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排序方式: 共有610条查询结果,搜索用时 15 毫秒
41.
Stazi F Palmisano G Turconi M Clini S Santagostino M 《The Journal of organic chemistry》2004,69(4):1097-1103
1,1,4,7,10,10-Hexamethyltriethylenetetramine (HMTTA) emerged from a limited parallel screening of selected polyamines as the most appropriate additive for an especially problematic Koenigs-Knorr glucuronidation. This initial finding rapidly evolved into a reliable and high-yielding procedure through the use of two sets of experimental designs. The detailed effect of the stoichiometry of reagents and the amount of amine additive on reaction yield was elucidated. The complexity of the response surface for product yield, described by a third-order polynomial equation, together with ancillary kinetic experiments evidenced the multiple role of HMTTA in the present glucuronidation process. 相似文献
42.
Structural characterization of a new lipid/DNA complex showing a selective transfection efficiency in ovarian cancer cells 总被引:5,自引:0,他引:5
Caracciolo G Pozzi D Caminiti R Congiu Castellano A 《The European physical journal. E, Soft matter》2003,10(4):331-336
We investigated, for the first time, by using Energy Dispersive X-ray Diffraction, the structure of a new ternary cationic
liposome formulated with dioleoyl trimethylammonium propane (DOTAP), 1,2-dioleoyl-3-phosphatidylethanolamine (DOPE) and cholesterol
(Chol) (DDC) which has been recently found to have a selective high gene transfer ability in ovarian cancer cells. Our structural
results provide a further experimental support to the widely accepted statement that there is not a simple and direct correlation
between structure and transfection efficiency and that the factors controlling cationic lipid/DNA (CL-DNA) complexes-mediated
gene transfer depend not only on the formulations of the cationic liposomes and their thermodynamic phase, but also significantly
on the cell properties.
Received: 28 October 2002 / Accepted: 21 March 2003 / Published online: 15 April 2003
RID="a"
ID="a"e-mail: a.congiu@caspur.it 相似文献
43.
Federica Galluzzi 《Indagationes Mathematicae》2000,11(4):547
Let X be a complex abelian fourfold of Mumford-type and let V = H1(X,
). The complex Mumford-Tate group of X is isogenous to SL(2)3. We recover information about the Hodge structure of X using representations of the Lie algebras
(2)3 and
(8) acting on V
. Using these techniques we show that there is a Kuga-Satake variety A associated to X in such a way that A is isogenous to X32. 相似文献
44.
45.
Mauro L. Bonardi Flavia Groppi Simone Manenti Elisa Persico Luigi Gini Kamel Abbas Uwe Holzwarth Federica Simonelli Zeev B. Alfassi 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(1):1-7
Very high specific activity (AS) 186gRe could be produced by either proton or deuteron cyclotron irradiation on highly enriched 186W target in no-carrier-added (NCA) form, leading to a AS very close to the theoretical carrier free (CF) value of 6.88 GBq μg−1. Thick Target Yields (TTYs), obtained irradiating both thick metal W targets of natural isotopic composition and highly enriched
powdered 186W targets, were measured at different particles energies taking into account high accuracy and precision. The evaluation of
radionuclidic purities of 186gRe obtained activating highly enriched 186W by both p and d were also carried out and accurately compared. The thin-target excitation functions for all Re (A = 181,
182, 183, 184, 186 and their metastable levels), and W and Ta coproduced radionuclides will be presented elsewhere in deep
details. 相似文献
46.
Jennifer P. Pascali Eloisa LiottaRossella Gottardo Federica BortolottiFranco Tagliaro 《Journal of chromatography. A》2009,1216(15):3349-3352
After decades of neglect, bromide has recently been re-introduced in therapy as an effective anti-epileptic drug. The present paper describes the methodological optimization and validation of a method based on capillary zone electrophoresis for the rapid determination of bromide in serum using a high-viscosity buffer and a short capillary (10 cm). The optimized running buffer was composed of 90 mM sodium tetraborate, 10 mM sodium chloride, pH 9.24 and 25% glycerol. The separation was carried out at 25 kV at a temperature of 20 °C. Detection was by direct UV absorption at 200 nm wavelength. The limit of detection (signal-to-noise ratio = 5) in serum was 0.017 mM. The precision of the method was verified in blank serum samples spiked with bromide, obtaining intra-day and day-to-day tests, relative standard deviation values ≤0.2% in terms of migration times and values <2% in terms of peaks areas, respectively. 相似文献
47.
