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21.
To examine the separate effects of viscosity and sweetness on astringency, aqueous solutions of grape seed tannin (GST) were thickened with carboxymethyl cellulose (CMC) from 2 to 45 cP (experiment 1) or sweetened with 0 to 1.8 g/L aspartame (experiment 2). Trained subjects continuously rated astringency and bitterness in duplicate. Subjects were categorized by the salivary flow induced by citric acid and ability to taste n-propyl thiouracil (PROP). In experiment 1, maximum intensity and total duration of astringency were significantly decreased as viscosity rose, although time to maximum intensity of astringency was not affected. Maximum intensity and total duration of bitterness were not significantly affected by increasing viscosity; however, the onset of bitterness was significantly delayed. In experiment 2, increasing sweetness had no affect on any astringency parameter, although maximum intensity of bitterness was significantly decreased. Neither PROP nor salivary flow-status had any effect on perception of bitterness or astringency in either experiment. 相似文献
22.
As the antibiotic arsenal expands with the development of new oral agents, selecting appropriate therapy is becoming more difficult. What are the therapeutic indications for the newer antimicrobials, and what advantages do they have over traditional agents? Drs Gleckman and De La Rosa discuss current issues related to antibiotic treatment and offer specific recommendations for the best use of the newer agents. 相似文献
23.
South Korea and Cuba are dissimilar in religion, economy, culture and attitudes toward premarital sexual relations. In 1960, Korea instituted a national family planning programme to combat rapid population growth. Cuba explicitly rejected Malthusian policies, but made family planning universally available in 1974 in response to health needs. Both countries have undergone rapid fertility declines and today have less than replacement level fertility. Both countries have also used a similar mixture of methods, including a high prevalence of female sterilisation. Abortion has played a major role in the fertility decline of both countries, rising in the first half of the fertility transition and then falling, although remaining a significant variable in the second half. It is concluded that access to contraception, voluntary sterilisation, and safe abortion has a direct impact on fertility and has been associated with a rapid fall in family size in two very different countries. 相似文献
24.
Conditions for stability of the extended Kalman filter and their application to the frequency tracking problem 总被引:1,自引:0,他引:1
Barbara F. La Scala Robert R. Bitmead Matthew R. James 《Mathematics of Control, Signals, and Systems (MCSS)》1995,8(1):1-26
The error dynamics of the extended Kalman filter (EKF), employed as an observer for a general nonlinear, stochastic discrete time system, are analyzed. Sufficient conditions for the boundedness of the errors of the EKF are determined. An expression for the bound on the errors is given in terms of the size of the nonlinearities of the system and the error covariance matrices used in the design of the EKF. The results are applied to the design of a stable EKF frequency tracker for a signal with time-varying frequency.This research was supported by the Co-operative Research Centre for Robust and Adaptive Systems ((CR)2 ASys). The authors wish to acknowledge the funding of the activities of (CR)2 ASys by the Australian Commonwealth Government under the Co-operative Research Centre Program. 相似文献
25.
G La Nasa A Pizzati A Ledda A Vacca M Arras L Contu 《Canadian Metallurgical Quarterly》1996,81(2):178-181
OBJECTIVE: To determine the distribution and amount of elastic fibers in the dermis of clinically normal dogs and dogs with dermatoses, particularly solar dermatitis. DESIGN: Skin specimens from 7 anatomic sites were obtained from 19 clinically normal dogs after euthanasia to evaluate the normal distribution of elastic fibers. Biopsy specimens also were obtained from 34 dogs with dermatoses, including 16 with solar dermatitis. Tissue sections were stained with H&E, Verhoeff-van Gieson, and periodic acid-Schiff. ANIMALS: 19 clinically normal dogs and 34 dogs with dermatoses. PROCEDURE: Numbers of elastic fibers were graded subjectively. Comparisons between clinically normal dogs and dogs with dermatoses were made. RESULTS: Normal elastic fibers were present in low numbers in the dermis of adult dogs, regardless of anatomic site or presence or severity of dermatitis. Condensed elastotic material was visualized in only 2 dogs with solar dermatitis. In both dogs, the elastotic material was Verhoeff-van Gieson and periodic acid-Schiff stain positive but was not visible with H&E stain. The most frequent histopathologic finding in the dermis of dogs with solar dermatitis was superficial dermal fibrosis. CONCLUSIONS: The dermis of clinically normal dogs does not contain abundant elastic fibers. Alterations of elastic fibers in dogs with solar dermatitis are rare. Superficial dermal fibrosis may be a better indicator of solar damage. 相似文献
26.
Low-temperature interface reaction in aluminium-silicon carbide particulate composites produced by mechanical alloying 总被引:1,自引:0,他引:1
An experimental investigation has been carried out on the reaction that takes place between 3 and 20 μm SiC particles and
the aluminium alloy 1050 matrix of composite materials prepared by a mechanical alloying process. The work is different from
that undertaken by other researchers in that the SiC-Al interface reaction has been studied in the temperature range 853–933
K, i.e., with the matrix initially in the solid state. Differential thermal analysis, X-ray diffraction and scanning electron
microscopy all show that the SiC-Al reaction initiates in the solid state at temperatures as low as 883 K. The reaction produces
Al4C3 and Si, the latter entering into solid solution in the aluminium matrix. At temperatures exceeding 903 K, the reaction
produces a liquid phase and at this stage the speed of the interface reaction increases significantly. The results are discussed
in terms of Al-Si-C metastable equilibrium and the kinetics of the reaction.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
27.
28.
单晶空心叶片用AC-2陶瓷型芯的组织和性能研究 总被引:8,自引:1,他引:7
利用扫描电镜技术和X射线衍射技术研究了AC-2氧化铝基陶瓷型芯的微观结构和相组成,并测试了该型芯的室温和高温性能,结果表明AC-2型氧化铝基陶瓷型芯的综合性能优于AC-1型芯。 相似文献
29.
Methodological issues in geropsychological assessment research are discussed and exemplified with recent investigations. Increased use of short-term longitudinal designs, more diverse and representative sampling, and routine inclusion of measures of health are among the recommendations made for future studies. Caution is urged in the application of new tests or screening batteries until sufficient independent validation studies are completed. Research contrasting neuropsychological performance of older persons from different racial and ethnic groups is briefly reviewed, and applications of geropsychological assessment to practical arenas such as competency determination are critiqued. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
30.