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排序方式: 共有311条查询结果,搜索用时 15 毫秒
11.
PA von dem Borne LO Mosnier G Tans JC Meijers BN Bouma 《Canadian Metallurgical Quarterly》1997,78(2):834-839
The activation of factor XI by meizothrombin was investigated using recombinant meizothrombin (R155A meizothrombin) that is resistant to autocatalytic removal of fragment 1. Meizothrombin was capable of activating factor XI at an activation rate similar to that of thrombin. Dextran sulphate and heparin, known cofactors of thrombin-mediated factor XI activation, did not stimulate the activation of factor XI by meizothrombin. However, the activation of factor XI by meizothrombin was markedly enhanced by vesicles containing phosphatidylcholine (PC), phosphatidylserine (PS) and phosphatidylethanolamine (PE), whereas PC/PS or PC/PE vesicles only had a minor effect on the activation. Thrombin-mediated factor XI activation was not influenced by phospholipids. The effect of PC/PS/PE and PC/PS vesicles was studied in a factor XI dependent clot lysis assay. In this assay, factor XI inhibits clot lysis by a feedback loop in the intrinsic pathway via thrombin-mediated factor XI activation. Removal of endogenous phospholipids in plasma by centrifugation resulted in an increased clot lysis, which could be restored to the pre-centrifugation level by the addition of PC/PS/PE vesicles, but not by PC/PS vesicles. When clot lysis was initiated by factor IXa in the presence of a factor XIa blocking antibody, there was no difference in inhibitory effect of PC/PS/PE or PC/PS vesicles. These data suggested that the differences in clot lysis inhibition observed between PC/PS/PE and PC/PS vesicles were caused by factor XI activation by meizothrombin. Meizothrombin-mediated factor XI activation may therefore play an important role in the antifibrinolytic feedback loop in the intrinsic pathway. 相似文献
12.
为了使移动终端用户能够及时查看到电力业务更新消息,提出消息推送技术在移动高级应用中的研究。首先介绍消息推送的实现方式及原理,然后就iOS与Android系统两大主流移动系统平台的消息推送机制进行研究,提出在两大主流移动系统平台上实现消息推送的解决方案,并在企业移动驾驶舱的高级应用中实现消息推送,使终端用户能够实时查看到更新的消息。 相似文献
13.
Tropical corn silage was compared with sorghum silage as a basal forage in the diets of high producing dairy cows. Sorghum and tropical corn silages were each included in place of ground corn at incremental concentrations in the experimental diets. Eight separate diets were fed, four diets containing each silage ranging in forage neutral detergent fiber (NDF) from approximately 25 to 31% and ranging in total NDF from approximately 41 to 45%. Diets were arranged in a 2 x 4 factorial design and were fed to lactating cows (n = 24; pretrial mean milk production = 39 kg/d; body weight = 656 kg; and days in milk = 81). As concentrations of dietary NDF increased, intake and milk production decreased linearly. The impact of dietary NDF on intake was greater for diets based on tropical corn silage than for diets based on sorghum silage. Energy intake and milk production were reduced, but cows consumed more fiber when challenged with higher dietary concentrations of fiber. The in vitro rate and extent of digestion of dietary samples were correlated with intake response. The rate of in vitro fiber digestion was slower for samples that contained tropical corn silage than for samples that contained sorghum silage. In vivo digestibility measurements were influenced by intake and dietary composition. Results of this trial indicated that sorghum silage can have equal or slightly greater nutritional value than tropical corn silage when these forages are fed at equal concentrations of dietary fiber. 相似文献
14.
15.
Prosthetic valve endocarditis: superiority of surgical valve replacement versus medical therapy only
VL Yu GD Fang TF Keys AA Harris LO Gentry PC Fuchs MM Wagener ES Wong 《Canadian Metallurgical Quarterly》1994,58(4):1073-1077
The objective of our study was to assess the long-term outcome of patients with prosthetic valve endocarditis. We used a multicenter, prospective, observational study design. Six university teaching hospitals with high volume cardiothoracic surgery participated. Seventy-four patients with prosthetic valve endocarditis as defined by explicit, objective criteria were selected for participation. All patients were followed up prospectively for 1 year. Thirty-one percent and 69% had development of endocarditis within 60 days of valve insertion ("early") and after 60 days ("late"), respectively. The most common causes were Staphylococcus epidermidis (40%), Staphylococcus aureus (20%), streptococcal species (18%), and aerobic gram-negative bacilli (11%). Physical signs of endocarditis (new or changing murmur, stigmata, emboli) were seen in 58%. At 6 months and 12 months, mortality was 46% and 47%, respectively. Surgical replacement of the infected valve led to significantly lower mortality (23%) as compared with medical therapy alone (56%), as assessed by both univariate and multivariate analyses (p < 0.05). Improved outcome was seen for the surgical group even when controlling for severity of illness at time of diagnosis. From these findings we conclude that accurate assessment of outcome in prosthetic valve endocarditis requires long-term follow-up of at least 6 months following diagnosis. Surgical therapy warrants greater scrutiny; evaluation in controlled clinical trials is appropriate. 相似文献
16.