Matteo Perini Federica Camin Luana Bontempo Andreas Rossmann Edi Piasentier 《Rapid communications in mass spectrometry : RCM》2009,23(16):2573-2585
The study focuses on the 2H/H, 13C/12C, 15N/14N, 18O/16O and 34S/32S values of defatted dry matter (DFDM) and on the 2H/H, 13C/12C and 18O/16O values of the fat fraction of meat samples from various lamb types reared in seven Italian regions, following different feeding regimes (forage, concentrate, milk). The 13C/12C (r = 0.922), 2H/H (r = 0.577) and 18O/16O (r = 0.449) values of fat and DFDM are significantly correlated, the fat values being significantly lower for C and H and higher for O than for DFDM values and the differences between the two fractions not being constant for different lamb types. The feeding regime significantly affected the 13C/12C, 15N/14N, 18O/16O and 2H/H of fat. The DFDM 2H/H, and 18O/16O values, excluding an outlier, are significantly correlated with the corresponding values in meteoric waters, thus allowing us to trace the variability of geoclimatic factors. 15N/14N is influenced by pedoclimatic conditions, whereas 34S/32S is influenced by the sea spray effect and the surface geology of the provenance area. By applying stepwise linear discriminant analysis only the 2H/H of fat was found not to be significant and 97.7% of the samples were correctly assigned to the lamb type and more than 90% cross‐validated. With the feeding regime, 97.7% of the samples were both correctly assigned and cross‐validated using a predictive model including 13C/12C, 15N/14N, 18O/16O, 34S/32S of DFDM and 18O/16O of fat. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
48.
49.
In this paper we consider the Bounded Length Median Path Problem which can be defined as the problem of locating a path-shaped facility that departures from a given origin and arrives at a given destination in a network. The length of the path is assumed to be bounded by a given maximum length. At each vertex of the network (customer-point) the demand for the service is given and the cost to reach the closest service-point is computed. The objective is to minimize the sum of these costs over all the customer-points in the network. 相似文献
50.
Federica Rossella Elisa Polledri Valentina Bollati Andrea Baccarelli Silvia Fustinoni 《Rapid communications in mass spectrometry : RCM》2009,23(17):2637-2646
A method for the determination of DNA global methylation, taken as the ratio (%) of 5‐methylcytosine (5mCyt) versus the sum of cytosine (Cyt) and 5mCyt, via gas chromatography/mass spectrometry (GC/MS), was developed and validated. DNA (2.5 µg) was hydrolyzed with aqueous formic acid 88%, spiked with cytosine‐2,4‐13C2,15N3 and 5‐methyl‐2H3‐cytosine‐6‐2H1 as internal standards, and derivatized with N‐methyl‐N‐(tert‐butyldimethylsilyl)trifluoroacetamide and 1% tert‐butyldimethylchlorosilane, in the presence of acetonitrile and pyridine. GC/MS, operating in single ion monitoring mode, separated and specifically detected all nucleobases as tert‐butyldimethylsilyl derivatives, without interferences, with the exception of guanosine. The method was linear throughout the range of clinical interest and had good sensitivity, with a limit of quantification of 3.2 pmol for Cyt and 0.056 pmol for 5mCyt, the latter corresponding to a methylation level of 0.41%. Intra‐ and inter‐day precision and accuracy were below 4.0% for both analytes and methylation. The matrix absolute effect, process efficiency and coefficient of variation ranged from 96.5 to 101.2%. The matrix relative effect was below 1%. The method was applied to the analysis of different human DNAs, including: nonmethylated DNA from PCR (methylation 0.00%), hypermethylated DNA prepared using M.SssI CpG methyltransferase (methylation 18.05%), DNA from peripheral blood leukocytes of healthy subjects (N = 6, median methylation 5.45%), DNA from bone marrow of leukemia patients (N = 5, 3.58%) and DNA from myeloma cell lines (N = 4, 2.74%). Copyright © 2009 John Wiley & Sons, Ltd. 相似文献