海上大风延伸期预报研究进展

海上大风是海洋产业的重大灾害性天气,而延伸期预报是世界性难题。目前,延伸期预报主要分成动力延伸、低频振荡、经验波传播、数理统计、气候扰动分解和集合预报等6种方法,以动力延伸中的数值模式和低频振荡中的MJO监测诊断最为流行。随着大数据时代的到来,基于大数据分析,以数值预报产品为基础的集合预报成为未来业务发展的重点方向。这6种方法都可以用于海上大风等重大灾害性天气预报,许多学者尝试较多的是气候扰动分解、低频振荡中的低频天气图等方法中的溯源技术,通过找到源头,实现重大灾害性天气的延伸期预报。     

Composite structure of sterilization and descaling system for circulating cooling water

In order to resolve the hazard of biofouling and scale in circulating cooling water system of power stations, this paper takes the lead in combining high voltage pulses and high frequency pulses for sterilization and descaling process. It analyzes both electromagnetic effects and biochemical effects on sterilizing and descaling process caused by the high voltage pulses and high frequency pulses respectively. The pulse generator is designed according to the requirements of electromagnetic parameters for effective operation. The design and improvement of process chambers are assisted by electromagnetic field simulation technology. Experimental data prove that the system can output high voltage pulse whose maximum peak value reaches 7 kV and high frequency pulse whose maximum peak value reaches 100 V the frequency ranges from 500 kHz to 2 MHz. The rate of sterilization can be as high as 91,and the rate of descaling reaches 71. This system is expected to achieve the standards of industrial water treatment through further research.     

不同条件下有机物料在黑土中分解规律的研究

通过在土壤中埋置砂滤管的方法明确不同积温、水分、pH以及物料与黑土不同配比条件下有机物料的分解情况。结果表明：小麦和草木樨秸秆在低温下也易于分解,但不利于土壤有机质的积累,而玉米和大豆残体,在高温条件下易于分解,低温有利于土壤有机物的积累;在灌溉的条件下,小麦和草木樨秸秆易于分解;而玉米和大豆残体,在灌溉条件下易于碳的积累;不同量有机物料与土壤混合发现,加入秸秆量越少,分解越少;土壤pH在作物残体还田的第一年影响其分解速度,加速积累不易于分解,以后影响不明显。     

甘薯遗传转化研究现状、问题及展望

甘薯是世界上重要的粮食、饲料和工业原料作物，由于遗传改良进展缓慢，转基因技术逐渐成为研究的热点，并应用于常规育种中去。到目前为止，甘薯已利用叶片、叶柄、茎、原生质体、愈伤组织、新鲜块根、胚性愈伤组织和胚性悬浮细胞系作为遗传转化受体材料，其中早期以叶片、叶柄为主，目前利用胚性愈伤组织和胚性悬浮细胞系作为转化受体的研究越来越多。用于甘薯遗传转化的方法有农杆菌介导法、电击法和基因枪法，其中以根癌农杆菌介导法为主。最初甘薯遗传转化外源基因表达频率很低，随着转化条件研究的深入，转化频率得到较大的提高，越来越多的目的基因被应用到甘薯遗传转化中去。到目前已有抗虫、抗病毒、抗病、抗除草剂和品质改良等五大类基因转入甘薯基因组中，并且获得了转基因植株。尽管甘薯遗传转化取得了一定的进展，但目前仍缺乏一个有效的遗传转化体系，获得的转基因植株数量有限，还不能应用于生产。存在转化基因型有限、外源基因匮乏、转化方法单一、标记基因存留的问题，以及还不清楚外源基因在转基因植株中的遗传规律等。因此，本文从甘薯遗传转化受体系统、主要转化方法、转化系统以及有益农艺性状基因的应用等对甘薯遗传转化现状进行了综述，分析了目前存在的问题，以及未来甘薯遗传转化研究方向和发展前景。     

Study on Vibration Performance of Engineered Wood Truss Joist Floors

In recent years wood trusses are widely used in buildings due to their excellent performance and ease of construction. As with solid lumber joists, however, the vibration of wood truss joist floors can cause occupants to feel discomfort. To understand the relationship between the vibration performance of wood truss joist floors and the perceptions of occupants, experimental and subjective evaluations were conducted on six truss joist floors. The results show there is close relationship between perceptions of occupants and the fundamental natural frequency, static deflection and vibration acceleration of truss joist floors. The installation of bracings and straps greatly improved the vibration performance of light truss joist floors. We suggest that two or more factors should be included in the design criteria for controlling wood floor vibration, such as static deflection and fundamental natural frequency. Peak acceleration can be adopted as a factor in the evaluation system of vibration performance of wood truss joist floors.     

