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1.
2.
The solid phase synthesis of the phosphopeptide Leu-Arg-Arg-Ala-Tyr(P)-Leu-Gly is reported via the stepwise incorporation of the protected phosphoamino acid Nα -tert-butyloxycarbonyl-O-dimethyl-phosphono-L-tyrosine. 相似文献
3.
The solvent extraction behaviour of thiocyanic acid with isobutyl methyl ketone and xylene as solvents is described. In the ketone system the thiocyanic acid is solvated in the organic phase to give a complex with a proposed composition of HSCN. 2IBMK. Deviations from ideal behaviour, which can be attributed to variations in the activity coefficient of the acid in the aqueous phase, are shown. 相似文献
4.
The stereochemistry and regiochemistry of cycloadditions of α-amino acid ester imines is dependent both on imine structure and on the reactivity of the dipolarophile. Phenylglycine imines undergo competing dipole stereomutation and cycloaddition with some dipolarophiles. 相似文献
5.
R. Kemp 《BIT Numerical Mathematics》1980,20(2):157-162
Assume that in one unit of time a node is stored in the stack or is removed from the top of the stack during postorder-traversing of a binary tree. If all binary trees are equally likely the average stack size aftert units of time and the variance is computed as a function of the proportion=t/n.Part of this paper was presented at the 6th Colloquium on Automata, Languages and Programming, ICALP' 79, July 1979. 相似文献
6.
The formation of cyclic sulfates (4) from syn,syn-3-[N-(benzyloxycarbonyl)amino] 1,2-diols provides a common intermediate to access other diastereomers via two inversion procedures. Thermolysis of the cyclic sulfates in acetonitrile normally leads to inversion of the distal hydroxyl group to form a 1,3-oxazin-2-one (6). Catalytic hydrogenation of the cyclic sulfates under basic conditions (NEt(3)) results in inversion at the proximal hydroxyl group to form a 1,3-oxazolidin-2-one (5). 相似文献
7.
Niamh NicDaéid Saravana Jayamana William J. Kerr Wolfram Meier-Augenstein Helen F. Kemp 《Analytical and bioanalytical chemistry》2013,405(9):2931-2941
A number of methods of clandestine manufacture of methylamphetamine involve the extraction and subsequent reaction of pseudoephedrine hydrochloride with other essential chemicals. The precursor can be easily extracted from over-the-counter medication widely available in the UK and elsewhere. Essential chemicals such as iodine and red phosphorous are also readily available and can be extracted from iodine tinctures and matchboxes, respectively. This work reports the repetitive preparation of methylamphetamine using two popular routes (the Moscow and Hypophosphorous synthesis). The focus was on the extraction solvent used for isolation of the precursor chemical and any consequential isotopic variation which may arise in the final product. Six batches of methylamphetamine were prepared under precisely controlled conditions for each synthetic route and for each of three different precursor extraction solvents. Synthesis of the final product from laboratory grade precursor using the synthetic methods described was used as a template for comparison. The resultant IRMS data from all 48 prepared samples suggests some underlying trends in the identification of the synthetic route which may aid in the interpretation of IRMS data derived from clandestine samples. 相似文献
8.
Paul V. Jones Alexa F. DeMichele LaKeta Kemp Mark A. Hayes 《Analytical and bioanalytical chemistry》2014,406(1):183-192
Bacteria play a significant role in both human health and disease. An estimated 9.4 million cases of foodborne illness occur in the United States each year. As a result, rapid identification and characterization of microorganisms remains an important research objective. Despite limitations, selective culturing retains a central role among a cadre of identification strategies. For the past decade, separations-based approaches to rapid bacterial identification have been under investigation. Gradient insulator dielectrophoresis (g-iDEP) promises benefits in the form of rapid and specific separation of very similar bacteria, including serotypes of a single species. Furthermore, this approach allows simultaneous concentration of analyte, facilitating detection and downstream analysis. Differentiation of three serotypes or strains of Escherichia coli bacteria is demonstrated within a single g-iDEP microchannel, based on their characteristic electrokinetic properties. Whole cells were captured and concentrated using a range of applied potentials, which generated average electric fields between 160 and 470 V/cm. Bacteria remained viable after exposure to these fields, as determined by cellular motility. These results indicate the potential g-iDEP holds in terms of both separatory power and the possibility for diagnostic applications. 相似文献
9.
The stagnation pressure p(s) of imploding cylindrical ( n = 2) and spherical ( n = 3) shells is found to scale as p(s)/p(0)~M(2(n+1)/(gamma+1))(0), where M0 is the Mach number of the imploding shell and p(0) its maximum pressure. The result holds approximately for Mach numbers in the range 2相似文献
10.
Ping Y Shepherd R Lasinski BF Tabak M Chen H Chung HK Fournier KB Hansen SB Kemp A Liedahl DA Widmann K Wilks SC Rozmus W Sherlock M 《Physical review letters》2008,100(8):085004
We report the first direct measurements of total absorption of short laser pulses on solid targets in the ultrarelativistic regime. The data show an enhanced absorption at intensities above 10(20) W/cm(2), reaching 60% for near-normal incidence and 80%-90% for 45 degrees incidence. Two-dimensional particle-in-cell simulations demonstrate that such high absorption is consistent with both interaction with preplasma and hole boring by the intense laser pulse. A large redshift in the second harmonic indicates a surface recession velocity of 0.035c. 相似文献