提高小学数学课堂教学效率的几点思考

提高教师认识,是提高小学数学课堂教学效率的前提.提高课堂教学效率、提高课堂教学效果或提高课堂教学效益、质量、水平等提法报刊杂志上出现的频率很高.这一方面说明这些问题受到越来越多的人们的关心、重视;另一方面说明提高课堂教学效率对于全面提高教学、教育质量,提高学生素质确确实实具有重要的现实意义.     

提高直筒型转炉炉龄的经验

提高白云石炉衬中的炭素含量、提高制砖质量、选择合理炉型、提高烘烤质量可以提高转炉炉衬寿命。     

提高锰回收率的生产实践

本文阐述了锰铁冶炼中采取提高炉渣碱度、提高炉温、增加炉渣MgO含量、采用富氧鼓风、提高风温和使用高MgO的高碱度烧结锰矿等措施以提高锰回收率的生产实践.     

提高钒钛磁铁精矿烧结矿铁份的试验研究

在实验室条件下,通过调整配料结构,可以实现烧结铁份的提高;在烧结提高TFe降低SiO2时,采取提高碱度、用活性灰代替生石灰、添加硼化物、燃料分加、熔剂分加、精矿预制粒、澳矿分加、提高料层厚度等措施,可起到强化提高TFe降低SiO2烧结的作用.     

提高UHP电炉单炉产量的途径

改造炉壳、保持熔池形状、适当提高装入量和提高操作水平、减少事故是提高UHP电炉单炉产量的主要途径。     

一种热轧花纹板生产方法

本发明涉及一种热轧花纹板生产方法，通过提高加热温度、优化除鳞制度，从而提高精轧出口温度、改善钢材塑性、提高花纹成型性；加大花纹辊的花纹加工深度、增大花纹面积、改善花纹成型阻力，从而相应提高花纹板花纹高度、降低花纹辊机架压下率。本发明能够有效提高花纹板的产量和质量，具有显著的经济效益。     

7号板坯连铸机高效生产实践

分析了7号板坯连铸机高效生产中存在的问题,介绍实施的提高拉速、提高作业率、提高铸坯合格率等措施,使连铸机稳定生产的最高拉速从1.4 m/min提高到1.65 m/min,作业率从88%提高到93%,铸坯合格率从99.6%提高到99.9%。     

提高首钢炼铁厂矮胖高炉喷煤比的生产实践

结合首钢炼铁生产的具体情况，分析了影响其喷煤比提高的原因，介绍了提高喷煤比的生产经验，提出了提高精料质量、改造喷煤系统、提高风温、富氧鼓风和保障炉内顺行等措施。     

青钢高炉提高喷煤量实践

通过改造原煤仓下煤管、提高磨辊压力,使制粉能力提高12～18t/h;通过控制煤粉粒度、水分、温度等,改善了煤粉性能;又通过提高氮气压力、提高喷吹罐压力、降低补气流量、广喷匀喷等技术手段,使各高炉喷煤量提高2t/h,达到了降低燃料成本的目的。     

莱钢二铁2#高炉生铁降硅实践

莱芜钢铁总厂第二铁厂２＃７５０ｍ３高炉在生产中采取提高烧结矿碱度、配用高品位进口矿、减少入炉粉末、稳定焦炭质量及稳定炉温、适当提高炉渣碱度、提高风温和顶压等一系列措施，使生铁含硅量由０．８４１％降为０．６３７％，生铁一级品率由４２．６７％提高到５４．６１％，高炉综合技术经济指标提高。     

Acidosis, alkalosis, and aqueous humor dynamics in rabbits

Systemic acidosis induced by intravenous administration of hydrochloric acid lowered intraocular pressure in unanesthetized rabbits. Aqueous humor flow was reduced by approximately 50%, as measured by the iodide method and as calculated from tonographic data. Outflow facility, episcleral venous pressure, plasma osmolality, blood pressure, pulse, and body temperature were not altered by systemic acidosis. Systemic alkalosis induced by intravenously administered sodium bicarbonate was associated with an increased intraocular pressure. Aqueous humor flow following systemic alkalosis was increased by approximately 100%, as measured by the iodide method and as calculated from tonographic data. Alkalosis was not associated with alterations in outflow facility, episcleral venous pressure, plasma osmality, blood pressure, pulse, or rectal temperature.     

