宁夏青铜峡灌区年退水量时间序列预测模型研究

针对宁夏青铜峡灌区年退水量预测问题,采用时间序列方法分析了灌区年退水量特性,建立了预测模型,结果发现青铜峡灌区年退水量在年际间相互关联,其时间序列是一个非白噪声非平稳时间序列,一阶差分序列是一个非白噪声平稳序列,建立了ARIMA年退水量时间序列模型,模型模拟的平均相对误差为5.66%,预测的相对误差在5%以内,精度较高,可以用于灌区退水量的预测。     

Metabolic detoxication and synergistic ratio of lindane analogs in house flies

Biodegradability of lindane analogs using house fly whole body, microsomes, and microsome supernatant fraction was examined. It decreased in the order of alkoxy ～ methylthio > methyl analogs > lindane in the whole body experiments, as well as with microsomes in the presence of NADPH. With the supernatant in the presence of glutathione, a different trend was observed. The synergistic effects of piperonyl butoxide when used together with lindane analogs were mostly explained in terms of the inhibition of the microsomal metabolism. Piperonyl butoxide was also shown to inhibit the penetration of compounds into the fly body and to make the central nervous system of the American cockroach less sensitive to the action of insecticides causing after and repetitive discharges. It was observed that the value of the percentage of metabolic disappearance of insecticides after a certain period decreases as the dose level initially applied in the whole body experiments increases. The synergistic ratio parallels the percentage of disappearance value after the insecticidal activity test period when a dose corresponding to the unsynergized LD₅₀ is initially applied. When quantitative comparisons are required for biodegradability of insecticides using house flies as the test insects, it should be on the basis of direct metabolism experiments using a fixed dose throughout the series of insecticides, but not on the basis of the synergistic ratio.     

Use of linear free energy related and other parameters in the study of fungicidal selectivity

The modulation of fungicidal activity in a congeneric series of compounds is dependent on several processes taking place in the biological object which may be influenced by the different hydrophobic, electronic and steric properties of the members of the series. These possible influences can be studied in a quantitative way with multiple regression analysis using substituent constants for the properties mentioned. The comparative study of the resulting regression equations for the activity on different fungi or on a fungus and another biological subject may contribute to an understanding of fungicidal selectivity. This is illustrated in studies on the fungitoxicity of isophthalonitriles, 2-chlorobenzonitriles, arylsulphonyl- and arylsulphinyl-alkylthio-cyanates, acetylenic sulphones, methyl benzimidazol-2-ylcarbamates and phosphorus compounds derived from 3-amino-1,2,4-triazole. In these studies new steric parameters were used, which have been introduced recently.     

近10年黄河三角洲地区粮食产量及灰色预测

通过收集粮食产量的历史数据,分析了黄河三角洲地区近10年来粮食产量的变化趋势、19个县(市、区)的粮食贡献以及其空间分布格局。基于灰色理论和Matlab软件编程建立了现代黄河三角洲地区的粮食产量定量预测模型,并进行不确定性分析。结果表明,黄河三角洲地区未来几年内粮食产量呈上升趋势,GM(1,1)模型模拟预测值序列与实际值序列残差的关联度R、均方差比值C及小误差概率均判定该模型的精度为一级,误差较小,预测结果可靠。本研究所得结果可为粮农管理部门做相关决策提供依据。     

基于量化反应性指数的氨基甲酸酯类农药定量构效关系研究

氨基甲酸酯类农药被广泛用于农业生产中,其作用机理主要是通过与乙酰胆碱酯酶共价结合,从而抑制其正常的生物活性,但此类农药的无节制使用导致其大量残留于生态环境中,对整个生态系统的生存安全造成了严重威胁.本文作者基于量化反应性指数,采用遗传/偏最小二乘法,对氨基甲酸酯与其对乙酰胆碱酯酶的抑制活性进行了定量构效关系研究.结果表...     

