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1.
对钢筋混凝土结构锈蚀损伤定位进行了研究,以频率变化平方比作为锈蚀损伤参数,从理论上证明该参数是锈蚀损伤位置的函数。锈蚀钢筋混凝土结构试验结果表明预测的损伤位置和实际的损伤位置较一致,模态参数用于检测混凝土结构构件中的损伤,为大型结构的鉴定和评估提供了新的途径。  相似文献   
2.
The effects of variety and growth location on grain composition and starch structures were investigated using three rice (Oryza sativa L.) cultivars (Phka Romduol, Sen Pidao and IR66) with different amylose contents. All the three cultivars were planted in three different agro-climatic zones (Phnom Penh, Coastal and Plateau) of Cambodia. The protein content of polished grains increased when rice was planted at a location with higher average temperature, but their lipid content decreased. The amylose content and degree of branching were not greatly affected by the minor temperature differences among the growing locations. Starch fine structures characterized by the chain-length distribution were significantly different among the cultivars, but not significantly among different locations. The results suggested that protein and lipid biosyntheses were more sensitive to the environmental temperature than that of starch in rice grains.  相似文献   
3.
铁西区通过打造装备制造业产业聚集区。形成了高档数控机床、通用石化装备等六大主导产业以及电气及新能源等五大千亿产业集群,成为我国老工业基地振兴的区域典范。介绍铁西装备制造业聚集区发展现状,采用区位熵法测算沈阳装备制造业的产业集中度,对全市装备制造业的现状及问题进行分析,得出相应结论。  相似文献   
4.
Although the effects of cover crops (CC) on various soil parameters have been fully investigated, less is known about the impacts at different stages in CC cultivation. The objective of this study was to quantify the influence of CC cultivation stages and residue placement on aggregates and microbial carbon (Cmic). Additionally, the influence of residue location and crop species on CO2 emissions and leached mineralized nitrogen (Nmin) during the plant degradation period was also investigated. Within an incubation experiment, four CC species were sown in soil columns, with additional columns being kept plant‐free. After plant growth, the columns were frozen (as occurs in winter under field conditions) and then incubated with the plant material either incorporated or surface‐applied. With CC, concentrations of large and medium macroaggregates were twice that of the fallow, confirming positive effects of root growth. Freezing led to a decrease in these aggregate size classes. In the subsequent incubation, the large macroaggregates decreased far more in the samples with CC than in the fallow, leading to similar aggregate size distributions. No difference in Cmic concentration was found among the CC cultivation stages. CO2 emissions were roughly equivalent to the carbon amounts added as plant residues. Comparison of columns with incorporated or surface‐applied residues indicated no consistent pattern of aggregate distribution, CO2 emission or Cmic and Nmin concentrations. Our results suggest that positive effects of CC cultivation are only short term and that a large amount of organic material in the soil could have a greater influence than CC cultivation.  相似文献   
5.
Dong village is very valuable for research work because of its special regional and national character and rich cultural implication. In this paper, some information about the location, form and features of Dong village is given. Then, the relationship between the culture and the settlement is analyzed, which provides a clue for understanding Dong village and will be beneficial to creating modern human settlements.  相似文献   
6.
为选育抗倒伏玉米品种,挖掘甜玉米茎秆强度相关性状的数量性状基因座(quantitative trait locus,QTL),应用复合区间作图法以甜玉米组合T49×T56的F2为作图群体,通过测定F2:3家系的茎秆穿刺强度、茎秆抗压强度和茎秆弯折性能3个性状进行相关性状的QTL定位。结果表明,遗传连锁图谱包含153个SSR标记位点,覆盖玉米基因组1 199.1 cM,平均图距7.83 cM。3个性状共检测到10个QTL,其中与茎秆穿刺强度相关的2个QTL位于第3、7染色体上,解释11.81%和22.15%的表型变异,与茎秆抗压强度相关的4个QTL位于第1、3、7染色体上,单个QTL可解释3.68%~33.26%的表型变异,与茎秆弯折性能相关的4个QTL位于第3、6、8染色体上,单个QTL可解释3.55%~18.58%的表型变异。第7染色体检测到1个同时控制茎秆穿刺强度和茎秆抗压强度2个性状的QTL,位于umc1015~umc1987标记区间,分别可解释11.81%和33.26%的表型变异,第3染色体检测到1个同时控制茎秆穿刺强度、茎秆抗压强度、茎秆弯折性能3个性状的QTL,位于umc1400~dupssr23标记区间,分别可解释22.15%、13.27%和18.58%的表型变异。3个茎秆强度性状共同检测到的主效QTL,可在育种实践中用于分子标记辅助选择和抗倒伏玉米品种的选育。  相似文献   
7.
