Blazar天体射电波段的周期分析研究

从文献中收集了11个Blazar天体在22GHz和37GHz射电辐射流量的观测数据,获得了这些天体从1980-2005年射电辐射流量的变化曲线。用Jurkevich方法分析研究了它们射电辐射流量的变化周期。结果表明:11个天体在22GHz和37GHz波段都表现出周期性变化的特征,变化周期从1.4年至10.4年不等,并且天体在22GHz和37GHz的变化特征基本相同。对得到的周期分析结果作了简要讨论。     

Competence to replicate in the unfertilized egg is conferred by Cdc6 during meiotic maturation

Meiotic maturation, the final step of oogenesis, is a crucial stage of development in which an immature oocyte becomes a fertilizable egg. In Xenopus, the ability to replicate DNA is acquired during maturation at breakdown of the nuclear envelope by translation of a DNA synthesis inducer that is not present in the oocyte. Here we identify Cdc6, which is essential for recruiting the minichromosome maintenance (MCM) helicase to the pre-replication complex, as this inducer of DNA synthesis. We show that maternal cdc6 mRNA but not protein is stored in the oocyte. Cdc6 protein is synthesized during maturation, but this process can be blocked by degrading the maternal cdc6 mRNA by oligonucleotide antisense injections or by translation inhibition. Rescue experiments using recombinant Cdc6 protein show that Cdc6 is the only missing replication factor whose translation is necessary and sufficient to confer DNA replication competence to the egg before fertilization. The licence to replicate is given by Cdc6 at the end of meiosis I, but the cytostatic factor (CSF) pathway, which maintains large amounts of active Cdc2/Cyclin B2, prevents the entry into S phase until fertilization.     

响应面法优化龙胆苦苷脂质体的复乳法制备工艺

采用复乳法制备脂质体,使用3因素3水平的Box-Behnken响应面设计,以脂质体的包封率、载药量和综合评价为响应值,考察龙胆苦苷药液质量浓度、第一次乳化超声时间及膜材中磷脂与胆固醇的质量比对响应值的影响,并用Design-Expert 7.1.3软件（试用版）进行数据拟合、数学建模和预测分析。优化出的龙胆苦苷脂质体的最佳处方为龙胆苦苷药液质量浓度为2.04 mg/mL、第一次乳化超声时间为7.07 min、脂质体膜材中胆固醇与磷脂质量比为0.45。研究结果表明,在最优处方下龙胆苦苷脂质体形态完整、状态稳定,平均粒径为131 nm,其包封率为52.39%,与预测值的偏差率小于1%。     

延伸课堂实现理论与实际的对接——从一堂《概率论与数理统计》公开课对课堂延伸的思考与实践

为了更好地讲授比较抽象、难度较大的理论内容,实现教学目标,在实际教学工作中,要把课备到课外,把课堂延伸到课外,有目的地引导学生感知教材,实现理论与实际的对接,为课堂的理论学习打下坚实的基础,同时培养学生探究精神.     

新时期公共图书馆过期报刊的利用

本文阐述了公共图书馆过刊的现状和利用价值,就现状摆在公共图书馆过刊存在的一些问题,以及在新的环境下公共图书馆根据过刊的新要求,就如何提高过刊的利用率的几点思考.     

鸭疫里默氏杆菌三价灭活疫苗的免疫保护期研究

选择免疫原性好的血清1,2,4型鸭疫里默氏杆菌（RA）分离株制备三价灭活油乳剂苗,疫苗抗原含量为5×109CFU/ml,分别用0.5,1.0和1.5ml/只剂量接种7日龄樱桃谷肉鸭以检验器其安全性;用0.25ml/只的剂量接种樱桃谷肉雏鸭,分别于免疫后第1、2、3,4、5和9周攻毒,以检验其免疫效果.安全性检验结果显示,肉雏鸭接种后未见局部和全身异常反应;攻毒保护试验结果显示,免疫后2～9周雏鸭对3个血清型的RA的攻毒保护率达70％ ～ 100％.证明该三价灭活疫苗具有良好的安全性免疫保护力,免疫保护期不少于9周.     

