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排序方式: 共有288条查询结果,搜索用时 15 毫秒
101.
S. V. Larionov T. G. Leonova N. I. Batrachenko I. V. Korol’kov V. S. Danilovich V. E. Platonov A. M. Maksimov V. P. Fadeeva 《Russian Journal of Inorganic Chemistry》2008,53(2):209-212
Silver(I) compounds with perfluorinated aromatic thiols (4-nonafluorodiphenylthiol C6F5C6F4SH (HL1), 2-heptafluoronaphthalenethiol C10F7SH (HL2), and pentafluorothiophenol C6F5SH (HL3), namely AgL1 (I), AgL2 (II), AgL3 (III), were prepared. The thermal properties of compounds I–III and the composition of thermolysis products were studied. By powder X-ray diffraction and electron microscopy, it was shown that thermolysis of compounds I–III under argon and thermolysis of compound III in air yield Ag nanoparticles. 相似文献
102.
Natalia P. Tarasova Evgeniya G. Vasileva 《Phosphorus, sulfur, and silicon and the related elements》2016,191(11-12):1447-1451
ABSTRACTIn this paper the screening calculations of the removal time of phosphorus from water bodies of federal districts of Russia are presented. Calculations are made using the matrix algebra based approach and are applied as a tool for the estimation of the fate of phosphates in different environmental media (water, air, soil, biota, etc.). The results show that the use of phosphate fertilizers is sometimes quite high in the most vulnerable federal districts. It means that the application of fertilizers in order to increase the yield of agriproducts should be accompanied by detailed assessment of the risks of eutrophication. Calculations have shown high vulnerability in the district of the Lake Baika. 相似文献
103.
N. V. Lyskov Yu. G. Metlin K. I. Astaf’eva Yu. D. Tret’yakov L. S. Leonova Yu. A. Dobrovol’skii 《Russian Journal of Electrochemistry》2007,43(4):390-397
Composites ZrO2-(Bi2CuO4+ 20 wt % Bi2O3) (50–80 vol % ZrO2) are synthesized and their physicochemical properties are studied. It is demonstrated that the composites comprise triple-phase mixtures of ZrO2 of a monoclinic modification, Bi2CuO4, and solid solution Bi2?x Zr x O3 + x/2 and retain their mechanical strength up to 800°C. Impedance spectroscopy is used to examine their electroconductivity at 700–800°C in the interval of partial oxygen pressures extending from 37 to 2.1 × 104 Pa. Contributions made by electronic and ionic constituents to their overall conductivity are evaluated. The best specimens’ conductivity is ~0.01 S cm?1, with the electronic and ionic transport numbers nearly equal. The composite consisting of 50 vol % ZrO2 and 50 vol % (Bi2CuO4 + 20 wt % Bi2CuO4) is tested in the role of an oxygen-separating membrane. The selective flux of oxygen in the temperature interval 750–800°C amounts to (2.2–6.3) × 10?8 mol cm?2 s?1, testifying that these materials may be used as gas-separating membranes. 相似文献
104.
We study the boundedness of the Cauchy singular integral operators on curves in complex plane in generalized Morrey spaces. We also consider the weighted case with radial weights. We apply these results to the study of Fredholm properties of singular integral operators in weighted generalized Morrey spaces. 相似文献
105.
M. V. Leonova M. R. Baimuratov Yu. N. Klimochkin 《Russian Journal of Organic Chemistry》2017,53(3):326-334
Hydrolytic cleavage of cage γ-sultones have been studied. Alkaline hydrolysis of homoadamantane γ-sultone leads to the formation of sulfonates with erythro configuration. The reduction of homoadamantane γ-sultone with LiAlH4–AlCl3 yields desulfurization and deoxygenation products. 相似文献
106.
Tszin Chzhao A. E. Ukshe L. S. Leonova Yu. A. Dobrovol’skii 《Russian Journal of Electrochemistry》2011,47(5):595-604
Heteropoly acids Cs
x
H3 − x
PW12O40 · nH2O with different cesium content are synthesized as nanostructured compositions. Their actual composition and specific surface
are determined, microstructure studied and proton conductivity measured. Composite electrocatalytic systems based on platinized
cesium salt of phosphorus-tungsten heteropolyacid Cs2.3H0.7PW12O40 · nH2O are prepared with admixture of Vulcan XC-72 carbon black. Mixed electronic-ionic conduction of the composite systems with
different carbon black content is studied. Platinum-based nanostructured electrocatalyst based on the Cs2.3H0.7PW12O40 · nH2O-materials as support is synthesized and studied. The possible effective using of the studied nanocomposite as electrode
for low-temperature hydrogen-air fuel cells is demonstrated. Electrochemical studies of catalytic properties of the Pt-Cs2.3H0.7PW12O40 · nH2O-C-electrodes in hydrogen and air are carried out by example of the prepared materials with different carbon black content. 相似文献
107.
