全文获取类型
收费全文 | 24120篇 |
免费 | 58篇 |
国内免费 | 46篇 |
专业分类
化学 | 10150篇 |
晶体学 | 409篇 |
力学 | 944篇 |
综合类 | 11篇 |
数学 | 3476篇 |
物理学 | 9234篇 |
出版年
2023年 | 14篇 |
2022年 | 180篇 |
2021年 | 368篇 |
2020年 | 377篇 |
2019年 | 552篇 |
2018年 | 1005篇 |
2017年 | 1117篇 |
2016年 | 1324篇 |
2015年 | 537篇 |
2014年 | 1099篇 |
2013年 | 1669篇 |
2012年 | 1499篇 |
2011年 | 1560篇 |
2010年 | 1778篇 |
2009年 | 1726篇 |
2008年 | 1687篇 |
2007年 | 1628篇 |
2006年 | 1418篇 |
2005年 | 890篇 |
2004年 | 627篇 |
2003年 | 326篇 |
2002年 | 318篇 |
2001年 | 311篇 |
2000年 | 616篇 |
1999年 | 349篇 |
1998年 | 448篇 |
1997年 | 426篇 |
1996年 | 111篇 |
1995年 | 37篇 |
1994年 | 36篇 |
1993年 | 8篇 |
1992年 | 20篇 |
1991年 | 10篇 |
1990年 | 19篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 11篇 |
1986年 | 8篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1978年 | 7篇 |
1977年 | 10篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1971年 | 4篇 |
1968年 | 11篇 |
1967年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
B. P. Aduev N. R. Nurmukhametov R. P. Kolmykov A. P. Nikitin M. V. Anan’eva A. A. Zvekov A. V. Kalenskii 《Russian Journal of Physical Chemistry B, Focus on Physics》2016,10(4):621-627
The kinetics of the explosive decomposition of pressed pentaerythritol tetranitrate pellets containing nickel nanoparticles with various radii has been investigated experimentally, with the explosion initiated by a neodymium laser pulse (wavelength, 1064 nm; pulse duration at half-height, 14 ns), and probability curves for this process have been recorded. The experimental values of critical initiation energy density corresponding to 50% explosion probability are 0.9, 0.7, and 1.4 J/cm2 at a nickel particle radius of 67, 78, and 138 nm, respectively. The initial time interval in which the intensity of light emission accompanying the explosive decomposition increases begins during the action of the pulse and is described by a Gaussian function with an effective constant of k = (1.4 ± 0.1) × 108 s–1, which is independent of the nanoparticle radius. Experimental data of this study can be interpreted within the micro-hotspot model of thermal explosion. 相似文献
992.
I. V. Kumpanenko A. V. Roshchin N. A. Ivanova I. D. Epinat’ev A. M. Skryl’nikov M. V. Dyubanov T. N. Korneeva 《Russian Journal of Physical Chemistry B, Focus on Physics》2016,10(5):740-747
The selective catalytic reduction (SCR) of nitrogen dioxide in an air flow modeling the exhaust gas from an internal combustion engine is studied. Granulated V2O5 (13.5%)–MnO2 (0.7–1.0%)/Al2O3 powder (AVK-10M catalyst) and ammonia injected into a SCR catalytic cell are used as a heterogeneous catalyst of NO2 reduction and a reducing agent, respectively. If the efficiency of NO2 removal is high enough and satisfies the requirements of the State Sanitary Standards for the maximum permissible concentrations of substances emitted into the atmosphere (\(MP{C_{N{O_2}}}\) = 0.085 mg/m3), the reducing agent (ammonia) is not completely consumed during SCR, so a considerable amount of NH3 can be released into the atmosphere. Therefore, a strict control of both NO2 and unreacted ammonia emissions is needed. The dependences of the concentrations of [NH3] and [NO2] on the [NH3]/[NO2] ratio for the model air flow passed through the AVK-10M granular heterogeneous catalyst are measured. It is found that the maximum degree of removal of NO2 from the air takes place at [NH3]/[NO2] = 1.3. In the conventional process, the concentration of [NO2] drop from 530.00 to 0.07 mg/m3, i.e., below the \(MP{C_{N{O_2}}}\). At the same time, the ammonia concentration increases to [NH3] = 3.4 mg/m3, which becomes 85 times the \(MP{C_{N{O_2}}}\), 0.04 