Fetal occipital cortical neurones transplanted to the rostral cortex can extend and maintain a pyramidal tract axon

In adult rats, cortical neurones that send axons through the pyramidal tract are confined to layer V, over the rostral two-thirds of the cerebral hemisphere. However, during the first postnatal week, many neurones in layer V in the occipital cortex (including the visual cortex) also extend axon collaterals through the pyramidal tract and into the spinal cord. These occipital corticospinal collaterals are completely eliminated over the subsequent 2 weeks, although their cells of origin do not die. We now report that when portions of the occipital cortex from fetal rats are transplanted to more rostral cortical regions of newborn rats, some of the transplanted neurones not only extend axons through the pyramidal tract, but also maintain these axons beyond the stage at which they are normally eliminated. These results suggest that normally-eliminated cortical axons can be 'rescued' and, in the case of pyramidal tract neurones, the position of the neurones within the tangential plane of the cortex is a critical factor in determining which neurones retain and which lose their pyramidal tract collaterals.     

渗流理论在多个染病阶段的疾病传播中的应用

为了研究具有多染病期的疾病在人群中传播所形成的疾病爆发情况,将疾病传播网络研究和生成函数理论与渗流原理结合起来,使得网络的拓扑结构更加清晰和便捷。把染病期分为n个阶段:I1,I2,…,In,得出了由一个染病节点开始在网络中传播所引起的疾病的爆发阈值、爆发规模、疾病爆发时染病节点的平均度、未染病节点的平均度等的计算方法。     

液膜乳化液的离心-脉冲电场连续破乳

在分析离心-脉冲电场连续破乳原理的基础上,设计和制作了竖式圆柱绝缘电极实验室用的离心-脉冲电场连续破乳器.在M6401-L113B-煤油-H2SO4和Lix984N-L113A-煤油-H2SO4乳化液膜体系处理含Cu2 废水的实验中,研究了离心-脉冲电场连续破乳时的各种影响因素.结果表明,离心-脉冲电场能有效地对上述乳化液膜体系进行连续破乳,且其破乳效果比单一脉冲电场连续破乳效果要好.     

Use of numbers by a chimpanzee

Recent studies have examined linguistic abilities in apes. However, although human mathematical abilities seem to be derived from the same foundation as those in language, we have little evidence for mathematical abilities in apes (but for exceptions see refs 7-10). In the present study, a 5-yr-old female chimpanzee (Pan troglodytes), 'Ai', was trained to use Arabic numerals to name the number of items in a display. Ai mastered numerical naming from one to six and was able to name the number, colour and object of 300 types of samples. Although no particular sequence of describing samples was required, the chimpanzee favoured two sequences (colour/object/number and object/colour/number). The present study demonstrates that the chimpanzee was able to describe the three attributes of the sample items and spontaneously organized the 'word order'.     

利用关系矩阵判断二元关系的传递性

目的判断一个二元关系是否具有传递性,从定义与关系图的方法比较繁琐,利用关系矩阵判断其传递性,能避免繁琐的过程。方法利用关系矩阵中元素的特点与关系。结果找零元素法;矩阵的逻辑加运算法;十字画法。结论对于给定一个集合元素的个数较多时,能方便地判断其是否具有传递性。     

乳状液在岩心中运移的影响因素研究

为了研究乳状液在多孔介质中运移的影响因素及运移规律,了解乳状液对提高采收率的作用,利用长岩心作为模型进行驱替实验,研究了乳状液液滴粒径、液滴密度及运移速度对其运移规律的影响.结果表明,乳状液在孔喉中的宏观运移阻力是乳状液液滴对孔喉堵塞的累积结果.大液滴的乳状液在孔隙介质中运移阻力明显大于小液滴的乳状液.注入速度对乳状液在岩心中运移阻力影响较大,在粒径孔径匹配的条件下,存在一个临界注入速度,在临界速度下乳液在岩心中才能形成明显的封堵.速度太低,乳状液破乳严重,乳状液变形通过孔喉的能力强不容易封堵孔喉;速度太高,乳状液液滴被分散破碎、粒径变小不容易封堵孔喉.     

