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91.
We propose first a generalization of the Density Functional Theory. This theory leads to single-particle equations of motion
with a quasilocal mean-field operator, which contains a quasiparticle position-dependent effective mass and a spin—orbit potential.
The energy density functional is constructed using the extended Thomas—Fermi approximation. Some ground-state properties of
doubly magic nuclei are considered within the framework of this approach. Calculations are performed using the finite-range
Gogny D1S forces, and the results are compared with the exact Hartree—Fock calculations. Next, we present an extension of
the density functional theory to include pairing correlations without formal violation of the particle-number condition. This
problem, which is nonlocal, can be simplified by a suitable quasilocal reduction, which is also briefly discussed in this
paper.
The text was submitted by the authors in English. 相似文献
92.
It is found that in many physical, chemical and biological systems the nonuniform active media may be considered as a “matrix” controlling the selection of the dissipative structures of definite type. 相似文献
93.
Mathematische Zeitschrift - 相似文献
94.
Viñas C Llop J Teixidor F Kivekäs R Sillanpää R 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(6):1933-1941
Rotation about the centroid/metal/centroid axis in ferrocene is facile; the activation energy is 1-5 kcal mol(-1). The structurally similar sandwich complexes derived from closo-[3-Co(eta5-NC4H4)-1,2-C2B9H11] (1) have a different rotational habit. In 1, the cis rotamer in which the pyrrolyl nitrogen atom bisects the carboranyl cluster atoms is 3.5 kcal mol(-1) more stable in energy than the rotamer that is second lowest in energy. This cis rotamer is wide, spanning 216 degrees , and may be split into three rotamers of almost equal energy by substituting the N and the carboranyl carbon atoms adequately. To support this statement, closo-[3-Co(eta5-NC4H4)-1,2-(CH3)2-1,2-C2B9H9] (2), closo-[3-Co(eta5-NC4H4)-1,2-(mu-CH2)3-1,2-C2B9H9] 3, 2-->BF3, and 3-->BF3 have been prepared. Two rotamers are found at low temperature for 2-->BF(3) and 3-->BF3. Compounds 2, 3, and 1-->BF3 behave similarly to 1. Rotational energy barriers and the relative populations of the different energy states are calculated from 1H DNMR spectroscopy (DNMR, dynamic NMR). These results agree with those of semiempirical calculations. Without exception, the cis rotamer is energetically the more stable. The fixed conformation of 1 assists in elucidating the rotational preferences of the [3,3'-Co(1,2-C2B9H11)2]- ion in the absence of steric hindrance; the [3,3'-Co(1,2-C2B9H11)2]- ion is commonly accepted to present a cisoid orientation. Complex 1 is electronically similar to the [3,3'-Co(1,2-C2B9H11)2]- ion. Both have heteroatoms in the pi ligands, and they have the same electronegativity difference between the constituent atoms. This leads to a view of the [NC4H4]- as [7,8-C2B9H11]2- ion, with no steric implications. Therefore the [3,3'-Co(1,2-C2B9H11)2]- ion should be considered to have a cisoid structure, and the different rotamers observed to be the result of steric factors and of the interaction of the counterion with either B-H groups and/or ancillary ligands. The rotamer adopted is the one with the atoms holding the negative charges furthest apart. 相似文献
95.
Cobaltabis(dicarbollide) [3,3'-Co(1,2-C2B9H11)](-)-doped polypyrrole (PPy) films have been prepared galvanostatically on glassy carbon electrodes in acetonitrile solution. The potential response behavior of the film of this new material has been investigated in some common pH buffers and in acid-base titrations. The potentiometric characteristics of the resulting films are indicative of a quasi-Nernstian response (approximately 50 mV/pH unit), a linearity range from pH 12 to 3 and correlation coefficients (r2) of approximately 0.98. The electrode is suitable for pH measurements and for monoprotic titrations of strong alkalis with strong acids, and weak bases with strong acids, but the long response time hinders the use of this electrode for multiprotic titrations. The time response has been dramatically improved by reducing the film thickness by using the template effect of a non-conducting polymer (PVC) cast over the graphite surface before PPy deposition. PPy polymerization occurs in the free channels of PVC leading to the formation of PPy wires. The morphological change of PPy does not affect the slope or linearity range. The response of the PVC-PPy electrochemical sensor is rapid and the sensor is easy to prepare, at low cost, and its performance is comparable with that of commercial glass electrodes. 相似文献
96.
