全文获取类型
收费全文 | 313篇 |
免费 | 11篇 |
国内免费 | 1篇 |
专业分类
化学 | 223篇 |
晶体学 | 1篇 |
力学 | 9篇 |
数学 | 45篇 |
物理学 | 47篇 |
出版年
2023年 | 4篇 |
2022年 | 9篇 |
2021年 | 18篇 |
2020年 | 7篇 |
2019年 | 14篇 |
2018年 | 13篇 |
2017年 | 13篇 |
2016年 | 12篇 |
2015年 | 14篇 |
2014年 | 17篇 |
2013年 | 16篇 |
2012年 | 16篇 |
2011年 | 22篇 |
2010年 | 18篇 |
2009年 | 17篇 |
2008年 | 23篇 |
2007年 | 12篇 |
2006年 | 11篇 |
2005年 | 16篇 |
2004年 | 11篇 |
2003年 | 7篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1998年 | 1篇 |
1996年 | 4篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有325条查询结果,搜索用时 15 毫秒
41.
42.
Marco?Dozzi Yuriy?Kozachenko Yuliya?Mishura Kostiantyn?RalchenkoEmail authorView authors OrcID profile 《Statistical Inference for Stochastic Processes》2018,21(1):21-52
We construct the least-square estimator for the unknown drift parameter in the multifractional Ornstein–Uhlenbeck model and establish its strong consistency in the non-ergodic case. The proofs are based on the asymptotic bounds with probability 1 for the rate of the growth of the trajectories of multifractional Brownian motion (mBm) and of some other functionals of mBm, including increments and fractional derivatives. As the auxiliary results having independent interest, we produce the asymptotic bounds with probability 1 for the rate of the growth of the trajectories of the general Gaussian process and some functionals of it, in terms of the covariance function of its increments. 相似文献
43.
In the present paper we consider and study numerically two systems based on model FitzHugh–Nagumo neurons, where in the presence of periodic modulation of parameters it is possible to implement chaotic dynamics on the attractor in the form of a Smale–Williams solenoid in the stroboscopic Poincaré map. In particular, hyperbolic chaos characterized by structural stability occurs in a single neuron supplemented by a time-delay feedback loop with a quadratic nonlinear element. 相似文献
44.
45.
Marina Tikhonova Yuliya Kuzminova Xiaoying Fang Weiguo Wang Rustam Kaibyshev 《哲学杂志》2013,93(36):4181-4196
The effect of processing and annealing temperatures on the grain boundary characters in the ultrafine-grained structure of a 304-type austenitic stainless steel was studied. An S304H steel was subjected to multidirectional forging (MDF) at 500–800°C to total strains of ~4, followed by annealing at 800–1,000°C for 30 min. The MDF resulted in the formation of ultrafine-grained microstructures with mean grain sizes of 0.28–0.85 μm depending on the processing temperature. The annealing behaviour of the ultrafine-grained steel was characterized by the development of continuous post-dynamic recrystallization including a rapid recovery followed by a gradual grain growth. The post-dynamically recrystallized grain size depended on both the deformation temperature and the annealing temperature. The recrystallization kinetics was reduced with an increase in the temperature of the preceding deformation. The grain growth during post-dynamic recrystallization was accompanied by an increase in the fraction of Σ3n CSL boundaries, which was defined by a relative change in the grain size, i.e. a ratio of the annealed grain size to that evolved by preceding warm working (D/D0). The fraction of Σ3n CSL boundaries sharply rose to approximately 0.5 in the range of D/D0 from 1 to 5, which can be considered as early stage of continuous post-dynamic recrystallization. Then, the rate of increase in the fraction of Σ3n CSL boundaries slowed down significantly in the range of D/D0 > 5. A fivefold increase in the grain size by annealing is a necessary condition to obtain approximately 50% Σ3n CSL boundaries in the recrystallized microstructure. 相似文献
46.
