全文获取类型
收费全文 | 112篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
化学 | 83篇 |
力学 | 4篇 |
数学 | 8篇 |
物理学 | 20篇 |
出版年
2023年 | 2篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2016年 | 2篇 |
2015年 | 4篇 |
2014年 | 3篇 |
2013年 | 10篇 |
2012年 | 6篇 |
2011年 | 9篇 |
2010年 | 7篇 |
2009年 | 5篇 |
2008年 | 8篇 |
2007年 | 6篇 |
2006年 | 8篇 |
2005年 | 3篇 |
2004年 | 8篇 |
2003年 | 6篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1985年 | 1篇 |
1976年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有115条查询结果,搜索用时 140 毫秒
1.
V. A. Sadovnichy V. V. Alexandrov E. Soto T. B. Alexandrova T. G. Astakhova R. Vega N. V. Kulikovskaya V. I. Kurilov S. S. Migunov N. E. Shulenina 《Journal of Mathematical Sciences》2007,146(3):5938-5947
A mathematical model of the system composed of two sensors, the semicircular canal and the sacculus, is suggested. The model
is described by three lines of blocks, each line of which has the following structure: a biomechanical block, a mechanoelectrical
transduction mechanism, and a block describing the hair cell ionic currents and membrane potential dynamics. The response
of this system to various stimuli (head rotation under gravity and falling) is investigated. Identification of the model parameters
was done with the experimental data obtained for the axolotl (Ambystoma tigrinum) at the Institute of Physiology, Autonomous
University of Puebla, Mexico. Comparative analysis of the semicircular canal and sacculus membrane potentials is presented.
__________
Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 11, No. 7, pp. 207–220, 2005. 相似文献
2.
Ryabov AD Otto S Samuleev PV Polyakov VA Alexandrova L Kazankov GM Shova S Revenco M Lipkowski J Johansson MH 《Inorganic chemistry》2002,41(16):4286-4294
Structural and mechanistic aspects of orthoplatination of acetophenone and benzaldehyde oximes by the platinum(II) sulfoxide and sulfide complexes [PtCl(2)L(2)] (2, L = SOMe(2) (a), rac-SOMePh (b), R-SOMe(C(6)H(4)Me-4) (c), and SMe(2) (d)) to afford the corresponding platinacycles cis-(C,S)-[Pt(II)(C(6)H(3)-2-CR'=NOH-5-R)Cl(L)] (3, R, R' = H, Me) have been investigated. The reaction of acetophenone oxime with sulfoxide complex 2a in methanol solvent occurs noticeably faster than with sulfide complex 2d due to the fact that the sulfoxide is a much better platinum(II) leaving ligand than the sulfide. Evidence is presented that the orthoplatination is a multistep process. The formation of unreactive dichlorobis(N-oxime)platinum(II) cations accounts for the rate retardation by excess acetophenone oxime and suggests the importance of pseudocoordinatively unsaturated species for the C-H bond activation by Pt(II). A comparative X-ray structural study of dimethyl sulfoxide platinacycle 3b (R = R' = Me) and its sulfide analogue 3e (R = H, R' = Me), as well as of SOMePh complex 3c (R = H, R' = Me), indicated that they are structurally similar and a sulfur ligand is coordinated in the cis position with respect to the sigma-bound phenyl carbon. The differences concern the Pt-S bond distance, which is notably longer in the sulfide complex 3e (2.2677(11) A) as compared to that in sulfoxide complexes 3b (2.201(2)-2.215(2) A) and 3c (2.2196(12) A). Whereas the metal plane is practically a plane of symmetry in 3b due to the H-bonding between the sulfoxide oxygen and the proton at carbon ortho to the Pt-C bond, an S-bonded methyl of SOMePh and SMe(2) is basically in the platinum(II) plane in complexes 3c and 3e, respectively. There are intra- and intermolecular hydrogen bond networks in complex 3b. An interesting structural feature of complex 3c is that the two independent molecules in the asymmetric unit of the crystal reveal an extremely short Pt-Pt contact of 3.337 A. 相似文献
3.
V. A. Alexandrova L. N. Shirokova G. N. Bondarenko A. S. Petrosyan 《Polymer Science Series A》2013,55(2):107-114
Nanocomposite macromolecular systems consisting of silver nanoparticles immobilized in a carboxymethyl chitin matrix are obtained. The method of ultrasonic treatment of a heterophase system (isooctane-water) in the presence of antioxidants of plant origin is used to transfer silver nanoparticles from their micellar solution in isooctane to an aqueous polymer solution. The formation of hydrogen bonds between the functional groups of carboxymethyl chitin and hydroxyl groups of antioxidants is confirmed by Fourier transform infrared spectroscopy. This interaction can provide additional stabilization of metal nanoparticles in the macromolecular system. The transmission electron microscopy data shows that the size of silver nanoparticles increases in a series of antioxidants (gallic acid, dihydroquercetin, and syringic acid). The increase is presumably caused by significant differences in the structures of these antioxidants and their interaction with the polymer matrix. 相似文献
4.
5.
