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1.
采用幼苗浸渍法,测定3种不同浓度的12种化合物对黄瓜镰刀菌培养滤液活性的抑制作用。研究结果表明:不同化合物、不同质量浓度的抑制效果不相同。10μg/mL的烟酸、NaOH、FeCl3和ZnSO4的效果最好,相对抑制效果在95%以上,抑制作用表现稳定、持久;50μg/mL的维生素B1、CuSO4、KAl(SO4)2和100μg/mL的MnSO4相对抑制效果在90%以上;50μg/mL的KMnO4、KOH相对抑制效果在85%以上;维生素B6、蛋氨酸效果较差,相对抑制效果低于70%。该研究为进一步筛选镰刀菌酸毒素的抑制物质,探索黄瓜枯萎病防治新途径提供了参考。 相似文献
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Context
Predicting and managing edge effects requires an understanding of the mechanisms that drive them. However, analytical methods that dominate edge effects research are not well suited to discriminating mechanisms, because they do not measure ‘indirect’ edge effects: effects that are mediated by covariates in statistical models.Objective
To discuss the value of indirect effects for improving mechanistic understanding of edge effects.Methods
We explain how measuring indirect effects improves mechanistic understanding, and provide guidance on how to do so. We also conduct a literature review to examine awareness of indirect effects in empirical studies of mechanisms underpinning edge effects. Finally, we use a recent paper in Villaseñor et al. (Landscape Ecol 30:229–245, 2015) as a case study to discuss how failure to measure indirect edge effects may limit mechanistic understanding.Results
Indirect effects provide a means to translate conceptual models of edge effects into mechanistic pathways that are testable and quantifiable. Moreover, failure to measure indirect edge effects can result in impacts of habitat edges being underestimated. However, few studies that we identified in our literature review quantified indirect effects (7 %, n = 72). Worryingly, 11 % of studies did not account for indirect effects despite using statistical models that potentially contained them, possibly resulting in incorrect inference.Conclusions
A better awareness of indirect effects will help researchers to understand the mechanisms that underpin edge effects, while ensuring that impacts of habitat edges are not underestimated.3.
This paper reviews current parameterizations developed and implemented within Computational Fluid Dynamics models for the study of the effects linking vegetation, mainly trees, to urban air quality and thermal conditions. In the literature, passive mitigation via deposition is parametrized as a volumetric sink term in the transport equation of pollutants, while a volumetric source term is used for particle resuspension. The aerodynamics effects are modelled via source and sink terms of momentum, turbulent kinetic energy and turbulent dissipation rate. A volumetric cooling power is finally considered to account for the thermal (transpirational cooling) effects of vegetation. The most recent applications are also summarized with a focus on the relative importance of both aerodynamic and deposition effects, together with recent studies evaluating thermal effects. Those studies have shown that the aerodynamic effects of trees are stronger than the positive effects of deposition, however locally the pollutant concentration increases or decreases depending on the complex inter-relation between local factors such as vegetation type and density, meteorological conditions, street geometry, pollutant characteristics and emission rates. Unlike aerodynamic and deposition effects on pollutant dispersion which were also found in street far from trees, the thermal effects were in general locally restricted to the close vicinity of the vegetation and to the street canyon itself. Future requirements in CFD modelling include more in depth investigation of resuspension and thermal effects, as well as of the VOCs emissions and chemical reactions. The overall objective of this review is to provide the scientific community with a comprehensive summary on the current parameterizations of urban vegetation in CFD modelling and constitutes the starting point for the development of new parametrizations in CFD as well as in mesoscale models. 相似文献
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不同杀虫(螨)剂对蔬菜叶螨的田间防效评价 总被引：1，自引：0，他引：1
蔬菜田小区试验比较了11种杀虫(螨)剂对蔬菜叶螨的防治效果。结果表明,3种专一性杀螨剂哒螨灵、克螨特、噻螨酮及6种广谱性杀虫杀螨剂阿维菌素、虫螨腈、高效氟氯氰菊酯、甲维盐、氧苦.内脂和螺螨酯对叶螨均有良好的防治效果,彼此之间差异不显著。其中低毒药剂克螨特、噻螨酮、阿维菌素和甲维盐的防治效果最佳,药后3、7、10d的防效分别达到79.96%、88.50%和99.01%(克螨特),82.64%、88.79%和97.77%(噻螨酮),73.24%、91.16%和97.73%(阿维菌素),74.12%、87.46%和98.62%(甲维盐),适合用于蔬菜叶螨的防治。高效氟氯氰菊酯属中等毒性,而螺螨酯防治效果稍低,使用时间和剂量应有所限制。而氯虫苯甲酰胺和多杀菌素对叶螨没有防治效果。 相似文献
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HUANG Xiang-hua ZHANG Xiang-hong YAN Xia YIN Gui-ran LI Yue-hong TAN Yan-wei WANG Jun-ling WANG Feng-rong 《园艺学报》2002,18(2):169-171