Transcription factors of the PEA3 group in mammary cancer

OBJECTIVE: To discover the predominant determinant of systolic pressure variation during positive-pressure ventilation in mechanically ventilated patients after a vascular surgical procedure. DESIGN: Case control study. SETTING: Postanesthesia care unit at a university hospital. PARTICIPANTS: Eleven patients who were sedated during mechanical ventilation after abdominal aortic surgery. INTERVENTIONS: Radial arterial pressure and airway pressure were simultaneously recorded. The systolic pressure variation was measured as the mean difference between the maximal and minimal systolic pressure values during five consecutive mechanical breaths. The delta down was measured as the difference between the systolic blood pressure during apnea and the minimal values of the systolic pressure after one mechanical breath. The velocity time integral, which is closely related to stroke volume, was measured throughout the systolic pressure measurements. MEASUREMENTS AND MAIN RESULTS: Positive correlation was found between changes in velocity time integral and the magnitude of both systolic pressure variation (r = 0.73) and delta down (r = 0.80). Volume loading did not significantly modify systolic blood pressure. However, it did not significantly decrease systolic pressure variation and delta down. The corresponding changes in velocity time integral provoked by mechanical ventilation decreased significantly as well. CONCLUSIONS: The decrease in systolic pressure provoked by positive-pressure inspiration reflects simultaneous decreases in stroke volume. This suggests that a decrease in left ventricular filling, associated with positive-pressure inspiration, is responsible for systolic pressure variation. This finding confirms the interest in considering systolic pressure variation to provide reliable information about the responsiveness of the heart to preload variations.     

Dilatational and Compacting Behavior around a Cylindrical Cavern Leached?Out in a Solid–Fluid Elastic Rock Salt

A fluid-filled cylindrical cavern of circular cross section in a homogeneous infinite fluid-saturated polycristalline (salt) formation subjected to isotropic stress is set under internal pressure that differs from the confining pressure. The fluid in the cavern and in the mixture is treated as ideal and the solid as elastic. The state of stress that is established as a consequence of an outside pressure and a cavern pressure serves as the reference state. Perturbing the cavern pressure induces small changes in the solid and fluid densities and in the solid displacements. We compute these and other fields as functions of the radial distance from the cavern center and show that, depending on the relative stress levels, the (salt) formation experiences either a dilatation or a compaction that is highly concentrated in a thin boundary layer near the cavern wall and tapers off as one moves away from it. The amount of dilatation/compaction of the cylindrical wall and the thickness of the boundary layer grow with an increase in the difference between the referential confining pressure and the pressure in the cavern.     

Increased urinary excretion of 3-oxo-delta4 bile acids in Japanese patients with idiopathic neonatal cholestasis

This report examines the reliability of nighttime blood pressure dipping. Twenty-one individuals were studied twice with ambulatory blood pressure monitoring. On one occasion they were studied as outpatients, and on the other as inpatients on a clinical research ward. Blood pressure monitoring revealed the expected dip in blood pressure at nighttime. However, there was little test-retest reliability across the two settings. The test-retest correlations for the dip in blood pressure across the two settings were nonsignificant for systolic, diastolic, and mean arterial blood pressure. Caution is advised before diagnosing dipping or nondipping on the basis of one 24-h ambulatory blood pressure recording.     

Changes in canine saliva ion concentration induced by increased intraluminal pressure

Hydrostatic pressure was applied to a cannula inserted into Wharton's duct of adult dogs anesthetized with pentobarbital and the effect of pressure on saliva flow rate and ionic composition of saliva was measured. Increasing the back pressure on a secreting gland resulted in a decrease in flow rate. Over the range of 0-100 mmHg back pressure the decrease in flow was proportional to the applied back pressure. The potassium concentration of saliva collected in the absence of back pressure and at raised pressure was similar even though back pressure reduced flow. In contrast, sodium concentration decreased when back pressure caused salivary flow rate to be reduced. However, when examined at the same flow rates the concentration of sodium is increased when back pressure is applied to the gland as compared to absence of back pressure. Under conditions of constant stimulation the total output of sodium and potassium into saliva decreases as back pressure is increased; but when equal flow rates are compared total sodium output increases in the presence of applied back pressure, whereas potassium output remains constant.     