mg/m3. To remove unreacted ammonia from air flows, we developed [P–(SO3 -)2 · Me2+] sulfocationites, where Me are the Cu and/or Ca ions, P is a styrene–divinylbenzene copolymer. It is shown that the concentration of ammonia passed through the adsorption cell filled with a freshly sulfocationite drops below \(MP{C_{N{H_3}}}\) = 0.04 mg/m3. The dependences of the dynamic exchange capacity (DEC) before ammonia breakthrough for the [P–(SO3 -)2 · Cu2+] delta-sulfocationite on the air flow rate, [NH3] concentration, and humidity are measured. The maximum value of the DEC, δ = 59.5 mg/cm3, is observed at an air flow velocity of 2.171 m/s, [NH3] = 0.0035 mg/L, and 75% humidity. To illustrate practical applications of the proposed improved SCR method, it is shown that a 3-L replaceable [P–(SO3 -)2 · Cu2+] sorbent cartridge in a SCR exhaust gas purifier for a car internal combustion engine does not need replacement more frequently than every 50000 km. 相似文献
993.
G. G. Savenkov V. A. Morozov I. A. Os’kin V. A. Bragin A. A. Lukin 《Russian Journal of Physical Chemistry B, Focus on Physics》2016,10(5):769-773
Experimental results on the ignition of energetic two- and three-layer potassium picrate- and lead(II, IV) oxide-based compositions with a high-current electron beam of nanosecond duration are reported. It is shown that the sustainability of explosive transformations in layered compositions depends on the boundary conditions and the additional impact of the cathode flame (high-temperature metal plasma). 相似文献
994.
V.?Kh.?FedotovEmail author N.?I.?Kol’tsov 《Russian Journal of Physical Chemistry B, Focus on Physics》2016,10(5):753-759
A new method is suggested for solving the inverse problem of chemical kinetics. This method provides means to derive, from unsteady-state experimental data, the rate constants of catalytic reactions in which each step involves at least one main reactant. Examples of applying this method to two- and three-step reactions are presented. 相似文献
995.
The effect of low-temperature annealing on the magnetization curve of YBa2Cu3O6 + x ceramics in the superconducting state (x ≈ 0.9) is investigated. When the annealing time is fairly long, the field dependence of magnetic moment M exhibits a feature in the form of a plateau, where the value of M remains almost constant. The evolution of this feature in the magnetization curves of annealed samples with annealing time and temperature is studied. It is assumed that low-temperature annealing gives rise to metastable ferromagnetic clusters in YBa2Cu3O6 + x ceramics, the contribution of which to the magnetic moment accounts for the feature in the magnetization curves of the annealed samples. 相似文献
996.
S. G. Barsov S. I. Vorob’ev V. P. Koptev S. A. Kotov S. M. Mikirtych’yants G. V. Shcherbakov L. A. Aksel’rod G. P. Gordeev V. N. Zabenkin I. M. Lazebnik 《Physics of the Solid State》2007,49(8):1492-1497
The Pd1?x Fe x )0.95Mn0.05 alloy with random competing interaction was studied by measuring the muon spin relaxation in an external transverse magnetic field and in a zero magnetic field. Using the measured temperature dependence of the dynamic relaxation rate λ and the characteristics of the distribution of local static fields, the phase states of the sample under study are refined. In particular, it is shown that the ferromagnetic and spin-glass states coexist simultaneously in the sample below 25 K. Combined studies of the sample using the μSR and neutron depolarization methods made it possible to determine the size of magnetic inhomogeneities to be 2–6 μm in the temperature range 5–40 K. 相似文献
997.