7‐(4,6‐Dimethoxypyrimidinyl)oxy‐ and ‐thiophthalides as novel herbicides: Part 1. CGA 279 233: a new grass‐killer for rice

A series of novel types of 7‐(4,6‐dimethoxypyrimidin‐2‐yl)oxy ‐ and ‐thio‐3‐methyl‐1 (3H)‐isobenzofuranones were discovered at Dr R Maag AG. From the thio‐isobenzofuranyl series, CGA 279 233—BSI‐proposed common name pyriftalid—was chosen for further development as a grass herbicide for use in rice. General synthetic approaches to these new phthalic acid‐derived compounds are given, with emphasis on the synthesis of pyriftalid and its physico‐chemical behaviour. © 2001 Society of Chemical Industry     

The use of artificial intelligence systems for predicting toxicity

This review concentrates on the use of artificial intelligence (AI) systems for the prediction of toxic hazard via the establishment of structure-activity correlations. Methods for the analysis of the structure and physicochemical properties of molecules referred to include topological analysis, molecular orbital calculations, input of chemical structures, molecular modelling, cluster analysis and pattern recognition. Emphasis is placed on the importance of identifying substructural fragments of sufficient size and physicochemical specificity to act as toxicophores. Procedures for processing structural information include decision-tree and probabilistic systems, as well as algebraic and related statistical analyses for obtaining quantitative structure-activity relationships (QSARs). The principal differences between knowledge-based and automated rule-induction expert systems, and their utilisation for predicting the activity of chemicals, are discussed by reference to the use of several methods, including DEREK, HAZARDEXPERT, COMPACT, CASE and TOPKAT. It is concluded that these AI expert approaches have an important role to play in predictive toxicity screening as alternatives to animal experiments. Also, knowledge-based expert systems are being developed further for risk assessment.     

河西走廊东部高温天气成因分析及预报研究

利用河西走廊东部武威市5个气象站1971-2005年逐日极端最高气温≥35℃资料,使用数值预报产品,应用诊断预报和统计预报方法,分析了高温天气气候特征、形成原因及预报着眼点。结果表明:河西走廊东部高温天气主要发生在中部平原和北部荒漠地带;西太平洋副热带高压动力抬升、青藏高压热力加强是造成极端高温事件发生的直接原因。并系统分析了高温天气发生的主要环流形势,总结出武威市高温诊断预报指标和高温定量预报方程,开发出高温预报业务系统,投入业务使用,预报效果良好。     

气候预测对象与影响因子关系不稳定性及其统计集合预测模型的改进

通过对"滑动相关——逐步回归——集合分析"短期气候预测方法的研究及其业务应用进行了综述。从深入分析气候预测对象与影响因子关系不稳定性问题入手,提出物理统计与集合分析相结合的气候预测建模理念,设计了"滑动相关——逐步回归——集合分析"气候预测模型。在改进该预测方法的过程中,先后提出了"交叉建模"集合预测思路,建立了"持续异常"与"转折影响"不同因子信息拓展方案,构建了"原始序列"与"去线性趋势"不同建模方案,再对最优模型进行集成分析。近8 a该方法参与国家气候中心全国汛期预测、全国秋季初霜冻初日预测,试用效果良好。在新疆地方气候预测服务中广泛应用,包括降水、气温、积温、热量指数、界限温度初终日期、沙尘日数的预测等。该方法在极端气候事件指数、应用气候指数的预测领域具有应用潜力。     

基于加权马尔可夫模型的条件植被温度指数预测研究

条件植被温度指数(VTCI)是一种近实时的干旱监测指标。利用加权马尔可夫模型对陕西关中平原的条件植被温度指数(VTCI)时空变化序列进行了2步预测,并将预测结果与实际监测结果进行对比分析,结果表明,预测的干旱监测结果与实际的干旱监测结果空间分布特征基本一致,进一步的误差分析显示,2步预测的误差平均值分别为0.042和0.152。     

基于EMD的洮河年径流量变化多时间尺度分析

在分析小波变换不足之处的基础上,提出了水文时间序列多分辨率分析的EMD方法,并将其应用于洮河天然年径流量时序波动特征的多时间尺度研究。结果表明其年径流量变化存在准2~6年、准8~10年、准26年的波动周期,并分析了各分量的趋势变化。EMD方法作为一种全新的非线性、非平稳信号处理理论,可以更精确地提取水文时序中不同波动周期的分量,在水文水资源系统变量的分析及预测中具有广阔的应用前景。     

