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51.
Application of polyamorphism in water to spontaneous crystallization of emulsified LiCl-H2O solution
Mishima O 《The Journal of chemical physics》2005,123(15):154506
Aqueous solutions are widely explained by the hydration or the bound waterfree water notion. Amorphous polymorphism (polyamorphism) in pure water, which is presently under vigorous discussion, may provide a different view over the solutions. Here, I changed pressure, P, temperature, T, and concentration, C, of emulsified LiCl-H2O solutions and studied their freezing by detecting its heat evolution. It was experimentally indicated that the homogeneous nucleation of low-density crystalline ice I (phase Ih or Ic), in pure water and in solutions, connects to the polyamorphic transition of high-density amorphous ice (HDA) to low-density amorphous ice (LDA). Thus, the polyamorphism of water relates to the phase behavior of aqueous solution. In accordance with the recent simulation result, the nucleation was thought to occur in two stages: the appearance of the LDA-like state and the crystallization. Usefulness of the polyamorphic point of view about the solutions was seen. 相似文献
52.
A short-step synthesis of , the right-hand half of antibiotic saframycin (), is described. The key steps of this synthesis are the acid catalyzed intramolecular double cyclization of and the oxidative demethylation of to the quinone (). 相似文献
53.
Takashi Matsuda Yu Mishima Saeid Azizian Hiroki Matsubara Takanori Takiue Makoto Aratono 《Colloid and polymer science》2007,285(14):1601-1605
We measured the interfacial tension and the density of air/n-hexane, n-decane, 1-perfluorohexane/1-hexyl-3-methyl-imidazolium hexafluorophosphate systems as a function of temperature. From the
air/ionic liquid surface tension values, it was suggested that Coulombic interaction between imidazolium cations and counter
anions are not so much different between the surface and bulk. The density values indicated that the decrease of surface tension
by saturating organics was closely correlated to the mutual solubility between ionic liquid and organics. Interfacial tension
at the oil/ionic liquid interfaces suggested that ionic liquid molecules were more ordered at the oil/ionic liquid interfaces
compared to the air/ionic liquid interfaces, but the decrease of the entropy due to the interfacial orientation of ionic liquid
was compensated by the increase of the entropy due to the contact of different chemical species. The initial spreading coefficients
and the Hamaker constants indicated that all the oil phases spread at the air/ionic liquid interfaces spontaneously, and form
the complete wetting films. 相似文献
54.
We make glass of dilute LiCl aqueous solution by cooling micrometer-sized droplets of the solution extremely quickly and measure the Raman spectra of the glass. It is found that the OH stretching vibration mode of the glass of dilute solution is composed of the OH stretching vibration mode of pure glassy water and that of the glass of solvent water in the highly concentrated solution. This is consistent with the possibility of the existence of two distinct glassy states of water in dilute LiCL solution at low temperature. 相似文献
55.
Kohei Tamao Masayuki Mishima Jun-ichi Yoshida Masataka Takahashi Neyoshi Ishida Makoto Kumada 《Journal of organometallic chemistry》1982,225(1):151-162
The reactions of potassium 5-norbornen-2-ylpentafluorosilicate (I) and 5-norbornen-2-yltrimethylsilane (II) with NBS were examined. The former reaction gave 3-nortricyclyl bromide (IV) as the only detectable product, arising from the carbon—silicon bond cleavage. The latter reaction, however, gave 3-bromo-1-nortricyclyltrimethylsilane (V) as the major product, resulting from cleavage of the carbon—hydrogen bond α to silicon, together with IV and an unidentified product. GLC-monitoring of the reactions showed the higher reactivity of the norbornenyl derivative having the leaving group in theendo position irrespective of whether the leaving group is SiF5 or H. Since no inhibition was observed by the addition of hydroquinone in the dark, the reactions have been regarded as homoallylic electrophilic substitutions. A concerted mechanism seems to be consistent with the experimental data. Cleavage of 1-nortricyclyltrimethylsilane by iodine monochloride to give 1-iodonortricyclene has also been studied. 相似文献
56.
