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排序方式: 共有783条查询结果,搜索用时 15 毫秒
1.
The metabolism of the poly(A) tail is a process important for the translational regulation of maternal mRNAs in Xenopus laevis oocytes and early embryos. Two poly(A) nuclease (PAN) activities have been described in Xenopus embryo or activated egg extracts (Legagneux et al (1995) RNA 1, 1001-1008). These activities (default PAN and EgPAN) are distinguishable by their deadenylation kinetics and their substrate specificities. In this report, we show that these activities display different sensitivities to biochemical treatments. Urea and, to a lesser extent, spermidine, inhibit EgPAN at concentrations which have no effect on default PAN. Heparin activates default PAN but inhibits EgPAN. When extracts are fractionated by ultracentrifugation, the default activity is recovered in one unique fraction, whereas two fractions must be combined to reconstitute the EgPAN activity. Moreover, these two deadenylation activities are separable by size exclusion chromatography under native conditions. We conclude that these two deadenylation activities are mediated by two protein complexes. 相似文献
2.
Joseph A Wehrmeyer Zhongxian ChengDavid M Mosbacher Robert W PitzRobin Osborne 《Combustion and Flame》2002,128(3):232-241
Several opposed jet flames, produced by a lean H2-air jet opposing a rich or lean C3H8-air jet, are investigated. Spontaneous Raman spectroscopy is used for major species concentration and temperature measurements along the opposed jet centerline. The hot products of the H2-air flame simulate the burnt gases of strong-burning near-stoichiometric reactants as they impinge upon a weak-burning lean or rich hydrocarbon-fueled reactant mix, a situation encountered in stratified charge operation of direct injection spark ignition engines. In addition the H2-air flame hot products facilitate experimental data interpretation through the absence of carbon-bearing species. Good agreement between numerical and experimental data are obtained for a rich (equivalence ratio, φ = 1.25) C3H8-air jet versus a lean (φ = 0.4) H2-air jet. Two lean C3H8-air jets (φ = 0.64 or 0.60), versus the φ = 0.4 H2-air jet, are also investigated. For both of these flames, the amount of CO2 production strongly depends upon φ, with the φ = 0.64 flame having a peak CO2 mole fraction an order of magnitude higher than for the φ = 0.60 flame, and the C3H8 flames burning either as a normal flame (high CO2) or as a “negative flame speed” flame producing little CO2 and then only through diffusion of C3H8 into the hot products jet. The numerically predicted and experimental CO2 profiles agree well for the positive flame speed flame, but the large discrepancy between predicted and measured peak CO2 in the negative flame speed flame suggests modeling improvements are needed for this type of flame. 相似文献
3.
4.
AA Guglielmone CI Lugaresi MM Volpogni OS Anziani VR Vanzini 《Canadian Metallurgical Quarterly》1997,70(1-3):33-39
The efficacy of vaccination of Argentinean cattle against babesiosis and anaplasmosis using live immunogens was tested to detect specific antibodies in samples obtained about 60 days after vaccination. Under these conditions a higher than expected proportion of cattle failed to show antibodies against Babesia bigemina. Therefore, a study was designed to evaluate if this failure was due to insensitivity of the routine test to detect antibodies to B. bigemina or to lack of infectivity of the live vaccine. Four groups (G) of cattle were each inoculated subcutaneously with 10 million Babesia bovis (vaccinal strain R1A), 10 million B. bigemina (vaccinal strain S1A) and 10 million Anaplasma centrale (strain M1). G1 and G2 consisted of ten Angus bulls 20-24 months old and ten Angus bulls 15-18 months old, respectively; G3 and G4 consisted of ten and 16 Holstein 1-month-old male calves, respectively. Blood samples were obtained on days 0, 10, 20, 30, 40, 50 and 60 after vaccination and the sera were analysed with an indirect immunofluorescent (IFA) test to detect antibodies to B. bovis (baseline dilution for a positive result 1:60) and B. bigemina (baseline dilution 1:120). Positive IFA titres were considered as evidence of the infectivity of the Babesia vaccinal strains contained in the vaccine. All Angus bulls were found positive to antibodies against both Babesia species, by day 20 (B. bovis) and day 30 (B. bigemina), whereas 10-25% of Holstein calves were negative throughout. The partial lack of vaccine infectivity in the calves was considered to be a consequence of innate resistance of young calves to Babesia. Antibody titres to B. bovis and B. bigemina declined by day 60 after vaccination. However, all cattle that were positive to B. bovis antibodies on day 50 were still positive to the IFA test 10 days later while 10%, 30% and 12% of cattle of G1, G2 and G3 that were positive to B. bigemina antibodies on day 50 after vaccination were found negative to the IFA test on day 60. In future, samples taken on days 40-50 will be used for detection of B. bigemina antibodies in vaccinated cattle, on day 60 for A. centrale and on either occasion for B. bovis. The reaction to the inoculation of B. bigemina S1A strain appears to lag behind the reaction to B. bovis R1A strain. It is not certain if this is a normal reaction to this B. bigemina strain or the result of interaction with the B. bovis strain. 相似文献
5.
