全文获取类型
收费全文 | 675篇 |
免费 | 38篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 5篇 |
综合类 | 3篇 |
化学工业 | 150篇 |
金属工艺 | 19篇 |
机械仪表 | 11篇 |
建筑科学 | 17篇 |
能源动力 | 42篇 |
轻工业 | 37篇 |
水利工程 | 6篇 |
无线电 | 65篇 |
一般工业技术 | 174篇 |
冶金工业 | 56篇 |
原子能技术 | 7篇 |
自动化技术 | 124篇 |
出版年
2024年 | 5篇 |
2023年 | 9篇 |
2022年 | 26篇 |
2021年 | 37篇 |
2020年 | 29篇 |
2019年 | 22篇 |
2018年 | 39篇 |
2017年 | 36篇 |
2016年 | 31篇 |
2015年 | 21篇 |
2014年 | 28篇 |
2013年 | 66篇 |
2012年 | 29篇 |
2011年 | 43篇 |
2010年 | 32篇 |
2009年 | 31篇 |
2008年 | 27篇 |
2007年 | 23篇 |
2006年 | 25篇 |
2005年 | 14篇 |
2004年 | 20篇 |
2003年 | 14篇 |
2002年 | 14篇 |
2001年 | 7篇 |
2000年 | 5篇 |
1999年 | 5篇 |
1998年 | 7篇 |
1997年 | 7篇 |
1996年 | 11篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1980年 | 1篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有716条查询结果,搜索用时 515 毫秒
111.
Yuanxin Zhou Mahesh Hosur Shaik Jeelani P. K. Mallick 《Journal of Materials Science》2012,47(12):5002-5012
In this study, dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), and flexural tests were performed on unfilled,
1, 2, 3, and 4 wt% clay filled SC-15 epoxy to identify the effect of clay weight fraction on thermal and mechanical properties
of the epoxy matrix. The flexural results indicate that 2.0 wt% clay filled epoxy showed the highest improvement in flexural
strength. DMA studies also revealed that 2.0 wt% system exhibit the highest storage modulus and T
g as compared to neat and other weight fraction. However, TGA results show that thermal stability of composite is insensitive
to the clay content. Based on these results, the nanophased epoxy with 2 wt% clay was then utilized in a vacuum assisted resin
transfer molding set up with carbon fabric to fabricate laminated composites. The effectiveness of clay addition on thermal
and mechanical properties of composites has been evaluated by TGA, DMA, tensile, flexural, and fatigue test. 5 °C increase
in glass transition temperature was found in nanocomposite, and the tensile and flexural strengths improved by 5.7 and 13.5 %,
respectively as compared to the neat composite. The fatigue strength was also improved significantly. Based on the experimental
result, a linear damage model combined with the Weibull distribution function has been established to describe static failure
processing of neat and nanophased carbon/epoxy. The simulated stress–strain curves from the model are in good agreement with
the test data. Simulated results show that damage processing of neat and nanophased carbon/epoxy described by bimodal Weibull
distribution function. 相似文献
112.
Mahesh Chand Sharma 《Materials Chemistry and Physics》2012,131(3):600-604
Low cost deposition of large area CuInSe2 (CIS) thin films have been grown on Mo-coated glass substrate by simple and economic stacked elemental layer deposition technique in vacuum. The grown parameters such as concentration of Cu, In and Se elements have been optimized to achieve uniform thin film in vacuum chamber. The as-grown Cu/In/Se stacked layers have been annealed at 200 °C and 350 °C for 1 h in air ambient. The as-grown and annealed films have been further subjected to characterization by X-ray diffraction (XRD), optical absorption, atomic force microscopy (AFM) and I-V measurement techniques. XRD patterns revealed that as-grown Cu/In/Se stacked layers represent amorphous nature while annealed CIS film reproduces nano-polycrystalline nature with chalcopyrite structure. The optical band gap of annealed films increases with respect to air annealing which confirms the reduction of crystallite size. Surface morphology of as-grown Cu/In/Se stacked layers and annealed CIS thin films have been confirmed by AFM images. The electrical measurements show enhancement of conductivity which is useful for solar cell application. 相似文献
113.
114.
Bhadraiah Vempati Mahesh V. Panchagnula Alparslan Öztekin Sudhakar Neti 《Acta Mechanica》2010,210(1-2):1-12
This paper presents experimental and numerical results of interfacial dynamics of liquid–liquid flows when an immiscible core liquid is introduced into a continuous liquid flow. The fully developed flow model predicts multiple solutions of the jet diameter over a range of dimensionless numbers: flow rate ratio, viscosity ratio, Bond and Capillary numbers. Experiments have been carried out using Polyethylene Glycol (PEG) and Canola oil to investigate the realizability of the three possible solutions predicted by the fully developed flow model. The measured values of inner fluid radii agree very well with the lower branch of the three branched solution while deviating from the top branch beyond a critical flow ratio value. This deviation is attributed to the fact that the flow develops a non-axisymmetric solution at this critical point. Computational fluid dynamics simulations have also been performed to examine the developing core annular flow and to compare the analytical solution results of liquid jet radius. The results predicted by numerical simulations agree very well with both the lower and upper branches of solution predicted by the analytical theory. 相似文献
115.
