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1.
A programme of field trials for the study of the winter barley–Rhynchosporium commune pathosystem is reported. The associated seedborne disease rhynchosporium leaf scald is regarded as having an important impact on barley yields. The analysis in this study relates to the impact of the seed source (commercial or farm-saved seed) on disease incidence and to the spatial pattern of rhynchosporium leaf scald disease incidence. Disease incidence data were calculated from field data recorded as disease severity. Mean disease incidence was higher in the crops grown from farm-saved seed than in those grown from commercial seed, although great agronomic significance cannot be attached to this result. The spatial pattern of rhynchosporium leaf scald disease incidence was characterized in terms of the binary power law (BPL) and was indicative of an aggregated pattern. Programme-wide BPL results were described using a novel phytopathological application of a random coefficients model. These results have application in field sampling for rhynchosporium leaf scald disease.  相似文献   
2.
以青海贵德地区作为研究区域,以NaCl作为示踪剂,一次性瞬时投放,进行野外弥散试验,观测示踪剂浓度随时间的变化过程,使用标准曲线配线法和使用Matlab数据拟合法进行求解,得到了责德地区潜水含水层弥散系数,并分析了试验结果,比较了两种计算方法.  相似文献   
3.
J. Che  B. Su  B. Tang  X. Bu  J. Li  Y. Lin  Y. Yang  X. Ge 《Aquaculture Nutrition》2017,23(5):1128-1135
A study was conducted to determine apparent digestibility coefficients (ADCs) of dry matter (DM), crude protein (CP), lipid, gross energy, phosphorus and amino acids (AAs) from Peruvian fish meal (PFM), native fish meal (NFM), meat bone meal (MBM), dried daphnia meal (DDM), soybean meal (SBM), full‐fat soybean (FSBM), cottonseed meals (CSM), rapeseed meal (RSM) and corn gluten meal (CGM) for Pseudobagrus ussuriensis (7.8 ± 0.06 g). Test diets were formulated to contain a 70:30 mixture of reference diet to test ingredient with chromic oxide (5 g kg–1) serving as the inert marker. ADCs of DM ranged from 49.94% (CGM) to 87.11% (PFM), the highest ADCs of DM were observed in PFM and the lowest was found in CGM. ADCs of CP in the test ingredients ranged from 74.92% (CGM) to 93.41% (SBM). ADCs of crude lipid ranged from 51.80% (CGM) to 94.07% (PFM) for fish. ADCs of energy ranged from 56.42% (CGM) to 90.09% (PFM). ADCs of phosphorus ranged from 21.81% (CSM) to 65.70% (PFM). AA availability for the test ingredients followed a similar pattern to ADCs of CP, in which values for PFM, NFM and MBM were generally higher (p < .05) than those of other protein ingredients. Among all plant meals, the AA availability values in SBM were higher (p < .05) than those in CGM, CSM and RSM. The availability of most AAs in CGM was the lowest (p < .05) among all tested ingredients. In conclusion, PFM and NFM are good sources of available protein and AAs. When fishmeal supply is limited, MBM and DDM are substitutes for fishmeal reduction in P. ussuriensis diets; at the same time, SBM and FSBM are also very acceptable protein feedstuffs. However, CSM, RSM and CGM could not be used at high levels in P. ussuriensis diets because of their inferior digestibilities.  相似文献   
4.
An 8‐week feeding trial was performed to examine the potential of total replacement of fish meal with animal by‐products with or without enzymatic components in juvenile genetically improved farmed tilapia (GIFT) diets, Oreochromis niloticus, (mean initial weight, 19.71 ± 0.28 g), reared in RAS system. Five isonitrogenous and isoenergetic diets were formulated with fish meal for the diets with total replacement of the isonitrogenous amounts of enzymatic fish meal (E‐FM), chicken liver meal (CLM), enzymatic chicken liver meal (E‐CLM), dried porcine solubles (DPS) and enzymatic dried porcine solubles (E‐DPS) respectively. The results indicated that the weight gain rate (WGR) and specific growth rate (SGR) in the FM group were significantly higher than the E‐FM and E‐CLM groups (p < .05), but the specific growth rate (SGR) in the E‐CLM group lower than the E‐FM group. The feed conversion ratio (FCR) in FM and CLM was significantly lower than the E‐FM, E‐CLM and E‐DPS groups (p < .05), and no significant difference was observed among the FM, CLM and DPS groups (p > .05). The values of the protein retention efficiency (PRE) and protein efficiency ratio (PER) in FM, CLM and DPS groups were significantly higher than the E‐CLM group (p < .05). The values of feed intake ratio (FIR) in FM and CLM groups were significantly lower than the E‐FM, E‐CLM and E‐DPS groups (p < .05). There was no significant difference in the whole body contents of moisture, crude lipid and crude ash among the FM and E‐CLM groups (p > .05). The whole body contents of crude protein in the FM group were significantly higher than the E‐FM, CLM, E‐CLM DPS and E‐DPS groups (p < .05). The apparent digestibility coefficients (ADC) of dry matter, crude protein and crude lipid in the FM, E‐FM, E‐CLM and E‐DPS groups were not significantly different (p > .05). The serum glucose(GLU), total cholesterol (TCHO) and triglycerides (TG), or the activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were not affected by the different treatments (p > .05). There was no significant difference in serum total protein (TP) or albumin (ALB) and between the FM group and other groups (p > .05). There was no significant difference in the serum urea nitrogen (BUN) content in the FM, CLM, E‐CLM and DPS groups (p > .05). Fish fed with the CLM and DPS diets had significantly lower hepatic GHR1, IGF1 and IGF2 gene mRNA expression levels than in fish fed the FM diet (p < .05). The present data showed that 6% of dietary fish meal can be totally replaced by the chicken liver meal and dried porcine solubles with no effect on the growth performance of GIFT strain tilapia.  相似文献   
5.
