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101.
棉田玉米螟的田间发生为害观察   总被引:1,自引:0,他引:1  
刘立春  邵晓泉 《昆虫知识》1994,31(5):277-279
灯下所诱玉米螟Ostriniafurnacalis(Güenée)雌蛾,二、三代分别为76.05%及59.91%,蛾峰后4~5天出现卵峰。主茎叶及棉株下部的卵量随产卵时间的推移,逐渐递减,而趋向棉株上部及外围。二代卵以下部2~3层为多,三代卵以2~4层果枝为多,内围多于外围;93%以上的卵产于绿叶反面;棉田卵寄生的高低与施药有关,且明显低于玉米田;二代5~10层蛀茎占总数的84.44%,三代4~8层蛀铃占59.79%。卵密度不同,蛀铃分布也不同。  相似文献   
102.
以藁城为例,采用淘土、扫网、挂黄板等方法对太行山前平原麦田昆虫群落进行了调查,结果表明该区域超高产麦田昆虫种类相对较少,总计22种,隶属于6目14科。害虫主要有2类,吸浆虫类和麦蚜类。小麦吸浆虫以麦红吸浆虫为主。天敌昆虫常见有蚜茧蜂、食蚜蝇、草蛉和瓢虫4类。采用氧乐果、毒死蜱、高效氯氰菊酯、吡虫啉4种常用药剂对麦红吸浆虫成虫进行了田间药效实验,结果表明上述4种药剂对麦红吸浆虫均有较好的防治效果,虫口减退率均在80%以上。其虫口减退率从高到低依次为:氧乐果、毒死蜱、高效氯氰菊酯、吡虫啉。建议根据麦红吸浆虫的发生情况,选择中低毒药剂毒死蜱、高效氯氰菊酯、吡虫啉交替使用。  相似文献   
103.
为充分了解不同产地南方红豆杉也Taxus wallichiana var. mairei ( Lemée et H. Lév.) L. K. Fu et Nan Li页各家系幼苗生长、光合生理及株高生长节律的差异,以产自江西分宜( FY)、浙江龙泉( LQ)、福建建瓯( JO)和福建明溪( MX)的20个家系的2年生容器苗为研究对象,对幼苗的株高和地径以及叶片的净光合速率和叶绿素含量进行比较,并对各家系的株高生长进行Logistic拟合回归分析以及拟合曲线参数和株高生长节律参数的计算和分析;在此基础上,分析了不同指标间的相关性并对供试的20个家系进行聚类分析。结果显示:不同产地间南方红豆杉的株高、地径、叶绿素含量和净光合速率均无显著差异,但这些指标在不同家系间均有极显著差异(P<0.01);各家系的株高、地径、净光合速率( Pn)以及叶绿素a( Chla)、叶绿素b( Chlb)和总叶绿素( Chl)含量的最大值较最小值分别高52.99%、29.63%、115.65%、39.81%、30.95%和37.24%。4个产地的株高生长均呈明显的“S型”曲线;各家系的最大生长速率( MGR)、线性生长速率( LGR)、线性生长总量( TLG)和线性生长持续时间( LGD)的最大值较最小值分别高60.00%、61.54%、63.73%和22.73%;从线性生长始期(t1)和线性生长终期(t2)来看,各家系的速生期为5月中旬或下旬至8月上旬。幼苗的株高与MGR、TLG、LGR、地径、Pn、Chlb和Chl等指标均极显著正相关,并与Chla显著正相关,而地径与MGR、TLG、LGR、Pn和Chlb等指标显著正相关,但株高和地径与LGD均无显著相关性。聚类分析结果表明:在欧氏距离10处,供试的20个家系被分成4个类型,其中,第Ⅳ类的6个家系的幼苗生长最佳且生长潜力最高。研究结果表明:不同产地南方红豆杉各家系的遗传变异丰富,且株高和地径生长主要受生长速率的影响;总体来看,家系LQ09、LQ11、FY21、FY26、MX12和MX18的幼苗生长潜力较高,可作为南方红豆杉的优良家系进行推广。  相似文献   
104.
105.
BackgroundPityriasis versicolor (PV) is an infection caused by various species of Malassezia yeast. There is no agreement in the literature concerning the species of Malassezia and the demographic, clinical, and mycological data.AimsTo prospectively identify Malassezia species isolated from lesions of patients with extensive, long standing and recurrent forms of PV and to estimate the relationship between Malassezia species and the demographic and clinical data of the patients.MethodsAll patients with PV were enrolled over a four-year period. Malassezia species were isolated in cultures and identified by morphological features and physiological tests. In the last 2 years a PCR-based technique was used to confirm the species’ identification.ResultsA total of 74 patients (43 males and 31 females, mean age 39.5 years) were enrolled. Only one species was isolated in 45 patients, and more than one species were identified in the remaining 28 patients (38%). M. globosa was the most frequently isolated (60.3%) species. There was a significant association between the isolation of 2 or more species and the presence of at least one predisposing factor. In the last 29 cases, which were subjected to PCR, there were no differences in the identification of isolated species as compared to traditional methods.ConclusionsThe isolation of more than one species in a single lesion is not infrequent in PV and is related to the presence of one predisposing factor. The isolated species isolated were not influenced by demographic and clinical features. The traditional and more recent (PCR) procedures gave the same results in the isolated species.  相似文献   
106.