V. I. Gatal’skaya H. Dabkowska P. Dube J. E. Greedan S. V. Shiryaev 《Physics of the Solid State》2007,49(6):1125-1131
The temperature and field dependences of the magnetization of a single crystal of a new class of layered cobaltites, TbBaCo4O7+x , with a structure containing a Kagomé lattice and a triangular lattice were measured. The measurements were performed on a SQUID magnetometer at temperatures in the range 2–300 K and in magnetic fields of up to 55 kOe for two field orientations. The anisotropy of the magnetization was studied, and the presence of antiferromagnetic ordering in fields H < H c and a weak magnetic-field-induced (H > H c ) ferromagnetic component in the low-temperature range was demonstrated. The magnetic characteristics of the initial TbBaCo4O7+x single crystal and the single crystal annealed in an O2 atmosphere were compared. 相似文献
998.
Yu. I. Yuzyuk I. N. Zakharchenko V. A. Alyoshin I. N. Leont’ev L. M. Rabkin V. M. Mukhortov P. Simon 《Physics of the Solid State》2007,49(9):1759-1765
Heteroepitaxial thin films of Ba0.7Sr0.3TiO3 (BST-0.3) solid solutions were grown on single-crystal (001) MgO substrates by high-frequency cathode sputtering of a stoichiometric ceramic target. The parameters of the tetragonal unit cell of a film were determined by x-ray diffraction methods, and the temperature dependence of the parameter c was studied depending on the synthesis conditions in the temperature range 293–520 K. An E(TO) soft mode was observed in the Raman spectra, the frequency of which correlates with two-dimensional stresses arising in films. It is shown that the two-dimensional stresses in a film are controlled not only by the film-substrate lattice constant mismatch and the difference of their thermal expansion coefficients but also are significantly dependent on the heteroepitaxial growth mechanism. It is shown that the phase transition to the tetragonal paraelectric phase during film heating occurs irrespective of the growth mechanism. 相似文献
999.
S. M. Podgornykh V. A. Kazantsev V. I. Myakon’kikh E. V. Shcherbakova A. A. Ermakov 《Journal of Experimental and Theoretical Physics》2007,105(1):62-64
The low-temperature specific heat C p of La(Fe0.873Co0.007Al0.12)13 compound has been measured in two states: (i) antiferromagnetic (AFM) with a Néel temperature of T N = 192 K and (ii) ferromagnetic (FM). The FM order appears at T = 4.2 K in a sample exposed to an external magnetic field with induction B C ≥ 2.5 T and is retained for a long time in a zero field at temperatures up to T*C = 23 K. The coefficient γFM in the low-temperature specific heat C = γT + βT 3 in the FM state differs quite insignificantly from that (γAFM) in the AFM state. Contributions to the low-temperature specific heat, which are related to a change in the elastic and magnetoelastic energy caused by magnetostrictive deformations, are considered. 相似文献
1000.
E. A. Popova N. Tristan C. Hess R. Klingeler B. Büchner L. N. Bezmaternykh V. L. Temerov A. N. Vasil’ev 《Journal of Experimental and Theoretical Physics》2007,105(1):105-107
The neodymium ferroborate NdFe3(BO3)4 undergoes an antiferromagnetic transition at T N = 30 K, which manifests itself as a λ-type anomaly in the temperature dependence of the specific heat C and as inflection points in the temperature dependences of the magnetic susceptibility χ measured at various directions of an applied magnetic field with respect to the crystallographic axes of the sample. Magnetic ordering occurs only in the subsystem of Fe3+ ions, whereas the subsystem of Nd3+ ions remains polarized by the magnetic field of the iron subsystem. A change in the population of the levels of the ground Kramers doublet of neodymium ions manifests itself as Schottky-type anomalies in the C(T) and χ(T) dependences at low temperatures. At low temperatures, the magnetic properties of single-crystal NdFe3(BO3)4 are substantially anisotropic, which is determined by the anisotropic contribution of the rare-earth subsystem to the magnetization. The experimental data obtained are used to propose a model for the magnetic structure of NdFe3(BO3)4. 相似文献