GR Login M Aoki M Yamakawa LO Lunardi EC Digenis N Tanda LB Schwartz AM Dvorak 《Canadian Metallurgical Quarterly》1997,45(10):1379-1391
The subcellular events responsible for release of mediators by mast cells may help to clarify roles for mast cells in health and disease. In this study we show that the granule-associated protease chymase is also within cytoplasmic vesicles in appropriately stimulated rat peritoneal mast cells. Rat peritoneal mast cells were recovered before or 1-10 sec after exposure to the secretogogue compound 48/80 (10 micrograms/ml) and then were examined by radioimmunoassay to quantify histamine release or were processed, using routine methods for postembedding immunoelectron microscopy, to identify the subcellular localization of chymase. In comparison to unstimulated cells, compound 48/80 stimulated cells in two independent experiments showed an increase (15%, 28%) in the surface area of the cell and a decrease (12%, 6%) in the surface area of the total granule compartment before degranulation channel formation. These global cellular changes occurred in a background of transient but significant (p < 0.01) increases in the area and number of chymase-immunoreactive vesicles per microns2 cytoplasm. These changes were detectable at 5 or 7 sec after stimulation with compound 48/80 but returned to near prestimulation levels by 9 or 10 sec after addition of compound 48/80 (total cumulative histamine release was 28% by 8 sec and 47% by 14 sec). These observations suggest that vesicles participate in the early stages of regulated secretion of chymase from rat peritoneal mast cells. 相似文献
17.
高层建筑火灾安全模糊评价 总被引:9,自引:0,他引:9
将模糊数学中的综合评判模型与高层建筑中对火灾安全有影响的因子相结合,建立了高层建筑火灾安全评价的模糊综合评判模型.在该模型中对数据的处理、权重的选取、多层次的综合评判进行了方法上的研究.对某高层建筑火灾安全评价中的评价指标与等级的选取、评价指标标准的确定、权重的确定等进行了实例分析,给出了评价结果并对结果进行了分析. 相似文献
18.
三级配混凝土输送泵在鱼塘水电站混凝土施工中的应用 总被引:1,自引:0,他引:1
鱼塘水电站溢洪道混凝土共计14.9万m3,由于受不良地质和洪水冲毁围堰等因素影响致使开挖结束时工期严重滞后,而整个电站安全度汛又迫在眉睫,故必须寻求加快溢洪道混凝土浇筑速度的办法。为此,采用国内首批HBT120A三级配混凝土输送泵作为混凝土主要的入仓手段,使施工进度明显加快,弥补了原已滞后的工期,保证了鱼塘水电站溢洪道工程安全度汛目标的实现,并为2005年9月底水库下闸蓄水目标的实现奠定了坚实的基础。本文主要介绍HBT120A三级配混凝土输送泵在该工程施工中的应用。 相似文献
19.
BD Spiess MH Wall BS Gillies JC Fitch LO Soltow WL Chandler 《Canadian Metallurgical Quarterly》1997,78(2):820-826
Thromboelastography (TEG) has been used after cardiopulmonary bypass (CPB) to diagnose excessive postoperative hemorrhage. Conventional TEG during CPB is not possible due to the sensitivity of the TEG to even small amounts of heparin, which produces a nondiagnostic tracing. The purpose of this study was to compare heparin neutralization using heparinase or protamine in TEG blood samples obtained during CPB. TEG testing was performed on 48 patients before, during and after CPB. Tissue plasminogen activator activity and antigen were measured on a subset of 32 patients. We found: 1) heparinase neutralized at least 10 IU/ml heparin while 1.6 ug/ml protamine neutralized up to 7 IU/ml heparin, 2) in samples with complete heparin neutralization by both methods, there was no significant difference in the R values, 3) while there was good correlation for other TEG parameters between heparinase and protamine treated samples, heparinase treatment produced shorter K values and higher angle, MA and A60, 4) while fibrinolysis was detected using both methods, heparinase treatment suppressed fibrinolysis in the TEG in both samples from patients and after in vitro addition of tissue plasminogen activator, 5) TEG was not a sensitive indicator of t-PA activity, detecting only 21% of samples with increased t-PA activity during bypass, and 5) heparinase was at least 100 times more expensive than protamine. We conclude that while both heparinase and protamine can be used to neutralize heparin in TEG samples obtained during CPB, protamine neutralization is more sensitive to fibrinolysis and less expensive, but the protamine dose must be carefully selected to match the heparin level used at individual institutions. 相似文献
20.
A. T ROWLEY R WROE D VAZQUEZ-NAVARRO WAI LO D. A CARDWELL 《Journal of Materials Science》1997,32(17):4541-4547
The properties (superconducting and non-superconducting) of YBa2Cu3O7-δ bulk ceramics (YBCO) are strongly dependent on the oxygen deficiency, δ. Unfortunately, whether sintering or melt-processing
is used to form the material, the final oxygen content is usually far from that which gives the optimum superconducting properties
(δ≲0.1). Because of this, an additional oxygenation stage has to be carried out in which the material is heated and held at
some elevated temperature (∼400–500 °C) for a significant time (often > 100 h) to allow oxygen to diffuse into the sample.
Other diffusion-based processes (e.g. sintering) are known to be substantially enhanced in the presence of a microwave field,
and it is reasonable to expect that the diffusion of oxygen into YBCO may also benefit from the application of such technology.
The oxygenation of melt-processed YBCO using conventional and microwave-assisted heating has been compared. The diffusion
coefficient at 400 and at 450 °C is shown to be enhanced by about 30% through the application of a high-frequency microwave
field. Because the oxygenation time is inversely proportional to the diffusion coefficient, this represents a significant
reduction in process time. The equilibrium value of the oxygen content is not affected by the application of a microwave field,
and therefore the sample temperature must be the same for both microwave-assisted and conventional processing. Consequently,
the observed enhancement is an example of a genuine non-thermal microwave effect.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献