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51.
52.
Andrea Cianchi 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1989,40(4):558-569
Summary Letu be a real valued function on ann-dimensional Riemannian manifoldM
n. We consider an inequality between theL
q-norm ofu minus its mean value overM
n and theL
p-norm of the gradient ofu.The best constant in such inequality is exhibited in the following cases: i)M
n is an open ball inIR
n andp=1, 0<qn/(n–1); ii)M
n is a sphere inIR
n
+1 and eitherp=1, 0<qn/(n–1) orp>n,q=.
Sunto Siau una funzione a valori reali dafinita su una varietà riemannianan-dimensionaleM n. Si considera una disuguaglianza tra la normaL q diu meno il suo valor medio suM n e la normaL p del gradiente diu.Si determina la costante ottimale in tale disuguaglianza nei seguenti casi: i)M n è un disco aperto inIR n ep=1, 0<qn/(n–1); ii)M n è una sfera inIR n +1 ep=1, 0<qn/(n–1) oppurep>n,q=.相似文献
53.
Andrea Laforgia Martin E. Muldoon 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1988,39(2):267-271
Summary We show, among other things, that the positive zeros of a solution ofy
+x
y=0,y(0)=0 decrease to 1 as increases, 0.
To the memory of Milo Háik
This research was supported by grants from the Natural Sciences and Engineering Research Council (Canada) and Consiglio Nazionale delle Ricerche (Italy). Some of the work was done while the second-named author was visiting the Department of Mathematics, University of Torino. 相似文献
Sommario Si dimostra, tra l'altro, che gli zeri positivi d'una soiuzione diy +x y=0,y(0)=0 decrescono al limite 1, quando cresce, 0.
To the memory of Milo Háik
This research was supported by grants from the Natural Sciences and Engineering Research Council (Canada) and Consiglio Nazionale delle Ricerche (Italy). Some of the work was done while the second-named author was visiting the Department of Mathematics, University of Torino. 相似文献
54.
Simultaneous separation and identification of hashish constituents by coupled liquid chromatography-mass spectrometry (HPLC-MS) 总被引:1,自引:0,他引:1
C. Rustichelli V. Ferioli F. Vezzalini M. C. Rossi G. Gamberini 《Chromatographia》1996,43(3-4):129-134
Summary This paper reports the use of liquid chromatography for the separation and determination of the major cannabinoids extracted from hashish samples. The direct coupling to the mass spectrometer enables the selective identification both of neutral and acidic cannabinoids. The developed method does not require any preliminary derivatization and should, therefore, be of interest in forensic analysis for simple and unequivocal determination of hashish constituents.Part of this work was presented at the 2nd Italian-Spanish Joint Meeting of Medicinal Chemistry, 30 August–3 September 1995, Ferrara, Italy. 相似文献
55.
56.
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
57.
Francesco De Sarlo Antonio Guarna Andrea Goti Alberto Brandi 《Journal of organometallic chemistry》1984,269(2):115-121
Organomercury fulminates react with acetylene derivatives to give unstable 3-(organomercurio)isoxazoles, which isomerize to 2-cyanoenolates. These are hydrolyzed with hydrochloric acid to the corresponding enols and are cleaved by water at the double bond. With monosubstituted acetylenes, substitution at the free position by the organomercury residue is predominant. 相似文献
58.
Thomas P J Linsinger Alexander Bernreuther Philippe Corbisier Marta Dabrio Håkan Emteborg Andrea Held Andrée Lamberty Gaida Lapitajs Marina Ricci Gert Roebben Stefanie Trapmann Franz Ulberth Hendrik Emons 《Accreditation and quality assurance》2007,12(3-4):167-174
The potential approaches for third-party assessment of reference material producers are revisited and the activities of the
Reference Materials (RM) Unit of the Institute for Reference Materials and Measurements (IRMM) to obtain accreditation to
ISO Guide 34 and ISO 17025 are described. Accreditation was related to the Unit as all matrix RM activities of the institute
are concentrated there. A management system was established that allows sufficient flexibility to be applicable to a wide
range of RMs while being precise enough to ensure compliance with ISO Guides 30, 31 and especially 34 and 35. Accreditation
was achieved in 2004 with independent scopes for testing and RM production and was confirmed and extended in 2005. The key
aspects of the RM Unit's management system for RM production are presented.
Presented at BERM-10, April 2006, Charleston, SC, USA 相似文献
59.
Eliana M. Alhadeff Andrea M. Salgado Nei Pereira Jr. Belkis Valdman 《Applied biochemistry and biotechnology》2004,113(1-3):125-136
An automated flow injection analysis (FIA) system for quantifying ethanol was developed using alcohol oxidase, horseradish
peroxidase, 4-aminophenazone, and phenol. A colorimetric detection method was developed using two different methods of analysis,
with free and immobilized enzymes. The system with free enzymes permitted analysis of standard ethanol solution in a range
of 0.05–1.0 g of ethanol/L without external dilution, a sampling frequency of 15 analyses/h, and relative SD of 3.5%. A new
system was designed consisting of a microreactor with a 0.91-mL internal volume filled with alcohol oxidase immobilized on
glass beads and an addition of free peroxidase, adapted in an FIA line, for continued reuse. This integrated biosensor-FIA
system is being used for quality control of biofuels, gasohol, and hydrated ethanol. The FIA system integrated with the microreactor
showed a calibration curve in the range of 0.05–1.5 g of ethanol/L, and good results were obtained compared with the ethanol
content measured by high-performance liquid chromatography and gas chromatography standard methods. 相似文献
60.
The self‐complementary tetrameric propargyl triols 8, 14, 18 , and 21 were synthesized to investigate the duplex formation of self‐complementary, ethynylene‐linked UUAA, AAUU, UAUA, and AUAU analogues with integrated bases and backbone (ONIBs). The linear synthesis is based on repetitive Sonogashira couplings and C‐desilylations (34–72% yield), starting from the monomeric propargyl alcohols 9 and 15 and the iodinated nucleosides 3, 7, 11 , and 13 . Strongly persistent intramolecular H‐bonds from the propargylic OH groups to N(3) of the adenosine units prevent the gg‐type orientation of the ethynyl groups at C(5′). As such, an orientation is required for the formation of cyclic duplexes, this H‐bond prevents the formation of duplexes connected by all four base pairs. However, the central units of the UAUA and AAUU analogues 18 and 14 associate in CDCl3/(D6)DMSO 10 : 1 to form a cyclic duplex characterized by reverse Hoogsteen base pairing. The UUAA tetramer 8 forms a cyclic UU homoduplex, while the AUAU tetramer 21 forms only linear associates. Duplex formation of the O‐silylated UUAA and AAUU tetramers is no longer prevented. The self‐complementary UUAA tetramer 22 forms Watson–Crick‐ and Hoogsteen‐type base‐paired cyclic duplexes more readily than the sequence‐isomeric AAUU tetramer 23 , further illustrating the sequence selectivity of duplex formation. 相似文献