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91.
N.Z. Lyakhov A.P. Chupakhin V.P. Isupov V.V. Boldyrev 《Journal of solid state chemistry》1978,26(2):173-178
The dependence of the growth rate vg of nuclei during CuSO4·5H2O dehydration upon water vapor pressure PH2O has been investigated. At small PH2O (less than 1 Torr at 50°C), vg falls rapidly with decreasing PH2O, and simultaneously vg anisotropy disappears. At PH2O = 1–9 Torr, vg for elliptic and round nuclei is constant and independent of PH2O. The influence of initially keeping the samples in water vapor upon the kinetics of the following dehydration has been studied. Treatment by water vapor leads to slowing of dehydration and increasing its degree of transformation. On the basis of data obtained a kinetic interpretation of the Topley-Smith effect has been proposed. 相似文献
92.
Thermal decomposition of ammonium perchlorate 总被引:10,自引:0,他引:10
V.V. Boldyrev 《Thermochimica Acta》2006,443(1):1-36
This review represents an attempt to summarize literature data on thermal decomposition of ammonium perchlorate. The mechanism of thermal decomposition and various factors which influence on the thermal decomposition of ammonium perchlorate are discussed. 相似文献
93.
The lowest-energy isomers of the high-order carboxide series, COn (n = 3-8), have been elucidated via ab initio quantum chemical calculations. The structures of the lowest order of these (3 and 4) are in close agreement with previous calculations and with experimental data. The structures of the higher-order species are elucidated and correlated to the previous structures, showing similarities in structure and reactivity pathways. The reaction energies of the formation of all products are shown to be related. Exothermic pathways of formation often involve a C2v form of CO2, which was shown to be metastable. The newly identified species could be intermediates in atmospheric reactions. The calculated vibrational frequencies and IR intensities may be used to identify these metastable species. 相似文献
94.
Alexandrova AN Boldyrev AI Fu YJ Yang X Wang XB Wang LS 《The Journal of chemical physics》2004,121(12):5709-5719
The application of the ab initio genetic algorithm with an embedded gradient has been carried out for the elucidation of global minimum structures of a series of anionic sodium chloride clusters, Na(x)Cl(x+1) (-) (x=1-4), produced in the gas phase using electrospray ionization and studied by photoelectron spectroscopy. These are all superhalogen species with extremely high electron binding energies. The vertical electron detachment energies for Na(x)Cl(x+1) (-) were measured to be 5.6, 6.46, 6.3, and 7.0 eV, for x=1-4, respectively. Our ab initio gradient embedded genetic algorithm program detected the linear global minima for NaCl(2) (-) and Na(2)Cl(3) (-) and three-dimensional structures for the larger species. Na(3)Cl(4) (-) was found to have C(3v) symmetry, which can be viewed as a Na(4)Cl(4) cube missing a corner Na(+) cation, whereas Na(4)Cl(5) (-) was found to have C(4v) symmetry, close to a 3x3 planar structure. Excellent agreement between the theoretically calculated and the experimental spectra was observed, confirming the obtained structures and demonstrating the power of the developed genetic algorithm technique. 相似文献
95.
V. V. Nefedova A. I. Boldyrev J. Simons 《International journal of quantum chemistry》1995,55(6):441-457
Potential energy curves for the ground and low-lying excited states of the AH2+ (A = Mg—Ar) dications have been calculated using high-level ab initio methods with large atomic orbital basis sets. Quasi-bound potential energy curves with local minima and deprotonation barriers have been found for most of the dications studied. The energies, tunneling lifetimes, and widths of the quasi-bound states have been calculated by numerical solution of the radial Schrodinger equation using the Numeov method. All these dications except ArH2+ have low-lying states which support quasi-bound vibrational states. The ArH2+ dication has a 2∏i potential energy curve with a minimum so shallow that it does not support any quasi-bound vibrational states. Results of our calculations are compared with previous ab initio calculations and available experimental data. © 1995 John Wiley & Sons, Inc. 相似文献
96.
