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1.
Powder compaction of granular material plays a substantial role in the manufacturing process of ceramics industry and powder metallurgy industry. The compaction behaviour is ruled by granular flow and densification of deformable particles. Discrete element method (DEM) allows to investigate the powder compaction process numerically on the microscale by modeling the forces on the particle level and simulating the particle motion. Three-dimensional data about particle size distribution and spatial structure of the particle packing can be extracted from micro-computed tomography (µCT). An average stress tensor can be computed from DEM results, evaluating the contact forces and the distances from the particle center to the contact point with respect to an average cell volume. A weighted Voronoi tesselation of the polydisperse particle assembly is proposed for mapping a cell volume to each individual particle. With this approach all structural information of the particle system can be transferred from a discrete particle model to a heterogeneous volume model of micro-structure. Discrete stress distributions for uniaxial powder compaction are presented. (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
2.
Martin Heise Bertold Rasche Dr. Anna Isaeva Dr. Alexey I. Baranov Prof. Dr. Michael Ruck Konrad Schäfer Prof. Dr. Rainer Pöttgen Jens‐Peter Eufinger Prof. Dr. Jürgen Janek 《Angewandte Chemie (International ed. in English)》2014,53(28):7344-7348
Nanoparticles of Bi3Ir, obtained from a microwave‐assisted polyol process, activate molecular oxygen from air at room temperature and reversibly intercalate it as oxide ions. The closely related structures of Bi3Ir and Bi3IrOx (x≤2) were investigated by X‐ray diffraction, electron microscopy, and quantum‐chemical modeling. In the topochemically formed metallic suboxide, the intermetallic building units are fully preserved. Time‐ and temperature‐dependent monitoring of the oxygen uptake in an oxygen‐filled chamber shows that the activation energy for oxide diffusion (84 meV) is one order of magnitude smaller than that in any known material. Bi3IrOx is the first metallic oxide ion conductor and also the first that operates at room temperature. 相似文献
3.
Stefan Sutorius Dr. David van Gerven Dr. Selina Olthof Dr. Bertold Rasche Dr. Jörn Bruns 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(22):e202200004
(SO4)-rich silicate analogue borosulfates are able to stabilise cationic cluster-like and chain-like aggregates. Single crystals of [Au3Cl4][B(S2O7)2] and [Au2Cl4][B(S2O7)2](SO3) were obtained by solvothermal reaction with SO3, and the electronic properties were investigated by means of density functional theory–based calculations. [Au3Cl4][B(S2O7)2] exhibits a cluster-like cation, and the cationic gold-chloride strands in [Au2Cl4][B(S2O7)2](SO3) are found to resemble one-dimensional metallic wires. This is confirmed by polarisation microscopy. 相似文献
4.
Bertold Laschinger 《Archiv der Mathematik》1986,47(3):281-288
Ohne Zusammenfassung 相似文献
5.
MR fluoroscopy is likely to gain increasing importance for the visualization of dynamic processes such as cardiac function and for the guidance of interventional procedures. In many applications the dynamic processes are restricted to a part of the object under study making reduced field of view (rFOV) imaging desirable. The restriction to a smaller FOV can either be used to increase the spatial or the temporal resolution. In projection reconstruction (PR) and spiral imaging severe backfolding artifacts occur if a rFOV is used. In this paper efficient suppression schemes are proposed for PR- and spiral imaging to avoid backfolding artifacts. Evaluation of the proposed schemes was done on an interactive real-time MR-scanner. Cardiac function studies clearly showed the potential of this technique for PR- and spiral imaging. 相似文献
6.
A sample pretreatment technique for silicon nitride involving digestion and matrix/traces separation was developed by means of radiotracers and applied to analysis of this material by inductively coupled plasma atomic emission spectrometry, inductively coupled plasma mass spectrometry and graphite furnace atomic absorption spectrometry. The results obtained for a high purity silicon nitride material by these methods are compared each with the other and with those obtained by neutron activation analysis. The limits of detection and the capabilities of the methods are compared and discussed. 相似文献
7.
8.
