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991.
F. Grard J. Kesteman J. Laurent J. Schlesinger M. Pratap R. Windmolders M.A. Jabiol S. Otwinowski E. Pauli N.G. Deminov P.F. Ermolov 《Physics letters. [Part B]》1975,59(4):409-412
We report the results of a study of the reaction , where the recoiling proton has a small laboratory momentum. The reaction is studied in the 4.5 m Mirabelle bubble chamber at Serpukhov. We compare the diffractive dissociation of the incident antiproton to other incident particles. 相似文献
992.
The proton spin-lattice relaxation time, T1, is measured as a function of temperature in α -(COOH)2·-2H2O, K2HgCl4· H2O and LiCHO·H2O. The relaxation is caused by 180° flips of the water molecules about their 2-fold axes and good agreement is obtained between calculated and observed values of T1. Empiricly the flip rate follows a classical Arrhenius equation: P· exp . A literature survey of values of P and ΔH obtained from similar investigations on other hydrates is given. The survey shows that the preexponential factor, P, is a function of the activation enthalpy, ΔH. P increases from 1012 to 1017 Hz when ΔH changes from 2 to 17 . Using a dynamical rate theory as formulated by Feit, we find the flip rate is given by: K2· √(ΔH)· exp (K1ΔH)· exp . This expression can be fitted to the observed data using K1 = 0.69 and K2 = 2 × 1011 Hz · . Thus both the frequency factor, K2√ (ΔH), and the entropic factor, exp (K1ΔH), have been obtained for flipping water molecules in hydrates. The values of K1 and K2 are shown to be physically reasonable. 相似文献
993.
994.
995.
996.
The cellulose and its derivatives are used more and more, especially like excipients in pharmaceutical industry.The identification of cellulose and some of its derivatives: cellulose acetophthalate, hydroxy-propylmethylcellulose acetosuccinate, sodium carboxymethylcellulose, hydroxysthylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, methylcellulose, hydroxypropylmethyl-cellulose phthalate, is possible by thermal analysis (simultaneous DTA-TG). For that reason, one consider the temperature of the DTA maximum peaks and the DTG minimum peaks. This identification is easy when these products are a majority in pharmaceutical specialities. 相似文献
997.
We show that for a C1-dynamical system (A, G, α) with G discrete (abelian) the Connes spectrum Γ(α) is equal to if and only if every nonzero closed ideal in G × αA has a nonzero intersection with A. Denote by GJ the closed subgroup of G that leaves fixed the primitive ideal J of A. We show for a general group G that if all isotropy groups GJ are discrete, then GXαA is simple if and only if A is G-simple and . This result is applicable not only when G is discrete but also when G? or G? provided that A is not primitive. Specializing to single automorphisms (i.e., G=) we show that if (the transposed of) α acts freely on a dense set of points in , then Λ(α)=. The converse is only proved when A is of type I. 相似文献
998.
999.
J. Borggreen G. Sletten S. Bjørnholm J. Pedersen R.V.F. Janssens I. Ahmad P. Chowdhury T.L. Khoo Y.H. Chung P.J. Daly 《Nuclear Physics A》1985,443(1):120-134
The population of the yrast and near-yrast levels in Gd, Dy and Er nuclei has been investigated experimentally in (heavy ion, xn) reactions through high-resolution γ-ray intensity measurements. A clear difference between non-rotor (N ? 86) and rotor nuclei (N > 86) is evident from the data. For the non-rotor nuclei we define the spin value Isat below which the yrast population saturates. One finds that Isat is independent of the bombarding energy when the latter becomes sufficiently high. We discuss the feeding pattern in relation to the single-particle structure of the yrast and near-yrast levels and in relation to the effect of shape changes, including the possibility of superdeformed shapes at high spin. 相似文献
1000.
Positron-annihilation lifetime spectra have been measured for mixtures of CH3Cl and CH3Br in cyclohexane and of CH3Cl in benzene. The ortho-positronium (Ps) yield decreased monotonically from 38% and 43% in cyclohexane and benzene respectively to 11% in pure CH3Cl and 6% in pure CH3Br. The strength of the inhibition of Ps formation by CH3Br was ten times that of CH3Cl in cyclohexane, because the CH3Br? anion debrominates rapidly, while CH3Cl? is long-lived (= 30 ns) compared to the maximum time of Ps formation of 400–500 ps. as shown in radiation chemistry. The positron can pick off the electron from the CH3X? anions to form Ps. while it forms a bound state with the halides. X?. CH3Cl was a roughly three times weaker Ps inhibitor in benzene than in cyclohexane, which shows that CH3Cl? does not dechlorinate in times comparable to or shorter than 400–500 ps in benzene. An improved model for the explanation of Ps formation in mixtures, where the Ps yield versus electron scavenger concentration has a minimum, is proposed and discussed. 相似文献