Summary Response functions for underground muons are obtained by solving numerically the equations of hadronic cascades in the atmosphere,
by assuming Feynman scaling for hadronic interactions over the whole energy region. For practical use of the response functions
in cosmic-ray modulation study, calculations are made for various combinations of parameters such as zenith angle, atmospheric
depth and muon threshold energy. The present response functions are consistent with cosmic-ray measurements and can be well
utilized for the study on the cosmic-ray modulation.
Riassunto Si ottengono funzioni di risposta per muoni sotterranei risolvendo numericamente le equazioni per le cascate adroniche nell'atmosfera, assumendo lo scaling di Feynman per interazioni adroniche nell'intera regione di energia. Per l'uso pratico di funzioni di risposta nello studio di modulazione dei raggi cosmici, si fanno calcoli per varie combicazioni di parametri come l'angolo di zenit, la profondità atmosferica e l'energia muonica di soglia. Le attuali funzioni di risposta sono coerenti con le misurazioni dei raggi cosmici e possono essere bene utilizzate per lo studio della modulazione dei raggi cosmici.相似文献
57.
We have observed the InSb(001)-c(8 x 2) surface by using high-resolution transmission electron microscopy in the profile-imaging geometry. All images observed at temperatures up to 420 degrees C agree well with the c(8 x 2) model reported by Kumpf et al. [Phys. Rev. Lett. 86, 3586 (2001)]]. 1/30 sec real-time observations at 420 degrees C evidence that a part of the subsurface and surface layers (called a gull-type segment) undergo switching to and from a bulk configuration. The finding is suggestive of large anisotropy in the mean square displacement of the c(8 x 2) surface. 相似文献
58.
Evaluation analysis of prediction methods for two-phase flow pressure drop in mini-channels 总被引:1,自引:0,他引:1
Two-thousand and ninety-two data of two-phase flow pressure drop were collected from 18 published papers of which the working fluids include R123, R134a, R22, R236ea, R245fa, R404a, R407C, R410a, R507, CO2, water and air. The hydraulic diameter ranges from 0.506 to 12 mm; Rel from 10 to 37,000, and Reg from 3 to 4 × 105. Eleven correlations and models for calculating the two-phase frictional pressure drop were evaluated based upon these data. The results show that the accuracy of the Lockhart–Martinelli method, Mishima and Hibiki correlation, Zhang and Mishima correlation and Lee and Mudawar correlation in the laminar region is very close to each other, while the Muller-Steinhagen and Heck correlation is the best among the evaluated correlations in the turbulent region. A modified Chisholm correlation was proposed, which is better than all of the evaluated correlations in the turbulent region and its mean relative error is about 29%. For refrigerants only, the new correlation and Muller-Steinhagen and Heck correlation are very close to each other and give better agreement than the other evaluated correlations. 相似文献
59.
Anharmonicity plays a very important role in the high temperature range for photo-induced electron transfer. A simple truncated oscillator model is used to investigate the effect of the disallowed states of anharmonicity on the photo-induced electron transfer. The obtained formula shows that in the high temperature limit, the electron transfer rate becomes a constant, independent of temperature, but the Marcus equation approaches zero. 相似文献
60.
Min Zhang Takaaki Sonoda Masaaki Mishima Tsunetoshi Honda Ivo Leito Ilmar A. Koppel Werner Bonrath Thomas Netscher 《Journal of Physical Organic Chemistry》2014,27(8):676-679
The gas‐phase acidity (GA) values were determined for a number of perfluoroalkyl‐substituted sulfonylimides by measuring proton‐transfer equilibria using a Fourier transform ion cyclotron resonance (FT‐ICR) mass spectrometer. The GA scale below 286.5 kcal mol?1 for (CF3SO2)2NH was extended and partially revised. The GA value of (C4F9SO2)2NH which is currently the strongest acid was revised from 284.1 to 278.6 kcal mol?1. The effect of fluorine atoms on the acidity of perfluoroalkyl‐substituted sulfonylimides was described with the following model where N(α), N(β), N(γ), and N(δ) are the numbers of fluorine atoms at α, β, γ, and δ position in RfSO2 (Rf = perfluoroalkyl group), respectively. This correlation indicates that the electron‐withdrawing ability of the RfSO2 group can be described in terms of the number of fluorine atoms in the perfluoroalkyl group corrected by taking into account their positions. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献