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采用表面光滑玻璃珠作为载体材料,用1:40的腹泻性大肠杆菌诊断血清进行包被。可制成免疫珠。这种免疫珠能与腹泻性大肠杆菌发生特异性结合。经乳糖蛋白胨培养液培养,然后根据其产酸产气进行判断。能在18h内完成腹泻性大肠杆菌的检测。其灵敏度为样液中含有腹泻性大肠杆菌数必须大于10CFu/mL.该法简单、快速、易操作、灵敏度高。 相似文献
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We report viscometric data collected in a Couette rheometry on dilute, single‐solvent polystyrene (PS)/dioctyl phthalate (DOP) solutions over a variety of polymer molecular weights (5.5 × 105 ≤ Mw ≤ 3.0 × 106 Da) and system temperatures (288 K ≤ T ≤ 318 K). In view of the essential viscometric features, the current data may be classified into three categories: The first concerns all the investigated solutions at low shear rates, where the solution properties are found to agree excellently with the Zimm model predictions. The second includes all sample solutions, except for high‐molecular‐weight PS samples (Mw ≥ 2.0 × 106 Da), where excellent time–temperature superposition is observed for the steady‐state polymer viscosity at constant polymer molecular weights. No similar superposition applies at a constant temperature but varied polymer molecular weights, however. The third appears to be characteristic of dilute high‐molecular‐weight polymer solutions, for which the effects of temperature on the viscosity curve are further complicated at high shear rates. The implications concerning the relative importance of hydrodynamic interactions, segmental interactions, and chain extensibility with increasing polymer molecular weight, system temperature, and shear rate are discussed. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 787–794, 2006 相似文献
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近年来,分子内环加成反应已广泛用于甾体化合物全合成,其主要一步是由取代的苯并环丁烯热裂而成的5,6-二亚甲基-1,3-环己二烯发生区域专一和立体选择性的环加成反应,构成甾体骨架。现在用此法已合成了一系列消旋和光学活性的甾体化合物。 相似文献
6.
A. S. Balueva E. I. Ayupova G. N. Nikonov Yu. T. Struchkov A. P. Pisarevskii 《Russian Chemical Bulletin》1994,43(9):1561-1567
Fused 1,3,2-dioxaborinanes, derivatives of 4-diphenylphosphino- and 4-diphenylphosphoryl-4H-1, 3-dioxa-2-boraphenanthrenes, and their complexes with amines have been synthesized. According to X-ray diffraction data, the complex of 2-phenyl-4-diphenylphosphoryl-4H-1, 3-dioxa-2-boraphenanthrene with butylamine exists as a dimer due to the formation of intermolecular hydrogen bonds.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1649–1655, September, 1994.The present work was financially supported by the International Science Foundation (grant No. RHBOOO). 相似文献
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Domino carbocationic rearrangements of α-[bis(methylthio)methylene]alkyl-2-(heteroaryl)cyclopropyl ketones (X=O, S, NMe) bearing five-membered heteroaryl group have been investigated. Although the cyclopropyl ketones (R1=H) gave similar products like their aryl counterparts under these conditions, the corresponding α-methylcyclopropyl ketones (R1=Me) yielded a variety of unexpected products depending on the nature of heteroaryl group in the substrate cyclopropyl ketones and the type of acid catalyst used. A probable mechanism for the formation of various products in these transformations has been proposed. 相似文献
9.
P. Torline G. du Plessis N. Schnautz J. C. Thompson 《Journal of separation science》1979,2(10):613-616
A detailed method for the routine preparation of glass capillary columns is presented. The method consists of coating a glass tube with quartz powder prior to pulling the tube into a capillary. The inner surface of the capillary consists of an even distribution of quartz particles fused to the walls. This surface has been found readily deactivated by standard procedures and ideal for the preparation of thick-film glass capillary columns. The method has been thoroughly tested in two independent laboratories to ensure that the procedures described are reproducible. 相似文献
10.
The mechanical properties of glass bead filled low density polyethylene (LDPE) composites in tension have been investigated by using an Instron material testing machine. It is found that with increase of the glass bead weight fraction (φ) the tensile modulus (Ec) and the tensile yield stress (σyc) increase as a form of nonlinear function but contrary to the elongation strain at break; the correlation between Ec and φ accords with the logarithmic mixing rule and the relationship between σy and the volume fraction (φf) can be described by means of a second order equation; the effects of the glass bead diameter on the mechanical properties are not large; when φ and the bead size are suitable, the enhanced toughness effect of the filled-systems is more significant; the tensile strength of the glass bead filled system pretreated with a coupling agent are somewhat greater than those of the untreated system. In addition, the morphology of the samples is studied to explain the relationship between the micro-structure and the mechanical properties of the composites. 相似文献