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81.
A SPLEEM (spin polarized low energy electron microscope) has been designed with a numerical simulation of electrostatic and magnetic field distributions and electron ray trajectories. Highly (more than 90%) spin polarized electron source has been used. A Wien type spin manipulator and a magnetic lens type spin rotator are used to align spin direction. A magnetic field free objective lens is designed to observe magnetic domain structure of magnetic materials. High or low magnification mode can be selected by using a combined electrostatic and magnetic objective lens for a high spatial resolution and a wide imaging area observation. An electrostatic mirror aberration corrector is installed after the image forming objective lens. A double deflection 45° beam separator is used to bend the direction of electrons from the source to the objective lens and from the objective lens to the mirror aberration corrector. 相似文献
82.
Hosoi K Inagi S Kubo T Fuchigami T 《Chemical communications (Cambridge, England)》2011,47(30):8632-8634
Electron transfer behavior of 1,2-diphenyl-o-carborane was investigated by cyclic voltammetry (CV). In the presence of 1,2-dibromo-1,2-diphenylethane, a significant catalytic current was observed. The macroscale electrocatalytic reduction of the dibromide using a catalytic amount (1 mol%) of the carborane mediator afforded the desired trans-stilbene in excellent yield. 相似文献
83.
Stroke patterns for Purcell's three-link swimmer are optimized. We model the swimmer as a jointed chain of three slender rods moving in an inertialess flow. The swimmer is optimized for efficiency and speed. We were able to attain swimmer designs significantly more efficient than those previously suggested by authors who only consider geometric design rather than kinematic criteria. The influence of slenderness on optimality is considered as well. 相似文献
84.
Ogawa S Hosoi K Ikeda N Makino M Fujimoto Y Iida T 《Chemical & pharmaceutical bulletin》2007,55(2):247-250
Oxyfunctionalization of the bioactive terpenoids, ursolic acid acetate (1), oleanolic acid acetate (5), lupeol acetate (12), and kaurenic acid (17), with dimethyldioxirane (DMDO) was investigated. Treatment of the terpenoids with DMDO under mild conditions afforded a variety of oxidation and oxydegradation products to yield naturally occurring and/or novel compounds in one step. After chromatographic separation, the structures of the individual isolated products were determined using spectroscopic methods including several homonuclear (1H-1H) and heteronuclear (1H-13C) shift-correlated 2D-NMR techniques. The inhibitory activity of the terpenoid derivatives against alpha-glucosidase was investigated and compounds 1, 3, 7, and 9 were found to exhibit potent activity. 相似文献
85.
K. Iida M. Nango H. Yasue K. Okuda M. Okita A. Kashiwada N. Takada M. Maekawa Y. Kurono 《Colloid and polymer science》1998,276(2):152-159
The effect of denaturants such as urea and normal alcohols on the formation of light-harvesting (LH) polypeptides/bacteriochlorophyll
a (BChla) complex (LH1 complex) in n-octyl-β-D-glucopyranoside (OG) micelle was examined to provide an insight into stability of the complex. The stabilities
of the LH1 complex in OG micelle and of the complex in the chromatophore of photosynthetic bacteria were compared by addition
of denaturants. The extent of stability of these complexes was monitored by the change in absorbance of Qy band of BChla in these complexes, resulting generally in the blue-shifting of the Qy band from near 870 nm to about 777 nm upon addition
of these denaturants. Urea and guanidium hydrochloride (Gnd) showed a relatively weak denaturing effect. Normal alcohols showed
stronger denaturing effect, depending on the hydrophobicity of the alcohols. These results imply that the stability of LH1
complex in OG micelle can be largely attributed to the hydrophobic interactions in the complex as well as that of the complex
in the chromatophore of photosynthetic bacteria.
Received: 23 May 1997 Accepted: 13 September 1997 相似文献
86.
M. Yasue T. Tanabe S. Kubono J. Kokame M. Sugitani Y. Kadota Y. Taniguchi M. Igarashi 《Nuclear Physics A》1982,391(2):377-412
The 27Al(α, t) and (α, 3He) reactions have been measured at Eα = 64.5 MeV. The experimental angular distributions were analyzed by the exact finite-range DWBA calculations assuming a nucleon stripping mechanism. The distributions of spectroscopic strengths for the single-particle transitions with transferred angular momenta l = 0, 1, 2, 3 and 4 have been obtained. The strengths for the transitions to the stretched 6? states in 28Si and 28Al are compared to those obtained from inelastic scattering on 28Si. The present results show no distinctive differences in the structures for 6?T = 0 and 1 states in 28Si such as are observed in proton and pion inelastic scattering on 28Si. 相似文献
87.
