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981.
It has been established that the Vaskovsky-Svetashev reagent has no influence on the general and positional composition of the fatty acids of phospholipids. For the qualitative identification of PLs on one plate it is possible to use successively iodine, ninhdrin, the Dragendorff reagent, the Vaskovsky-Svetashev reagent, 50% H2SO4, and the Malachite Green reagent.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 40–42, January–February, 1988. 相似文献
982.
A. F. Pozharskii V. V. Kuz'menko Yu. V. Kolodyazhnyi A. M. Simonov 《Chemistry of Heterocyclic Compounds》1972,8(9):1131-1141
1- (or)-Pyridyl- and 1- (or)-pyridylethylbenzimidazoles were synthesized, and their behavior with respect to methyl iodide and sodium amide was studied. The results are discussed from the point of view of the basicities, magnitudes of the dipole moments, interaction of the heterorings, and the electron density distribution in them, calculated by the Hückel MO method or estimated on the basis of the relative position of the chemical shifts in the PMR spectra. It was established that the benzimidazole system undergoes the Chichibabin reaction considerably more readily than the pyridine system. On the basis of the PMR spectral data for the pyridine and benzimidazole bases and cations, it is assumed that this is due to the greater polarizability of the C = N bond of benzimidazole as compared with the C = N bond of pyridine during coordination with NaNH2.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1252–1263, September, 1972.The authors sincerely thank L. E. Nivorozhkin and G. V. Gorshkova for their assistance in measuring the PMR spectra. 相似文献
983.
G. G. Pimenov V. D. Skirda V. Yu. Maksimenko V. P. Morozov O. A. Opanasyuk 《Colloid Journal》2004,66(6):722-725
Pulsed NMR and X-ray diffraction analysis are employed to study the influence of adsorbed toluene, p-xylene, acetone, and di(ethylene glycol) (DEG) molecules on phase transitions in a ZSM-5 silicalite. In the region of phase transitions, times T1 and T2 of longitudinal and transverse magnetic relaxation of apolar molecules adsorbed in silicalite micropores increase and decrease in a jumpwise manner, respectively, with a rise in the total content of the liquid. Such changes in T1 and T2 occur for hexane, decane, toluene, and p-xylene molecules. Qualitatively different concentration dependences of T1 and T2 are observed for polar acetone and DEG molecules, because these liquids do not cause a earrangement in the crystal lattice of silicalite; this is confirmed by the X-ray diffraction data.Translated from Kolloidnyi Zhurnal, Vol. 66, No. 6, 2004, pp. 802–806.Original Russian Text Copyright © 2004 by Pimenov, Skirda, Maksimenko, Morozov, Opanasyuk. 相似文献
984.
A. K. Karimdzhanov A. I. Ismailov Z. S. Abdullaev Sh. Yu. Islambekov F. G. Kamaev A. S. Sadykov 《Chemistry of Natural Compounds》1977,12(2):211-214
Summary A new phenolic compound — gossyvertin — has been isolated from the stems of a cotton plant infected with fungusVerticillium dahliae Kleb.; the structure 8-formyl-1,7-dihydroxy-5-isopropyl-2-methoxy-3-methylnaphthalene has been proposed for gossyvertin.Division of Bioorganic Chemistry, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 238–242, March–April, 1976. 相似文献
985.
V. A. Pestunovich M. G. Voronkov V. N. Perchenko Yu. Yu. Popel L. G. Batalova N. S. Nametkin 《Chemistry of Heterocyclic Compounds》1969,5(4):561-562
By the PMR method we have established the existence of a high frequency of the inversion of the nitrogen atom in the molecules of -aziridin-1-ylalkoxysilanes. This is due to the fact that the high (because of p-d bonding with the silicon atom) electronegativity of the oxygen atom in the Si-O-C-N system makes possible an interaction between the unshared electron pair of the nitrogen atom and the antibonding orbital of the C-O bond. The latter, in its turn, increases the degree of p-d bonding between the oxygen and silicon atoms (in these compounds the order of the Si-O bond is greater than in the alkoxysilanes). 相似文献
986.