渭河流域气象及水文旱涝演变规律分析

降水是径流的基本来源,分析极端旱涝条件下降水与径流之间演变规律的异步性,可有效表征径流丰枯变化对人类活动的响应。基于渭河流域降水、径流资料,采用泰森多边形法计算渭河流域面降水量及12个月标准化降水指数(SPI12),对比典型频率下SPI12的空间分布特征及其对径流系数的影响;采用经验正交函数和时间序列分析法挖掘SPI12和年径流量的演变规律,对比演变规律的同步及异步变化特征。结果表明:在25%、50%、75%频率下,流域面降水量分别为582.5 mm、518.6 mm、467.5 mm。SPI12第一主成分减少趋势显著,自1991年7月开始突变,于1962-09(1962年9月,下同)—1969-07—1983-02—1985-08—1991-07—1999-12呈现湿润~正常~湿润~正常~干旱状态。渭河年径流量呈显著减少趋势,自1989年开始突变,且分别于1950—1968和1982—1993年经历湿润和正常阶段,于1970—1974、1976—1980、1994—2007年经历干旱阶段。以流域内大规模水利、水土保持措施及城市化等为代表的人类活动使流域年径流量较SPI12第一主成分突变年份提前,使二者于1970—1996年间旱涝类型不匹配,年径流量相对SPI12第一主成分呈现旱化趋势。     

Monte-carlo与NNBR模型结合在年降水量预测中的应用

以内蒙古五原气象站近40 a的降水资料为例,从降水发生的随机性、统计规律性和统计相似性入手,将蒙特卡罗方法(Monte-carlo)和最近邻抽样回归模型(NNBR)结合,对降水量进行预报。Monte-carlo方法的预报结果虽能很好地体现研究区降水发生的随机性和统计的规律性,但却不能准确反映出降水序列之间的排列顺序,使预报序列具有多解性。利用NNBR模型对Monte-carlo的预报序列依据最相似理论重新排列,确定预报序列中各个成员之间的排列次序,从而实现预报序列不仅能体现出研究区内降水序列的统计规律性和相似性,同时也能反映出单一个体出现的随机性。通过检验证明模型具有合理性和较好的适用性。     

番茄褪绿病毒SYBR Green I实时荧光定量PCR方法

 根据番茄褪绿病毒(Tomato chlorosis virus, ToCV)热激蛋白70(Hsp70)的基因序列,设计ToCV实时荧光定量PCR特异引物。利用重组质粒ToCV-1为标准品建立SYBR Green I实时荧光定量方法。针对引物浓度、退火温度、特异性、灵敏度、重复性和稳定性进行系列优化。结果表明,最适退火温度为63℃,最适引物浓度为0.3 μmol·L^-1。熔解曲线为特异性单峰,表明其特异性良好。建立的SYBR Green I实时荧光定量PCR较常规PCR灵敏100倍,且具有良好的重复性和稳定性。基于SYBR Green I实时荧光定量PCR技术建立的ToCV检测方法,速度快、特异性强、灵敏度高、重复性好,可以用于ToCV的定量检测。     

基于PCR技术的植物病原菌分子定量检测技术研究进展

植物病原菌的菌源量是病害发生和流行的重要因子之一,对其精准的定量测定或检测可大大提高植物病害预测的准确性,本文对实时荧光定量PCR (qPCR)与数字PCR在植物病原菌定量检测、以及基于RNA水平的real-time PCR和基于核酸染料(EMA/PMA)与qPCR相结合的技术在植物病原菌活体定量检测中的应用进行了综述,并展望其在植物病害流行和预测中的应用前景。     

A specific and sensitive assay to quantify the herbicidal activity of chloroacetamides