Principles of urodynamics pressure measurement and its implication to female continence function

Urodynamic pressure measurements using catheters have been widely used among clinicians. More often objective interpretation of urodynamic pressure measurements requires fundamental understanding of pressure measurement techniques due to many measurement artifacts. In this study we developed a simplified compound thick-walled cylinder model to investigate the mechanical nature of urodynamic pressure measurement as well as pressure transmission. Efficacy of collagen implantation was also explored. Lamé's formulation was used to find analytical solutions. Pressure transmission can be related to catheter caliber and the compressibility of the urethral tissue (poisson ratio) in a simple mathematical form. The theoretical pressure transmission ratio will be 133% with the additional incompressibility assumption, reflecting the passive structural transmission of intraabdominal pressure increase. The relationship between the pressure measurement error and the catheter caliber was found to be linear (r2 = 0.94 +/- 0.04) and two or more pressure measurements need to be used to find the uninstrumented pressure. It was predicted that collagen implantation treatment might improve the pressure transmission ratio maximally by 33%.     

Treatment results with isoglaucon eye drops in sympatheticotone patients with early appearing primary glaucoma (author's transl)

The sympatholytic substance Clonidin (Isoglaucon) that lowers the intraocular pressure as well as the general blood pressure was tested on a small but homogenous group of patients. This group consisted of 11 middle aged male patients with wide angle glaucoma, elevated blood pressure and sympathicotonia. The intraocular pressure was well controlled in 9 of these, and sufficiently lowered in the remaining two. At the same time the general blood pressure was consistently lowered to some extent and the sympathicotonia improved.     

Understanding, applying, and evaluating pressure modes of ventilation

Volume ventilation has long been the preferred method of mechanical ventilation, especially in critically ill patients. Recently, pressure ventilation has been introduced as a potentially superior method of ventilating stable and unstable respiratory patients. The positive characteristics of pressure modes such as the associated decelerating flow pattern and the ability to limit pressure and thus prevent barotrauma have resulted in numerous clinical applications. Although promising, the applications require that clinicians understand the flow, volume, and pressure characteristics of the modes. To this end, two popular pressure modes, pressure support and pressure-controlled inverse ratio, are described. A new option (available on only a few ventilators) called volume-guaranteed pressure ventilation, also is introduced.     

真空浇注对结晶器内流体流动行为的影响

对真空浇注下结晶器内流体流动行为进行了研究.将中间包浇注水口上部区域进行密封得到真空室,通过降低真空室压力减小钢水进入结晶器的驱动压力,从而减小钢水进入结晶器的流速,最终减小结晶器内液面波动造成的卷渣.试验研究了不同真空室压力和不同进入真空室阀门开启度下的结晶器液面波动和窄面压力变化,得到真空室压力减小、开启度增加可以减小结晶器液面波动和窄面压力变化,同时得到了各位置液面波动和窄面压力变化的规律.     

Diagnosing gestational hypertension and preeclampsia with the 24-hour mean of blood pressure

The use of ambulatory blood pressure monitoring has provided a method of blood pressure assessment that may compensate for some of the limitations of isolated measurements. Here we aim to examine prospectively the effectiveness of the commonly used 24-hour mean as a potential screening test for the identification of gestational hypertension and preeclampsia. We analyzed 503 blood pressure series from 71 healthy pregnant women and 256 series from 42 women who developed gestational hypertension or preeclampsia. Forty-eight-hour blood pressure monitoring was done once every 4 weeks after the first obstetric consultation. Sensitivity and specificity of the 24-hour mean of blood pressure were computed for each trimester of pregnancy by comparing distributions of values obtained for healthy and complicated pregnancies, without assuming an a priori threshold for diagnosing gestational hypertension on the basis of mean blood pressure. Sensitivity ranges from 31.8% for diastolic blood pressure in the second trimester to 84.1% for systolic blood pressure in the third trimester. However, specificity is as low as 6.9% for diastolic blood pressure in the first trimester. The positive predictive value does not reach 55% for any variable in any trimester. The higher relative risk was consistently obtained for systolic blood pressure (4.9 in the third trimester). Despite the highly statistically significant differences in blood pressure found between healthy and complicated pregnancies in all trimesters, the daily mean of blood pressure does not provide a proper and stable individualized test for diagnosing hypertensive complications in pregnancy. Other indexes obtained from the blood pressure series have been shown, however, to identify early in pregnancy those women who subsequently will develop gestational hypertension or preeclampsia, rendering ambulatory blood pressure monitoring a useful, but still costly, technique in pregnancy.