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21.
L. N. Bortnikov D. A. Pavlov M. M. Rusakov A. P. Shaikin 《Russian Journal of Physical Chemistry B, Focus on Physics》2011,5(1):75-83
The experimental unit, procedure for testing, and the results and reliability of the determination of the composition of combustion products formed from gasoline-hydrogen-air (containing 0–100% hydrogen), gasoline-air, and isooctane-hydrogen-air mixtures in a constant-volume chamber are described. Studies were performed at initial mixture temperatures of 20–70°C and a 0.1 MPa pressure. 相似文献
22.
Normal halogen dependence of 13C NMR chemical shifts of halogenomethanes revisited at the four‐component relativistic level
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Dmitry O. Samultsev Yury Yu. Rusakov Leonid B. Krivdin 《Magnetic resonance in chemistry : MRC》2016,54(10):787-792
The ‘Normal Halogen Dependence’ of 13C NMR chemical shifts in the series of halogenomethanes is revisited at the four‐component relativistic level. Calculations of 13C NMR chemical shifts of 70 halogenomethanes have been carried out at the density functional theory (DFT) and MP2 levels with taking into account relativistic effects using the four‐component relativistic theory of Dirac‐Coulomb within the different computational methods (4RPA, 4OPW91) and hybrid computational schemes (MP2 + 4RPA, MP2 + 4OPW91). The most efficient computational protocols are derived for practical purposes. Relativistic shielding effect reaches as much as several hundreds of ppm for heavy halogenomethanes, and to account for this effect in comparison with experiment at the qualitative level, relativistic Dyall's basis sets of triple‐zeta quality or higher are to be used within the framework of the four‐component relativistic theory taking into account solvent effects. Relativistic geometrical optimization (as compared with the non‐relativistic level) is essential for the molecules containing at least two iodines at one carbon atom. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
23.
Yury Yu. Rusakov Leonid B. Krivdin Maxim V. Penzik Vladimir A. Potapov Svetlana V. Amosova 《Magnetic resonance in chemistry : MRC》2012,50(10):653-658
Stereochemical structure of nine Z‐2‐(vinylsulfanyl)ethenylselanyl organyl sulfides has been investigated by means of experimental measurements and second‐order polarization propagator approach calculations of their 1H–1H, 13C–1H, and 77Se–1H spin–spin coupling constants together with a theoretical conformational analysis performed at the MP2/6‐311G** level. All nine compounds were shown to adopt the preferable skewed s‐cis conformation of their terminal vinylsulfanyl group, whereas the favorable rotational conformations with respect to the internal rotations around the C–S and C–Se bonds of the internal ethenyl group are both skewed s‐trans. Stereochemical trends of 77Se–1H spin–spin coupling constants originating in the geometry of their coupling pathways and the selenium lone pair effect were rationalized in terms of the natural J‐coupling analysis within the framework of the natural bond orbital approach. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
24.
A theoretical study of geminal and vicinal 77Se‐1 H coupling constants in the benchmark dimethyl and diethyl selenides has been performed at the SOPPA level followed by the NJC analysis within the NBO approach to reveal their stereochemical behavior in respect with the three main structural factors, namely, (i) the dihedral angle dependences, (ii) the bond angle dependences and (iii) the lone pair effects. It has been demonstrated that both geminal and vicinal couplings provide a unique stereospecificity in respect with the orientational lone pair effect together with the geometry of a coupling pathway, which is of prime importance for the stereochemical studies of organoselenium compounds. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
25.
26.
The well-known expressions for the Burnett components of the stress tensor and the heat flux vector in a monatomic gas are transformed to a more effective form. The greatest simplifications are obtained for the stress tensor when using the usually employed approximate values of the Burnett transport coefficients, which are exact for the gas consisting of Maxwellian molecules. 相似文献
27.
N. N. Eremin V. S. Urusov V. S. Rusakov O. V. Yakubovich 《Crystallography Reports》2002,47(5):759-767
The structure and some physical properties of malayaite CaSnOSiO4 have been studied by the precision X-ray diffraction, Mössbauer spectroscopy, and computer simulation of the structure. The unit-cell parameters a = 7.152(2) Å, b = 8.888(2) Å, c = 6.667(2) Å, β = 113.37(2)°, V = 389.0(3) Å3, and μr = 0.68 are refined on a synthetic impurity-free sample. The distribution of the deformation electron density is analyzed in the basic fragments of the crystal structure forming an anionic framework. The constructed potentials of pair and three-particle interaction reproduced quite well the elastic, dielectric, and energy characteristics and allowed us to predict their numerical values, which are in good agreement with the limited available experimental data. 相似文献
28.
N. V. Anshukova A. I. Golovashkin L. I. Ivanova I. B. Krynetskii A. P. Rusakov D. A. Shulyatev 《Physics of the Solid State》2005,47(9):1595-1599
For single-crystal samples of the (Sr1?xLax)3Ru2O7 ruthenates, the temperature dependence of the thermal expansion coefficient α(T)) is measured in the range 4.2–80 K. The effect of magnetic fields H ≤ 3.5 T on thermal expansion is analyzed. It is found that the (Sr1?xLax)3Ru2O7 ruthenates exhibit an anomalous (negative) thermal expansion coefficient in the temperature range T ≤ 18 K. The position and width of the anomaly revealed in the temperature dependence of the thermal expansion coefficient α(T)) depend substantially on the magnetic field. The origin of the thermal expansion anomaly in ruthenates, the correlation of this anomaly with the stability of the crystal lattice, and the common nature of the anomalies in the thermal properties of ruthenates and high-temperature superconductors are discussed. 相似文献
29.
N. V. Anshukova A. I. Golovashkin L. I. Ivanova I. B. Krynetskii A. P. Rusakov D. A. Shulyatev 《Physics of the Solid State》2004,46(8):1394-1397
Single-crystal samples of the Bi2 + xSr2 ? x ? yCu1 + yO6 + δ system revealed anomalous (negative) thermal expansion in the temperature range 10–20 K. Magnetic fields of 1–3 T were found to strongly affect the position and width of the anomaly region. A thermal-expansion singularity was detected at temperatures T≈30–50 K, which may be related to the formation of a pseudogap. 相似文献
30.
N. V. Anshukova B. M. Bulychev A. I. Golovashkin L. I. Ivanova A. A. Minakov A. P. Rusakov 《Physics of the Solid State》2003,45(7):1207-1212
The temperature dependences of the specific heat C(T) and thermal conductivity K(T) of MgB2 were measured at low temperatures and in the neighborhood of T c . In addition to the well-known superconducting transition at T c ≈40 K, this compound was found to exhibit anomalous behavior of both the specific heat and thermal conductivity at lower temperatures, T≈10–12 K. Note that the anomalous behavior of C(T) and K(T) is observed in the same temperature region where MgB2 was found to undergo negative thermal expansion. All the observed low-temperature anomalies are assigned to the existence in MgB2 of a second group of carriers and its transition to the superconducting state at Tc2≈10?12 K. 相似文献