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171.
Rehan Aqil William B. Motherwell Lee R. Roberts C.Adam Russell 《Tetrahedron letters》2002,43(52):9671-9674
Regiospecific trapping of organozinc carbenoids generated from carbonyl compounds with Z-1-acetoxybutadiene provides a useful preparative route to functionalised vinyl and divinylcyclopropanes. 相似文献
172.
H. Roberts 《Hyperfine Interactions》1997,107(1-4):91-97
The potential applications of the gamma-ray laser are discussed to illustrate the potential benefit of the development of
this field of nuclear science, as well as the risks and responsibilities associated with isomer development beyond their current
status as nuclear curiosities. The similarities and differences between the development of a gamma-ray laser based on nuclear
isomers and the initial development of nuclear science and engineering are compared.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
173.
In this work we investigate the ability of DLTS to detect the presence of interface states at metal/GaAs(100) (n-type) interfaces where the semiconductor surface has been prepared by two different procedures. A correlation is observed between the magnitude of the ideality parameter determined from the current-voltage (I-V) characteristic of the diode and presence in the DLTS spectrum of a feature attributable to interface states. Schottky diodes have been fabricated with both gold and iron contacts which exhibit near ideal behaviour (n<1.1). No interface states were detected by DLTS on either of these diodes. However, diodes fabricated on oxidised GaAs surfaces, with higher idealities (1.5 <n < 2), exhibit additional electron trap levels in the DLTS spectrum. For the case of iron, a deep level of activation energy 0.55 eV is observed in the conventional reverse bias pulse sequence mode of DLTS operation. In addition, for both gold and iron diodes, a spectral feature which can be attributed to a broad distribution of interface states within the deplation region is observed during a forward bias pulse sequence. 相似文献
174.
The National Health Service and the Social Services are engaged on a massive transfer of resources in which, wherever possible, care will be delivered to vulnerable patients in their own homes. This paper deals with two pilot medical practices in Rochdale. The needs of patients are considered on a subjective scale in five categories. It was confirmed that there was a consistency of subjective measurement between the nurses involved but there was no relation between these particular measures and the amount of nursing care being delivered. However, there was a strong relationship between age and the probability of being on the nursing care list, with a significant difference between the sexes. The model can lead to the identification of categories of patients who might have slipped through the net and also to estimates of the total home care nursing list in a practice. 相似文献
175.
176.
Maria Luiza LAPA DE Souza 《K-Theory》2002,25(3):233-249
We construct two cohomological invariants associated to pairs of Lagrangian sub-bundles of a symplectic bundle on a compact manifold upon which a compact Lie group is acting. The first invariant, which we call the classical equivariant Maslov H-invariant, provides an obstruction to Lagrangian transversality and lives in the Borel cohomology. The second invariant, which we call the equivariant Maslov U-invariant, generalises the author's results in K-Theory 13 (1998), 347–361 to the equivariant context and provides a necessary and sufficient condition for equivariant Lagrangian transversality, up to homotopic stability, and lives in the U-theory (intermediate between the real complex K-theories). As an application, we show that two Lagrangian sub-bundles of a symplectic bundle on a homogeneous space are always stably transverse. 相似文献
177.
BARB FLORIN DAN; KONING WILLEM DE 《IMA Journal of Mathematical Control and Information》1994,11(1):63-73
In this paper we consider the fixed finite-order digital linear-quadraticcontrol of Pritchard-Salamon infinite-dimensional systems withunbounded input and output operators under gaussian disturbances.A set of necessary conditions is given in terms of the solvabilityof a discrete-time Hyland-Bernstein system of equations (twomodified Riccati equations and two modified Lyapunov equationscoupled by an projection operator). 相似文献
178.
The rate coefficients of thermal decomposition of peroxyacetic nitric anhydride (PAN) and peroxymethacrylic nitric anhydride (MPAN) were measured over the temperature range 302–323 K. The resulting Arrhenius expressions were k = 1017.4±0.4 exp(?28.5 ± 0.5/RT) for PAN, and k = 1016.2±0.7 exp(?26.8 ± 1.0/RT) for MPAN, where the activation energy is in Kcal/mol. These results are in good agreement with previous studies of PAN and other PAN-type compounds, and imply that energies of RC(O)OO? NO2 bonds are relatively independent of the nature of R. 相似文献
179.
We show that an extremal Kerr black hole, appropriately lifted to M theory, can be transformed to a Kaluza-Klein black hole in M theory, or a D0-D6 charged black hole in string theory. Since all the microstates of the latter have recently been identified, one can exactly reproduce the entropy of an extremal Kerr black hole. We also show that the topology of the event horizon is not well defined in M theory. 相似文献
180.
Ultrasound pasteurization: the effects of temperature, soluble solids, organic acids and pH on the inactivation of Escherichia coli ATCC 25922 总被引:1,自引:0,他引:1
The objectives of this research were to study the effects of temperature, sugar concentration (8, 12, and 16 g/100ml), organic acids (citric and malic acids) and pH (2.5 and 4.0) on ultrasound pasteurization. The model organism used for the research was Escherichia coli ATCC 25922, and ultrasound treatment times were conducted to achieve a 5 log (base 10) reduction. Ultrasound generates heat, therefore the study involved removing the heat using a jacketed beaker with refrigerant (-30 degrees C) to maintain processing temperature at or below 30 degrees C and eliminate the thermal inactivation effects. Overall, ultrasound increased the sensitivity of E. coli to thermal inactivation. The presence of soluble solids had a protective effect where the sonication time requirement increased. Similar to heat sensitivity, the lower pH environment resulted in E. coli having less resistance to sonication. The type of organic acid had the least significant effect on ultrasound inactivation of E. coli. 相似文献