Based on a recently discovered property of chloroacetamide herbicides—the inhibition of the incorporation of oleic acid into sporopollenin of Scenedesmus acutus—a rapid quantitative test was developed for chloroacetamide-type herbicidal activity. In this test, algal cells are incubated for 3 h with [¹⁴C]oleic acid, saponified and the lipids (including non-saponifiable ones) extracted and discarded. The radioactivity incorporated into the residual non-lipid fraction is determined, and inhibition of this incorporation is used as a marker of chloroacetamide-type activity. Twenty-two agrochemical compounds were screened in this assay, which was found to be very sensitive, a 50% inhibition being reached with submicromolar herbicide concentrations. It is specific to chloroacetamides and related amides, since all these herbicides tested were potent inhibitors, while other herbicides were not. Highest inhibition was shown by cafenstrole followed by butachlor, fluthiamid, metazachlor, alachlor, dimethenamid, metolachlor and mefenacet. For these herbicides (with the exception of butachlor) sensitivity in the test was positively correlated (r=0·984) with their phytotoxic effect on the alga. © 1998 SCI     

Is virulence phenotype evolution driven exclusively by Lr gene deployment in French Puccinia triticina populations?

Puccinia triticina is a highly damaging wheat pathogen. The efficacy of leaf rust control by genetic resistance is mitigated by the adaptive capacity of the pathogen, expressed as changes in its virulence combinations (pathotypes). An extensive P. triticina population survey has been carried out in France over the last 30 years, describing the evolutionary dynamics of this pathogen in response to cultivar deployment. We analysed the data set for the 2006–2016 period to determine the relationship between the Lr genes in the cultivars and virulence in the pathotypes. Rust populations were dominated by a small number of pathotypes, with variations in most of the virulence frequencies related to the corresponding Lr gene frequencies in the cultivated landscape. Furthermore, the emergence and spread of a new virulence matched the introduction and use of the corresponding Lr gene (Lr28), confirming that the deployment of qualitative resistance genes is an essential driver of evolution in P. triticina populations. However, principal component analysis (PCA) revealed that certain pathotype–cultivar associations cannot be explained solely by the distribution of Lr genes in the landscape. This conclusion is supported by the predominance of a few pathotypes on some cultivars, with the persistence of several other compatible pathotypes at low frequencies. Specific interactions are not, therefore, sufficient to explain the distribution of virulence in rust populations. The hypothesis that quantitative interactions between P. triticina populations and bread wheat cultivars—based on differences in aggressiveness—is also a driver of changes in pathotype frequencies deserves further investigation.     

Difenzoquat, 1,2-dimethyl-3,5-diphenylpyrazolium ion,a selective herbicide for the control of wild oats (Avena spp.) in wheat and barley

The results of a series of replicated trials and of a series of commercial grower trials conducted in the United Kingdom during 1972 and 1973, established the effectiveness of difenzoquat (1,2-dimethyl-3,5-diphenylpyrazolium ion) as the methyl sulphate as a selective post-emergence herbicide for the control of wild oats in wheat and barley. Doses of 0.75 to 1.0 kg cation/ha applied at 200 or 400 litre/ha and at 2.1 or 3.5 kg/cm² gave good to excellent results when applied at crop growth stages 3 to 5 (Feekes—Large scale) for spring crops and at crop growth stages 4 to 6 for winter crops. In these experiments wild oats over a range of stages from 1st leaf to tillering were well controlled.     

Terbufos biodegradability and efficacy against Radopholus similis in soils from banana cultivation having different histories of nematicide use,and the effect of terbufos on plant growth of in vitro-propagated Musa AAA cv. Grande Naine

The aims of this investigation were to: (1) determine whether there is enhanced biodegradability of terbufos in soils of banana plantations infested with Radopholus similis; (2) whether nematicide use history affects the degree of biodegradation; and (3) establish whether terbufos has phytotoxic side-effects on banana root growth. A greenhouse bioassay, using soils collected from different banana fields in Costa Rica, revealed that terbufos underwent enhanced biodegradation in the soil of a plantation having a long history of terbufos use. In the soils of two other plantations, where terbufos had never been used, and in another where the most recent terbufos application had occurred over a year before soil collection, high nematicide activity against R. similis was obtained even 60 days after application. Our study demonstrated that terbufos efficacy lasted longer in soils with no or low history of terbufos than in soils that had been treated several times. Terbufos did not reduce root fresh weight of in vitro-propagated bananas, and its positive effect was related to a control of R. similis.