Lidia Alexandrova Michail Nedyalkov Dimo Platikanov Roberta Razzetti Federico Bianco 《Colloid and polymer science》2013,291(11):2725-2731
The wetting properties of pulmonary surfactant aqueous solutions with respect to solid surfaces with different degree of hydrophobicity have been studied. The contact angles θ of drops from a pulmonary surfactant solution onto SiO2-glass surfaces have been measured as a function of their degree of hydrophobicity θ w. The completely hydrophilic SiO2-glass surface is essentially hydrophobized by the animal-derived pulmonary surfactant Curosurf. The hydrophobization depends on the surfactant concentration—the contact angles increase with increasing the Curosurf concentration C s in the low concentration range, but they remain almost constant in a wide range of C s >90 μg/ml. Additions like NaCl and bovine serum albumin influence the θ-values. The contact angles θ naturally increase with increasing θ w but this dependence is not linear—the curve steepens at larger θ w values. The thickness h of the wetting thin liquid films from Curosurf aqueous solutions depends on the hydrophobicity θ w of the solid surface and the h(θ w) curves always pass a minimum. The h-values, as well as the h(θ w) curve, are mainly determined by the steric and hydrophobic disjoining pressures, which depend on the orientations and conformations of the molecules adsorbed on the solid surface from the very complicated multi-component aqueous solutions. 相似文献
6.
A. P. Kuznetsov A. S. Alexandrova O. I. Buzhinsky K. L. Gubskiy T. V. Kazieva A. V. Savchenkov S. N. Tugarinov 《Physics of Atomic Nuclei》2015,78(10):1155-1163
The results of experimental studies into efficiency of removal of films with a complex composition from metal mirrors by pulsed fiber laser irradiation are presented. It is shown that the initial reflectivity of optical elements can be restored by the selection of modes of irradiation impacting the surface with the sputtered film. Effective cleaning is performed by radiation with a power density lower than 107 W/cm2. The removal of contaminations at such a relatively low power density occurs in a solid phase, owing to which the thermal effect on the mirror is insignificant. 相似文献
7.
Juan M. Venegas Zisheng Zhang Theodore O. Agbi William P. McDermott Anastassia Alexandrova Ive Hermans 《Angewandte Chemie (International ed. in English)》2020,59(38):16527-16535
Boron‐containing materials, and in particular boron nitride, have recently been identified as highly selective catalysts for the oxidative dehydrogenation of alkanes such as propane. To date, no mechanism exists that can explain both the unprecedented selectivity, the observed surface oxyfunctionalization, and the peculiar kinetic features of this reaction. We combine catalytic activity measurements with quantum chemical calculations to put forward a bold new hypothesis. We argue that the remarkable product distribution can be rationalized by a combination of surface‐mediated formation of radicals over metastable sites, and their sequential propagation in the gas phase. Based on known radical propagation steps, we quantitatively describe the oxygen pressure‐dependent relative formation of the main product propylene and by‐product ethylene. Free radical intermediates most likely differentiate this catalytic system from less selective vanadium‐based catalysts. 相似文献
8.
For a rigid/plastic, hardening material model, it is shown that the velocity fields adjacent to surfaces of maximum friction must satisfy the sticking condition. This means that the stress boundary condition, the maximum friction law, may be replaced by the velocity boundary condition. Axisymmetric flows without rotation and planar flows are considered. 相似文献
9.
The switching and memory effects in composite films based on conducting polymers [poly(phenylenevinylene), thiophene, and carbazole derivatives] and inorganic nanoparticles (ZnO, Si) are investigated. It is established that the introduction of inorganic nanoparticles (ZnO, Si) exhibiting strong acceptor properties into polymer materials leads to the appearance of memory effects, which manifest themselves in the transition of the polymer from a low-conductivity state to a high-conductivity state. For a number of composites, this transition is accompanied by the formation of a region with a negative differential resistance and a hysteresis in the current-voltage characteristics. It is demonstrated that the observed effects are determined by the mechanism of charge carrier transfer in the composite. In particular, the main mechanism of transport in films based on thiophene derivatives is associated with electrical conduction due to the tunneling of charge carriers between conducting regions embedded in a nonconducting matrix, whereas the dominant mechanism of transport in “polymer-semiconductor nanoparticle” composite films is hopping conduction, which is responsible for the effects observed in these objects. 相似文献
10.
C. Aguilar‐Lugo R. Le Lagadec Alexander D. Ryabov G. Cedillo Valverde S. Lopez Morales L. Alexandrova 《Journal of polymer science. Part A, Polymer chemistry》2009,47(15):3814-3828
Cationic substitutionally inert cyclometalated ruthenium (II) and osmium (II) complexes, ([Mt(o‐C6H4‐2‐py)(LL)2]PF6), where LL‐1,10‐phenanthroline (phen) or 2,2′‐bipyridine (bipy), were used for radical polymerization of styrene. Gradual modification of the complexes within the series allowed comparison of the catalytic activity and the redox properties. There was no correlation between the reducing powers of the complexes and their catalytic activities. The osmium compound of the lowest reduction potential was not active. All the ruthenium complexes catalyzed the polymerization of styrene in a controlled manner; but the level of control and the catalytic activity were different under the same polymerization conditions. [Ru(o‐C6H4‐2‐py)(phen)2]PF6 demonstrated the best catalytic performance though its redox potential was the highest. It catalyzed the “living” polymerization with a reasonable rate at a catalyst‐to‐initiator ratio of 0.1. 1 equiv. of Al(OiPr)3 accelerated the polymerization and improved the control, but higher amount of Al(OiPr)3 did not speed up the polymerization and moved the process into the uncontrollable regime. Under the most optimal conditions, the controlled polymerization occurs fast without any additive and the catalyst degradation. Added free ligands inhibited the polymerization suggesting that the catalytically active ruthenium intermediates are generated via the reversible dechelation of bidentate phen or bipy ligands. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3814–3828, 2009 相似文献