全文获取类型
收费全文 | 112篇 |
免费 | 3篇 |
专业分类
化学 | 40篇 |
力学 | 2篇 |
数学 | 11篇 |
物理学 | 62篇 |
出版年
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 4篇 |
2012年 | 2篇 |
2011年 | 5篇 |
2010年 | 3篇 |
2009年 | 6篇 |
2008年 | 3篇 |
2007年 | 6篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 4篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
排序方式: 共有115条查询结果,搜索用时 31 毫秒
61.
The disorder in ion motion in a LaF3 superionic conductor with tysonite structure is determined from NMR spectra. The method is sensitive to dynamic effects with
correlation times of 5×10−3<τ<10−6 s. Within the 260–400-K interval, ion movement is observed only on one of the sublattices (F1), and it exhibits a correlation time distribution. The shape of the distribution is well fitted by a log-Gaussian. The distribution
in correlation times reflects noticeable spatial fluctuations of local potentials in the LaF3 superionic conductor.
Fiz. Tverd. Tela (St. Petersburg) 41, 1616–1620 (September 1999) 相似文献
62.
A lidar equation for Raman backscattering of semiconductor laser radiation by I2 and H2 molecules is solved. The obtained results allow laser wavelength optimization for probing atmospheric I2 and H2 molecules at a distance up to 2 km. 相似文献
63.
Il’in E. G. Parshakov A. S. Privalov V. I. Goryunov E. I. Goryunova I. B. Nifant’ev E. E. 《Russian Journal of Coordination Chemistry》2019,45(9):667-674
Russian Journal of Coordination Chemistry - The complex formation of TiF4 with the phosphorylated ketone Ph2P(O)CH(Me)CH2C(O)Et (L), containing an asymmetric carbon atom in the aliphatic... 相似文献
64.
D. Kruk A.F. Privalov P. Gumann F. Fujara 《Solid state nuclear magnetic resonance》2009,35(3):187-193
Fluorine relaxation profiles for a BaF2 single crystal collected at several temperatures have been analyzed in terms of essentially different motional models: free rotational and free translational diffusion. The analysis has been performed to critically review the sensitivity of field dependent relaxation studies to mechanisms of molecular motions. The tested motional models do not realistically describe the fluorine dynamics within the crystal lattice. They have been chosen to attempt to answer quite fundamental questions regarding the feasibility of the field dependent nuclear spin relaxation studies to provide unique information on dynamic processes: 1. Is it possible to get information about the motional mechanisms by analyzing relaxation profiles collected in a broad frequency range? 2. To what extent is it possible to reasonably reproduce relaxation profiles in terms of unrealistic motional models?It has been concluded from the analysis that the rotational model leading to a single exponential correlation function explains the experimental data much better than the translational one. Validity regimes of the second order perturbation theory have been discussed in the context of the investigated system and the applied models. 相似文献
65.
Samec JS Ell AH Aberg JB Privalov T Eriksson L Bäckvall JE 《Journal of the American Chemical Society》2006,128(44):14293-14305
Reaction of [2,3,4,5-Ph(4)(eta(5)-C(4)COH)Ru(CO)(2)H] (2) with different imines afforded ruthenium amine complexes at low temperatures. At higher temperatures in the presence of 2, the complexes decomposed to give [Ru(2)(CO)(4)(mu-H)(C(4)Ph(4)COHOCC(4)Ph(4))] (1) and free amine. Electron-rich imines gave ruthenium amine complexes with 2 at a lower temperature than did electron-deficient imines. The negligible deuterium isotope effect (k(RuHOH)/k(RuDOD) = 1.05) observed in the reaction of 2 with N-phenyl[1-(4-methoxyphenyl)ethylidene]amine (12) shows that neither hydride (RuH) nor proton (OH) is transferred to the imine in the rate-determining step. In the dehydrogenation of N-phenyl-1-phenylethylamine (4) to the corresponding imine 8 by [2,3,4,5-Ph(4)(eta(4)-C(4)CO)Ru(CO)(2)] (A), the kinetic isotope effects observed support a stepwise hydrogen transfer where the isotope effect for C-H cleavage (k(CHNH)/k(CDNH) = 3.24) is equal to the combined (C-H, N-H) isotope effect (k(CHNH)/k(CDND) = 3.26). Hydrogenation