We analyzed chemical bonding in low-lying isomers of the recently computationally predicted B(6)H(6)Li(6) molecule. According to our calculations the benzene-like B(6)H(6)Li(6) (D(2h), (1)A(1g)) arachno structure with the planar aromatic B(6)H(6)(6-) anion is the most stable one. A nido isomer with two aromatic B(6)H(6)(4-) (pentagonal pyramid) and Li(3)(+) (triangular) moieties, which can be considered as derived from the global minimum structure through a two-electron intramolecular transfer from B(6)H(6)(6-) to three Li(+) cations, was found to be 10.7 kcal/mol higher in energy. A closo isomer with three aromatic moieties (octahedral B(6)H(6)(2-) and two Li(3)(+)) was found to be 31.3 kcal/mol higher in energy than the global minimum. Another isomer with three aromatic moieties (two B(3)H(3)(2-) and Li(3)(+)) was found to be substantially higher in energy (74.4 kcal/mol). Thus, the intramolecular electron transfers from the highly charged B(6)H(6)(6-) anion to cations are not favorable for the B(6)H(6)Li(6) molecule, even when a formation of three-dimensional aromatic B(6)H(6)(2-) anion and two sigma-aromatic Li(3)(+) cations occurs in the closo isomer. 相似文献
97.
We investigated the electronic structure and chemical bonding of the B3
–, Al3
–, and Ga3
– anions, and the gas phase NaB3, NaAl3, and NaGa3 molecules. We found that the ground state of the neutral gas phase salts contains an equilateral triangular anion interacting with a Na+ cation. The B3
–, Al3
–, and Ga3
– anions possess two delocalized electrons and are found to be aromatic. The triangular anions have been shown to be related to recently synthesized organometallic compound containing an aromatic -Ga3
2– unit, but they are differ from them by four valence electrons. The reason for earlier appearance of the -orbital in the B3
–, Al3
–, and Ga3
– anions is discussed. 相似文献
98.
A. V. Dushkin I. B. Troitskaya V. V. Boldyrev I. A. Grigor'ev 《Russian Chemical Bulletin》2005,54(5):1155-1159
Samples of cellulose labeled with stable nitroxyl radicals were prepared by mechanochemical synthesis. The samples were studied
by IR and EPR spectroscopies, X-ray phase analysis, and electron microscopy. The EPR spectral patterns indicate a uniform
distribution of “grafted” paramagnetic centers over the cellulose macromolecular chains. X-Ray diffraction patterns obtained
and the results of crystallinity index calculations for the samples showed that strong bonding of spin labels causes changes
in the cellulose structure up to nearly complete amorphization of the material.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1127–1130, May, 2005. 相似文献
99.
The thermal decomposition of lead thiosulfate (LTS) was studied by various methods: X-ray phase analysis, IR and ESR spectroscopy, etc. A mechanism of thermal decomposition is suggested, including rupture of the S-S bond and the formation of radicals. According to the mechanism, the reaction rate can be enhanced in the presence of the PbS phase. The formation of PbS is the cause of the topochemical character of the reaction. The composition of the thermolysis products of LTS containing a radioactive isotope of sulfur is predicted.
Zusammenfassung Die thermische Zersetzung von Bleithiosulfat PbS2O3 wurde durch Röntgenphasenanalyse, IR- und ESR-Spektroskopie und Thermogravimetrie untersucht. Ein Mechanismus der thermischen Zersetzung wird angegeben, der über die Trennung von S-S-Bindungen und die Bildung von Radikalen verläuft. Nach diesem Mechanismus wird die Reaktionsgeschwindigkeit in Gegenwart der PbS-Phase beschleunigt, was den topochemischen Charakter der Reaktion bedingt.Für die Verteilung radioaktiven Schwefels auf die Zersetzungsprodukte unterschiedlich markierten (PbS*SO3 bzw. PbSS*O3) Bleithiosulfats wird eine Vorhersage gemacht.
, - . , S—S . , . . , .相似文献
100.
G. L. Gutsev A. I. Boldyrev A. A. Ovchinnikov 《International journal of quantum chemistry》1986,30(5):625-631
The electronic structure of the C2H2, C2H4, and trans-C4H6 molecules is calculated using the discrete variational Xα-method (DVM -Xα). The calculated energies of optical excitations and ionization potentials are compared with both experimental data and results of other nonempirical methods. We conclude that DVM -Xα is a reliable method for investigating the electronic structure of polyenes. 相似文献