Transition Metal Phosphido Complexes. VIII. X-Ray Diffraction Studies of Transition Metal Phosphorus Four- and Six-Membered Ring Complexes. Structures of [(CO)4MnPH2]2, [(CO)4MnPH2]3, and [cpNiPH2]3 [(CO)4MnPH2]2 1 crystallizes triclinic in the space group P1 with a = 680.4 pm, b = 706.4 pm, c = 919.1 pm, α 110.5°, β = 91.92°, γ 115.65°, and Z = 1 formula unit. The molecule exhibits a centrosymmetrical structure. The bond angles within the planar four-membered (Mn? P)2-ring are 76.1° at the Mn atoms and 103.9° at the P atoms, respectively. The average Mn? P bond distance is found to be 235.1 pm. [(CO)4MnPH2]3 2 crystallizes monoclinic in the space group P2/n with a = 905.2 pm, b = 974.8 pm, c = 1264.2 pm, β = 109.1°, and Z = 2 formula units. The framework of the six-membered (Mn? P)3-ring can be described as having a twist boat conformation. The average endocyclic bond angles are with 89.1° at the Mn atoms and 130.1° at the P atoms, respectively, largely widened compared to 1 . The average Mn? P bond distance, which is found to be 238.5 pm, is also slightly increased compared to 1 . [cpNiPH2]3 3 crystallizes rhombohedral in the space group R3. The cell constants (hexagonal setting) are a = b = 1686.1 pm, c = 561.1 pm and Z = 3 formula units. The six-membered (Ni? P)3-ring exhibits a chair conformation. The endocyclic bond angles are with 92.3° at the Ni atoms and 124.3° at the P atoms, respectively, comparable with those of the six-membered ring compound 2 . The Ni? P bond distance is found to be 215.2 pm. The eyclopentadienyl ligands are disordered and have been refined as rigid groups. 相似文献
9.
Bertold Rasche Minjun Yang Lothar Nikonow Joshaniel F. K. Cooper Claire A. Murray Sarah J. Day Karin Kleiner Simon J. Clarke Richard G. Compton 《Angewandte Chemie (International ed. in English)》2019,58(43):15401-15406
We report the precise postsynthetic control of the composition of β‐Fe1+xSe by electrochemistry with simultaneous tracking of the associated structural changes via in situ synchrotron X‐ray diffraction. We access the full phase width of 0.01<x<0.04 and identify the superconducting state below 8 K, which in contrast to earlier reports is independent of the composition. However, in a second set of in situ X‐ray diffraction experiments, we demonstrate that β‐Fe1+xSe forms a new phase in the presence of oxygen above a 100 °C which has the same anti‐PbO type structure but is not superconducting down to 1.8 K. The latter process can be reversed electrochemically to reinstate the superconducting state. These observations exploit the exquisite control afforded by electrochemistry in contrast with classical approaches of chemical synthesis. 相似文献
10.
Franziska Hufsky Martin Rempt Florian Rasche Georg Pohnert Sebastian Böcker 《Analytica chimica acta》2012
The automated fragmentation analysis of high resolution EI mass spectra based on a fragmentation tree algorithm is introduced. Fragmentation trees are constructed from EI spectra by automated signal extraction and evaluation. These trees explain relevant fragmentation reactions and assign molecular formulas to fragments. The method enables the identification of the molecular ion and the molecular formula of a metabolite if the molecular ion is present in the spectrum. These identifications are independent of existing library knowledge and, thus, support assignment and structural elucidation of unknown compounds. The method works even if the molecular ion is of very low abundance or hidden under contaminants with higher masses. We apply the algorithm to a selection of 50 derivatized and underivatized metabolites and demonstrate that in 78% of cases the molecular ion can be correctly assigned. The automatically constructed fragmentation trees correspond very well to published mechanisms and allow the assignment of specific relevant fragments and fragmentation pathways even in the most complex EI-spectra in our dataset. This method will be very helpful in the automated analysis of metabolites that are not included in common libraries and it thus has the potential to support the explorative character of metabolomics studies. 相似文献