Yuliya S. Rozhkova Irina V. Plekhanova Alexey A. Gorbunov Olga G. Stryapunina Evgeny N. Chulakov Victor P. Krasnov Marina A. Ezhikova Mikhail I. Kodess Pavel A. Slepukhin Yurii V. Shklyaev 《Tetrahedron letters》2019,60(11):768-772
A new approach for the synthesis of functionalized racemic 3,4-dihydroferroceno[c]pyridines via the Ritter reaction of 2-methyl-1-ferrocenylpropan-1-ol with nitriles in the presence of methansulfonic acid was developed. The scope and limitations of the reaction were evaluated. Selected racemic 3,4-dihydroferroceno[c]pyridines were successfully separated by preparative HPLC on a Chiralcel OD-H column. The absolute configuration of the enantiomers was determined by X-ray crystal structure analysis. 相似文献
47.
The synthetic samples of nickel olivine were measured in the temperature range 100–630 K by the X-ray powder diffraction method. Temperature dependencies of molar volumes and coefficients of bulk thermal expansion of liebenbergite were determined. Interpolation and extrapolation of the experimental data were performed by the procedure based on the Debye–Mie–Gruneisen theory of solid body in the range from 50 to 2000 K, and the Gruneisen coefficient and Debye temperature were calculated. Heat capacity and its behavior in accordance with temperature were evaluated.
相似文献48.
Gimranov Dmitriy R. Abdullina Aisylu F. Sevast’yanova Ekaterina V. Petrova Yuliya Yu. 《平面色谱法杂志一现代薄层色谱法》2015,28(5):343-351
JPC – Journal of Planar Chromatography – Modern TLC - The thin-layer chromatography (TLC) procedures of metal cations, modified with amines and cationic surfactant micelles, followed by... 相似文献
49.
Irina Balakhnina Nikolay Brandt Andrey Chikishev Natalia Rebrikova Yuliya Yurchuk 《Applied Physics A: Materials Science & Processing》2014,117(4):1865-1871
Old paper samples are bleached using pulsed laser radiation with a wavelength of 532 nm. The ablation products of five paper samples that differ by composition and production dates are studied using Raman microspectroscopy. Cellulose, protein, calcite, titanium dioxide (anatase, rutile, and brookite), quartz, lazurite, bonattite, and dolomite are identified as ablation products. 相似文献
50.
Michalkova A Kosenkov D Gorb L Leszczynski J 《The journal of physical chemistry. B》2008,112(29):8624-8633
High-level ab initio predictions of the tautomerization equilibrium and rate constants of water-assisted proton transfer of 1-methyl-cytosine (MeC) to its MeC* imino tautomeric form in the presence of up to two water molecules (W) and the Na(+) cation were carried out. The calculated energy values were used to obtain the thermodynamic parameters and equilibrium concentration of MeC, its rare tautomer, and their complexes with up to two water molecules and the Na (+) cation. The rate constants for the tautomerization were obtained by using the instanton approach (a quasiclassical method based on the least-action principle). Hydration of MeC by one water molecule leads to an increase of the concentration of the MeC* tautomer in the equilibrium mixture and a decrease of the barrier of the MeC* formation (to 15.6 kcal/mol). If the Na(+) cation is present, the tautomeric form is much less favored, and the tautomerization barrier increases to 25.2 kcal/mol. It was found that MeC monohydrate has both the highest equilibrium (2.9 x 10(-2)) and rate (7.9 x 10(5) s(-1)) constants of tautomerization in comparison to the MeC*NaW and MeC*Na2W complexes containing the Na(+) cation. Moreover, this study also allows one to estimate the concentration of MeC present in the cell during DNA synthesis as the unwanted tautomer, which in forming a mismatched base pair can cause spontaneous point mutations. Kinetic simulations have demonstrated that the low values of equilibrium (10(-14)-10(-13)) and rate constants (10(-17)-10(-16) s(-1)) of tautomerization make contribution of the MeC*Na(+)W and MeC*Na(+)2W complexes to the point mutations in DNA unlikely. In contrast to these Na(+) complexes, MeC*W can reach an equilibrium concentration of 2.9 x 10(-2) within 10(-7) s; thus, it can increase the probability of the point mutations. 相似文献