Dynamic signatures method for analysis of vehicle bridge resonance

The dynamic behavior of railway bridges (dynamic deflection and acceleration) is one of the running safety control indices for high speed trains. Therefore, the dynamic behavior of railway bridges is studied based on the concept of the dynamic signatures of the train and the bridge. By simplifying the train excitation as a series of moving concentrated forces, the mathematical expressions of the dynamic signatures of the train are obtained through theoretical derivations, and then a method is presented for calculating the resonance speed of trains and the maximum vertical acceleration of the bridge. With this method, the dynamic responses of the simple supported bridge can be calculated quickly. The feasibility of this method is validated through some examples, in which the resonance mechanism of train bridge system and the influencing factors are investigated. In addition, the effect of high frequency components to the bridge acceleration is also analyzed.     

农杆菌介导陆地棉转化和再生体系的研究进展

陆地棉通过体细胞胚胎发生的农杆菌介导转化体系的主要瓶颈在于:基因型限制、转化周期长、胚胎发生率低、易出现畸形胚等问题.针对这些问题,研究者对传统转化体系的各个环节进行了优化,并在拓展受体基因型、筛选高频再生品(种)系或株系、选择不同的组织或器官做受体和建立新的不依赖于组织培养和基因型限制的农杆菌转化体系等方面进行了探索...     

玉米3种非组培转基因方法转化外源bar基因研究

本试验用3种非组培型转基因方法，即花粉介导、子房注射、萌动种胚法在玉米上转化bar基因，经大田筛选及PCR和PCR-Southern检测，证明均可获得转化植株。还分析了3种方法的转化机理，并通过转化率与操作简便程度的比较，认为花粉介导优于萌动种胚法，二者又优于子房注射法。     

水平与竖向加速度-时程曲线叠加效应下边坡永久位移计算的极限上限分析

实际边坡动力稳定性受地震竖向与水平方向效应共同作用,传统边坡地震永久位移计算方法较少考虑竖向地震波影响,采用实际地震的竖向与水平方向加速度-时程曲线共同效应更符合工程实际。基于极限分析上限法和Newmark刚塑性滑块模型,提出一种基于实际水平向与竖向地震加速度-时程曲线的边坡永久位移计算改进方法,以3个工程边坡为例,探讨了两组具有代表性实测典型水平和竖向地震地面运动记录对边坡地震永久位移计算的影响。研究结果表明:不考虑竖向地震加速度时程曲线时,本文方法可蜕化为与前人方法兼容;不同地震波的竖向与水平地震动时程曲线的叠加效应不同,竖向地震对边坡永久位移的影响不可忽略。     

Wavelet denoising method of temperature signal in the process of coal gas absorption and desorption

The study on the temperature evolutionary trend under both the ground stress and gas pressure is significant in the process of coal gas absorption and desorption. However, the valid signal is difficult to gain because of much noise in the experimental data, so according to the characteristics of the temperature signal gained under different experimental conditions of coal gas absorption and desorption, this essay filtrates noise and restores the valid signal by using the wavelet denoising of MATLAB to obtain the valid temperature evolutionary curve. Through contrasting and analyzing wavelet basis function and different decomposition levels, the essay chooses the sym8 wavelet basis function which has a higher order of vanishing moments and better smoothness. The reconstructed signal filtrates most of high frequency signal, and keep low frequency, as well as smooth signal. The result shows that the de-noising effect is good and the temperature evolution rule can be well reflected in the process of the coal gas absorption and desorption.     