AIM:To explore the putative effects of sterigmatocystin (ST) on human help T lymphocyte(Th1)function. METHODS:The effects of ST on interferon-γ(IFN-γ)secretion of human peripheral blood mononuclear cells(HPBMc) in vitro were determined with ELISA method. RESULTS:The effects of ST on IFN-γ secretion of HPBMc in vitro were closely dependent on ST concentrations. ST at relatively lower concentrations (0.03125-0.12500 mg/L) showed inhibiting effects on IFN-γ secretion. While, stimulating effects could be found when ST concentration was above 0.25mg/L. The highest level was seen in ST 1 mg/L group (P＜0.05)。At concentration ranging from 0.25 mg/L to 1 mg/L, a positive dose- effects correlation was found between ST concentration and IFN-γ secretion (r=0.492, P＜0.01). Time-effects analysis from 1 h to 64 h after ST treatment (1 mg/L)showed that the effects of ST on IFN-γ secretion varied as the changes of treatment times. An inhibiting effect on IFN-γ secretion of HPBMc 4 h and 8 h after ST treatment was found (8 h, P＜0.05). As the treatment time prolonged from 16 h, IFN-γ level gradually increased (32 h, P<0.05). There was a positive correlation between treatment time of ST and IFN-γ level of HPBMc in vitro from 16 h to 64 h after ST treatment (r=0.736, P＜0.01).CONCLUSION:The effects of ST on IFN-γ secretion of HPBMc in vitro closely depended on concentration and treatment time of ST. Generally, inhibiting effects were found at relatively lower ST concentration and shorter treatment period, while stimulation effects could be seen at relatively higher ST concentration and longer ST treatment time period. 相似文献
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辣椒胞质雄性不育恢复性的主基因 + 多基因混合遗传分析 总被引：1，自引：0，他引：1
以辣椒胞质雄性不育系8A 及其恢复系F19 为原始材料,利用主基因 + 多基因联合分析方
法对辣椒胞质雄性不育恢复性进行遗传分析。结果表明,辣椒胞质雄性不育恢复性的遗传受两对加性—
显性上位性主基因 + 加性—显性多基因控制。第1 对主基因的加性效应与显性效应分别为0.9314 和
1.1549,均使恢复性增加。第2 对主基因的加性效应与显性效应分别为–0.5276 和–0.1930,均使恢复性
降低。多基因的加性效应与显性效应分别为–2.4038 和0.1036。主基因的遗传率高达97.57%,表现出很
高的遗传力,说明在早期世代就可对恢复性进行有效选择。 相似文献
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Previous research has suggested that ducks and songbirds may benefit from prairie landscapes that consist primarily of contiguous
grasslands. However, the relative importance of landscape-level vs. local characteristics on mechanisms underlying observed
patterns is unclear. We measured effects of grassland amount and fragmentation on upland and wetland songbird and duck density
and nest success, and on some nest predators, across 16 landscapes in southern Alberta, Canada. We compared these landscape-level
effects with local-scale responses, including distance to various edges and vegetation characteristics. We also evaluated
several statistical approaches to comparing effects of habitat characteristics at multiple spatial scales. Few species were
influenced by grassland amount or fragmentation. In contrast, distance to edge and local vegetation characteristics had significant
effects on densities and nest success of many species. Previous studies that reported effects of landscape characteristics
may have detected patterns driven by local mechanisms. As a corollary, results were very sensitive to statistical model structure;
landscape level effects were much less apparent when local characteristics were included in the models. 相似文献
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Harvesting and forest fire change the spatial configurations of forest habitat. We used multivariate statistical models to
evaluate the individual and cumulative effects of these two disturbances on habitat configuration in managed boreal forest
landscapes in western Canada. We evaluated three aspects of configuration (core area, inter-patch distance and shape) using
indices normalized for total habitat abundance. The two disturbances types had different effects on the three configuration
metrics in terms of both the magnitude and direction of change. We found that the magnitudes of harvesting effects were larger
than for fire. The direction of change was the same for core area and shape, but opposite for inter-patch distance which decreased
slightly after fire. The combined effects of the two disturbances are distinct from the effects of either disturbance alone,
and the effects are not always additive or compensatory for all metrics. Pre-treatment configuration was a significant covariate
in all models, and total habitat abundance was significant in 4/9 models, but these were often not the most important covariates.
