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31.
Florian Kleemiss Erna K. Wieduwilt Dr. Emanuel Hupf Ming W. Shi Dr. Scott G. Stewart Prof. Dylan Jayatilaka Dr. Michael J. Turner Prof. Kunihisa Sugimoto Prof. Eiji Nishibori Prof. Dr. Tanja Schirmeister Dr. Thomas C. Schmidt Prof. Dr. Bernd Engels PD Dr. Simon Grabowsky 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(10):3407-3419
The crystal interaction density is generally assumed to be a suitable measure of the polarization of a low-molecular weight ligand inside an enzyme, but this approximation has seldomly been tested and has never been quantified before. In this study, we compare the crystal interaction density and the interaction electrostatic potential for a model compound of loxistatin acid (E64c) with those inside cathepsin B, in solution, and in vacuum. We apply QM/MM calculations and experimental quantum crystallography to show that the crystal interaction density is indeed very similar to the enzyme interaction density. Less than 0.1 e are shifted between these two environments in total. However, this difference has non-negligible consequences for derived properties. 相似文献
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33.
Local detection of ferromagnetic resonance in magnetically ordered materials is achieved by local thermal modulation of the microwave resonance absorption with a scanning thermal microscope. A scanning thermal microwave resonance microscope was constructed based on a microwave bridge with an X-band cavity and a thermal nano-probe contacted to the sample at the wall of the cavity. The technique has been tested on an epitaxial iron film which exhibited lateral inhomogeneities due to a partial oxidation of iron. Different types of oxidation could be distinguished. The locally resolved ferromagnetic resonance spectra are compared with the result of an integral measurement using conventional detection techniques of the ferromagnetic resonance with the same set-up. The lateral resolution achievable with the thermally modulated ferromagnetic resonance measurements was about 200 nm for the investigated iron film. 相似文献
34.
Insulating lines and channels prepared by focused ion beam implantation on SIMOX wafers have been investigated by thermally modulated optical reflectance microscopy using optical and electrical excitation. Continuous hot lines and hot spots can be visualized by modulated electrical heating, whereas insulating lines forming channels can be imaged only with simultaneous optical and electrical excitation. Three different schemes have been investigated for the combined excitation: (i) optical modulation with additional DC voltage, (ii) optical and electrical pumps modulated at the same frequency with the detection effected at higher harmonics and (iii) two different modulation frequencies used for optical and electrical excitation with the detection effected at sum and difference frequencies. When detecting at higher frequencies, best contrast for the observation of the insulating lines adjacent to a channel is achieved by recording the modulated reflectance signal at the fourth harmonic 4f where f is the modulation frequency of the optical and electrical pump. The observed contrast enhancement of the double excited thermoreflectance signal is found to be mainly of a thermal origin. 相似文献
35.
36.
D. Dietzel R. Meckenstock S. Chotikaprakhan J. Bolte J. Pelzl R. Aubry J. C. Jacquet S. Cassette 《Superlattices and Microstructures》2004,35(3-6):477
The temperature and thermo-elastic expansion of the heated area in a high power, high electron mobility transistor (HEMT) device have been investigated by means of finite element calculations and scanning thermal expansion microscopy. With both procedures a hot line is located near the gate line of the transistor. To determine the absolute temperature, the thermo-elastic response was calibrated on the basis of the force–distance curve of the AFM and the thermal expansion of the gold layer on top of the heated areas. The maximum temperatures deduced by the two procedures are in reasonable agreement whereas discrepancies are found for the temperature profile of the hot line, pointing towards a possible influence of the large aspect ratio of the device on the thermo-elastic measurement. 相似文献
37.
Trimethylphenylammonium superoxide (1) and tetrabutylammonium superoxide (2) were prepared by ion-exchange reaction in liquid ammonia. Both compounds were structurally characterized by single-crystal X-ray diffraction. The crystal structure of 2 contains solvent ammonia molecules that are hydrogen bonded to the superoxide ion and therefore may influence the bonding properties of the superoxide ion. The crystal structure of 1 does not contain any solvent molecules. Therefore, it represents the best known approximation to the virtually isolated superoxide ion in the solid state to date. The O-O bond length is 1.332(2) A in 1 and 1.312(2) A in 2. Magnetization measurements show that the susceptibilities of both compounds follow an ideal Curie law down to 2 K reflecting an absence of intermolecular exchange effects between the superoxide ions. The effective magnetic moments of both compounds are larger than the spin-only value due to contributions of the orbital momentum in the superoxide ion. The values of the magnetic moment comply well with the g factors obtained from electron paramagnetic resonance spectra. The g tensors themselves reflect the anisotropic environment of the superoxide ions. The Pi(g) energy levels which are degenerate in the free superoxide ion split up in crystal fields of lower than tetragonal symmetry. The energy splitting is estimated from the diagonal elements of the g tensor of 1. 相似文献
38.
Richard Dietzel 《Colloid and polymer science》1926,40(3):240-248
Ohne ZusammenfassungDiese Veröffentlichung stellt im wesentlichen den Inhalt des Referates dar, das ich am 25. September 1926 auf der V. Hauptversammlung der Kolloid-Gesellschaft in Düsseldorf zu dem Hauptverhandlungsthema: Säurewirkung und Wasserstoffionenkonzentration in der reinen und angewandten Kolloidchemie erstattet habe. 相似文献
39.
Pascal D. C. Dietzel Robert Dinnebier Martin Jansen Prof. Dr. Dr. h. c. 《无机化学与普通化学杂志》2007,633(9):1410-1416
Dimethylammonium trifluoromethanesulfonate 1 was synthesized by reaction of trifluoromethanesulfonic acid with an excess of dimethylamine. A temperature variable synchrotron measurement on the polycrystalline substance reveals that 1 passes through a phase transition below room temperature. The transition occurs in the temperature range of 282–285 K on heating and 272–280 K on cooling as determined by DSC. The room temperature phase crystallizes in space group Cmca (a = 11.031(6) Å, b = 18.466(14) Å, c = 8.173(9) Å, V = 1665(2) Å3, Z = 8) and the low temperature phase in space group P 21/c (a = 8.8717(18) Å, b = 8.0838(16) Å, c = 10.968(2) Å, β = 92.128(4)°, V = 786.0(3) Å3, Z = 4). The structures of both phases were determined by single crystal X‐ray diffraction, but refinement did not yield satisfactory residuals for the low temperature phase because of twinning of the crystal. It was, therefore, independently solved from the synchrotron powder diffraction data using rigid body models of the constituent ions and ab‐initio direct space methods. Both, the CF3 group and the SO3 group of the triflate ion, are rotationally disordered around the S–C bond, in the room temperature phase. In the low temperature phase, the triflate ion is well localized. Like in the alkali metal triflates, the triflate ions are arranged in double layers with the hydrophobic trifluoromethyl groups and the sulfonate groups, respectively, pointing towards each other. The dimethylammonium ion is located closer to the sulfonate group with contacts indicating hydrogen bonding. The packing in both phases is of the topological CsCl structure type. 相似文献
40.
W. Gerlach A. Dietzel W. Rollwagen und LI. W. Staples 《Fresenius' Journal of Analytical Chemistry》1937,111(7-8):297-298
Ohne Zusammenfassung 相似文献