A solid phase microextraction fiber based on high temperature silicone glue coated on a stainless steel wire is presented
for use in the extraction of amino acid derivatives. Amino acids were derivatizad using ethyl chloroformate. Effects of the
extraction and desorption parameters including extraction and desorption time, desorption temperature and ionic strength on
the extraction/desorption efficiency have been studied and quality parameters of the method were measured. A possibility to
apply the proposed method for the identification of proteinaceous binders was demonstrated. 相似文献
97.
J. Ortín A. Ramos V. Torra J. Viñals E. Margas W. Zielenkiewicz 《Thermochimica Acta》1984,76(3):325-332
This work analyses the performance of the method of obtaining the time constant (rate reaction constant) defining a first-order process after the deconvolution of the experimental record given by a heat conduction calorimeter. The analysis is carried out for different signal/noise ratios and the results given in relative time and frequency scales. 相似文献
98.
The complex polar Kerr effect spectra in diamagnetically substituted hexagonal ferrite system PbFe12–xGaxO19 (x= 0, 1, 3,4) at 290 K between 2 and 5·5 eV are studied. The previously published data on optical constants in this system are employed to obtain the offdiagonal permittivity tensor element spectra.Dedicated to Dr. Svatopluk Krupika on the occasion of his 65th birthday. 相似文献
99.
Planas JG Viñas C Teixidor F Comas-Vives A Ujaque G Lledós A Light ME Hursthouse MB 《Journal of the American Chemical Society》2005,127(45):15976-15982
The existence of a dihydrogen bond (S-H...H-B) and its combination with a C-H...S hydrogen bond in an unusual cooperative effect are demonstrated from a combination of experimental and theoretical methods. This cooperative effect seems to be responsible for self-assembly of mercaptane-metallacarborane complexes such as closo-[3-Ru(eta6-C6H6)-8-HS-1,2-C2B9H10] (1) and closo-[3-Co(eta5-C5H5)-8-HS-1,2-C2B9H10] (3), which present identical supramolecular two-dimensional polymeric networks. The findings, besides documenting structurally the first S-H...(H-B)2 dihydrogen bond and the unconventional cooperative ability of a boron-attached SH group, prove that substituted carboranes have the potential to serve as building blocks for assembling complex structures. 相似文献
100.
N. Keller J. Mistrík Š. Višňovský D.S. Schmool Y. Dumont P. Renaudin M. Guyot R. Krishnan 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,21(1):67-73
Orthoferrites present, as bulk materials, reorientation transitions of their magnetic moment alignment at temperatures depending
on the rare-earth (RE) ion. In particular, orthoferrites (REFeO3) with RE = Sm, Dy, present this transition at T
SRT = 443 K and 36 K, respectively. The spectra of the complex Kerr and Faraday angle have been measured on orthoferrite thin
films (RE = Sm, Dy, Y), which were prepared by pulsed laser deposition on amorphous quartz substrates. The obtained spectra
exhibit contributions of both surfaces and interfaces. Propagation effects of the polarized light in the magneto-optical medium
which is interpreted in terms of a simplified theoretical formalism, is also observed. For selected photon energies, temperature
dependent Faraday rotation measurements, , on orthoferrite thin films (RE = Sm, Dy, Y) have been performed. A quite different thermal variation compared to the bulk
magnetization has been observed. Curie temperatures are found to be close to the bulk values or slightly larger by 10 K to
20 K as in the case of DyFeO3 and YFeO3. For RE = Sm and Dy, increases with increasing temperature contrary to the saturation magnetization, passes through a maximum at about 460 K and
vanishes with a T
C of 647±18 K, 695 K for RE = Sm and Dy respectively.
Received 28 July 2000 相似文献