高纯球形纳米SiO2的制备、改性与应用研究

高纯球形纳米SiO_2是一种具有诸多优越性能的新型材料,对于诸多行业产品的提档升级具有极其重要的意义。本文综述了纳米SiO_2的制备及改性方法,对各种方法进行了归纳和评价,并对其应用领域作了简要概括。通过研究表明,以粉石英为基本原料,采用溶胶-凝胶法制备的纳米SiO_2具有纯度高、球形度高、成本低等特点。     

高水效农业是我国农业发展的必由之路

本文提出了高水效农业是指同时追求和实现单位耗水的高水分利用效率、高经济效益、高生态效益及社会效益的一种具有高新科学技术体系和经济市场紧密结合的新型农业体系。是我国农业发展的必由之路。结合我国目前粮食生产下降的问题和节水农业发展，分析了我国粮食减产的原因主要是南方经济发达地区重工商业轻农业，因此粮食生产不足。因此，提出了我们不但要重视北方节水农业的发展，更要重视南方高水效农业的发展，以解决北粮南运的状况。从粮食安全和经济安全及水安全，南北方农业资源，农业结构调整，农艺抗旱节水措施，作物高产育种，高效的水管理体系等方面，论述了发展高水效农业发展的迫切性、可行性和必然性。     

高性能氧化锌阀片研究新进展

文章综述了近年来高性能氧化锌阀片研究的最新进展,包括氧化锌阀片通流容量和阀片侧面耐大电流性能方面的研究进展,并且指出了高性能氧化锌阀片未来发展趋势。     

Respiratory function of blood and relative weight of certain organs in two species of shrew: Crocidura russula and Suncus etruscus (Soricidae mammals)]

A high oxygen capacity combined with a low oxygen affinity and a large Bohr effect achieve a high oxygen transport capacity in small shrews. The high metabolic rate (Suncus estruscus: 100 to 350 ml O2/kg. min) can be explained by the combination of the favorable blood parameters with a high relative heart weight (1,2% of body weight) and heart frequencies of 1,000 to 1,350 per minute.     

Presynaptic effects of spider toxins: increase of high affinity uptake in the arthropod peripheral glutamatergic system

In contrast to the reported effects of polyamines on the high affinity neurotransmitter uptake, two polyamine-like spider toxins significantly increase the high affinity uptake of glutamate as demonstrated with high resolution autoradiography. The effects of both spider toxins were compared to those of a polyamine toxin from the wasp Philanthus triangulum, which is known to inhibit the high affinity glutamate uptake.     

Presynaptic effects of spider toxins: Increase of high affinity uptake in the arthropod peripheral glutamatergic system

In contrast to the reported effects of polyamines on the high affinity neurotransmitter uptake, two polyamine-like spider toxins significantly increase the high affinity uptake of glutamate as demonstrated with high resolution autoradiography. The effects of both spider toxins were compared to those of a polyamine toxin from the waspPhilanthus triangulum, which is known to inhibit the high affinity glutamate uptake.     

Heterogeneous responses of canine basilar and middle cerebral arteries to serotonin at normal and high CO2 tension.

The responses of basilar arteries (BAs) to serotonin were attenuated by high PCO2 (86 +/- 1 mm Hg) and the pH matched acidotic solution (PCO2 37 +/- 1 mm Hg), whereas the responses of middle cerebral arteries (MCAs) were not. High PCO2 decreased the basal tone of both arteries, and the changes in basal tone due to high PCO2 were not influenced by 3 x 10(-7) M imipramine, 10(-5) M pargyline or 10(-4) M aspirin. The responses of BAs to serotonin were attenuated by high PCO2 in the presence of imipramine, pargyline and aspirin. The responses of MCAs to serotonin were not influenced by high PCO2 in the presence of pargyline and aspirin, but attenuated by high PCO2 in the presence of imipramine.     