花粉管通道转基因技术及在小麦分子育种中的应用

文章首先简要回顾了花粉管通道法转基因技术的发展历程,并从花粉管通道法转化的发育及分子证据的提出出发,详细介绍了转化的作用机理和操作技术,提出花粉管通道法转基因技术是一种十分有效的转基因技术,并以变异频率高,性状变异广泛,类型丰富,稳定快,一次导入片段多及低成本等优点而受到科研工作者的亲睐;其次,就花粉管通道转基因技术在小麦分子育种中的应用进行了综述,指出花粉管通道转基因技术在小麦品质创新及分子育种中具有特殊的意义,主要体现在品质改良育种和抗性育种方面,并且取得了可喜的成就,选育出了一系列新品系,如春小麦89122,丰富了品质资源;最后,就花粉管通道法转基因技术存在的问题和应用前景进行了探讨和展望。     

Key weather extremes affecting potato production in The Netherlands

The possible impact of climate change on frequency and severity of weather extremes is hotly debated among climate scientists. Weather extremes can have a significant impact on agricultural production, but their effect is often unclear; this due to interaction with other factors that affect yield and due to lack of precise definitions of relevant weather extremes. We show that an empirical analysis of historical yields can help to identifying such rare, high impact climate events. A reconstructed time series of ware potato production in Flevoland (The Netherlands) over the last 60 years (1951-2010) enabled us to identify the two main yield affecting weather extremes. In around 10% of the years yield anomalies were larger than −20%. We found that these anomalies could be explained from two weather extremes (and no other), namely a wet start of the growing season and wet end of the growing season. We derived quantitative, meteorological definitions of these extremes. Climate change scenarios for 2050 show either no change or increased frequency of the two extremes. We demonstrate there is large uncertainty about past and future frequencies of the extremes, caused by a lack of sufficiently long historical weather records and uncertainties in climate change projections on precipitation. The approach to identify weather extremes presented here is generally applicable and shows the importance of long term crop and weather observations for investigating key climatic risks to production.     

Genetic Variability for Net Photosynthesis in Finger Millet (Eleusine coracana Gaertn) Genotypes An Approach to Identify High CER Types

Germplasm lines of finger millet (400 lines) with diverse genetic background were screened to identify high CER and CGR genotypes. Considerable variation was noticed in LA, biomass and all the growth and yield attributes but range in stomatal frequency was relatively less. The difference in plant stomatal number was more due to variation in LA but not the frequency. Since high TDM is a primary criteria for achieving higher grain yield, from amongst the high biomass types, genotypes differing in LA/DM ratios but with similar DM and HI were selected. In six genotypes each from low and high LA/DM group which showed stability across the environment, gas exchange characteristics were studied. The CER in low LA/DM types was 45 per cent higher. A significant negative relationship (r = -0.87) exists between CER and LA/DM ratios. Higher net assimilation rate in these genotypes therefore could be attributed mainly due to CER rather than the dark respiration.
An approach to identify high CER types with high CGR and low plant conductances from the germplasm lines has been proposed. These conceptual types will have high CGR but with low functional LA, thus low transpiration leaf surface. These conceptual types will have specific advantage under rainfed water limited conditions.     

蛋白质型油脂模拟物的研究进展机理及在食品中的应用

高脂食品引起的肥胖、高血脂等许多疾病,严重影响着消费者的健康,因此,国内外许多研究者的注意力开始转移到开发低脂食品上。介绍了以蛋白为基质的油脂模拟物的研究进展、机理及在食品工业中的应用。     

移动Ad Hoc网络AODV路由协议的研究与优化

无线移动自组网是仅由移动节点所组成的网络,具有分布式控制、自组织、多跳等特点,由于该网络具有抗毁性能高、易铺设等性质,越来越受到业界的广泛关注。原始的路由协议已经满足不了现有网络不可预测、频繁变化的拓扑结构的需要,因此,在之前研究的基础上,对现有Ad Hoc网络AODV路由协议进行了研究,并设计出一种基于AODV协议的改进路由协议——基于认知的AODV协议(Cognitive-based AODV,CAODV)。通过NS2进行试验仿真,结果表明,CAODV协议具有比AODV协议更加优良的性质,可以有效降低重启路由发现频率,增加断裂链路的修复成功率,降低协议的控制负载,对现有网络的动态变化具有很强的适应能力。     

