全文获取类型
收费全文 | 2109篇 |
免费 | 54篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 17篇 |
综合类 | 1篇 |
化学工业 | 360篇 |
金属工艺 | 24篇 |
机械仪表 | 18篇 |
建筑科学 | 16篇 |
能源动力 | 70篇 |
轻工业 | 74篇 |
水利工程 | 5篇 |
石油天然气 | 1篇 |
无线电 | 59篇 |
一般工业技术 | 186篇 |
冶金工业 | 1232篇 |
原子能技术 | 15篇 |
自动化技术 | 87篇 |
出版年
2023年 | 14篇 |
2022年 | 30篇 |
2021年 | 43篇 |
2020年 | 32篇 |
2019年 | 37篇 |
2018年 | 41篇 |
2017年 | 44篇 |
2016年 | 56篇 |
2015年 | 21篇 |
2014年 | 35篇 |
2013年 | 65篇 |
2012年 | 52篇 |
2011年 | 59篇 |
2010年 | 39篇 |
2009年 | 32篇 |
2008年 | 25篇 |
2007年 | 24篇 |
2006年 | 24篇 |
2005年 | 18篇 |
2004年 | 15篇 |
2003年 | 14篇 |
2002年 | 13篇 |
2001年 | 12篇 |
2000年 | 9篇 |
1999年 | 50篇 |
1998年 | 335篇 |
1997年 | 188篇 |
1996年 | 140篇 |
1995年 | 101篇 |
1994年 | 73篇 |
1993年 | 82篇 |
1992年 | 17篇 |
1991年 | 23篇 |
1990年 | 24篇 |
1989年 | 18篇 |
1988年 | 26篇 |
1987年 | 32篇 |
1986年 | 20篇 |
1985年 | 27篇 |
1984年 | 9篇 |
1983年 | 13篇 |
1982年 | 28篇 |
1981年 | 28篇 |
1980年 | 25篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 42篇 |
1976年 | 82篇 |
1973年 | 4篇 |
1972年 | 4篇 |
排序方式: 共有2165条查询结果,搜索用时 343 毫秒
91.
Density functional theory and polarizable continuum model are used to calculate ionization potential of thin-films of 12 organic molecules. Computed values are compared with experimental values obtained from ultraviolet photoemission spectroscopy. The excellent correlation shows that it is possible to determine the ionization potential of organic molecules in solid-state within ±0.15 eV of the experimental value. This method is useful for chemists in designing molecules for organic electronics. 相似文献
92.
S. S. Nayak V. H. Baltazar Hernandez Y. Zhou 《Metallurgical and Materials Transactions A》2011,42(11):3242-3248
In sequel to our recent report,[1] we demonstrate in this article the effect of chemistry on nonisothermal tempering and softening behavior of dual-phase steels.
The martensite morphology and tempered structure were analyzed using electron microscopy. Electron energy loss spectrometry
and energy-dispersive X-ray spectroscopy were used for a compositional analysis. It was observed that characteristic of the
tempered structure in dual-phase (DP) steels was a function of prior martensite structure and chemistry, which in turn influence
the extent of softening. 相似文献
93.
K. P. Bhuvana R. Joseph Bensingh M. Abdul Kader S. K. Nayak 《Polymer-Plastics Technology and Engineering》2018,57(17):1784-1800
Polymer Light Emitting Diodes (PLEDs), the most promising name in the field of display technology has received tremendous attention from various research groups. The research on light emitting polymers are an interdisciplinary zone which has challenging investigates on materials science and engineering, physics of device architecture and technology. This review addresses the wide range of tailored polymers, evolution of LED device structure for high performance, single and multicolor polymer based LEDs. Though, polymers are possessing better efficiency and easy fabrication processes, it has very low stability and short life. This study also reviews, device degradation during device fabrication and operation. 相似文献
94.
Subhadarshi Nayak Jyoti Agrawal 《JOM Journal of the Minerals, Metals and Materials Society》2012,64(3):393-399
ScienceTomorrow is developing a high-speed, low-cost process for synthesizing high-porosity electrodes for electrochemical
double-layer capacitors. Four types of coal (lignite, subbituminous, bituminous, and anthracite) were used as precursor materials
for spark discharge activation with multiscale porous structure. The final porosity and pore distribution depended, among
other factors, on precursor type. The high gas content in low-grade carbon resulted in mechanical disintegration, whereas
high capacitance was attained in higher-grade coal. The properties, including capacitance, mechanical robustness, and internal
conductivity, were excellent when the cost is taken into consideration. 相似文献
95.
