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321.
研究了在甲基弯菌(Methylosimus trichosporium)IMV 3011整细胞催化甲烷制甲醇的反应过程中,菌体浓度、阻断剂乙二胺四乙酸(ethylenediamine tetraacetic acid,简称EDTA)浓度、外源性电子给体、混合气组分及压力与甲醇积累的关系。批式反应的实验结果表明,在菌体浓度为7.4mg/mL时,以2mmol/L EDTA作阻断剂效果最好;作为电子给体,甲酸钠(20mmol/L)的效果优于琥珀酸钠(40mmol/L),使用前者时的甲醇积累量是用后者时的2.8倍左右;当甲烷与空气的体积比为1:1.7时,转化率为6.0%,甲醇积累量最大;压力选用0.16MPa。连续反应中,于培养基中无铜离子培养的细胞与有铜离子的相比,持续时间长,甲醇积累高(最大产量达374μmol),前者是后者的2倍。 相似文献
322.
323.
M.C. Henry-Feugeas I. Idy-Peretti B. Blanchet D. Hassine G. Zannoli E. Schouman-Claeys 《Magnetic resonance imaging》1993,11(8):1107-1118
The purpose of this study was to measure normal cerebrospinal fluid (CSF) pulsations within the intracranial and upper cervical subarachnoid spaces and the ventricular system. Phase contrast cine MR sequences were performed in sagittal and axial planes on 13 volunteers with flow encoding in the craniocaudal direction. CSF pulsations displayed considerable variations in healthy subjects, depending both on measurements localization and subjects, with CSF peak velocities ranging from 0 to 7 cm/s. In the subarachnoid spaces, the highest velocities occurred in the anterior location and increased from the cerebellar pontine angle cisterns towards the lower cervical spaces. In the ventricular system, the highest velocities occurred through the aqueduct of Sylvius. CSF flow within the third ventricle seemed to reflect a circular motion. There was a caudal net CSF flow in the aqueduct whereas in the upper cervical spaces net CSF flow was caudal anteriorly and cranial laterally. Velocity profiles of CSF pulsations demonstrated arterial morphology. After the R wave, caudal systolic motion was first observed in the posterior subarachnoid spaces, soon after in the anterior subarachnoid spaces and later in the ventricular system. Considering the morphology of CSF pathways, three successively initiated phenomena may explain the temporal course of CSF motion: the systolic expansion of the main arteries at the base of the brain, the systolic expansion of the cerebrospinal axis and, finally, the systolic expansion of the choroid plexuses. 相似文献
324.
325.
Dieter Stäben Dietrich Mootz 《Journal of inclusion phenomena and macrocyclic chemistry》1995,22(2):145-154
Of the various hydrates oftert-butylamine, the title compound has been identified as the second-highest, melting incongruently at –19°C. Its crystal structure (orthorhombic, space groupPca21,Z=32 formula units per unit cell,a=24.80,b=16.440,c=25.29 Å) and the exact composition have been determined from X-ray diffraction at –150°C. The hydrate is a rather complex semi-clathrate, with the amine molecules not merely encaged, but also hydrogen-bonded, in a three-dimensional water host structure, which in turn is not fully four-connected. Nevertheless, it bears a clear relationship to the basic and genuine clathrate-hydrate cubic 12 Å type.Dedicated to Professor G. A. Jeffrey on his 80th birthday.
Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82196 (8 pages).Part 14 of the seriesHydrates of Weak and Strong Bases; for part 13 see [1]. 相似文献
326.
327.
Membrane electrodes for the determination of glutathione 总被引:1,自引:0,他引:1
Four glutathione (GSH)-selective electrodes were developed with different techniques and in different polymeric matrices. Precipitation-based technique with bathophenanthroline-ferrous as cationic exchanger in polyvinyl chloride (PVC) matrix was used for sensor 1 fabrication. β-Cyclodextrin (β-CD)-based technique with either tetrakis(4-chlorophenyl)borate (TpClPB) or bathophenanthroline-ferrous as fixed anionic and cationic sites in PVC matrix was used for fabrication of sensors 2 and 3, respectively.β-CD-based technique with TpClPB as fixed anionic site in polyurethane (Tecoflex) matrix was used for sensor 4 fabrication. Linear responses of 1 × 10−5 to 1 × 10−4 M and 1 × 10−6 to 1 × 10−3 M with slopes of 37.5 and 32.0 mV/decade within pH 7-8 were obtained by using electrodes 1 and 3, respectively. On the other hand, linear responses of 1 × 10−5 to 1 × 10−2 and 1 × 10−5 to 1 × 10−3 M with slopes of 47.9 and 54.3 mV/decade within pH 5-6 were obtained by using electrodes 2 and 4, respectively. The percentage recoveries for determination of GSH by the four proposed GSH-selective electrodes were 100 ± 1, 100.5 ± 0.7, 100 ± 1 and 99.0 ± 0.8% for sensors 1, 2, 3 and 4, respectively. Determination of GSH in capsules by the proposed electrodes revealed their applicability for determination of GSH in its pharmaceutical formulations. Also, they were used to determine GSH selectively in presence of its oxidized form (GSSG). Sensor 4 was successfully applied for determination of glutathione in plasma with average recovery of 100.4 ± 1.11%. The proposed method was compared with a reported one. No significant difference for both accuracy and precision was observed. 相似文献
328.
Fatima Hassine Said Gmouh Mathieu Pucheault Michel Vaultier 《Monatshefte für Chemie / Chemical Monthly》2007,138(11):1167-1174
Summary. In this work was presented an application of the use of task specific onium salts (TSOSs) as soluble supports in Grieco’s multicomponent synthesis of tetrahydroquinolines. These soluble supports are of wide applicability and combine advantages
of solid phase synthesis without its limitations with those of solution phase chemistry. After a simple washing step, products
were cleaved from the supports and obtained in pure form and good yields. 相似文献
329.
330.
B. Jozefini M. Müller-Preussker N. Schultka H. Stüben 《Zeitschrift fur Physik C Particles and Fields》1991,51(3):491-497
The topological susceptibility 〈Q t 2 〉/V is computed for theCP 3-model appropriately discretized on simplicial lattices onT 2 andS 2, respectively. We concentrate on volumes 1?V/ξ2?100, ξ being the correlation length measured onT 2. Approximate scaling behaviour is found presumably not related to the continuum limit but rather to the occurence of dislocations. We observe finite-size effects which are fairly weak on the sphere, however. 相似文献