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1.
Zusammenfassung Die dielektrischen Verluste diphenylmethylierter und chlorierter Poly?thylene k?nnen in Einzelheiten quantitativ richtig dargestellt
werden, wenn man annimmt, da\ das Copolymerensystem pseudo-eutektischen Charakter hat. Die dipoltragenden Gruppen (CHCl bzw.
Diphenylmethan-CH) werden offenbar nicht in die Kristalle, wohl aber in die longitudinalen Grenzschichten eingebaut. Dasα-Maximum ist den Dipolen in der Grenzschicht, dasΒ-Maximum den Dipolen im Innern der amorphen Anteile zuzuordnen. Die Temperaturlage und die Fl?che unter diesen Verlustmaxima
h?ngen in bestimmter Weise von der mittleren Kristalldicke ab. Eine klare Zuordnung von Strukturdaten und Daten aus dem Relaxationsspektrum
ist durch eine erweiterte quantitative Analyse der dielektrischen Me\ergebnisse m?glich.
Es sind dann nicht nur die Temperaturlage desα- und desΒ-Maximums, sondern auch deren relative Fl?chen?nderungen in übereinstimmung mit dem Experiment berechenbar. Dies ist eine
scharfe quantitative Konsistenzprüfung des erweiterten Stuktur-modells, wonach die Kristalle longitudinale Grenzschichten
von definierter mittlerer Dicke besitzen sollen.
Mit Hilfe der Zwei-Drittel-Regel kann man bei Kenntnis der wahren Konzentration der Comonomereneinheiten in den amorphen Zwischenbereichen
kristallisierter Proben die Temperaturlage der glasigen Erstarrung abh?ngig von der Gesamtkonzentration sehr gut angeben.
Die Lage der Glastemperatur sollte hiernach im Vergleich zur Glastemperatur des ‚'unendlich gro\en“ amorphen Systems derselben
Konzentration durch die Kristallisation nicht ver?ndert werden.
Wir danken der Deutschen Forschungsge-meinschaft für die gro\zügige Bereitstellung von Sach- und Personalmitteln. 相似文献
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4.
RITVA LINDBERG GORAN SUNDHOLM JOHAN SJö BLOM PETRI AHONEN ESKO I. KAUPPINEN 《Journal of Dispersion Science and Technology》2013,34(1-2):715-722
The zeta-potentials of silica, copper, platinum and gold particles have been measured as a function of pH. The isoelectric points were found to be at pH 3.0, 5.8, 3.0 and 3.5, respectively. In the pH range 3.0 to 5.8 copper and silica particles are oppositely charged and accordingly the coating of silica with copper particles could be demonstrated. In the case of gold and platinum the sign of the charge is such that direct adhesion to silica particles cannot be expected and this was also demonstrated in the case of platinum. 相似文献
5.
Experiments in drums or cylinders partly filled with a granular system and rotated constantly about their horizontally aligned axis of symmetry show a hysteretic transition from discrete avalanches to continuous flow if the rotation rate is adiabatically changed. Herein, we show that this hysteresis can be explained by the impact of global Langevin-type fluctuations in a recently proposed minimal model for surface flow along granular piles. For too large magnitudes of the fluctuations corresponding to almost elastic grains, the hysteresis vanishes. This might explain why molecular dynamical simulations were not yet able to detect the hysteretic transition. (c) 1999 American Institute of Physics. 相似文献
6.
Peter Linz 《BIT Numerical Mathematics》1971,11(4):413-421
The numerical solution of Volterra integral equations of the first kind can be accomplished if the integral is replaced by certain simple quadrature rules, such as the midpoint or the trapezoidal methods. When the kernel of the integral equation oscillates more rapidly than the solution one can use product integration techniques to increase the accuracy. Such an approach is investigated in this paper. 相似文献
7.
van Enk SJ 《Physical review letters》2000,84(4):789; author reply 790
8.
Douglas McHugh Sherry SJ Hu Neta Rimmerman Ana Juknat Zvi Vogel J Michael Walker Heather B Bradshaw 《BMC neuroscience》2010,11(1):44
Background
Microglia provide continuous immune surveillance of the CNS and upon activation rapidly change phenotype to express receptors that respond to chemoattractants during CNS damage or infection. These activated microglia undergo directed migration towards affected tissue. Importantly, the molecular species of chemoattractant encountered determines if microglia respond with pro- or anti-inflammatory behaviour, yet the signaling molecules that trigger migration remain poorly understood. The endogenous cannabinoid system regulates microglial migration via CB2 receptors and an as yet unidentified GPCR termed the 'abnormal cannabidiol' (Abn-CBD) receptor. Abn-CBD is a synthetic isomer of the phytocannabinoid cannabidiol (CBD) and is inactive at CB1 or CB2 receptors, but functions as a selective agonist at this Gi/o-coupled GPCR. N-arachidonoyl glycine (NAGly) is an endogenous metabolite of the endocannabinoid anandamide and acts as an efficacious agonist at GPR18. Here, we investigate the relationship between NAGly, Abn-CBD, the unidentified 'Abn-CBD' receptor, GPR18, and BV-2 microglial migration. 相似文献9.
A series of pyrrolo[2,3‐d]pyrimidine Mannich bases of type 9, 12, 15 and 16 have been prepared as potential dopamine D4 receptor ligands. The syntheses start from 4‐aminopyrimidin‐6‐one 3 with pyrrole annulations and Mannich reactions with formaldehyde and phenylpiperazines 8 as new amine components. 相似文献
10.
Recently, Götzendorfer et al. [Götzendorfer A, Kruelle CA, Rouijaa M. Granular surface waves in a vibratory conveyor. In: Garcia-Rojo R, Herrmann HJ, McNamara S, editors. Powders and grains, Stuttgart; 2005. p. 1185] have observed subharmonic propagating surface wave patterns if granular material on a trough is subject to a combination of vertical and horizontal periodic driving. The observed structures are non-stationary in space, drift with a constant mean velocity along the trough and oscillate subharmonically with half the driving frequency. We present a phenomenological model for the surface evolution of the granular material that qualitatively reproduces and explains important aspects of the experimentally observed patterns. 相似文献