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排序方式: 共有2710条查询结果,搜索用时 31 毫秒
31.
KJ Clark AB Sarr PG Grant TD Phillips GN Woode 《Canadian Metallurgical Quarterly》1998,63(2-4):137-146
Rotaviruses are the leading cause and coronaviruses are the major contributors of acute gastroenteritis in the young of various mammalian and avian species. Despite numerous trials and decades of research, vaccines have limited efficacy particularly for calves. As an alternative method of controlling infection, we have investigated broad spectrum antiviral agents that are not discriminatory among various viruses. This report involves testing a variety of adsorbent agents including charcoal, clay, and clay minerals to adsorb rotavirus and coronavirus in vitro. Results revealed that all the adsorbent agents had good to excellent capability of adsorbing rotavirus and excellent capability of adsorbing coronavirus. Percent adsorptions ranged from 78.74% to 99.89% for rotavirus and 99.99% for coronavirus; while sand (negative control) was < 0.01%. A high affinity binding was present as determined by a low percent desorption (0.06-3.09%). However, the adsorbent bound virus complex retained, and may have actually enhanced, infectivity. 相似文献
32.
PJ Weston RB Panerai A McCullough PG McNally MA James JF Potter H Thurston JD Swales 《Canadian Metallurgical Quarterly》1996,39(11):1385-1391
Autonomic dysfunction in insulin-dependent diabetic (IDDM) patients has been associated with abnormalities of left ventricular function and an increased risk of sudden death. A group of 30 patients with IDDM and 30 age, sex and blood pressure matched control subjects underwent traditional tests of autonomic function. In addition, baroreceptor-cardiac reflex sensitivity (BRS) was assessed using time domain (sequence) analysis of systolic blood pressure and pulse interval data recorded non-invasively using the Finapres beat-to-beat blood pressure recording system. 'Up BRS' sequences-increases in systolic blood pressure associated with lengthening of R-R interval, and 'down BRS' sequences-decreases in systolic blood pressure associated with shortening of R-R interval were identified and BRS calculated from the regression of systolic blood pressure on R-R interval for all sequences. We also assessed heart rate variability using power spectral analysis and, after expressing components of the spectrum in normalised units, assessed sympathovagal balance from the ratio of low to high frequency powers. IDDM subjects underwent 2-D echocardiography to assess left ventricular mass index. Standard tests of autonomic function revealed no differences between IDDM patients and control subjects, but dramatic reductions in baroreceptor-cardiac reflex sensitivity were detected in IDDM patients. 'Up BRS' when supine was 11.2 +/- 1.5 ms/mmHg (mean +/- SEM) compared with 20.4 +/- 1.95 in control subjects (p < 0.003) and when standing was 4.1 +/- 1.9 vs 7.6 +/- 2.7 ms/mmHg (p < 0.001). Down BRS when supine was 11.5 +/- 1.2 vs 22 +/- 2.6 (p < 0.001) and standing was 4.4 +/- 1.9 vs 7.3 +/- 2.5 ms/mmHg (p < 0.003). There were significant relations between impairment of the baroreflex and duration of diabetes (p < 0.001) and poor glycaemic control (p < 0.001). From a fast Fourier transformation of supine heart rate data and using a band width of 0.05-0.15 Hz as low-frequency and 0.2-0.35 Hz as high frequency total spectral power of R-R interval variability was significantly reduced in the IDDM group for both low-frequency (473 +/- 62.8 vs 746.6 +/- 77.6 ms2 p = 0.002) and high frequency bands 125.2 +/- 12.9 vs 459.3 +/- 89.8 ms2 p < 0.0001. When the absolute powers were expressed in normalised units the ratio of low frequency to high frequency power (a measure of sympathovagal balance) was significantly increased in the IDDM group (2.9 +/- 0.53 vs 4.6 +/- 0.55, p < 0.002 supine: 3.8 +/- 0.49 vs 6.6 +/- 0.55, p < 0.001 standing). Thus, time domain analysis of baroreceptor-cardiac reflex sensitivity detects autonomic dysfunction more frequently in IDDM patients than conventional tests. Impaired BRS is associated with an increased left ventricular mass index and this abnormality may have a role in the increased incidence of sudden death seen in young IDDM patients. 相似文献
33.
