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71.
Surface layers of natural and technical amphiphiles, e.g., octadecanol, stearic acid and related compounds as well as perfluorinated fatty alcohols (PFA), have been investigated on the surface of acoustically levitated drops. In contrast to Langmuir troughs, traditionally used in the research of surface layers at the air-water interface, acoustic levitation offers the advantages of a minimized and contact-less technique. Although the film pressure cannot be directly adjusted on acoustically levitated drops, it runs through a wide pressure range due to the shrinking surface of an evaporating drop. During this process, different states of the generated surface layer have been identified, in particular the phase transition from the gaseous or liquid-expanded to the liquid-condensed state of surface layers of octadecanol and other related amphiphiles. Characteristic parameters, such as the relative permeation resistance and the area per molecule in a condensed surface layer, have been quantified and were found comparable to results obtained from surface layers generated on Langmuir troughs. 相似文献
72.
Aleksander S. Simonsen Sigurd Askeland Morten Førre 《Central European Journal of Physics》2013,11(9):1099-1106
In this paper, we present theoretical results for the process of non-sequential two-photon double ionization of helium at the photon energy 42 eV. Our approach is based on solving the time-dependent Schrödinger equation in a B-spline based numerical framework. Information about the process is obtained by extracting the double-ionized component by means of uncorrelated final states. The total (generalized) cross section for the process is extracted, as well as differential cross sections resolved in electron energies and ejection angles. We focus on the impact the final-state correlation has on the accuracy of the cross sections. 相似文献
73.
Silva ME Heim R Strasser A Elz S Dove S 《Journal of computer-aided molecular design》2011,25(1):51-66
A series of 51 5-HT2A partial agonistic arylethylamines (primary or benzylamines) from different structural classes (indoles, methoxybenzenes,
quinazolinediones) was investigated by fragment regression analysis (FRA), docking and 3D-QSAR approaches. The data, pEC50 values and intrinsic activities (Emax) on rat arteries, show high variability of pEC50 from 4 to 10 and of Emax from 15 to 70%. FRA indicates which substructures affect potency or intrinsic activity. The high contribution of halogens
in para position of phenethylamines to pEC50 points to a specific hydrophobic pocket. Other results suggest the significance of hydrogen bonds of the aryl moiety for
activation and the contrary effect of benzyl groups on affinity (increasing) and intrinsic activity (decreasing). Results
from fragment regression and data on all available mutants were considered to derive a common binding site at the rat 5-HT2A receptor. After generation and MD simulations of a receptor model based on the β2-adrenoceptor structure, typical derivatives were docked, leading to the suggestion of common interactions, e.g., with serines
in TM3 and TM5 and with a cluster of aromatic amino acids in TM5 and TM6. The whole series was aligned by docking and minimization
of the complexes. The pEC50 values correlate well with Sybyl docking energies and hydrophobicity of the aryl moieties. With this alignment, CoMFA and
CoMSIA approaches based on a training set of 36 and a test set of 15 compounds were performed. The correlation of pEC50 with steric, electrostatic, hydrophobic and H-bond acceptor fields resulted in sufficient fit (q
2: 0.75–0.8, r
2: 0.92–0.95) and predictive power (r
pred2: 0.85–0.88). The important interaction regions largely reflect the patterns provided by the putative binding site. In particular,
the fit of the aryl moieties and benzyl substituents to two hydrophobic pockets is evident. 相似文献
74.
SS Jester E Sigmund LM Röck S Höger 《Angewandte Chemie (International ed. in English)》2012,51(34):8555-8559
Seeing stars: The two-dimensional patterns of the polycyclic heteroaromatic star molecules 1 on graphite vary with the side chain length. For n=12, frustrated self-assembly leads to hierarchically organized superstructures: up to 10?molecules form triangular aggregates which pack densely into hexagonal patterns with very large (15.5?nm) lattice constants. 相似文献
75.
Theresa Eder Jan Vogelsang Sebastian Bange Klaas Remmerssen Daniela Schmitz Stefan‐S. Jester Tristan J. Keller Sigurd Hger John M. Lupton 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(52):19074-19078
Strong dipole–dipole coupling within and between π‐conjugated segments shifts electronic transitions, and modifies vibronic coupling and excited‐state lifetimes. Since J‐type coupling between monomers along the conjugated‐polymer (CP) chain and H‐type coupling of chromophores between chains of a CP compete, a superposition of the spectral modifications arising from each type of coupling emerges, making the two couplings hard to discern in the ensemble. We introduce a single‐molecule H‐type aggregate of fixed spacing and variable length of up to 10 nm. HJ‐type aggregate formation is visualized intuitively in the scatter of single‐molecule spectra. 相似文献
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