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排序方式: 共有98条查询结果,搜索用时 31 毫秒
1.
The effect of the removal of zinc from brass nanoparticles has been experimentally discovered upon irradiating their suspension in ethanol by laser radiation. The analysis of the absorption spectra of nanoparticles shows that brass nanoparticles are transformed to copper nanoparticles during irradiation. The results are interpreted in terms of the high-pressure-induced modification of the phase diagram of nanoparticles. This pressure is caused by, first, the small radius of nanoparticles and, second, the pressure of the surrounding-liquid vapors upon the laser heating of nanoparticles. 相似文献
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Ovshinsky SR Young RT Allred DD DeMaggio G Van der Leeden GA 《Physical review letters》1987,58(24):2579-2581
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S. I. Dolgaev A. A. Lyalin G. A. Shafeev Shafeev Voronov 《Applied Physics A: Materials Science & Processing》1996,63(1):75-79
The etching of polycrystalline SiC is studied with the help of radiation of a copper-vapor laser either in air or under the layer of a liquid (H2O, DMSO). The etching rate in air is as high as 0.24 m/pulse, in DMSO 0.07 gm/pulse at an energy density of 16 J/cm2. The etched surface is characterized with Scanning Electron Microscopy (SEM) and X-ray diffractometry. Etching of SiC ceramics in air revealed the partial amorphization of SiC and the formation of microcrystals of elementary Si with an average size of 300 Å. The etched surface of SiC ceramics takes on the ability to reduce Cu from a corresponding electroless plating solution. The adherence of the deposit is as high as 30 N/mm2 and is a function of the scanning velocity of the laser beam. 相似文献
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种植沙生植物--沙棘改善内蒙古地区生态环境 总被引:2,自引:0,他引:2
结合内蒙古地区现状,对沙棘的生物学和生态学特性、沙棘属植物化学成分和微量元素及种植沙生植物——沙棘的重要性和必要性进行了详细的研究和探讨。研究表明,沙棘属植物具有极强的生态适应性并富含多种营养成分和生物活性物质,并以耐干旱、耐瘠薄、萌蘖及固氮能力强等特点被称为治理非宜林地水土流失、改善生态环境的先锋树种。种植沙棘是治理内蒙古脆弱生态环境最经济、最有效的措施,是贫瘠的不毛之地发展经济、增加收入的经济树种。另外.种植沙棘的技术简便,容易掌握,投资少,见效快。 相似文献
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以内蒙古地区沙棘果实为原料,研究了提取黄色素的工艺条件,同时对该色素的性质进行了初步探讨。结果表明,以95%的乙醇溶液作浸提剂,提取的黄色素浓度最高,工艺流程简单易行,且无毒,无污染。对提取的黄色素进行的性质试验表明,沙棘黄色素对光、热具有较好的稳定性,适用于酸性或弱碱性的食品中,葡萄糖、氧化剂(H2O2)、还原剂(Na2SO3)等食品添加剂均无明显影响以上结果为这种优良天然色素的开发与应用提供了参考。 相似文献
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2-Trifluoromethyl-4H-thiochromene-4-thione obtained from 2-trifluoromethyl-4H-thiochromen-4-one and P2S5 reacts with aromatic amines, hydrazine hydrate, phenylhydrazine, and hydroxylamine at the C(4) atom of the chromene ring
to give the corresponding anils, azine, hydrazones, and oxime of thiochromone. 2-Trifluoromethyl-4H-thiochromen-4-one is oxidized by hydrogen peroxide in AcOH into 4-oxo-2-trifluoromethyl-4H-thiochromene 1,1-dioxide and reduced by NaBH4 to 2-trifluoromethyl-4H-thiochromen-4-ol or cis-2-(trifluoromethyl)thiochroman-4-ol. When treated with hydrazine hydrate, thiochromen-4-one gives 3(5)-(2-mercaptophenyl)-5(3)-trifluoromethylpyrazole.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 504–509, March, 2006. 相似文献
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S. F. Timashev A. V. Simakin G. A. Shafeev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2014,88(11):1980-1988
A brief review of results on initiation of nuclear transformations under conditions of the laser ablation of metals in aqueous media upon exposure to picosecond laser impulses with peak intensity J E ~ 1010–1013 W/cm2, which is orders of magnitude less than required for the direct initiation of nuclear processes, J E ~ 1018–1019 W/cm2, is presented. It is shown that the decay rate of radioactive nuclei (using the example of uranium 238) increases significantly (by orders of magnitude), nucleus transmutation processes are initiated (using the example of the transmutation of mercury 196 nuclei into gold 197), and the nuclear fusion of light elements occurs (using the example of tritium nuclei) under such conditions. Concepts regarding the processes of inelastic (with the generation of neutrino-antineutrino pair) interactions between electrons of high (on the chemical scale) energies (~5–10 eV) and nuclei are developed in order to understand the totality of the current experimental data on the initiation of such processes under conditions of the laser ablation of metals in solutions of ordinary and heavy water. This is reflected in the definition of such processes as nuclear-chemical. It is suggested that the state of nuclear matter in nuclei formed during such interactions is in an unbalanced in-shake-up state, and cannot be pictured in the standard manner, as an ensemble of a certain number of nucleons. Such states are reactive for a wide class of nuclear transformations. 相似文献
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