选择北京市为研究区域,采用1998—2007年的统计年鉴数据,以谢高地等的研究方法为基础,从影响森林资源生态系统服务价值因素的角度,建立修正指标体系,对传统生态系统服务价值测算方法进行修正,分析北京森林资源生态系统服务价值的变化情况。结果表明,北京1998—2007年森林资源生态服务价值总体上呈现先降后升的趋势,引入协调系数修正后的价值也呈这一趋势,但价值量总体降幅为9%。该结果显示在综合了社会和经济因素对森林资源生态系统服务价值的影响因素后,其价值在一定程度上更接近于实际,变化趋势良好。  相似文献   
6.
采用弯曲振动实验方法,测定、分析了无节子正常试件、截断后胶接(即含胶接面)及插入节子(即用木材节子取代正常试件中的一段)后试件的前四阶弹性模量、前二阶阻尼系数。研究结果表明:含胶接面试件的一阶至四阶弹性模量值相比无节子正常试件基本呈现降低的趋势,前二阶阻尼系数相对与无节子正常试件呈增大的趋势,其中一阶阻尼系数受影响最大;在正常试件中插入节子后,各阶弹性模量均呈现下降趋势,前二阶阻尼系数呈现增大的趋势,其中一阶弹性模量与一阶阻尼系数受插入节子的影响最大。  相似文献   
7.
The characteristics of deformation failure and stress brittle drop of granite under loading and unloading conditions are studied respectively based on two unloading stress path cases and conventional triaxial compression experiments. The experiments show that the primary deformation of rock is rebound or tension in the (main) unloading direction, but plastic deformation in the non or sub unloading direction is not significant. And the curves of stress strain after peak strength present obvious brittle. Whilst the primary deformation of rock under loading is axial pressure deformation, and plastic deformation increases with the raise of confining pressure. The fracture is characterized by strong tensile, and all tensile cracks are fully developed. Furthermore, when the rock samples are unloaded in two directions, and even normal to unloading direction, sub unloading annular tensile cracks are produced. The shear fractures is obvious comparatively when confining pressure becomes higher, and it develops following tensile cracks with more micro tension cracks formed in two sides along shear plane. But the fracture is characterized by shear under conventional triaxial compression with little tensile cracks; the coefficients of brittles stress drop of granite is increased with the growth of confining pressure under conventional triaxial compression and reduced under unloading. When the initial confining pressure is the same, the coefficients of brittles stress drop under unloading is less than that under loading. In SchemeⅡ, the coefficients of brittles stress drop reaches negative when initial confining pressure is up to 30 MPa, and the one (R)is RⅢ>RⅠ>RⅡ in three test cases.  相似文献   
8.
转基因小麦抗旱性鉴定及相关指标灰色关联度分析   总被引:1,自引:0,他引:1  
以9份转ABP9基因春小麦株系UC4-1~UC4-9及其受体亲本宁春4号为材料,在雨养和灌溉条件下,对这些材料的主要农艺性状和部分生化指标进行了测定,采用隶属函数值法和抗旱性度量(D)值法对其抗旱性进行了综合评价,并利用灰色关联度法对相关抗旱性状与抗旱指数之间的关联度进行了分析评价。结果表明:6份转基因小麦的抗旱性较受体亲本宁春4号增强,3份材料的抗旱性较非转基因春小麦品种定西35增强;各农艺性状和生化指标与抗旱指数的关联度从高到低依次分别为株高、单穗粒重、穗长、SOD活性、穗粒数、结实小穗数、有效分蘖数、POD活性、千粒重、脯氨酸含量、MDA含量。  相似文献   
9.
The genetic relationship among individuals at one locus is characterized by nine coefficients of identity. The coefficients of inbreeding, coancestry and dominance (or fraternity) are just linear functions of them. Here, it is shown how they can be estimated using biallelic and triallelic markers using the method of moments, and comparisons are made with other methods based on molecular coancestry or molecular covariance. It is concluded that in the general case of dominance and inbreeding with biallelic markers, only the coefficients of inbreeding and coancestry can be estimated, but neither the single coefficients of identity nor the coefficient of dominance can be estimated. More than two alleles are required for a full estimation as illustrated with the triallelic situation.  相似文献   
10.
通过将2012年8月、12月在苏北黄海海域野外调查获得的声学多普勒流速剖面仪(ADCP)后向散射强度数据与悬沙浓度进行拟合,得知两者的相关系数在0.8以上,反演结果较理想。并结合同步观测的温度、盐度等水文要素资料,对该区域夏、冬季两季悬浮泥沙的垂直分布特征、形成原因及输运进行了研究,结果表明苏北近岸海域悬浮泥沙分布的典型性季节变化明显,冬季悬沙浓度普遍高于夏季。悬浮泥沙分布及输运受苏北沿岸水、黄海西部沿岸流、长江冲淡水、黄海暖流、黄海冷水团等影响,其中黄海西部沿岸流的季节变化为主要的影响因素。苏北沿岸水携带废黄河口的再悬浮泥沙和近岸悬沙向东南外海扩散,冬季的搬运量和扩散范围显著大于夏季。黄海暖流阻碍悬沙向外海扩散,使其在近岸被大量捕集下来。夏季长江冲淡水的东北方向偏转,使得苏北南部海域悬沙分布出现层化现象。  相似文献   
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