全文获取类型
收费全文 | 217篇 |
免费 | 6篇 |
国内免费 | 2篇 |
专业分类
化学 | 124篇 |
晶体学 | 1篇 |
力学 | 9篇 |
数学 | 36篇 |
物理学 | 55篇 |
出版年
2024年 | 2篇 |
2023年 | 1篇 |
2022年 | 6篇 |
2021年 | 6篇 |
2020年 | 11篇 |
2019年 | 9篇 |
2018年 | 4篇 |
2017年 | 7篇 |
2016年 | 10篇 |
2015年 | 6篇 |
2014年 | 11篇 |
2013年 | 20篇 |
2012年 | 20篇 |
2011年 | 13篇 |
2010年 | 11篇 |
2009年 | 14篇 |
2008年 | 12篇 |
2007年 | 12篇 |
2006年 | 10篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 8篇 |
2002年 | 7篇 |
2001年 | 1篇 |
1998年 | 2篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有225条查询结果,搜索用时 171 毫秒
51.
Enantiomerically pure (3S,7R,8aS)-3-phenyloctahydropyrrolo[1,2-a]pyrazine-7-ol, (3S,7R,8aS)-3-methyl octahydropyrrolo[1,2-a]pyrazine-7-ol, (3S,7R,8aS)-3-isopropyloctahydropyrrolo[1,2-a]pyrazine-7-ol and (3S,7R,8aS)-3-isobutyloctahydropyrrolo[1,2-a]pyrazine-7-ol 16d were synthesized via preparation of the corresponding cyclic amides from enantiomerically pure l-proline and hydroxyproline derivatives followed by reduction using sodium borohydride-iodine. 相似文献
52.
53.
54.
55.
This paper reports the experimental results of parametric amplification applied to a harmonically forced MEMS gyroscope. Parametric amplification of the forced response at resonance in the range 10–100 is investigated. Several important factors pertinent to practical exploitation are highlighted. The main obstacle to high gain parametric amplification is the nonlinearity of the electrostatic force which becomes significant for high amplitude vibration. By significantly reducing the harmonic forcing level to just above the noise threshold, parametric amplification of the resonant response by a factor of 80 has been achieved whilst maintaining linear response characteristics. 相似文献
56.
K.R. Venugopala Reddy M.N.K. Harish M.H. Moinuddin Khan 《Journal of fluorine chemistry》2007,128(9):1019-1025
This publication discuss the synthesis and characterization of pure 1,3,8,10,15,17,22,24-octafluorophthalocyanines of copper(II), cobalt(II), nickel(II) and zinc(II). The complexes are characterized by elemental analysis, electronic spectra, IR spectra, thermal studies and X-ray powder diffraction method to check the purity and integrity of the complexes. The magnetic measurements over the range of magnetic field strength 1.03-2.32 kG showed a variation of magnetic moments with field strength indicating the presence of intermolecular co-operative effect. 相似文献
57.
Jani D. B. Bhabhor Kiran Dadi Mohsin Doshi Sachindra Jotaniya P. V. Ravat Harish Bhatt Kumar 《Journal of Thermal Analysis and Calorimetry》2020,140(5):2011-2031
Journal of Thermal Analysis and Calorimetry - Solid desiccant-assisted cooling and dehumidification systems are becoming very popular nowadays for maintaining the required thermal comfort in... 相似文献
58.
59.
Deposition and characterization of TiAlSiN nanocomposite coatings prepared by reactive pulsed direct current unbalanced magnetron sputtering 总被引:3,自引:0,他引:3
Harish C. Barshilia Moumita Ghosh Shashidhara Raja Ramakrishna K.S. Rajam 《Applied Surface Science》2010,256(21):6420-6426
This work reports the performance of high speed steel drill bits coated with TiAlSiN nanocomposite coating at different Si contents (5.5-8.1 at.%) prepared using a four-cathode reactive pulsed direct current unbalanced magnetron sputtering system. The surface morphology of the as-deposited coatings was characterized using field emission scanning electron microscopy. The crystallographic structure, chemical composition and bonding structure were evaluated using X-ray diffraction, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, respectively. The corrosion behavior, mechanical properties and thermal stability of TiAlSiN nanocomposite coatings were also studied using potentiodynamic polarization, nanoindentation and Raman spectroscopy, respectively. The TiAlSiN coating thickness was approximately 2.5-2.9 μm. These coatings exhibited a maximum hardness of 38 GPa at a silicon content of approximately 6.9 at.% and were stable in air up to 850 °C. For the performance evaluation, the TiAlSiN coated drills were tested under accelerated machining conditions by drilling a 12 mm thick 304 stainless steel plate. Under dry conditions the uncoated drill bits failed after drilling 50 holes, whereas, TiAlSiN coated drill bits (Si = 5.5 at.%) drilled 714 holes before failure. Results indicated that for TiAlSiN coated drill bits the tool life increased by a factor of more than 14. 相似文献
60.
Preeti Joshi Harish C. Joshi Sunil Kumar Sanghi Subir Kundu 《Mikrochimica acta》2010,169(3-4):383-388
An amperometric biosensor for dopamine is described. It is based on the enzyme monoamine oxidase immobilized on a glutaraldehyde-activated eggshell membrane that was deposited on a glassy carbon electrode. The Michaelis-Menten constant (Km) is 0.087 mM. Optimum pH and temperature conditions were obtained at pH 7.0 and 37 °C, respectively. The sensor showed a detection limit of 20 μM, a linear range from 50 μM to 250 μM, and a storage stability of ~25 days. In order to further improve the performance, a Nafion coating was applied on the electrode surface which gave favorable results with respect to shelf life of the enzyme (~40 days), the limit of detection, and the selectivity over ascorbic acid and uric acid. 相似文献