test problem investigated by us previously: two-dimensional (2-D) short-pulse plane wave scattering by a finite periodic array of perfectly conducting coplanar flat strips. Because the forward problem has been fully calibrated and parametrized, some quantitative measures can be assigned with respect to the tradeoffs of these time-frequency algorithms, yielding tentative performance assessments of the tested processing algorithms 相似文献
3.
R. M. Pillai S. G. K. Pilhii A. D. Damodaran 《JOM Journal of the Minerals, Metals and Materials Society》2002,54(10):12-16
Indian artisans and craftsmen have long been masters at extracting and shaping metals and alloys, as proven by archaeological
finds from the 2nd—3rd millennia B.C. For example, two well-known artifacts, castings of the dancing girl of Mohenjo Daro
and the Mother Goddess of Adichanallur, Tamilnadu, depict a high degree of metallurgical knowledge. Those castings were formed
by the lost wax process, which later was modified and became known as investment casting. In various parts of India, this
age-old casting process is still being practiced, without any major modifications. This paper discusses details of the process
used by the Indian artisans of Swamimalai, Tamilnadu, and Mannar, Kerala, South India in shaping copper-base alloys into icons
and utensils, bells, and lamps. 相似文献
4.
M. Ravi U. T. S. Pillai B. C. Pai A. D. Damodaran E. S. Dwarakadasa 《Metallurgical and Materials Transactions A》2002,33(2):391-400
The effect of Fe content (0.2 to 0.6 pct) on the microstructure and mechanical properties of a cast Al-7Si-0.3Mg (LM 25/356)
alloy has been investigated. Further, 1 pct mischmetal (MM) additions (a mixture of rare-earth (RE) elements) were made to
these alloys, and their mechanical properties at room and at elevated temperatures (up to 200 °C) were evaluated. A structure-property
correlation on this alloy was attempted using optical microstructure analysis, fractographs, X-ray diffraction, energy-dispersive
analysis of X-rays (EDX), and quantitative metallography by image analysis. An increase in Fe content increased the volume
percentage of Fe-bearing intermetallic compounds (β and π phases), contributing to the loweryield strength (YS), ultimate tensile strength (UTS), percentage elongation, and higher
hardness. An addition of 1 pct MM to the alloys containing 0.2 and 0.6 pct Fe was found to refine the microstructure; modify
the eutectic silicon and La, Ce, and Nd present in the MM; form different intermetallic compounds with Al, Si, Fe, and Mg;
and improve the mechanical properties of the alloys both at room and elevated temperatures. 相似文献
5.
Papain was immobilized on polymer supports with spacer arms of varying nature and length. As the length of the spacer arm increased, there was a marked increase in the extent of enzyme immobilization and activity of immobilized enzymes. When a long, flexible and hydrophilic polyethylene glycol spacer was introduced between the polystyrene backbone and the functional group used for immobilization, the extent of coupling and enzyme activity increased. Dependence of enzyme activity on the nature and extent of crosslinking and on the nature of the polymeric backbone was investigated. Hydrophilic polyacrylamide-based supports were found to be more efficient supports for immobilization compared to hydrophobic polystyrene-based supports. 相似文献
6.
7.
The kinetics and mechanism of oligomerization of cardanol over acid catalysts were studied. GPC results showed the formation of a mixture of oligomers such as dimer, trimer, tetramer, etc. IR spectra of the products of oligomerization showed a decrease in the intensity of the double bond absorption band at 1630 cm?1 and the disappearance of terminal vinyl bands at 895 cm?1 and 907 cm?1. 1H NMR spectra showed drastic changes in the unsaturated proton resonance signals at 5.5δ with respect to saturated protons at 0.2–2.5δ. The ratio of resonance integrals of unsaturated to saturated protons decreased from 1 : 6.5 to 1 : 20 after oligomerization. GPC studies showed that the rate of formation of the dimer, trimer, tetramer, etc. follow an identical path and that the individual oligomers are formed in the same weight percentage at any time during the reaction. A kinetic scheme is proposed to explain this phenomenon. Kinetic studies showed that the oligomerization reaction follows first order kinetics with respect to the monomer concentration and the rate constant is K = 6.6 × 10?5s?1. A probable mechanism for the oligomerization of cardanol is proposed. 相似文献
8.
Sorghum (cv. Maldandi M35-1) was modified to 12, 14 and 16% moisture content (m.c.) and heat-treated with microwave energy at 3 levels, for 30 sec (=4.5, 9 and 18 kJ), and 60 sec (=9, 18 and 36 kJ). The effect of microwave heating on rise and subsequent fall in grain temperature, reduction in m.c. and quality characteristics including germination, seedling dry matter, free fatty acids (FFA) and contaminant fungi was determined. The temperature attained and the moisture loss in the sorghum grain was affected by grain m.c. and the time of exposure. At the lowest and highest microwave treatment level grain temperatures reached 30–40°C and 90–101°C, respectively. However, a 60-sec treatment at the highest energy level was lethal for the grain, particularly at 14 and 16% m.c. The FFA values were unaffected by microwave treatment. Statistical analyses showed that the microwave power level and time individually, and power level × time interactions were significant for most quality characteristics. The fungi present most abundantly on the sorghum grain were Eurotium spp., Aspergillus candidus, A. niger and Penicillium spp. Increasing m.c. and microwave heating resulted in elimination of most fungi after a 30-sec exposure time. With a 60-sec exposure period, practically all fungi were eliminated from the grain. 相似文献
9.
Two series of semiflexible random thermotropic copolymers containing 8‐(3‐hydroxy phenyl) octanoic acid (HPOA) with either 3‐chloro‐4‐hydroxy benzoic acid or 3,5‐dibromo‐4‐hydroxy benzoic acid were prepared by melt polycondensation techniques. The copolyesters were characterized with Fourier transform infrared spectroscopy, dilute solution viscometry, hot‐stage polarized light microscopy, differential scanning calorimetry, thermogravimetric analysis, and wide‐angle X‐ray diffraction. Studies revealed that the amount of HPOA as a disruptor incorporated into the backbone of substituted 4‐hydroxy benzoic acids had a detrimental effect on the liquid‐crystalline behavior. Mesophase‐transition temperatures were observed between 210 and 250°C, and the optical textures were of typical nematic phases. The degree of crystallinity decreased with an increase in the HPOA content. The thermal stability of the copolymers was in the range of 310–370°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008 相似文献
10.