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91.
Milica D. Milosavljević Dr. Ulrich Burkhardt Prof. Dr. Philip J. W. Moll Dr. Markus König Dr. Horst Borrmann Prof. Yuri Grin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(57):14209-14216
In a joint effort utilizing modified sample preparation, microscopy, X-ray diffraction and micro-fabrication, it became possible to prepare single crystals of the “hidden” phase AlCr2. High-resolution X-ray diffraction analysis is described in detail for two crystals with the similar overall composition, but different degree of disorder, which seems to be the main cause for the differing unit cell parameters. Chemical bonding analysis of AlCr2 in comparison to prototypical MoSi2 shows pronounced differences reflecting the interchange of main group element vs. transition metal as majority component. 相似文献
92.
Marija Borna Alim Ormeci Ulrich Burkhardt Raul Cardoso-Gil 《Journal of solid state chemistry》2011,184(2):296-303
Application of high-pressure high-temperature conditions (3.5 GPa at 1673 K for 5 h) to mixtures of the elements (RE:B:S=1:3:6) yielded crystalline samples of the isotypic rare earth-thioborate-sulfides RE9[BS3]2[BS4]3S3, (RE=Dy-Lu), which crystallize in space group P63 (Z=2/3) and adopt the Ce6Al3.33S14 structure type. The crystal structures were refined from X-ray powder diffraction data by applying the Rietveld method. Dy: a=9.4044(2) Å, c=5.8855(3) Å; Ho: a=9.3703(1) Å, c=5.8826(1) Å; Er: a=9.3279(12) Å, c=5.8793(8) Å; Tm: a=9.2869(3) Å, c=5.8781(3) Å; Yb: a=9.2514(5) Å, c=5.8805(6) Å; Lu: a=9.2162(3) Å, c=5.8911(3) Å. The crystal structure is characterized by the presence of two isolated complex ions [BS3]3- and [BS4]5- as well as [□(S2-)3] units. 相似文献
93.
Journal of Statistical Physics - In the simplest model of single-file diffusion, N point particles wander on a segment of the x axis of length L, with hard core interactions, which prevent passing,... 相似文献
94.
95.
Jakob Steube Dipl.-Chem. Lukas Burkhardt Ayla Päpcke Johannes Moll Dr. Peter Zimmer Dr. Roland Schoch Dr. Christoph Wölper Prof. Dr. Katja Heinze Prof. Dr. Stefan Lochbrunner Prof. Dr. Matthias Bauer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(51):11826-11830
The complex class [Fe(N^N^C)(N^N^N)]+ with an Earth-abundant metal ion has been repeatedly suggested as a chromophore and potential photosensitizer on the basis of quantum chemical calculations. Synthesis and photophysical properties of the parent complex [Fe(pbpy)(tpy)]+ (Hpbpy=6-phenyl-2,2′-bipyridine and tpy=2,2′:6′,2′′-terpyridine) of this new chromophore class are now reported. Ground-state characterization by X-ray diffraction, electrochemistry, spectroelectrochemistry, UV/Vis, and X-ray spectroscopy in combination with DFT calculations proves the high impact of the cyclometalating ligand on the electronic structure. The photophysical properties are significantly improved compared to the prototypical [Fe(tpy)2]2+ complex. In particular, the metal-to-ligand absorption extends into the near-IR and the 3MLCT lifetime increases by 5.5, whereas the metal-centered excited triplet state is very short-lived. 相似文献
96.
Martin Juckel Primož Koželj Yurii Prots Alim Ormeci Ulrich Burkhardt Andreas Leithe-Jasper Eteri Svanidze 《无机化学与普通化学杂志》2020,646(14):1238-1243
Intermediate valence behavior is frequently observed in materials containing Ce, Yb, Eu, Sm, or Tm. In the current work, we report synthesis and characterization of Yb2Cu9Al8 (Th2Zn17 structure type). Its intermediate valence behavior can be described by an excitation energy Eex/kB = 319 K and a spin fluctuation temperature Tsf = 60 K. The valence state of Yb is estimated to be close to 2.04 for the low-temperature region. The valence gradually evolves to the value of 2.80 at T = 400 K. The specific heat coefficient of γexp = 59 mJ · molYb–1 · K–2 indicates a moderate effective mass enhancement, together with finite density of states at the Fermi level. The latter is also confirmed by the band structure calculations. 相似文献
97.
Laura Agnarelli Dr. Yurii Prots Dr. Marcus Schmidt Dr. Mitja Krnel Dr. Eteri Svanidze Dr. Ulrich Burkhardt Dr. Andreas Leithe-Jasper Prof. Dr. Yuri Grin 《ChemistryOpen》2022,11(6):e202200118
The new phase Be3Ru crystallizes with TiCu3-type structure (space group Pmmn (59), a=3.7062(1) Å, b=4.5353(1) Å, c=4.4170(1) Å), a coloring variant of the hexagonal closest packing (hcp) of spheres. The electronic structure revealed that Be3Ru has a pseudo-gap close to the Fermi level. A strong charge transfer from Be to Ru was observed from the analysis of electron density within the Quantum Theory of Atoms in Molecules (QTAIM) framework and polar three- and four-atomic Be−Ru bonds were observed from the ELI−D (electron localizability indicator) analysis. This situation is very similar to the recently investigated Be5Pt and Be21Pt5 compounds. The unusual crystal chemical feature of Be3Ru is that different charged species belong to the same closest packing, contrary to typical inorganic compounds, where the cationic components are located in the voids of the closest packing formed by anions. Be3Ru is a diamagnet displaying metallic electrical resistivity. 相似文献
98.
Abstract When estimating a regression function or its derivatives, local polynomials are an attractive choice due to their flexibility and asymptotic performance. Seifert and Gasser proposed ridging of local polynomials to overcome problems with variance for random design while retaining their advantages. In this article we present a data-independent rule of thumb and a data-adaptive spatial choice of the ridge parameter in local linear regression. In a framework of penalized local least squares regression, the methods are generalized to higher order polynomials, to estimation of derivatives, and to multivariate designs. The main message is that ridging is a powerful tool for improving the performance of local polynomials. A rule of thumb offers drastic improvements; data-adaptive ridging brings further but modest gains in mean square error. 相似文献
99.
100.
U. Wedig A. Burkhardt H. G. v. Schnering 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1989,13(4):377-384
By using transputers it is possible to build up networks of parallel processors with varying topology. Due to the architecture of the processors it is appropriate to use the MIMD (multiple instruction multiple data) concept of parallel computing. The most suitable programming language is OCCAM. We investigate the use of transputer networks in computational chemistry, starting with the direct SCF method. The most time consuming step, the calculation of the two electron integrals is executed parallelly. Each node in the network calculates whole batches of integrals. The main program is written in OCCAM. For some large-scale arithmetic processes running on a single node, however, we used FORTRAN subroutines out of standard ab-initio programs to reduce the programming effort. Test calculations show, that the integral calculation step can be parallelized very efficiently. We observe a speed-up of almost 8 using eight network processors. Even in consideration of the scalar part of the SCF iteration, the speed-up is not less than 7.1. 相似文献