The Rose Bengal is used as photosensitizer with d-Xylose as reductant and sodium lauryl sulphate (NaLS) as surfactant for the enhancement of the conversion efficiency and storage capacity of photogalvanic cell for its commercial viability. The observed value of the photogeneration of photopotential was 885.0 mV and photocurrent was 460.0 μA whereas maximum power of the cell was 407.10 μW. The observed power at power point was 158.72 μW and the conversion efficiency was 1.52%. The fill factor 0.3151 was experimentally determined at the power point of the cell. The rate of initial generation of photocurrent was 63.88 μA min−1. The photogalvanic cell so developed can work for 145.0 min in dark on irradiation for 165.0 min, i.e. the storage capacity of the photogalvanic cell is 87.87%. A simple mechanism for the photogeneration of photocurrent has also been proposed. 相似文献
116.
Ruben Van Coile Georgios P. Balomenos Mahesh D. Pandey Robby Caspeele 《Fire Technology》2017,53(5):1705-1744
The rise of Performance Based Design methodologies for fire safety engineering has increased the interest of the fire safety community in the concepts of risk and reliability. Practical applications have however been severely hampered by the lack of an efficient unbiased calculation methodology. This is because on the one hand, the distribution types of model output variables in fire safety engineering are not known and traditional distribution types as for example the normal and lognormal distribution may result in unsafe approximations. Therefore unbiased methods must be applied which make no (implicit) assumptions on the PDF type. Traditionally these unbiased methods are based on Monte Carlo simulations. On the other hand, Monte Carlo simulations require a large number of model evaluations and are therefore too computationally expensive when large and nonlinear calculation models are applied, as is common in fire safety engineering. The methodology presented in this paper avoids this deadlock by making an unbiased estimate of the PDF based on only a very limited number of model evaluations. The methodology is known as the Maximum Entropy Multiplicative Dimensional Reduction Method (ME-MDRM) and results in a mathematical formula for the probability density function (PDF) describing the uncertain output variable. The method can be applied with existing models and calculation tools and allows for a parallelization of model evaluations. The example applications given in the paper stem from the field of structural fire safety and illustrate the excellent performance of the method for probabilistic structural fire safety engineering. The ME-MDRM can however be considered applicable to other types of engineering models as well. 相似文献
117.
Widyani Darham Ahmad Lutfi Anis Izzul Adli Mohd Arif Nagamothu Kishore Babu Mohamad Kamal Harun Mahesh Kumar Talari 《Transactions of the Indian Institute of Metals》2017,70(3):649-654
The current study has investigated the influence of zirconium (Zr) addition to Mg–3Ca–xZr (x = 0.3, 0.6, 0.9 wt%) alloys prepared using argon arc melting on the microstructure and impression properties at 448–498 K under constant stress of 380 MPa. Microstructural analysis of as-cast Mg–3Ca–xZr alloys showed grain refinement with Zr addition. The observed grain refinement was attributed to the growth restriction effect of Zr in hypoperitectic Mg–3Ca–0.3 wt% Zr alloys. Heterogeneous nucleation of α-Mg in properitectic Zr during solidification resulted in grain refinement of hyperperitectic Mg–3Ca–0.6 wt% Zr and Mg–3Ca–0.9 wt% Zr alloys. The hardness of Mg–3Ca–xZr alloys increased as the amount of Zr increased due to grain refinement and solid solution strengthening of α-Mg by Zr. Creep resistance of Mg–3Ca–xZr alloys increased with the addition of Zr due to solid solution strengthening of α-Mg by Zr. The calculated activation energy (Qa) for Mg–3Ca samples (131.49 kJ/mol) was the highest among all alloy compositions. The Qa values for 0.3, 0.6 and 0.9 wt% Zr containing Mg–3Ca alloys were 107.22, 118.18 and 115.24 kJ/mol, respectively. 相似文献
118.
Mahesh Paidpilli Kapil Verma Rajat Pandey Anish Upadhyaya 《Transactions of the Indian Institute of Metals》2017,70(8):2017-2026
In the present work, one batch of prealloyed 6061Al powder was mixed with different lead compositions (5, 10, 15 vol.%) and another set with same composition was ball-milled for 5 h at 300 rpm. Microstructural features such as lattice constant, crystallite size, particle size and morphology were studied using XRD, particle size analyzer and SEM. Both the as-mixed as well as ball-milled powders were compacted at 300 MPa and sintered under N2 atmosphere for 1 h in tube furnace at 590 °C. The ball milling of 6061Al alloy powder improved sinter density and densification while lead addition showed negligible influence on these parameters. The microstructure of as-mixed 6061Al–Pb alloys exhibited equiaxial morphology whereas ball-milling resulted in elongated grains with uniform lead distribution. Quasi-static compressive mechanical behavior was investigated for 6061Al–Pb alloys at 1 × 10?3 s?1 strain rate. Results indicated that ultimate compressive and yield strength were sensitive to milling and lead volume fraction. 相似文献
119.
120.
K. V. Mahesh S. Anas S. Rahul S. Ananthakumar 《Journal of Materials Science: Materials in Electronics》2013,24(5):1495-1504
Nano size ZnO–Bi2O3 varistor precursor powders containing Y2O3 and Pr6O11 rare earth dopants were prepared by low temperature refluxing at 80 °C. Effect of rare earth dopants, densification by two-step sintering, evolution of microstructures and their influence on varistor properties were investigated. Chemically synthesized nano- precursor varistor powders produced controlled grain size in two-step sintering in which the average sintered ZnO grain size was reduced to at least half compared to the conventionally processed ZnO–Bi2O3 varistors. The study revealed that such grain size reduction is highly beneficial to attain enhanced varistor properties. 相似文献