Vladimir Kulyukin Chaitanya Gharpure John Nicholson Grayson Osborne 《Autonomous Robots》2006,21(1):29-41
We present a robot-assisted wayfinding system for the visually impaired in structured indoor environments. The system consists
of a mobile robotic guide and small passive RFID sensors embedded in the environment. The system is intended for use in indoor
environments, such as office buildings, supermarkets and airports. We describe how the system was deployed in two indoor environments
and evaluated by visually impaired participants in a series of pilot experiments. We analyze the system’s successes and failures
and outline our plans for future research and development. 相似文献
6.
7.
Prednisolone therapy of idiopathic feline lower urinary tract disease: a double-blind clinical study
CA Osborne JM Kruger JP Lulich GR Johnston DJ Polzin LK Ulrich J Sanna 《Canadian Metallurgical Quarterly》1996,26(3):563-569
A double-blind clinical study was performed to evaluate prednisolone as treatment for idiopathic feline lower urinary tract disease. No differences in response were observed in prednisolone- and placebo-treated cats. 相似文献
8.
AA Ovchinnikov VE Tsvettsikh BA Berdichevski? VN Lykov VR Suktanbaev AV Murychev 《Canadian Metallurgical Quarterly》1996,20(4):7-9
Through TCD test, observation on the blood flow dynamics change before and after treatment with 31 cases of the child cerebral atrophy was made. It is found that scalp therapy is able to speed up the blood flow of part artery, especially increase the even blood flow speed of MCA, ACA obviously (P < 0.05), which preliminary shows the mechanism of scalp therapy for child cerebral atrophy mean while. It is found that scalp therapy also has the function to restrain epilepsy. 相似文献
9.
PURPOSE: To assess the clinical performance of 2-year old gallium alloy restorations. Parameters evaluated include: (1) fracture at the margins, (2) tarnish, (3) surface roughness, (4) tooth fracture, (5) fracture through the body of the restoration, and (6) any medical or dental conditions arising during the study. MATERIALS AND METHODS: Nine patients received 30 Class I restorations of Galloy gallium alloy. These were placed as conservatively as possible under a rubber dam. Fifteen of the preparations were lined with a Bis-GMA resin to seal the restoration from moisture. The other 15 preparations were sealed with Amalgambond. After placement of the gallium alloy, the exposed surfaces of all restorations were sealed with the Bis-GMA resin, and the occlusion was checked. The restorations were examined at 2 weeks, 3 months, 6 months, 1 year and 2 years. RESULTS: At the 2-year recall, all restorations were intact with the exception of one tooth fracture (cause unknown). Forty-five percent of the restorations exhibited tarnish and 60% had a rough surface. The fracture at the margins of these restorations was minimal, and no significant difference could be found between those using Amalgambond and those sealed with the resin system. No medical problems were reported by the patients, and postoperative sensitivity was minimal. 相似文献
10.
VA Khil'ko VR Gofman AT Grechko LA Glaznikov IuA Shulev 《Canadian Metallurgical Quarterly》1997,(3):35-37
This paper presents the information on the early period of an explosive head trauma and trauma to the auditory system. Different types of hearing impairment, the staging of the pathological process were determined along with various immunological and biochemical changes occurring in this group of patients. The results of the study call for necessity of the early ENT observation of all patients in whom an explosive trauma is suspected. 相似文献