Konarev DV Kuźmin AV Simonov SV Khasanov SS Yudanova EI Lyubovskaya RN 《Dalton transactions (Cambridge, England : 2003)》2011,40(17):4453-4458
New ionic complex {Co(+)(dppe)(2)}·(C(60)˙(-))·(C(6)H(4)Cl(2))(2) (1) was obtained by the reduction of a Co(dppe)Br(2) and C(60) mixture by TDAE in o-dichlorobenzene followed by precipitation of crystals by hexane. Optical and EPR spectra of 1 indicated the formation of C(60)˙(-) radical anions and diamagnetic Co(+)(dppe)(2) cations. The structure of 1 solved at 100(2) K involves chains of C(60)˙(-) arranged along the lattice a-axis with a center-to-center distance of 10.271 ?. The chains are separated by bulky Co(+)(dppe)(2) cations and solvent molecules. All components of 1 are well ordered allowing the distortion of the C(60)˙(-) radical anion to be analyzed. An elongation of the C(60)˙(-) sphere by 0.0254(2) was found. It is essentially smaller than those in the salts (Cp*(2)Ni(+))·(C(60)˙(-))·CS(2) and (PPN(+))(2)·(C(60)(2-)) with greater distortion of the fullerene cage. The calculation of the electronic structure of fullerene by the extended Hückel method showed slight splitting of the C(60) LUMO, due to the distortion, by three levels. Two levels are located 180 and 710 cm(-1) higher than the ground level. The averaged 6-6 and 5-6 bonds in C(60)˙(-) with lengths of 1.397(2) and 1.449(2) ? are close to those determined for the C(60)(2-) dianions in (PPN(+))(2)·(C(60)(2-)), but are slightly longer and shorter, respectively, than the length of these bonds in neutral C(60). 相似文献
108.
Whenever water interacts with another dipolar entity, a broadening of its dielectric relaxation occurs. Often this broadening can be described by the Cole-Cole (CC) spectral function. A new phenomenological approach has been recently presented [A. Puzenko, P. Ben Ishai, and Y. Feldman, Phys. Rev. Lett. 105, 037601 (2010)] that illustrates a physical mechanism of the dipole-matrix interaction underlying the CC behavior in complex systems. By considering the relaxation amplitude Δε, the relaxation time τ, and the broadening parameter α, one can construct a set of 3D trajectories, representing the dynamic behavior of different systems under diverse conditions. Our hypothesis is that these trajectories will contribute to a deeper understanding of the dielectric properties of complex systems. The paper demonstrates how the model describes the state of water in aqueous solutions of non-ionic solutes. For this purpose complex dielectric spectra for aqueous solutions of D-glucose and D-fructose are analyzed. 相似文献
109.
AA Fokin LV Chernish PA Gunchenko EY Tikhonchuk H Hausmann M Serafin JE Dahl RM Carlson PR Schreiner 《Journal of the American Chemical Society》2012,134(33):13641-13650
The metal-induced coupling of tertiary diamondoid bromides gave highly sterically congested hydrocarbon (hetero)dimers with exceptionally long central C-C bonds of up to 1.71 ? in 2-(1-diamantyl)[121]tetramantane. Yet, these dimers are thermally very stable even at temperatures above 200 °C, which is not in line with common C-C bond length versus bond strengths correlations. We suggest that the extraordinary stabilization arises from numerous intramolecular van der Waals attractions between the neighboring H-terminated diamond-like surfaces. The C-C bond rotational dynamics of 1-(1-adamantyl)diamantane, 1-(1-diamantyl)diamantane, 2-(1-adamantyl)triamantane, 2-(1-diamantyl)triamantane, and 2-(1-diamantyl)[121]tetramantane were studied through variable-temperature (1)H- and (13)C NMR spectroscopies. The shapes of the inward (endo) CH surfaces determine the dynamic behavior, changing the central C-C bond rotation barriers from 7 to 33 kcal mol(-1). We probe the ability of popular density functional theory (DFT) approaches (including BLYP, B3LYP, B98, B3LYP-Dn, B97D, B3PW91, BHandHLYP, B3P86, PBE1PBE, wB97XD, and M06-2X) with 6-31G(d,p) and cc-pVDZ basis sets to describe such an unusual bonding situation. Only functionals accounting for dispersion are able to reproduce the experimental geometries, while most DFT functionals are able to reproduce the experimental rotational barriers due to error cancellations. Computations on larger diamondoids reveal that the interplay between the shapes and the sizes of the CH surfaces may even allow the preparation of open-shell alkyl radical dimers (and possibly polymers) that are strongly held together exclusively by dispersion forces. 相似文献
110.
Ekaterina Leonova Jekabs Grins Mohammadreza Shariatgorji Leopold L. Ilag Mattias Edn 《Solid state nuclear magnetic resonance》2009,36(1):11-18
We compare 29Si magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectra from the two modifications of silicon nitride, α-Si3N4 and β-Si3N4, with that of a fully (29Si, 15N)-enriched sample 29Si315N4, as well as 15N NMR spectra of Si315N4 (having 29Si at natural abundance) and 29Si315N4. We show that the 15N NMR peak-widths from the latter are dominated by J(29Si–15N) through-bond interactions, leading to significantly broader NMR signals compared to those of Si315N4. By fitting calculated 29Si NMR spectra to experimental ones, we obtained an estimated coupling constant J(29Si–15N) of 20 Hz. We provide 29Si spin-lattice (T1) relaxation data for the 29Si315N4 sample and chemical shift anisotropy results for the 29Si site of β-Si3N4. Various factors potentially contributing to the 29Si and 15N NMR peak-widths of the various silicon nitride specimens are discussed. We also provide powder X-ray diffraction (XRD) and mass spectrometry data of the samples. 相似文献