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61.
Kuvychko IV Streletskii AV Popov AA Kotsiris SG Drewello T Strauss SH Boltalina OV 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(18):5426-5436
Three previously reported procedures for the synthesis of pure C(s)-C60Cl6 from C60 and ICl dissolved in benzene or 1,2-dichlorobenzene were shown to actually yield complex mixtures of products that contain, at best, 54-80% C(s)-C60Cl6 based on HPLC integrated intensities. MALDI mass spectrometry was used for the first time to identify other components of the reaction mixtures. An improved synthetic procedure was developed for the synthesis of about 150 mg batches of chlorofullerenes containing 90% C(s)-C60Cl6 based on HPLC intensities. The optimum reaction time was decreased from several days to seven minutes. Small amounts of the product were purified by HPLC (toluene eluent) to 99% purity. The pure compound C(s)-C60Cl6 is stable for at least three months as a solvent-free powder at 25 degrees C. The Raman, far-IR, and MALDI mass spectra of pure C(s)-C60Cl6 are reported for the first time. The Raman and far-IR spectra, the first reported for any C60Cl(n) chlorofullerene, were used to carry out a vibrational analysis of C(s)-C60Cl6 at the DFT level of theory. 相似文献
62.
Nikolaos Vassilakos Sotirios Kalfas Thomas Arnebrant Jan Rundegren 《Colloids and surfaces. B, Biointerfaces》1993,1(6):341-347
A simple flow cell system was developed for studies of bacterial adhesion on hydrophobic or hydrophilic surfaces in the presence or absence of saliva. The system consists of flow cells made of borosilicate glass tubes (flow cell volume, 0.45 ml) that are connected to syringes mounted on an infusion pump. Hydrophilic or hydrophobic surfaces were obtained by treating the flow cells with acid or dichlorodimethylsilane, respectively. Liquids and bacterial suspensions were withdrawn directly into the flow cells and the flow rate was monitored through the infusion pump. The adhesion of 3H-labeled Streptococcus mutans cells to bare or saliva-coated surfaces was studied in this system by determining the radioactivity retained in the flow cells after rinsing with buffer at different flow rates. The results indicate that factors like the bacterial cell density, the surface properties, the presence of saliva pellicle and the rinsing flow rate significantly affect the adhesion of S. mutans. These results are in agreement with previous findings obtained with other flow cell systems. The present system has the advantages of using small volumes of liquids and allowing defined laminar flow conditions. Moreover, the entire cell, not only selected area spots, are used for the evaluation of bacterial adhesion. No part of the flow cell is re-used, thus avoiding the risk of contamination with other components. The system may therefore be suitable for assays testing the effect of different compounds on bacterial adhesion. 相似文献
63.
Sotirios E. Notaris 《Numerische Mathematik》1990,57(1):271-283
Summary We consider the Gaussian quadrature formulae for the Bernstein-Szegö weight functions consisting of any one of the four Chebyshev weights divided by an arbitrary quadratic polynomial that remains positive on [–1, 1]. Using the method in Akrivis (1985), we compute the norm of the error functional of these quadrature formulae. The quality of the bounds for the error functional, that can be obtained in this way, is demonstrated by two numerical examples. 相似文献
64.
Gerassimos Mineshos Sotirios Glavas Ulrich Schurath 《Monatshefte für Chemie / Chemical Monthly》1992,123(6-7):501-508
Summary The reaction of peroxyacetyl radicals with reduced sulfur compounds was studied at 55°C in N2 at 1 000 mbar total pressure. The radicals were generated in equilibrium with peroxyacetyl nitrate and NO2 in large excess. The pseudo first order decay ofPAN was measured in the absence and presence of several 100 ppm CH3SH, C2H5SH,n-C4H9SH, (CH3)2S, and (CH3S)2. Computer simulations yielded the following rate constants of peroxyacetyl radicals with the above mentioned sulfur compounds: 3.7, 2.8, 13.0, 0.9, and 1.8·10–16 cm3/s, respectively. An electron capturing compound of the thiols with NO2 was observed.
Reaktionen von Peroxyacetylradikalen mit reduzierten Schwefelverbindungen
Zusammenfassung Die Reaktionen von Peroxyacetylradikalen mit reduzierten Schwefelverbindungen wurden bei 55°C in NO2 bei einem Totaldruck von 1 000 mbar untersucht. Die Radikale wurden im Gleichgewicht mit Peroxyacetylnitrat und NO2 in großem Überschuß generiert. Der nach erster Ordnung verlaufende Zerfall vonPAN wurde in Abwesenheit und Anwesenheit und von einigen ppm CH3SH, C2H5SH,n-C4H9SH, (CH3)2S und (CH3S)2 gemessen. Computersimulierung der Geschwindigkeitskonstanten für die Peroxyacetylradikale ergab mit den genannten Schwefelverbindungen 3.7, 2.8, 13.0, 0.9 und 1.8·10–16 ch3/s. Eine elektronenfangende Verbindung der Thiole mit NO2 wurde beobachtet.相似文献
65.