Aluminium extraction and leaching characteristics of Talcher Thermal Power Station fly ash with sulphuric acid 总被引:2,自引:0,他引:2
Niva Nayak 《Fuel》2010,89(1):53-58
Although fly ash disposal is of environmental concern the quality of residues can be improved with respect to high value applications. Fly ash is considered as a potential source of aluminium and other strategic metals. Leaching and metal extraction behaviour of fly ash collected from Talcher Thermal Power Station have been thoroughly studied using sulphuric acid as extractant. The chemical and mineralogical composition of post-leached samples have been determined. Aluminium extraction by direct leaching at low acid concentration and ambient temperature is not suitable for high recovery. The extraction efficiency of aluminium increases significantly at a higher solid:liquid ratio. It is evident that the leachability of metals from fly ash depends on the nature of leaching medium, solid:liquid ratio, temperature and leaching time. 相似文献
96.
The following study investigated wrist torque strength measurements of a group of younger and older adults. The aim of the study was to examine the impact of shape, diameter and height of lid on wrist torque opening strength. Forty participants took part in the study in four groups, younger males and females and older males and females. Data were collected for 12 test pieces. Anthropometric data were also obtained for stature, weight, hand breadth, hand length, chuck grip force, grip force, lateral grip force and pinch grip force. The analysis of the wrist torque strength measurements found that participants could exert greater force with square test pieces compared to circular test pieces of the same diameter. Examination of the circular test pieces found that as diameter and height increased, so did torque exertion data for the test pieces between 20 mm and 50 mm diameter. The surface area of the test pieces was found to be highly correlated with the level of torque exertion, thus a linear model was developed to describe this relationship. The model could be used to predict maximal torque closure levels for use in the packaging industry. The anthropometric data revealed that as height, weight, hand length and hand breadth increased, there was a correlation with the levels of torque exerted. Future research needs to further examine the relationship between surface area and torque exerted and the design of spherical lids to increase the contact area between the hand and the lid. 相似文献
97.
Nayak J. Tuncel E. Rose K. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2006,52(10):4626-4629
This correspondence presents a novel application of the theta function defined by Lovasz. The problem of coding for transmission of a source through a channel without error when the receiver has side information about the source is analyzed. Using properties of the Lovasz theta function, it is shown that separate source and channel coding is asymptotically suboptimal in general. By contrast, in the case of vanishingly small probability of error, separate source and channel coding is known to be asymptotically optimal. For the zero-error case, it is further shown that the joint coding gain can in fact be unbounded. Since separate coding simplifies code design and use, conditions on sources and channels for the optimality of separate coding are also derived 相似文献
98.
A. Datta S. Kal S. Basu M. Nayak A. K. Nath 《Journal of Materials Science: Materials in Electronics》1999,10(9):627-631
-FeSi2 is an important semiconducting silicide which is being studied extensively. In this paper, we report our results of the effect of laser and laser-thermal annealing on the properties of -FeSi2. 5N purity Fe was deposited on Si substrate and was subsequently irradiated by CW and pulsed laser separately followed by thermal annealing to reduce the laser induced damage. The samples were then characterized by sheet resistance, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), optical reflectance and absorption studies. Lastly, -FeSi2/n-Si heterojunctions were fabricated and the effect of laser treatment on the junction ideality factor was investigated. All these characterizations indicated the formation of good quality -FeSi2, particularly after pulsed laser followed by thermal treatment. 相似文献
99.
A case of cardiac syncope is presented, associated with single vessel coronary disease. The mechanism of the syncope would appear to be a ventricular arrhythmia with transmural myocardial ischaemia due to transient occlusion of the diseased coronary artery. The symptoms and electrocardiographic abnormalities were reproduced and subsequently abolished by percutaneous coronary angioplasty. 相似文献
100.
The effects of deprenyl on methamphetamine-induced dopamine depletions were studied in mice. Four SC injections of 12.5 mg/kg of methamphetamine at two-hour intervals caused substantial (72-82%) and long-lasting depletions of striatal dopamine. Pretreatment with either 25 or 40 mg/kg of deprenyl did not significantly alter the magnitude of this depletion. These results indicate that, unlike what is observed following MPTP, there is no protection afforded dopaminergic cells by deprenyl pretreatment in the methamphetamine model of parkinsonism. 相似文献