S Umemoto S Im J Zhang M Hagihara A Murata Y Harada T Fukuzumi T Wazaki S Sasaoka K Nakatani 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(32):9999-10008
A series of xanthone and thioxanthone derivatives with aminoalkoxy substituents were synthesized as fluorescent indicators for a displacement assay in the study of small-molecule-RNA interactions. The RNA-binding properties of these molecules were investigated in terms of the improved binding selectivity to the loop region in the RNA secondary structure relative to 2,7-bis(2-aminoethoxy)xanthone (X2S) by fluorimetric titration and displacement assay. An 11-mer double-stranded RNA and a hairpin RNA mimicking the stem loop IIB of Rev response element (RRE) RNA of HIV-1 mRNA were used. The X2S derivatives with longer aminoalkyl substituents showed a higher affinity to the double-stranded RNA than the parent molecule. Introduction of a methyl group on the aminoethoxy moiety of X2S effectively modulated the selectivity to the RNA secondary structure. Methyl group substitution at the C1' position suppressed the binding to the loop regions. Substitution with two methyl groups on the amino nitrogen atom resulted in reducing the affinity to the double-stranded region by a factor of 40%. The effect of methyl substitution on the amino nitrogen atom was also observed for a thioxanthone derivative. Titration experiments, however, suggested that thioxanthone derivatives showed a more prominent tendency of multiple binding to RNA than xanthone derivatives. The selectivity index calculated from the affinity to the double-stranded and loop regions suggested that the N,N-dimethyl derivative of X2S would be suitable for the screening of small molecules binding to RRE. 相似文献
88.
Nadaoka I Watanabe K Yasue M Sami M Kitagawa Y Mimaki Y 《Natural product communications》2012,7(1):15-18
Dried rhizomes of Cimicifuga racemosa (CR), known as black cohosh, have been widely used as a herbal dietary supplement in the treatment of menopausal symptoms. Here we used experimental mouse stress models to investigate the role of anti-stress food factors, and found that a CR extract had stress-relieving effects. A single oral administration of CR extract (1,000 mg/kg) significantly attenuated plasma corticosterone and aspartate aminotransferase (AST) levels that had increased as a result of enforced immobilization. Bioassay-guided fractionation of the CR extract resulted in the isolation of 10 triterpenes, among which actein, 23-epi-26-deoxyactein, and cimiracemoside F (100 mg/kg, per os) were shown to contribute to the anti-stress effects. Furthermore, the CR extract significantly prevented the development of water immersion stress-induced gastric mucosal ulcers in rats. We propose that the CR extract might be suitable for the prevention and treatment of stress-related disorders. 相似文献
89.
90.
Summary The adsorption behaviour of 16 elements on the strongly acidic cation-exchange resin AG 50W, X-8 has been examined in mixed oxalic-nitric acid media. The distribution coefficients are presented as a function of nitric acid concentration (0.13.0 M) in 0.05 M oxalic acid solution. There are marked differences in adsorbability between terand quadrivalent metal and bivalent metal groups. The system can be applied to the multielement analysis of manganese nodules for iron, zinc, copper, cobalt, manganese and nickel, coupled with chromatographic elution of bivalent metals with mineral acid-organic solvent mixtures. The versatility of the system is also demonstrated by the analysis of a biological standard reference material, pepperbush, of NIES for the same six elements. The results are in good agreement with the certified values (NIES: National Institute for Environmental Studies, Japan Environment Agency).
Kationenaustausch in Oxalsäure-Salpetersäure-LösungAnalytische Anwendung zur Bestimmung von sechs Spurenelementen in Manganknollen und Pflanzenmaterial
Zusammenfassung Das Adsorptionsverhalten von 16 Elementen an dem stark sauren Kationenaustauscher AG 50W, X-8 wurde in Oxalsäure-Salpetersäure-Gemischen untersucht. Die Verteilungskoeffizienten werden angegeben als Funktion der Salpetersäurekonzentration (0,13,0 M) in 0,05 M Oxalsäure. Die Adsorbierbarkeit der drei- und viersowie zweiwertigen Metallionen weist deutliche Unterschiede auf. Das Verfahren kann zur Multielementanalyse von Manganknollen auf Fe, Zn, Cu, Co, Mn und Ni angewendet werden. Die Elution der zweiwertigen Metallionen erfolgt mit Gemischen von Mineralsäuren und organischen Lösungsmitteln. Die Vielseitigkeit der Methode wird durch die Analyse eines biologischen Referenzmaterials (Pepperbush, NIES) demonstriert. Die Ergebnisse stimmten mit den zertifizierten Werten gut überein.相似文献