全文获取类型
收费全文 | 234篇 |
免费 | 2篇 |
专业分类
化学 | 183篇 |
力学 | 1篇 |
数学 | 2篇 |
物理学 | 50篇 |
出版年
2022年 | 2篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 5篇 |
2017年 | 8篇 |
2016年 | 6篇 |
2015年 | 2篇 |
2014年 | 5篇 |
2013年 | 8篇 |
2011年 | 4篇 |
2010年 | 2篇 |
2009年 | 4篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 3篇 |
2005年 | 8篇 |
2004年 | 8篇 |
2003年 | 9篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1972年 | 3篇 |
1970年 | 2篇 |
1969年 | 7篇 |
1968年 | 8篇 |
1967年 | 6篇 |
1966年 | 4篇 |
1965年 | 5篇 |
1961年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有236条查询结果,搜索用时 15 毫秒
71.
O.E. Grikina N.F. Stepanov L.S. Khaikin E.A. Bovina L.V. Vilkov 《Journal of Molecular Structure》1977,37(2):251-259
The sp, spd and spd' approximations of the CNDO/2 method have been applied to energy calculations for some models of the acetyldimethylphosphine molecule generated during treatment of the electron diffraction data. The results obtained for trial configurations with different angles of rotation of the acetyl group about the PC ac bond predict two symmetric energy minima separated by a rather low barrier. This is in agreement with the electron diffraction data which are compatible with the suggestion of large amplitude torsional vibrations of the acetyl group. Energy calculations have also been performed for the final electron diffraction models. The calculations, however, fail to remove ambiguity from the question of a preferred model of the acetyldimethylphosphine molecule. 相似文献
72.
73.
L.S. Khaikin L.G. Andrutskaya O.E. Grikina L.V. Vilkov Yu.I. Elnatanov R.G. Kostyanovski 《Journal of Molecular Structure》1977,37(2):237-250
An electron diffraction study of the MeC(O)PMe2 molecule has been carried out which shows that the bond configuration at phosphorus in this compound is flattened from that observed in methylphosphines and dimethylcyanophosphine. This finding, as well as some lowering of barriers to inversion at phosphorus in acylphosphines, may be attributed to a contribution from conjugation of the amide type.Two models with different angles of rotation of the acetyl group about the PCAc bond, ψ, are consistent with the experimental data, those with ψ of 5.7 ± 6.6° (model I) and 78.8± 12.0° (model II) (ψ is measured relative to the Cs conformation with the CMePCMe bisector being cis with respect to the CO bond). Other parameters of the two models agree within uncertainties represented by three times standard deviation values 3σ (distances, ra, in nm; angles in degrees): model I model II PC (average) 0.1863(2) 0.1862(2) CC 0.1536(9) 0.1540(9) CO 0.1219(4) 0.1218(3) CH 0.1094(6) 0.1094(6) CMePCMe 105.7 (0.9) 105.1 (3.3) CMePCMe 99.3 (2.0) 102.2 (7.5) PCO 123.0 (0.6) 121.9 (0.6) PCC 115.3 (0.9) 112.7 (0.9) The greater errors for phosphorus valence angles and the angle of rotation, ψ, in the case of model II are due to high correlation between these para A possible difference between the PCMe and PCAc bond lengths has been estimated to be. ± 0.001nm(model I) or ± 0.003 nm(model II). Neither of the models can be preferred on the basis of the electron diffraction data; the results'obtained are also compatible with' the suggestion of large amplitude torsion motions. 相似文献
74.
75.
A. A. Anosov R. V. Belyaev V. A. Vilkov M. V. Dvornikova V. V. Dvornikova A. S. Kazanskii N. A. Kuryatnikova A. D. Mansfel’d 《Acoustical Physics》2013,59(1):103-108
The results of an acoustothermometric study of the human hand under local hyperthermia and hypothermia are presented. Individuals under testing plunged their hands in hot or cold water for several minutes. Thermal acoustic radiation was detected by two sensors placed near the palm and near the backside of the tested hand. The internal temperature profiles of the hand were reconstructed. The indirect estimate of the reconstruction error was 0.6°C, which is acceptable for medical applications. Hyperthermia was achieved by placing the hand in water with a maximal temperature of 44°C for 2 min. In this case, the internal temperature was 35.4 ± 0.6°C. Hypothermia was achieved by placing the hand in water with a temperature of 17.8°C for 15 min. In this case, the internal temperature decreased from 26 to 24°C. The use of a four-sensor planar receiving array allowed dynamic mapping of the acoustic brightness temperature of the hand. 相似文献
76.
Miroslava Martinková Jozef Gonda Alena Uhríková Jana Špaková Raschmanová Mária Vilková Beáta Oroszová 《Tetrahedron: Asymmetry》2013,24(2-3):121-133
The total synthesis of the HCl salts of two natural sphingolipid-related amino acid derivatives, mycestericins F 4 and G 5 together with unnatural ent-4·HCl, starting from the four crucial scaffolds 6, 8, 9, 11 and utilizing the Wittig reaction to build the C20 backbone, has been achieved. The selection of selective functional group interconversions accompanied with suitable protection–deprotection protocols in the coupling products 20 and 34 gave the desired structures. 相似文献
77.
Vilkov E. A. Chigarev S. G. Malikov I. V. Fomin L. A. 《Physics of the Solid State》2021,63(10):1574-1578
Physics of the Solid State - The terahertz radiation in the Fe/Mo magnetic transition, which occurs when pumping the upper spin subzone in the Fe/Mo interface with a high-density current, has been... 相似文献
78.
Sergei O. Filnov Dmitry A. Estyunin Ilya I. Klimovskikh Tatiana P. Estyunina Vladimir A. Golyashov Anton S. Tarasov Nikolay N. Kosyrev Vasily A. Komarov Gennady S. Patrin Anna A. Rybkina Oleg Yu Vilkov Alexander M. Shikin Oleg E. Tereshchenko Ratibor G. Chumakov Alexey M. Lebedev Artem G. Rybkin 《固体物理学:研究快报》2024,18(3):2300336
The utilization of graphene on silicon carbide (SiC) substrates holds substantial promise for advancements in spintronics and nanoelectronics. Furthermore, incorporating magnetic metals provides an optimal framework for probing fundamental physical phenomena. The approach to developing such systems is in situ intercalation of graphene with magnetic metals. Herein, the electronic structure is analyzed and the magnetic properties of the system are synthesized by the thermal decomposition of 6H-SiC(0001) surface and subsequent intercalation of graphene with cobalt (Co) and iron (Fe) atoms. X-ray photoemission spectroscopy and low-energy electron diffraction are employed to control the synthesis and metal intercalation processes. The morphological characteristics of the synthesized system are studied by means of atomic force microscopy. The findings derived from magneto-optic Kerr effect measurements reveal a homogeneous ferromagnetic ordering at room temperature. Angle-resolved photoemission spectroscopy is used to ascertain the impact of intercalation on graphene's electronic structure. The results of this study are essential for the development of graphene-based spintronics and nanoelectronic devices as well as for fundamental studies in magnetic graphene systems. 相似文献
79.
80.