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71.
P. B. Terent'ev O. A. Solov'ev R. A. Khmel'nitskii S. P. Gromov R. S. Sagitullin 《Chemistry of Heterocyclic Compounds》1982,18(6):578-580
Peaks of [M — NO]+ and [M — NO2]+ ions are characteristic for the mass spectra of nitroindolizines, whereas peaks of ions of the indole type, viz., [M — HCN]+ and [M- H,- HCN]+ (for alkylindoles), are not characteristic. In the mass spectra of nitroindoles the latter ions give more intense peaks, while the loss of a nitro group or its rearrangement is a considerably less significant process. When a dialkylamino group is introduced in the nitroindolizine molecule, the primary processes in the fragmentation of such compounds are due to fragmentation of the alkylamino group.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 765–768, June, 1982. 相似文献
72.
The graphite‐like yttrium hydride halides, YIHn (0.8 ? n ? 1.0), have been prepared in quantitative yields by heating either YI3, YH2 (1:2) or stoichiometric YI3, YH2, Y mixtures in sealed Ta ampoules at 900°C. A lower limit of the homogeneity range, n ≈ 2/3, has been determined from dehydrogenation experiments. All YIHn phases adopt the ZrBr‐type heavy‐atom structure. The hydrogen variation is accompanied by a change in the c lattice constant from 31.162(3) to 31.033(1) Å for n = 0.61(3) to 1.02(3). The YIHn phases reversibly react with hydrogen at 400‐600°C to form the light green transparent compound YIH2. However, increasing the reaction temperature above 700°C causes decomposition to an unidentified phase being in equilibrium with YH2 and YI3. The arrangement of the heavy atoms in YIH2 (P m1; a = 3.8579(3) Å, c = 10.997(1) Å) corresponds to a four‐layer I‐Y‐Y‐I slab with the stacking sequence (AbaB) as was found by x‐ray powder diffraction data refinement with the Rietveld method. A miscibility gap exists between YIH and YIH2. Samples YIHn (n ? 1.0) show metallic conductivity at room temperature, which changes into semiconducting behavior with decreasing temperature as n approaches its lower value ≈ 2/3. 相似文献
73.
Mikhail D. Borisover Felix D. Baitalov Boris N. Solomonov 《Journal of solution chemistry》1995,24(6):579-586
A new method was suggested for estimating the hydrophobic effect of contributions to the Gibbs energies and enthalpies of hydration of hydrocarbons, inorganic gases and rare gases. In accordance with this method the hydrophobic effect contribution to the Gibbs energy was evaluated from the difference between the hydration Gibbs energy of a solute and the non hydrophobic contribution. To estimate the latter value, the known dependence connecting the Gibbs energies of solvation of a solute in a number of aprotic solvents to the Hildebrand solubility parameter for these solvents was used. The non hydrophobic contribution to the Gibbs energy of hydration was calculated for various solutes from such dependences extended to water as solvent. The Hildebrand solubility parameter for water used in the calculation was corrected for the effect of association through hydrogen bonding. This correction was made by subtraction of the water self-association enthalpy from the enthalpy of vaporization of water. The evaluated Gibbs energies of the hydrophobic effect are positive for saturated hydrocarbons, inorganic gases and rare gases and linearly depend on the solute molecular refraction. The hydrophobic contribution to the hydration enthalpies of the solutes was calculated in the same manner as was made to calculate the hydrophobic contribution to Gibbs energies of hydration. Enthalpies of the hydrophobic effect for the solutes under study are negative. 相似文献
74.
75.
High resolution HF product time-of-flight spectra measured for the reactive scattering of F atoms from n-H2(p-H2) molecules at collision energies between 69 and 81 meV are compared with exact coupled-channel quantum mechanical calculations based on the Stark-Werner ab initio ground state potential energy surface. Excellent agreement between the experimental and computed rotational distributions is found for the HF product vibrational states v'=1 and v'=2. For the v'=3 vibrational state the agreement, however, is less satisfactory, especially for the reaction with p-H2. The results for v'=1 and v'=2 confirm that the reaction dynamics for these product states is accurately described by the ground electronic state 1 (2)A' potential energy surface. The deviations for HF(v'=3, j' > or =2) are attributed to an enhancement of the reaction resulting from the 25% fraction of excited ((2)P(12)) fluorine atoms in the reactant beam. 相似文献
76.
