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81.
LG Kupchinski? IuA Barshte?n BG Pogodaev AI Treshinski? 《Canadian Metallurgical Quarterly》1976,(3):80-84
A study was made of a possibility of using Soviet made membranes "Vladipor" with a pore diameter of 16--17 nm for the purpose of concentration and purification of antigenic extracts from stab cultures of S. typhi obtained by the action of typsin, hydrogen peroxide and detergents. Preparations, complete by antigenic structure, were obtained by ultrafiltration, with a good yield. The maximal rate of ultrafiltration was noted in case of "peroxide" antigenic preparations. The use of diafiltration provided a significant reduction of the ash content in the end products. 相似文献
82.
83.
J. Chen B. Wiley Z.‐Y. Li D. Campbell F. Saeki H. Cang L. Au J. Lee X. Li Y. Xia 《Advanced materials (Deerfield Beach, Fla.)》2005,17(18):2255-2261
The galvanic replacement reaction between a Ag template and HAuCl4 in an aqueous solution transforms 30–200 nm Ag nanocubes into Au nanoboxes and nanocages (nanoboxes with porous walls). By controlling the molar ratio of Ag to HAuCl4, the extinction peak of resultant structures can be continuously tuned from the blue (400 nm) to the near‐infrared (1200 nm) region of the electromagnetic spectrum. These hollow Au nanostructures are characterized by extraordinarily large cross‐sections for both absorption and scattering. Optical coherence tomography measurements indicate that the 36 nm nanocage has a scattering cross‐section of ~ 0.8 × 10–15 m2 and an absorption cross‐section of ~ 7.3 × 10–15 m2. The absorption cross‐section is more than five orders of magnitude larger than those of conventional organic dyes. Exposure of Au nanocages to a camera flash resulted in the melting and conversion of Au nanocages into spherical particles due to photothermal heating. Discrete‐dipole‐approximation calculations suggest that the magnitudes of both scattering and absorption cross‐sections of Au nanocages can be tailored by controlling their dimensions, as well as the thickness and porosity of their walls. This novel class of hollow nanostructures is expected to find use as both a contrast agent for optical imaging in early stage tumor detection and as a therapeutic agent for photothermal cancer treatment. 相似文献
84.
A guaranteed estimator for a general class of nonlinear systems and on‐line usage is developed and analysed. This filter bounds the linearization error, then applies a linear set‐membership filter such that stability guarantees hold for nonlinear systems. A tight bound on the linearization error is found using interval analysis. This filter recursively estimates an ellipsoidal set in which the true state lies. General assumptions include the use of bounded noises and twice continuously differentiable dynamics. When the system is uniformly observable, it is proven that the nonlinear set‐membership filter is stable. In addition, if no noise is present and the initial error is small, the error between the centre of the estimated set and the true value converges to zero. The result is an estimator which is computationally attractive and can be implemented robustly in real‐time. The proposed method is applied to a two‐state example to demonstrate the theoretical results. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
85.
A survey of QoS architectures 总被引:14,自引:0,他引:14
Over the past several years there has been a considerable amount of research within the field of quality-of-service (QoS)
support for distributed multimedia systems. To date, most of the work has been within the context of individual architectural
layers such as the distributed system platform, operating system, transport subsystem and network layers. Much less progress
has been made in addressing the issue of overall end-to-end support for multimedia communications. In recognition of this,
a number of research teams have proposed the development of QoS architectures which incorporate QoS-configurable interfaces
and QoS driven control and management mechanisms across all architectural layers. This paper examines the state-of-the-art
in the development of QoS architectures. The approach taken is to present QoS terminology and a generalized QoS framework
for understanding and discussing QoS in the context of distributed multimedia systems. Following this, we evaluate a number
of QoS architectures that have emerged in the literature. 相似文献
86.