of N-methyl(1-phenylethylidene)amine (14) by 2 in the presence of the external amine trap N-methyl-1-(4-methoxyphenyl)ethylamine (16) afforded 90-100% of complex [2,3,4,5-Ph(4)(eta(4)-C(4)CO)]Ru(CO)(2)NH(CH(3))(CHPhCH(3)) (15), which is the complex between ruthenium and the amine newly generated from the imine. At -80 degrees C the reaction of hydride 2 with 4-BnNH-C(6)H(9)=NPh (18), with an internal amine trap, only afforded [2,3,4,5-Ph(4)(eta(4)-C(4)CO)](CO)(2)RuNH(Ph)(C(6)H(10)-4-NHBn) (19), where the ruthenium binds to the amine originating from the imine, showing that neither complex A nor the diamine is formed. Above -8 degrees C complex 19 rearranged to the thermodynamically more stable [Ph(4)(eta(4)-C(4)CO)](CO)(2)RuNH(Bn)(C(6)H(10)-4-NHPh) (20). These results are consistent with an inner sphere mechanism in which the substrate coordinates to ruthenium prior to hydrogen transfer and are difficult to explain with the outer sphere pathway previously proposed. 相似文献
66.
Ab Initio Molecular Dynamics with Explicit Solvent Reveals a Two‐Step Pathway in the Frustrated Lewis Pair Reaction
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Maoping Pu Prof. Dr. Timofei Privalov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(49):17708-17720
The role solvent plays in reactions involving frustrated Lewis pairs (FLPs)—for example, the stoichiometric mixture of a bulky Lewis acid and a bulky Lewis base—still remains largely unexplored at the molecular level. For a reaction of the phosphorus/boron FLP and dissolved CO2 gas, first principles (Born–Oppenheimer) molecular dynamics with explicit solvent reveals a hitherto unknown two‐step reaction pathway—one that complements the concerted (one‐step) mechanism known from the minimum‐energy‐path calculations. The rationalization of the discovered reaction pathway—that is, the stepwise formation of P?C and O?B bonds—is that the environment (typical organic solvents) stabilizes an intermediate which results from nucleophilic attack of the phosphorus Lewis base on CO2. This finding is significant because presently the concerted reaction‐path paradigm predominates in the rationalization of FLP reactivity. Herein we point out how to attain experimental proof of our results. 相似文献
67.
68.
The lidar equation for the fluorescence of 127I2 molecules is numerically solved. All the radiation wavelengths of a copper vapor laser are considered with the aim of choosing the one that is the most appropriate for detection of the minimum possible concentration of iodine molecules when this laser is used as a radiation source of a fluorescence lidar. 相似文献
69.
Journal of Applied Spectroscopy - The lidar equation for Raman scattering of light by hydrogen fluoride molecules is solved in order to select the laser wavelength and lidar parameters and to... 相似文献
70.
How Frustrated Lewis Acid/Base Systems Pass through Transition‐State Regions: H2 Cleavage by [tBu3P/B(C6F5)3]
下载免费PDF全文
![点击此处可从《Chemphyschem》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We investigate the transition‐state (TS) region of the potential energy surface (PES) of the reaction tBu3P+H2+B(C6F5)3→tBu3P‐H(+)+(?)H?B(C6F5)3 and the dynamics of the TS passage at room temperature. Owing to the conformational inertia of the phosphane???borane pocket involving heavy tBu3P and B(C6F5)3 species and features of the PES E(P???H, B???H | B???P) as a function of P???H, B???H, and B???P distances, a typical reactive scenario for this reaction is a trajectory that is trapped in the TS region for a period of time (about 350 fs on average across all calculated trajectories) in a quasi‐bound state (scattering resonance). The relationship between the timescale of the TS passage and the effective conformational inertia of the phosphane???borane pocket leads to a prediction that isotopically heavier Lewis base/Lewis acid pairs and normal counterparts could give measurably different reaction rates. Herein, the predicted quasi‐bound state could be verified in molecular collision experiments involving femtosecond spectroscopy. 相似文献