The author presents an integral equation and method of moments (MM) solution to the problem of scattering by a thin material wire of circular cross section. In general the material wire has permittivity and permeability different from those of free space. The wire of radius a must be sufficiently thin so that k 0a ≪1, where k 0 is the free space wavenumber. However, there is no restriction on |k |a , where k is the wavenumber in the material wire. The method is referred to as unified in that it applies to thin material wires of arbitrary complex permittivity and permeability. Thus, a single or unified formulation applies to a low-density dielectric/ferrite wire or to a highly conducting metallic wire 相似文献
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Attempted to determine whether the order in which 2 counselors were presented on videotape would affect ratings of their performances. 70 participants (63 women and 7 men) randomly assigned to 2 groups viewed and rated counseling interviews conducted by C. Rogers and E. L. Shostrom. Groups differed only in the order of presentation of counselors. The resulting 2?×?2 split-plot factorial design had 1 between-Ss factor (order of presentation) and 1 within-S factor (counselor). A multivariate analysis of variance (MANOVA) yielded a statistically significant interaction, indicating that the order in which counselors were evaluated significantly affected the magnitude of ratings of their performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
37.
Newman H.S. Ebel J.L. Judy D. Maciel J. 《Microwave and Wireless Components Letters, IEEE》2008,18(2):100-102
Radio frequency microelectromechanical systems (RF MEMS) cantilever contact switches have been tested for lifetime. The mean cycles-to-failure measured on an ensemble of switches was 430 billion switch cycles. The longest lifetime exhibited without degradation of the switch was 914 billion switch cycles. The devices were switched at 20 kHz with an incident RF frequency of 10 GHz and an incident RF power of 20 dBm. Testing was performed continuously over a period of approximately 18 months. The switches were operated in a cold-switched mode. 相似文献
38.
MR Workman PG Wall P Tearle M O'Mahony WA Brunton 《Canadian Metallurgical Quarterly》1995,5(4):R54-R56
In microbiology laboratories highly infectious material is handled alongside complex and potentially dangerous equipment, and staff are therefore at risk of infections and accidents. Acts of parliament and regulations exist to protect staff in the workplace, including those exposed to biological agents. The current monitoring of health and safety in laboratories seeks to ensure that employers and employees comply with existing regulations, but this form of passive surveillance is of limited value because it does not highlight shortcomings in techniques, equipment, premises, or personnel. We propose a scheme for the surveillance of health and safety in microbiology laboratories that will actively seek information about laboratory incidents and practices, in order to enable appropriate preventive measures to be instituted. 相似文献
39.
There were 2040 patients with temporomandibular joint (TMJ) diseases in the investigation including clinical, physiological, X-ray methods of research, contrast arthrotomography, computer arthrotomography and magnetic resonance tomography. The changes of structure in different lesions were estimated. The result of received data was elaboration of classification of TMJ internal derangements with estimation of clinical forms in according with structural changes and characteristics of syndromes. 相似文献
40.
The region of the genome encoding the glucose-6-phosphate dehydrogenase gene zwf was analysed in a unicellular cyanobacterium, Synechococcus sp. PCC 7942, and a filamentous, heterocystous cyanobacterium, Anabaena sp. PCC 7120. Comparison of cyanobacterial zwf sequences revealed the presence of two absolutely conserved cysteine residues which may be implicated in the light/dark control of enzyme activity. The presence in both strains of a gene fbp, encoding fructose-1,6-bisphosphatase, upstream from zwf strongly suggests that the oxidative pentose phosphate pathway in these organisms may function to completely oxidize glucose 6-phosphate to CO2. The amino acid sequence of fructose-1,6-bisphosphatase does not support the idea of its light activation by a thiol/disulfide exchange mechanism. In the case of Anabaena sp. PCC 7120, the tal gene, encoding transaldolase, lies between zwf and fbp. 相似文献