Sotirios Nikolaropoulos Panayotis Catsoulacos 《Journal of heterocyclic chemistry》1988,25(6):1607-1611
Condensation of 17β-acetoxy-2α-bromo-5α-androstan-3-one with unsubstituted and substituted amino-pyridines, gives the corresponding 17β-acetoxy-5α-androstanimidazo[1,2-a]pyridines. Treatment of 16α-bromo-3-aza-A-homo-4α-androsten-4,17-dione with 2-aminopyridine or methyl-2-aminopyridine produces the corresponding 3-aza-A-homo-4α-androsten[16,17:2′,3′]imidazo[1,2-a]pyridines. Similarly, from 2α-bromo-17β-acetamido-5α-androstan-3-one and methylaminopyridine the 17β-acetamido-5α-androstan[2,3:2′,3′]imidazo[1,2-a]methylpyridine has been obtained. The structure of the compounds was apparent from their chemical properties and spectral data (ir, uv and nmr). 相似文献
66.
Sotirios E. Notaris 《Numerical Algorithms》1995,10(1):167-186
Given a fixedn1, and a (monic) orthogonal polynomial
n
(·)=
n
(·;d) relative to a positive measured on the interval [a, b], one can define the nonnegative measure
, to which correspond the (monic) orthogonal polynomials
. The coefficients in the three-term recurrence relation for
, whend is a Chebyshev measure of any of the four kinds, were obtained analytically in closed form by Gautschi and Li. Here, we give explicit formulae for the Stieltjes polynomials
whend is any of the four Chebyshev measures. In addition, we show that the corresponding Gauss-Kronrod quadrature formulae for each of these
, based on the zeros of
and
, have all the desirable properties of the interlacing of nodes, their inclusion in [–1, 1], and the positivity of all quadrature weights. Exceptions occur only for the Chebyshev measured of the third or fourth kind andn even, in which case the inclusion property fails. The precise degree of exactness for each of these formulae is also determined. 相似文献
67.
Tragoulias SS Obeid PJ Tataridis IE Christopoulos TK 《Analytical and bioanalytical chemistry》2008,390(6):1563-1573
Microarray technology covers the urgent need to exploit the accumulated genetic information from large-scale sequencing projects
and facilitate investigations on a genome-wide scale. Although most applications focus on DNA microarrays, the technology
has expanded to microarrays of proteins, peptides, carbohydrates, and small molecules aiming either at detection/quantification
of biomolecules or investigation of biomolecular interactions in a massively parallel manner. Microarray experiments require
two specialized instruments: An arrayer (or printer), for construction of microarrays, and a readout instrument (scanner).
We have designed, constructed, and characterized the first integrated microarray system (IMAS) that combines the functions
of a microarrayer and a three-laser confocal fluorescence scanner into a single instrument and provides excellent flexibility
for the researcher. The three-axis robotic system that moves the printing head carrying multiple pins for arraying is also
used for moving the microarray slide in front of a stationary optical system during scanning. Since the translation stages
are the most expensive and crucial components of microarray printers and scanners, the proposed design reduces considerably
the cost of the instrument and enhances remarkably its operative flexibility. Experiments were carried out at resolutions
of 2.5, 5, 10, and 20 μm. The scanner detects 0.128 nmol L−1 carboxyfluorescein (spots with diameters of 70 μm) corresponding to 1.8 molecules μm−2. The linear range extends over 3.5 orders of magnitude (R
2 = 0.997) and the dynamic range covers almost five orders of magnitude. DNA microarray model experiments were carried out,
including staining with SYBR Green I and hybridization with oligonucleotides labeled with the fluorescent dyes Alexa 488,
Alexa 594, and Alexa 633.
Figure Lay-out of the home-built integrated microarray system (IMAS). For the first time, the functions of a microarrayer (printer)
and a three-laser confocal fluorescence scanner are combined into a single instrument. The three-axis robotic system that
moves the printing head for arraying is also used to move the microarray slide in front of a stationary optical system during
scanning.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
68.
Athanasios Kottas Konstantinos Adamidis Sotirios Loukas 《Annals of the Institute of Statistical Mathematics》1999,51(2):331-344
In this article the most general class of bivariate distributions such that both conditional densities are Pearson Type VII, with fixed shape parameter, is fully characterized. Some of its properties and relations with other distributions are explored. The estimation of parameters is considered by the methods of maximum likelihood and pseudolikelihood and a method for random variate generation is presented along with a simulation experiment. Bivariate and multivariate extensions of the Pearson Type VII conditionals distribution are also discussed. 相似文献
69.
70.
Optical methods in gas analysis are very valuable mainly due to their non-intrusive character. That gives the possibility to use them for in-situ or online measurements with only optical intervention in the measurement volume. In processes like the gasification of biomass, it is of high importance to monitor the gas quality in order to use the product gas in proper machines for energy production following the restrictions in the gas composition but also improving its quality, which leads to high efficient systems. One of the main problems in the biomass gasification process is the formation of tars. These higher hydrocarbons can lead to problems in the operation of the energy system. Up to date, the state of the art method used widely for the determination of tars is a standardized offline measurement system, the so-called “Tar Protocol”. The aim of this work is to describe an innovative, online, optical method for determining the tar content of the product gas by means of fluorescence spectroscopy. This method uses optical sources and detectors that can be found in the market at low cost and therefore it is very attractive, especially for industrial applications where cost efficiency followed by medium to high precision are of high importance. 相似文献