Posudievskii O. Yu. Kurys' Ya. I. Biskulova S. A. Malinovskii Yu. K. Pokhodenko V. D. 《Theoretical and Experimental Chemistry》2002,38(5):278-282
The possibility of the production of nanocomposites based on V2O5 and conducting polymers by direct intercalation of macromolecules of secondary doped polyaniline into the interlayer galleries of nanoparticles of aqueous V2O5 sol was demonstrated for the first time. The driving force of the intercalation process is substitution of the protons present in the galleries of the V2O5 by a polyaniline chain carrying a positive charge. 相似文献
987.
E. I. Kapinus I. I. Dilung I. Yu. Kucherova V. P. Staryi 《Theoretical and Experimental Chemistry》1987,22(5):558-563
On the example of fluorescence quenching of perylene by organic electron acceptors we have shown that the radius of the quenching sphere depends on the electron affinity of the oxidizing agent. The deactivation of excited molecules of m-dinitrobenzene was achieved by tunnel electron transfer at a distance, which was significantly greater than the sum of the radii of the reagent molecules. The fluorescence quenching with phthalic anhydride, a weaker electron acceptor, occurs on contact between molecules. The kinetics of this process are described by the Smoluchowski theory of diffusion-controlled reactions. The rate of fluorescence quenching with carbon tetrachloride and nitromethane in polar solvents also increases with the increase of the coefficients of mutual diffusion, but the formal reaction radii of these processes are smaller than the sum of the radii of the interacting particles, which is due to the stereospecifity of the reaction. It was shown that the degree of stereospecificity increases with the decrease of the reaction radius.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 22, No. 5, pp. 585–590, September–October, 1986. 相似文献
988.
The collapse behavior of a single comblike copolymer chain has been studied by Monte Carlo simulations. It has been supposed that the solvent is good for the side chains but the solvent quality for the backbone chain changes. It has been shown that depending on the structural parameters of the comb copolymer (the lengths of the backbone and side chains, grafting density of the side chains) various thermodynamically stable morphologies of the collapsed backbone chain can be realized. In addition to ordinary spherical globule we have observed elongated structures as well as necklace-like conformations. The proposed model can be used to describe conformational behavior of stoichiometric complexes between block copolymers with a polyelectrolyte short block and oppositely charged linear homopolymers. 相似文献
989.
A. L. Aleksandrov V. M. Bedanov Yu. N. Morokov V. A. Shveigert 《Journal of Structural Chemistry》1996,37(4):578-587
A quantitative model of isomerization of carbon clusters is proposed, and possible ways of transformation of tricyclic structures
to fullerenes are considered in order to account for the spontaneous transformation of the polycyclic clusters arising during
the condensation of the carbon vapor. The isomerization process is calculated thermodynamically using the modified classical
interatomic potential, the relative effeciencies of different mechanisms of the fullerene formation are estimated, and the
main regularities of this process are established. The results of the simulation are consistent with the experimental data.
The model can be employed in the calculation of long isomerization chains of complex molecules. The accuracy of the quantitative
estimation of the kinetics is determined by the errors in the calculations of the bond energies of the isomers.
Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences. Institute of Computation Technologies,
Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 4, pp. 671–681, July–August, 1996.
Translated by I. Izvekova 相似文献
990.
Eremets MI Popov MY Trojan IA Denisov VN Boehler R Hemley RJ 《The Journal of chemical physics》2004,120(22):10618-10623
The high-pressure behavior of nitrogen in NaN(3) was studied to 160 GPa at 120-3300 K using Raman spectroscopy, electrical conductivity, laser heating, and shear deformation methods. Nitrogen in sodium azide is in a molecularlike form; azide ions N(3-) are straight chains of three atoms linked with covalent bonds and weakly interact with each other. By application of high pressures we strongly increased interaction between ions. We found that at pressures above 19 GPa a new phase appeared, indicating a strong coupling between the azide ions. Another transformation occurs at about 50 GPa, accompanied by the appearance of new Raman peaks and a darkening of the sample. With increasing pressure, the sample becomes completely opaque above 120 GPa, and the azide molecular vibron disappears, evidencing completion of the transformation to a nonmolecular nitrogen state with amorphouslike structure which crystallizes after laser heating up to 3300 K. Laser heating and the application of shear stress accelerates the transformation and causes the transformations to occur at lower pressures. These changes can be interpreted in terms of a transformation of the azide ions to larger nitrogen clusters and then polymeric nitrogen net. The polymeric forms can be preserved on decompression in the diamond anvil cell but transform back to the starting azide and other new phases under ambient conditions. 相似文献