Mikhail Katz 《Geometriae Dedicata》1991,40(2):171-190
We study the critical points of the diameter functional on the n-fold Cartesian product of the complex projective plane C
P
2 with the Fubini-Study metric. Such critical points arise in the calculation of a metric invariant called the filling radius, and are akin to the critical points of the distance function. We study a special family of such critical points, P
kC
P
1C
P
2, k=1,2... We show that P
k is a local minimum of by verifying the positivity of the Hessian of (a smooth approximation to) at P
k. For this purpose, we use Shirokov's law of cosines and the holonomy of the normal bundle of C
P
1C
P
2. We also exhibit a critical point of , given by a subset which is not contained in any totally geodesic submanifold of C
P
2. 相似文献
77.
M. Gromov 《Geometric And Functional Analysis》1991,1(3):253-320
Our basic results concerning harmonic maps are parallel to those in Part I [Gro11] about minimal subvarieties. First we produce compact harmonic foliations
by solving in some cases the asymptotic Dirichlet problem. Then we construct transversal measures by adopting the parabolic equation method of Eells and Sampson. Finally we indicate some applications to the rigidity and the pinching problems. 相似文献
78.
Selective etching has been applied to the mobilities of pyramidal dislocations in the {11¯22} 11¯23 system in Zn single crystals in the quasiviscous region in the simultaneous presence of mechanical treatment and current flow in order to establish the mechanisms whereby current pulses affect metal plasticity. The dislocation dynamics may be related to the current density and mechanical loading, which is examined in relation to the possible current-effect mechanisms. The dynamic retardation constant has been estimated and it has been found that the nonpolar pinch effect and direct force action from the current are decisive.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 5–8, August, 1991.We are indebted to A. M. Roshchupkin and I. L. Bataronov for discussions and critical comments. 相似文献
79.
In the course of comparing the reaction chemistry of (C5Me5)3U, 1, and its slightly less crowded analogue (C5Me4H)3U, 2, new syntheses of UI3, (C5Me4H)3U, (C5Me4H)3UCl, 3, and (C5Me5)3UCl, 4, have been developed. Additionally, (C5Me4H)3UI, 5, and (C5Me4H)2UCl2, 6, have been identified for the first time. A facile synthesis of unsolvated UI3 is reported that proceeds in high yield with inexpensive equipment from iodine and hot uranium turnings. Both UI3 and UI3(THF)4 react with KC5Me4H in toluene to make unsolvated (C5Me4H)3U in higher yield than in previous reports that involve reduction of tetravalent (C5Me4H)3UCl, 3. A more atom-efficient synthesis of complex 3 is also reported that proceeds from reduction of t-BuCl, PhCl, or HgCl2 by 2. Similarly, (C5Me4H)3U reacts with PhI or HgI2 to generate (C5Me4H)3UI. These studies also provided a basis to improve the synthesis of (C5Me5)3UCl from 1 by employing t-BuCl or HgCl2 as the halide source. Like (C5Me5)3UCl, the (C5Me4H)3UCl complex reacts with HgCl2 to form (C5Me4H)2 and (C5Me4H)2UCl2, 6, but unlike (C5Me5)3UX (X = Cl or I), the less substituted (C5Me4H)3UX complexes do not reduce t-BuCl or PhX. The synthesis of 6 from (C5Me4H)MgCl x THF and UCl4 is also included. 相似文献
80.
Kunshina G. B. Gromov O. G. Kuz'min A. P. Seitenova E. B. Lokshin E. P. Kalinnikov V. T. 《Russian Journal of Applied Chemistry》2004,77(6):915-920
Solid electrolytes were synthesized in the systems Li2O-Al2O3-TiO2-P2O5 and Li2O-Al2O3-TiO2-P2O5-H2O-H2O2. Their ionic conductivities were studied and compared. The possibility of obtaining a film of Li1
.
3Al0
.
3Ti1
.
7(PO4)3 solid electrolyte on a sapphire substrate from an aqueous peroxide solution of a precursor was analyzed. 相似文献