中国绿地空气微生物研究现状与展望

空气中广泛分布着细菌、真菌孢子、放线菌和病毒等生物粒子,而绿地具有杀菌、降尘、清洁空气等功效,对改善环境,提高人们生活品质具有重要意义。许多研究者开始关注绿地的抑菌功能,对绿地空气微生物的类型、浓度、粒径范围以及影响绿地空气微生物群落变化的因素进行了较系统的研究。笔者总结了中国绿地空气微生物的主要种类、检测内容以及变化动态,并简要探讨绿地空气微生物的发展前景,认为应进一步开展绿地空气微生物的毒理学研究以及植物协同抑菌功能是今后的研究方向。     

Application of Global Position System in Measuring Signal Frequency and the Stability of Signal Frequency

Crystals with high stability are generally adopted as benchmark in the measurement of signal's actual frequency and stability, but the requirement of high precision can not be met. Some researchers found out improved methods, but it resulted in high costs. We introduce a new method, in which we use the second pulse creating from Global Position System as benchmark and design corresponding circuits in High Density Programmable Logic Devices(HDPLD), after that, we observe the resulting signals on oscilloscope. The pulse from Global Position System is easy to get and the whole system is very cheap. As the Global Position System is based on atomic clock which is accurate and stable, the measuring precision is improved greatly.     

枇杷ISSR分子标记的研究进展

枇杷传统标记方法具信息量少、取材部位有限、无法进行早期鉴定、人为因素影响鉴定结果等局限。ISSR技术以其丰富的多态性、较低的实验成本、相对简单的操作、较高的稳定性以及呈共显性等优点,日益受到研究者的青睐。笔者总结了ISSR技术的原理及优缺点,归纳了ISSR技术在枇杷种质鉴定、遗传变异分析,枇杷分类研究,枇杷指纹图谱构建等方面的进展。发现ISSR技术目前在枇杷上的应用较少,研究深度不够。笔者认为今后可通过提高ISSR技术的准确性,延伸ISSR在枇杷上的研究深度和广度,加强ISSR的联合应用,促进研究团队间的合作交流等方面,使ISSR成为枇杷育种研究中不可或缺的分子标记技术。     

Occurrence of 2n and jumbo pollen in the Brazilian ginseng (Pfaffia glomerata and P. tuberosa)

An analysis of microsporogenesis was carried out in four populations of Pfaffia tuberosa (2n=4x=68) and in ten populations of P. glomerata(2n=2x=34). Monads, dyads and triads were reported at high frequency in all populations of P. tuberosa. In P. glomerata, on the other hand, only four populations presented monads, and at low frequency. Dyads and triads were observed in both species, albeit at a higher frequency in P. tuberosa populations. Certain abnormalities of spindles in the second division, such as sequential and tripolar spindles, led to triad formation by the rejoining of two chromosome sets. The precise causes of monad and dyad formation have not been found during meiosis, although evidence exists that dyads originated by omission of second meiosis and monads by omission of both meiotic divisions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Shear resistant performance of RC columns subjected to vertical near-fault velocity pulse-like earthquake actions

The aim is to evaluate the seismic properties of ancient timber structure after strengthening and analyze the failure process and corresponding failure state. Based on the hysteretic behavior and energy dissipation principle of the dovetail column-frame strengthened with CFRP and Arches Brackets under the low reversed cyclic loading, the “potential of destruction-resisting” of the two energy-consuming components is obtained. The dissipated energy of each energy-consuming component under the various earthquake conditions is calculated combining with the shaking table test of ancient timber structure. The model of seismic damage evaluation of the two energy-consuming components is established on the basis of the “potential of destruction-resisting” and the dissipated energy. By means of the energy distribution coefficient, the relationship of the failure state between energy-consuming components and overall strengthened structure is discovered, and the model of seismic damage evaluation of the overall structure under the various earthquake conditions is presented. With the derived model of seismic damage evaluation, the failure coefficient of the energy-consuming components and the overall strengthened structure is quantitatively calculated. According to the failure state, the corresponding damage grade of overall strengthened structure is obtained. The results can provide a reliable theoretical basis for predicting the destruction before earthquake and re-reinforcement to the strengthened ancient timber structures after earthquake.