Reduction of high affinity glutamate uptake in rat hippocampus by two polyamine-like toxins isolated from the venom of the predatory wasp Philanthus triangulum F

Two components of the venom of the predatory wasp Philanthus triangulum F. significantly reduce--to a greater or less extent--the high affinity uptake of glutamate in rat hippocampus. A concentration of 10 microM delta-PTX caused a reduction of 74%, while the other component, beta-PTX, at the same concentration, caused a reduction of 18%. Hence the effect of delta-PTX on high affinity glutamate uptake in the hippocampus is comparable with its effect on high affinity glutamate uptake in insect neuromuscular junctions. Contrary to our previous findings that beta-PTX has no effect on high affinity glutamate uptake in insect glutamatergic terminal axons, however, beta-PTX significantly reduces high affinity glutamate uptake in the hippocampus, albeit less effectively than delta-PTX.     

A tug of war of forecasting the US stock market volatility: Oil futures overnight versus intraday information

This study is the first to examine the impacts of overnight and intraday oil futures cross-market information on predicting the US stock market volatility the high-frequency data. In-sample estimations present that high overnight oil futures RV can lead to high RV of the S&P 500. Moreover, negative overnight returns are more powerful than positive components, implying the existence of the leverage effect. From statistical and economic perspectives, out-of-sample results indicate that the decompositions of overnight oil futures and intraday RVs, based on signed intraday returns, can significantly increase the models' predictive ability. Finally, when considering the US stock market overnight effect, the decompositions are still useful to predict volatility, especially during high US stock market fluctuations and high and low EPU states.     

PID神经网络控制在全自动多叶光栅中的应用

为满足全自动多叶光栅在Sliding工作模式下对光栅叶片的控制,要求具有很快的加速度和良好的动态性能以及很高的位置控制精度,提出了一种适用于该模式下的速度—位置双闭环电机控制模型,采用了神经网络与数字PID相融合的控制算法,并对该控制模型进行了仿真验证。实验表明:采用PID神经网络的速度—位置双闭控制具有很高的控制精度和良好的动态性能,能有效满足全自动多叶光栅Sliding工作模式的控制要求。     

Macroeconomic forecasting with mixed data sampling frequencies: Evidence from a small open economy

The aim of this study was to forecast the Singapore gross domestic product (GDP) growth rate by employing the mixed‐data sampling (MIDAS) approach using mixed and high‐frequency financial market data from Singapore, and to examine whether the high‐frequency financial variables could better predict the macroeconomic variables. We adopt different time‐aggregating methods to handle the high‐frequency data in order to match the sampling rate of lower‐frequency data in our regression models. Our results showed that MIDAS regression using high‐frequency stock return data produced a better forecast of GDP growth rate than the other models, and the best forecasting performance was achieved by using weekly stock returns. The forecasting result was further improved by performing intra‐period forecasting.     

Spontaneous mortality and vascular lesions in 3 rat strains with different blood pressure levels]

We have observed a high and significant mortality in spontaneously hypertensive rats compared to normotensive and hypotensive controls, in the fifth generation. The hypertensive rats exhibited a high frequency of cerebral haemorrhage and periarteritis nodosa.     

川西亚高山针叶林生产力和光能利用效率研究现状

本文回顾了目前已发表的有关川西地区云冷杉林光能利用率的研究资料，从概念、测量方法、研究结果、影响因子等几个方面做了比较，发现川西地区森林净初级生产力和叶面积指数(LAI)的异质性很强。这种异质性使地面测量和遥感测量不能满足对小尺度川西亚高山针叶林生态系统结构和功能测定和预测的要求。基于形态和生理生态的模型方法由于具有机理性强，对参数变化反应灵敏，在时间和尺度上的灵活性将是未来研究川西亚高山针叶林群落生态系统过程和全球变化响应的重要手段。     

沾化凹陷异常高压分布特征及其成因机制探讨

采用声波时差法计算沾化凹陷沙三、沙四段的地层压力。发现异常高压纵向上存在两个独立的异常高压系统,规模较大、持续活动强的断层往往是异常高压区的边界,并起到泄压的作用。平面上,以洼陷为中心形成异常高压区,向外逐渐过渡为正常压力带。从沙三上段至沙三四上段,异常高压范围经历了一个扩张-萎缩的旋回,沙三下段凹陷内异常高压分布面积达到最大。对沾化凹陷新生代沉降史及生排烃史的研究表明,较高的沉积速率及有机质生烃是沾化凹陷异常高压发育的主要因素。构造作用通过断层泄压、控制沉积速率及有机质展布起到对异常高压分布直接或间接的控制作用。     