Knowledge-based computing, in general, suffers from an inherent open-endedness that precludes its application in time-bounded domains where an answer must be computed within a stipulated time limit. We examine a two-way improvement of the shortcomings: a knowledge representation scheme that provides easy access to relevant knowledge and thereby reduces search time, and a reasoning scheme that is algorithmic in nature and thus makes computational requirements meaningfully estimable.In this work, we offer a cache-based architecture that is capable of both storing knowledge in different formats (e.g. rules, cases), and invoking an appropriate reasoning scheme to fit the available computing time. The cache helps in retrieving the most relevant pieces of knowledge (not only exact matches) required for solving a given problem. This cache relies on a reasoning tactic, knowledge interpolation, that can generate a solution from two near-matches in an algorithmic way, to generate time-bounded solutions. We illustrate the design of such a cache for solving resource allocation problems in the domain of shortwave radio transmission and evaluate its performance in observing imposed temporal bounds. 相似文献
87.
After the nucleation and sedimentation of primary Fe-rich phases, the microstructures of Al-11.5Si-0.4Mg cast alloys with
0.35–1.03Fe and 0.18–0.59Mn have been studied to investigate the solidification characteristics of Fe-rich phases. Depending
on the iron and manganese contents as well as cooling rates, Fe-rich phases may solidify as predendritic (primary), pre-eutectic,
coeutectic, and posteutectic intermetallics at the different stages of solidification through three types of reactions: (1)
predendritic (primary), (2) eutectic, and (3) peritectic reactions. It seems that Fe-rich phases may nucleate on the wetted
sides of double oxide films, while the gap of the dry sides of oxide films constitutes the cracks commonly observed in the
Fe-rich phases and aluminum matrix. Conventional metallurgical observations also suggest that the Fe-rich phases nucleated
early during the solidification might act as nuclei for those formed subsequently, although it has not been ruled out that
these phases may share the same oxide substrates. It is probable that these nucleation events may all work as suggested in
the possible nucleation hierarchy for Al-11.5Si-0.4Mg cast alloys. 相似文献
88.
This study used cluster analysis to identify three patterns of sexual health risk behaviors in a sample of adult rape survivors (N=102). Women in the 1st cluster (high risk) reported substantial increases from pre- to postrape in their frequency of sexual activity, number of sexual partners, infrequency of condom use, and frequency of using alcohol and/or drugs during sex. The 2nd cluster (moderate risk) reported increases in frequency of sexual activity and number of partners but mitigated that risk with increased condom use. Survivors in the 3rd cluster (low risk) indicated that their sexual health behaviors had become much less risky postrape. An ecological model predicting cluster membership revealed that individual-level and contextual factors predict patterns of risk behaviors. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
89.
Blount Ronald L.; Morris Julie A. B.; Cheng Patricia S.; Campbell Robert M.; Brown Ronald T. 《Canadian Metallurgical Quarterly》2004,72(4):597
The authors examined associations among parental and child adjustment, child syncope, somatic, and school problems. Participants were children (N = 56) ages 7-18 years with syncope. Measures included syncope severity, parental distress, and children's internalizing symptoms. For children diagnosed negative for neurocardiogenic syncope (NCS), their fathers' and their own psychological symptoms were positively associated with the severity of syncope, whereas their mothers' functioning was negatively associated with the severity of syncope. Also, for the negative NCS group, fathers' psychological functioning was associated with children's nonsyncope somatic complaints but not with their school problems. For the positive NCS group, few significant father-child associations were found, but several significant positive associations were revealed between mothers' psychological symptoms and their children's syncope as well as somatic and school problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
90.
The world’s first commercial installation for direct casting of low-carbon steel sheet utilizing CASTRIP® technology is undergoing production ramp-up at Nucor Steel’s plant in Crawfordsville, Indiana. Construction of the plant was initiated in February 2001 and the first ladle was delivered to the caster in May 2002. Since that time, Nucor Steel has been working with technology partners BlueScope Steel (formerly BHP Steel) and IHI (Ishikawajima-Harima Heavy Industries) to fully commercialize this exciting new technology for the direct production of steel sheet less than 2 mm in thickness. 相似文献