Control of Jupiter's radio emission and aurorae by the solar wind

Radio emissions from Jupiter provided the first evidence that this giant planet has a strong magnetic field and a large magnetosphere. Jupiter also has polar aurorae, which are similar in many respects to Earth's aurorae. The radio emissions are believed to be generated along the high-latitude magnetic field lines by the same electrons that produce the aurorae, and both the radio emission in the hectometric frequency range and the aurorae vary considerably. The origin of the variability, however, has been poorly understood. Here we report simultaneous observations using the Cassini and Galileo spacecraft of hectometric radio emissions and extreme ultraviolet auroral emissions from Jupiter. Our results show that both of these emissions are triggered by interplanetary shocks propagating outward from the Sun. When such a shock arrives at Jupiter, it seems to cause a major compression and reconfiguration of the magnetosphere, which produces strong electric fields and therefore electron acceleration along the auroral field lines, similar to the processes that occur during geomagnetic storms at the Earth.     

An expanding radio nebula produced by a giant flare from the magnetar SGR 1806-20

Soft gamma-ray repeaters (SGRs) are 'magnetars', a small class of slowly spinning neutron stars with extreme surface magnetic fields, B approximately 10(15) gauss (refs 1 , 2 -3). On 27 December 2004, a giant flare was detected from the magnetar SGR 1806-20 (ref. 2), only the third such event recorded. This burst of energy was detected by a variety of instruments and even caused an ionospheric disturbance in the Earth's upper atmosphere that was recorded around the globe. Here we report the detection of a fading radio afterglow produced by this outburst, with a luminosity 500 times larger than the only other detection of a similar source. From day 6 to day 19 after the flare from SGR 1806-20, a resolved, linearly polarized, radio nebula was seen, expanding at approximately a quarter of the speed of light. To create this nebula, at least 4 x 10(43) ergs of energy must have been emitted by the giant flare in the form of magnetic fields and relativistic particles.     

基于TRIZ理论延长喷煤弯头使用寿命的探究与实践

针对某公司高炉喷煤弯头使用寿命较短的现状,基于TRIZ理论,借助Pro/I Desktop V5和Pro-Evolver V5软件进行了系统分析、功能分析、资源分析、三轴分析、进化定位分析、问题求解等,获得了延长高炉喷煤弯头使用寿命的九种技术方案,并通过方案评估和方案选择,筛选出组合弯头,其具有使用寿命长、选材方便、结构简单、便于加工、成本低廉、更换便捷且不影响高炉正常喷煤的特点。     

Detection of a radio counterpart to the 27 December 2004 giant flare from SGR 1806-20

It was established over a decade ago that the remarkable high-energy transients known as soft gamma-ray repeaters (SGRs) are located in our Galaxy and originate from neutron stars with intense (< or = 10(15)G) magnetic fields-so-called 'magnetars'. On 27 December 2004, a giant flare with a fluence exceeding 0.3 erg cm(-2) was detected from SGR 1806-20. Here we report the detection of a fading radio counterpart to this event. We began a monitoring programme from 0.2 to 250 GHz and obtained a high-resolution 21-cm radio spectrum that traces the intervening interstellar neutral hydrogen clouds. Analysis of the spectrum yields the first direct distance measurement of SGR 1806-20: the source is located at a distance greater than 6.4 kpc and we argue that it is nearer than 9.8 kpc. If correct, our distance estimate lowers the total energy of the explosion and relaxes the demands on theoretical models. The energetics and the rapid decay of the radio source are not compatible with the afterglow model that is usually invoked for gamma-ray bursts. Instead, we suggest that the rapidly decaying radio emission arises from the debris ejected during the explosion.