The natural selection of conservative science

Social epistemologists have argued that high risk, high reward science has an important role to play in scientific communities. Recently, though, it has also been argued that various scientific fields seem to be trending towards conservatism—the increasing production of what Kuhn (1962) might have called ‘normal science’. This paper will explore a possible explanation for this sort of trend: that the process by which scientific research groups form, grow, and dissolve might be inherently hostile to such science. In particular, I employ a paradigm developed by Smaldino and McElreath (2016) that treats a scientific community as a population undergoing selection. As will become clear, perhaps counter-intuitively this sort of process in some ways promotes high risk, high reward science. But, as I will point out, risky science is, in general, the sort of thing that is hard to repeat. While more conservative scientists will be able to train students capable of continuing their successful projects, and so create thriving lineages, successful risky science may not be the sort of thing one can easily pass on. In such cases, the structure of scientific communities selects against high risk, high rewards projects. More generally, this project makes clear that there are at least two processes to consider in thinking about how incentives shape scientific communities—the process by which individual scientists make choices about their careers and research, and the selective process governing the formation of new research groups.     

水分利用效率--未来农业研究的关键问题

随着生物节水研究的深入发展，让每一滴生产出更多的食物，水分利用效率是未来农业研究的关键问题。抗旱、节水和水分利用效率的概念是不同的，在不同学科中有不同的研究尺度和层次。不同降水量和水资源地区的抗旱、节水和水分利用效率有不同的研究重点和不同的节水农业发展方向。从被动的耐旱性研究到主动的抗旱性研究再到节水研究，在未来必将转向水分高效利用研究。小麦高产育种进化中其水分利用效率有递增的趋势，作物抗旱耐旱育种要转向高水分利用效率育种是势在必行的，因为高水分利用效率育种，可以将抗旱性和丰产性统一于一体。增施肥料是提高大面积中低产田作物水分利用效率和产量的关键措施之一，今后应该继续受到全面重视。     

Zentrifugenfiltration mit hohen Drucken

Summary A filter apparatus for high pressure filtration and its use in normal centrifuges is described. The solution is filtered through a filter membrane under the influence of high centrifugal power.     

解聚复肾宁对大鼠肾小球系膜细胞增殖和细胞周期的影响

目的 观察中药复方解聚复肾宁（JJFSN）对高耱环境下大鼠肾小球系膜细胞（mesangial cell,MC）增殖和细胞周期的影响.方法 以高糖诱导MC增殖,采用血清药理学方法制备不同浓度JJFSN舍药血清,加入培养液中,用MTT法检测细胞增殖,流式细胞技术检测细胞周期.结果 MTT显示：JJFSN含药血清可抑制高糖诱导的MC过度增殖（P＜0.05）,并且这种作用具有药物剂量和时间依赖关系.流式细胞技术分析表明：JJFSN可逆转高糖对细胞周期的影响,使G0/G1期细胞比例增加,S期细胞比例下降（P＜0.05） 在高浓度时还能促进MC细胞凋亡.结论 JJFSN可以通过调节细胞周期,促进细胞凋亡,从而抑制高糖诱导的MC过度增殖,这可能是JJFSN防治DN早期的作用杌理.     

电动助力转向系统的建模及其全工况控制

将电动助力转向系统模型、轮胎模型以及非线性整车模型联系起来,建立完整的汽车转向动力学模型。针对EPS转向、回正、阻尼三种不同的工况,采用自适应模煳PID扣PID控制算法对EPS分刺进行了助力、回正、阻尼控制。仿真结果表明：所设计酶动力特性比较好的解决了转向轻便性和路感的矛盾,回正控制改善了车辆低速对低速时正性,抵制了车辆高速时的回正超调现象,阻尼控制能够有效的抑制路面的高频干扰,提高了汽车高速直线行驶的稳定性。