The discovery of Chauvet cave, at Vallon-Pont-d’Arc (Ardèche), in 1994, was an important event for our knowledge of palaeolithic parietal art as a whole. Its painted and engraved figures, thanks to their number (425 graphic units), and their excellent state of preservation, provide a documentary thesaurus comparable to that of the greatest sites known, and far beyond what had already been found in the group of Rhône valley caves (Ardèche and Gard). But its study – when one places it in its natural regional, cultural and thematic framework – makes it impossible to see it as an isolated entity of astonishing precocity. This needs to be reconsidered, and the affinities that our research has brought to light are clearly incompatible with the very early age which has been attributed to it. And if one extends this examination to the whole of the Franco-Cantabrian domain, the conclusion is inescapable: although Chauvet cave displays some unique characteristics (like every decorated cave), it belongs to an evolved phase of parietal art that is far removed from the motifs of its origins (known from art on blocks and on shelter walls dated by stratigraphy to the Aurignacian, in France and Cantabrian Spain). The majority of its works are therefore to be placed, quite normally, within the framework of the well-defined artistic creations of the Gravettian and Solutrean. Moreover, this phase of the Middle Upper Palaeolithic (26,000–18,000) coincides with a particularly intensive and diversified local human occupation, unknown in earlier periods and far less dense afterwards in the Magdalenian. A detailed critique of the treatment of the samples subjected to AMS radiocarbon dating makes it impossible to retain the very early age (36,000 cal BP) attributed by some authors to the painted and engraved figures of Chauvet cave.  相似文献   
107.
Pure and Li+‐doped Alq3 complexes were synthesized by simple precipitation method at room temperature, maintaining the stoichiometric ratio. These complexes were characterized by X‐ray diffraction, ultraviolet‐visible absorption and Fourier transform infrared and photoluminescence (PL) spectra. X‐ray diffraction analysis reveals the crystalline nature of the synthesized complexes, while Fourier transform infrared spectroscopy confirm the molecular structure, the completion of quinoline ring formation and presence of quinoline structure in the metal complex. Ultraviolet‐visible and PL spectra revealed that Li+ activated Alq3 complexes exhibit the highest intensity in comparison to pure Alq3 phosphor. Thus, Li+ enhances PL emission intensity when doped into Alq3 phosphor. The excitation spectra lie in the range of 383–456 nm. All the synthesized complexes other than Liq give green emission, while Liq gives blue emission with enhanced intensity. Thus, he synthesized phosphors are the best suitable candidates for green‐ and blue‐emitting organic light emitting diode, PL liquid‐crystal display and solid‐state lighting applications. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
108.
Natural rubber membranes were fabricated using latex from Hevea brasiliensis trees (clone RRIM 600) by casting, and controlling the time and temperature of thermal treatment. Three temperatures were used: 65, 80 and 120 °C and the corresponding annealing times of 6, 8, 10 and 12 h. The centrifugation of the latex produces the constituent phases: solid rubber (F1), serum or protein components (F2) and bottom fraction (F3). The photoluminescence properties could be correlated with organic acid components of latex. Natural rubber membranes were used as the active substrate (reducing agent) for the incorporation of colloidal Au nanoparticles synthesized by in situ reduction at different times. The intensity of photoluminescence bands assigned to the natural rubber decreases with the increase in amount of nanoparticles present on the membrane surface. It can be assumed that Au nanoparticles may be formed by reduction of the Au cation reacting with functional groups that are directly related to photoluminescence properties. However, the quenching of fluorescence may be attributed to the formation of a large amount of metal nanostructures on the natural rubber surface. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
109.
中国旧石器材料数量众多,表现出一定的地域特色,在世界旧石器考古学领域占有重要地位.研究表明,类型学在解读与提取石器所包含的人类技术行为信息方面的能力有较大的局限性,而且中国旧石器时代的一些石制品的形态和组合与欧洲和近东常常难以直接对比,对器物的分类定名也存在交流上的困难.由法国学者开创发展起来的史前石器技术研究理论和方法在分析形态特征的同时,通过关注支配石器工业生产体系的技术机制和逻辑规则,对深入细致地探讨史前人类的认知特征和技术行为可以发挥重要作用,也能为石器工业甚至跨地域文化之间的比较提供基础.本文对贵州观音洞遗址的石核标本为例进行了技术分析,说明其在研究中国旧石器材料上的可行性,特别是信息提取上的优势.  相似文献   
110.
Reducing sugars for example glucose, fructose, etc., and their phosphate derivatives non-enzymatically glycate biological macromolecules (e.g., proteins, DNA and lipids) and is related to the production of free radicals. Here we present a novel study, using differential scanning calorimetry (DSC) along with UV/Vis absorption and photon correlation spectroscopy (PCS), on normal and glycated human placenta DNA and have explored the antioxidant property of the naturally occurring polyhydroxy flavone quercetin (3,3',4',5,7-pentahydroxyflavone) in preventing the glycation. The decrease in the absorption intensity of DNA in presence of sugars clearly indicates the existence of sugar molecules between the two bases of a base pair in the duplex DNA molecule. Variations were perceptible in the PCS relaxation profiles of normal and glycated DNA. The melting temperature of placenta DNA was decreased when glycated suggesting a decrease in the structural stability of the double-stranded glycated DNA. Our DSC and PCS data showed, for the first time, that the dramatic changes in the structural properties of glycated DNA can be prevented to a significant extent by adding quercetin. This study provides valuable insights regarding the structure, function, and dynamics of normal and glycated DNA molecules, underlying the manifestation of free radical mediated diseases, and their prevention using therapeutically active naturally occurring flavonoid quercetin.  相似文献   
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