以辐射诱变获得的玉米红轴突变体698-3R为材料,通过遗传交配设计分析轴色的遗传规律,利用SSR-BSA法初步定位轴色基因,并对候选基因进行克隆和表达分析。结果表明:(1)突变体698-3R的红轴对白轴性状表现为显性遗传,受一对核基因控制,初步定位在第一染色体上的SSR标记phi095与umc1452之间,与phi095相距3.9cM,与umc1452相距7.1cM,将该基因暂定名为C(t);(2)以轴色基因 P1的cDNA为模板克隆C(t),发现698-3R有3个C(t)转录本,而野生型698-3中至少有2个;预测氨基酸序列比对发现,698-3R中3个C(t)蛋白的氨基酸序列与已知P_1-wr蛋白一致,突变使其获得完整的MYB结构域和酸性激活域,而野生型698-3中698-3-P-1蛋白由于编码序列缺失导致移码突变,不具有该功能结构域;(3)对C(t)基因qRT-PCR分析发现,除25DAP外,其余4个时期在698-3R中表达水平均显著或极显著高于698-3;以 A1和 C2基因表达验证分析发现,C(t)与验证基因表达模式一致,说明C(t)可能具有 P1激活调控 A1和 C2基因表达的功能。推测该红轴基因C(t)可能为一个 P_1-wr基因。  相似文献   
8.
利用广东高要和广西扶绥两地14个2~10年生桉树林分样地共287株样木,研究短轮伐期桉树人工林个体林木特征指标,并比较现有广西良种桉二元带皮和去皮材积公式估算个体林木材积的准确性,分析不同年龄、林分和径阶林木的出材率。结果表明:带皮和去皮林木的胸高形数为0.504±0.004 2和0.529±0.004 4、实验形数为0.410±0.002 4和0.427±0.002 7、形率为0.657±0.003 4和0.690±0.003 6、高径比为1.22±0.017和1.43±0.019。用广西良种桉二元带皮和去皮材积公式估算单株林木带皮和去皮材积与实际材积高度相关(r>0.99),但估算值普遍偏低,平均分别小3.7%和21.0%;尤以用带皮材积公式估算去皮材积比用去皮材积公式估计要准确,平均只小2.3%。如以6年生以上样地和尾径4 cm以上的去皮林木为实际出材,5个相关样地林分平均出材率为(73.3±4.31)%,最小为54.6%,最大为81.5%。  相似文献   
9.
Increasing use of spatial management tools in fisheries requires an understanding of fleet response, and in particular to where displaced fishing effort is likely to move. We develop a state‐dependent decision‐making model to address the spatial allocation of effort in an Australian tuna longline fishery. We assume that fishers have an economic objective in deciding where to fish, but that decisions in any period are also influenced by the remaining quota held at the time of the decision. Key features of the model include endogenous price dynamics, a moving stock and a competitive pool of different vessel types operating from different port locations. We utilize this model to illustrate fleet responses to marine reserves and limits on fishing effort. The results illustrate that the model framework provides advantages over statistically based models in that decisions made in response to the imposition of a reserve are not consistent with a proportional reallocation of effort. Rather, the stochastic dynamic model yielded an overall profit level of ~4% higher relative to scenarios with no reserve. Incorporating the opportunity cost of a quota into the model resulted in an optimal utilization of effort, in which effort was concentrated in time periods and locations yielding maximized profit. Under a low level of effort relative to the season length, the model indicated an overall profit level 43% greater than the highest obtained when the same level of effort was applied solely within any given quarter of the season.  相似文献   
10.
ABSTRACT

Most marine aquaculture activities remain strongly dependent on coastal ecosystems. In the case of shellfish farming, this dependency is related mainly to water quality and to the various ecological interactions resulting from the dynamics of coastal food webs. Such ecological constraints have influenced the overall evolution of blue mussel farming in the Mont-Saint-Michel Bay, leading producers to negotiate collective arrangements regarding production capacity and techniques and to develop production strategies at the farm level. This article presents an analysis of the location choices of mussel farmers in the Mont-Saint-Michel Bay based on an empirical investigation conducted in 2002. A typology of farms with respect to their land structure is developed in which some farms choose to concentrate their activity in a single part of the bay while others distribute their activity more widely. Determinants of the location choices of each farm category, including distance to port, natural productivity differentials, and predation of mussel stocks, are analyzed. The role of the institutional arrangements allowing mussel farmers to develop these location strategies is also discussed.  相似文献   
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