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排序方式: 共有1431条查询结果,搜索用时 15 毫秒
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DAndrea A. Tomassini N. Ferrari L. Righini M. Selci S. Bruni M. R. Simeoni G. 《Il Nuovo Cimento D》1995,17(11):1423-1427
Il Nuovo Cimento D - Normalized reflection spectra in GaInAs/GaAs quantum wells are shown for two sets of samples with different alloy concentration (x=9% and 18.5%) and well thickness ranging from... 相似文献
3.
4.
Giampiero Bettinetti Milena Sorrenti Laura Catenacci Franca Ferrari Silvia Rossi Ilaria Salvadeo Paolo Carraro 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):329-332
Triacetyl α-cyclodextrin, triacetyl β-cyclodextrin and triacetyl γ-cyclodextrin were tested as possible hydrophobic carriers
to prolong the release of hydrophilic teicoplanin (TCP). Physical–chemical characterization of individual components, drug-carrier
physical mixtures at 0.5, 0.67 and 0.75 mass fraction of carrier, and the respective interaction products by kneading or evaporative
crystallization under microwave irradiation was carried out using differential scanning calorimetry (DSC) and thermogravimetric
analysis (TGA). In vitro drug release in pH 7.4 phosphate buffer at 37 °C was determined by intrinsic dissolution rate (IDR)
measurements on non disintegrating compressed discs. Solid-state interactions of TCP with triacetyl α-cyclodextrin by evaporative
crystallization and kneading and with triacetyl β-cyclodextrin by evaporative crystallization (probably resulting in carrier
amorphization) were demonstrated. The role of carrier hydrophobicity, carrier mass fraction and preparation method of solid
drug-carrier combinations on solid-state drug-carrier interactions and slowing down of TCP release was assessed. Modulation
of drug release can be achieved using TCP-triacetyl γ-cyclodextrin combinations at 0.5 mass fraction of carrier. 相似文献
5.
Fermo P Gilardoni S Jauni Simarro T Bolzacchini E Lasagni M Gianelle V Pozzoli L Perrone G Librando V 《Annali di chimica》2003,93(4):389-396
The carbonaceous component in the Milan urban particulate matter, i.e. the two components black carbon (BC) and organic carbon (OC), has been measured by means of a thermogravimetric analyzer combined with an infrared spectrophotometer (TGA/FT-IR). While black carbon may be considered a primary pollutant, organic carbon includes both primary emissions and secondary organic aerosols. Since carbonaceous aerosol (including a small quantity of inorganic carbon, too) makes up roughly from 25% to 50% of the average annual PM 2.5 mass concentration, a deeper understanding of this component is required. The TGA/FT-IR technique, employed for the first time to our knowledge for the quantification of the particulate matter carbonaceous component, allows, thought the results here presented are preliminary, to assess the two components BC and OC in a simple way especially if compared with the methods reported in the literature. The total carbon (TC) determinations performed by TGA/FT-IR on Milan urban particulate matter are in good agreement with the results obtained by a total organic carbon (TOC) analyzer operating directly on the solid sample. 相似文献
6.
Marco Vincenti Claudio Minero Stefania Lago Costanza Rovida 《Journal of separation science》1995,18(6):359-362
A rapid and effective procedure, developed for the determination of polar compounds in water, has been applied to hydroxycarbamates. In few minutes, it is possible to perform a catalyzed derivatization of such compounds directly in the aqueous medium, using n-hexyl chloroformate. Extraction with n-hexane and injection into a benchtop GC-MS system are the only two further steps to complete the analysis. Chemical ionization proved to be more effective than electron impact to produce valuable mass spectra in terms of selectivity and sensitivity. Linear quantitative responses were demonstrated over a two-order-of-magnitude range. The minimum detectable concentration was 3 ppb for acetohydroxamic acid and 10 ppb for hydroxyurethane, obtained from Po river water samples spiked with the two hydroxycarbamate standards. 相似文献
7.
Archiv der Mathematik - We obtain an explicit Hölder regularity result for viscosity solutions of a class of second order fully nonlinear equations led by operators that are neither... 相似文献
8.
Antonio Cipiciani Stefania Primieri Antonio Arcelli 《Journal of inclusion phenomena and macrocyclic chemistry》1994,15(3):207-214
The hydrolysis reaction of 2-nitro-4-carboxyphenyl acetate was studied in dichloromethane in the presence of an added electrolyte (NaOH) and cationic surfactants systems with varying quantities of added water at 25°C. The kinetic and conductivity data were correlated. 相似文献
9.
Summary We consider the one dimensional nearest neighbors asymmetric simple exclusion process with ratesq andp for left and right jumps respectively;q<p. Ferrari et al. (1991) have shown that if the initial measure isv
,
, a product measure with densities and to the left and right of the origin respectively, <, then there exists a (microscopic) shock for the system. A shock is a random positionX
t
such that the system as seen from this position at timet has asymptotic product distributions with densities and to the left and right of the origin respectively, uniformly int. We compute the diffusion coefficient of the shockD=lim
t
t
–1(E(X
t
)2–(EX
t
)2) and findD=(p–q)(–)–1((1–)+(1–)) as conjectured by Spohn (1991). We show that in the scale
the position ofX
t
is determined by the initial distribution of particles in a region of length proportional tot. We prove that the distribution of the process at the average position of the shock converges to a fair mixture of the product measures with densities and . This is the so called dynamical phase transition. Under shock initial conditions we show how the density fluctuation fields depend on the initial configuration. 相似文献
10.