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881.
Physical properties of TmPtIn have been investigated by means of magnetic, electrical transport, calorimetric as well as neutron diffraction measurements. The compound crystallizes in the hexagonal ZrNiAl-type crystal structure. It orders antiferromagnetically below TN = 3.5 K with the Tm magnetic moments confined to the basal hexagonal plane. They form a non-collinear “triangular” magnetic structure that may be described by the propagation vector . At 1.6 K, the Tm magnetic moment is equal to 5.59(9)μB. The antiferromagnetic character of the electronic ground state is reflected in the low temperature behaviors of the magnetic susceptibility and the specific heat, which may be described by spin-wave theory of antiferromagnetic magnons with linear dispersion relation. The compound exhibits metallic character of electrical conduction. 相似文献
882.
M. Trzebiatowska‐Gusowska K. Piela T. Misiaszek M. M. Szostak J. Baran 《Journal of Raman spectroscopy : JRS》2010,41(10):1338-1347
Polarized Fourier transform‐infrared (FT‐IR) reflectance spectra and powder Raman spectra have been measured for 1,3‐dinitrobenzene crystal in order to revise the assignments of bands by means of the oriented gas model reinforced with quantum chemical [density functional theory (DFT)] calculations. Longitudinal optical/transverse optical (LO‐TO) splitting of some bands is observed indicating medium strong, long‐range, dipole–dipole interactions. The analysis of overtones in the polarized FT‐NIR spectra has allowed us to estimate the anharmonicity of vibrations in the crystal. The molecular motions of the nitro groups are analyzed on the basis of temperature‐dependent polycrystalline IR spectra. Based on the values of the energy difference (Δνel) between the forbidden A1g→B2u transition in the benzene molecule in the gas phase and the first electronic transition in 1,3‐dinitrobenzene, it has been concluded that the intermolecular interactions are medium strong. The nitro group interactions are proposed to play the main role in the optical nonlinearity. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
883.
A new approach to the enantiocontrolled synthesis of α-amino ketone derivatives is disclosed by employing a decarboxylative acylation strategy. Thus, when an acyl chloride and an α-amido-containing redox-active ester are exposed to a nickel catalyst, chiral ligand, and metal reductant, α-amido ketones are produced in good yield and high ee. The reaction exhibits broad substrate scope, can be easily scaled up, and is applied to dramatically simplify the synthesis of several known structures. 相似文献
884.
The spacings of the smectic layers are compared with the lengths of molecules of p-substituted phenyl 4-(trans-4′-n-decylcyclohexyl) benzoates. It has been found that if the NO2, CN or CHO groups are substituted in the p-position of the phenyl, then the smectic layers consist of dimers, whereas in the presence of the NCS, COCH3, I, Cl, Br, F substituents the smectic layers reveal a monomolecular spacing. 相似文献
885.
Jolanta Baran Andrzej Duda Adam Kowalski Ryszard Szymanski Stanislaw Penczek 《Macromolecular rapid communications》1997,18(4):325-333
A general kinetic treatment of the system with intermolecular chain transfer followed by fast reinitiation is given. It leads to the broadening of the molecular weight distribution (MWD), the number of growing chains being invariable. Thus, this system can be considered as a special case of living polymerization. A general method has been elaborated allowing the determination of the ratio of the rate constant of propagation (kp) to the rate constant of the bimolecular transfer (k(2)tr) from the dependence of the MWD on monomer conversion. Numerical values of kp/k(2)tr equal to ≈ 102 and 25 were thus determined for the polymerization of L , L -lactide (L , L -dilactide) initiated with aluminium tris(isopropoxide) trimer ({Al(OiPr)3}3) and tributyltin ethoxide (nBu3SnOEt), respectively. 相似文献
886.
Alberto F. Garrido-Castro Yuta Hioki Yoshifumi Kusumoto Kyohei Hayashi Jeremy Griffin Kaid C. Harper Yu Kawamata Phil S. Baran 《Angewandte Chemie (International ed. in English)》2023,62(42):e202309157
A mild, scalable (kg) metal-free electrochemical decarboxylation of alkyl carboxylic acids to olefins is disclosed. Numerous applications are presented wherein this transformation can simplify alkene synthesis and provide alternative synthetic access to valuable olefins from simple carboxylic acid feedstocks. This robust method relies on alternating polarity to maintain the quality of the electrode surface and local pH, providing a deeper understanding of the Hofer-Moest process with unprecedented chemoselectivity. 相似文献
887.
Monika Trzebiatowska‐Gusowska Anna Gagor Jan Baran Marek Drozd 《Journal of Raman spectroscopy : JRS》2009,40(3):315-322
We obtained a new complex containing sarcosine (CH3NH2+CH2COO−) and barium(2 + ) dibromide (TSBB) in 3:1 molar ratio, as well as its deuterated analog. Single‐crystal X‐ray diffraction measurements show that TSBB crystallizes in the monoclinic system, space group P2(1)/c. The unit cell parameters are as follows: a = 18.345(4) Å, b = 10.668(2) Å, c = 8.9212(18) Å, β = 91.86(3)°, and Z = 4. The structure was determined with final R1 = 0.0396 (for I > 2σI). The crystal possesses a pseudohexagonal symmetry down c axis showing the resemblance to the crystal structure of trissarcosine calcium chloride (TSCC). There are N HBr hydrogen bonds (HB) of six types. TSBB crystal undergoes a phase transition at 416 K (heating)–415 K (cooling) of continuous nature. The spectroscopic [Infrared (IR) and Raman] investigation of the crystal was performed at room temperature. The results are discussed with respect to the crystallographic data, as well as the results obtained for TSCC crystal. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
888.