In the cumulative disturbance model, covariates for the number or size of cut-blocks were significant. 相似文献
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AIM: To investigative the inhibitory effects of Paecilomyces cicadae polysaccharide (PcPS) against HBV in vitro, and the effects on the Toll like receptor 4 (TLR4) mRNA expression in HepG2.2.15 cell strain. METHODS: HepG2.2.15 cell strain was co-cultured in vitro with PcPS in different concentrations, and lamivudine (LMV) was applied as positive control. MTT assay was employed to detect the cytotoxicities of PcPS in vitro, when the HepG2.2.15 cells was used as target cells. The effects of PcPS on the secretion of HBsAg and HBeAg were assayed by ELISA method. Fluorescence quantitative-PCR (FQ-PCR) was used to detect the inhibitory effects of PcPS on the content of HBV-DNA and TLR4 mRNA in HepG2.2.15 cells. RESULTS: The inhibitory effects of PcPS on the HBsAg and HBeAg were observed and the maximum inhibitory ratio up to 44.8% and 31.0%, respectively. The same inhibitory effects of PcPS on the HBV-DNA replication and TLR4 mRNA expression in HepG2.2.15 cells were also found. CONCLUSION: A certain concentration of PcPS significantly inhibits HBV replication in vitro. 相似文献
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通过全轮配双列杂交试验，分析了黄瓜霜霉病抗性的遗传特性。结果表明：遗传方差组成中，基因的加性效应和显性效应都是显著的，控制抗性的加性作用比显性作用大，狭义遗传力值高，为95．24％。群体中显性等位基因频率少于隐性等位基因频率，该性状至少受两对基因控制。 相似文献
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过氧化氢对盐胁迫下黄瓜种子萌发的影响 总被引：1，自引：0，他引：1
采用黄瓜为试验材料,研究了不同浓度的过氧化氢对100mmol／L的NaCl胁迫下黄瓜种子萌发的影响。结果表明：lOOmmol／L的NaCl处理对黄瓜种子的发芽率无显著影响,但对胚根、上胚轴的生长有显著抑制作用。添加低浓度过氧化氢一定程度上缓解了盐胁迫对黄瓜种子上胚轴伸长的抑制作用,但增加了盐胁迫对黄瓜种子胚根伸长的抑制作用;高浓度的过氧化氢处理加剧了盐胁迫对黄瓜种子胚根和上胚轴的毒害,浓度越高毒害作用越强。 相似文献
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Koelemeijer Irena A. Ehrl&#;n Johan J&#;nsson Mari De Frenne Pieter Berg Peter Andersson Jenny Weibull Henrik Hylander Kristoffer 《Landscape Ecology》2022,37(7):1839-1853
Landscape Ecology - Both climatic extremes and land-use change constitute severe threats to biodiversity, but their interactive effects remain poorly understood. In forest ecosystems, the effects... 相似文献
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Vole outbreaks in a landscape context: evidence from a six year study of Microtus arvalis 总被引：1，自引：0，他引：1
Delattre P. De Sousa B. Fichet-Calvet E. Quéré J.P. Giraudoux P. 《Landscape Ecology》1999,14(4):401-412
Landscape Ecology - Analysis of population variations in space and time suggests that landscape may act as a substrate for several kinds of interactions: neighborhood effects, edge effects,... 相似文献
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榆耳发酵液抑菌作用的探讨 总被引：9，自引：0，他引：9
采用杯碟法和纸层析的方法,测定了榆耳发酵液对九种细菌的抑制作用。结果表明:榆耳发酵液对供试细菌均有不同程度的抑菌作用,尤其是对肠炎杆菌的抑制作用较为突出。用乙醇沉淀法除去多糖的榆耳发酵液,对肠炎杆菌、大肠杆菌、绿脓杆菌,金黄色葡萄球菌、炭疽杆菌仍表现出不同程度的抑制作用。用去多糖浓缩五倍的榆耳发酵液通过抗菌素常规的八个溶媒系纸层析显影试验,以肠炎杆菌为敏感菌展层,均未有明显显迹。 相似文献
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5种中草药提取液对裸仁美洲南瓜白粉病的防治效果 总被引：1，自引：0，他引：1
以蛇床子、紫苏、鱼腥草、甘草、细辛等5种中草药乙醇提取物为试验材料,通过室内盆栽试验测定乙醇提取物对裸仁美洲南瓜白粉病的保护和治疗效果。结果表明,供试的5种中草药提取液对南瓜白粉病都有一定的保护和治疗效果,且多数中草药提取液的浓度为0.02 g·mL~(-1)时的保护和治疗效果高于浓度为0.01 g·mL~(-1)的效果。其中蛇床子的保护和治疗效果最好,当浓度为0.02 g·mL~(-1)时保护和治疗效果分别达到87.57%和86.80%。浓度为0.02 g·mL~(-1)的蛇床子、细辛对南瓜白粉病的保护效果均显著优于化学药剂15%三唑酮可湿性粉剂1 000倍液。甘草对南瓜白粉病的保护和治疗效果最差。0.02g·mL~(-1)的蛇床子提取液可优先用于南瓜白粉病的新型生物药剂开发。 相似文献