钻孔误差产生原因及防止方法探究

职业学校钳工实习教学的钻孔是钳工专业一项重要基本操作技能,要求进行系统的技能和技巧训练,掌握加工要求较高的孔及位置精度的方法。但由于钻孔中的累积误差很难完全消除,钻孔的位置精度也就很难保证,因此如何消除或减少钻孔的误差是钳工实习教学中的难点和终点。文章从钻孔误差产生的原因和防止方法两个角度出发,探索了钳工实习教学中,如何消除或减少钻孔误差的教育教学生产实践。     

UG残料粗加工方法研究

残料加工对编程来说是一个比较复杂的环节,不同的软件拥有不同的功能,对不同形状的零件有不同的加工方法,文章针对UG CAM模块,了解其残料加工的原理,优化这些加工方法,追求更安全、更高效的残料粗加工方法。     

山区道路生态环境评价指标体系研究

针对山区道路的生态环境特性，遵循评价指标选取的原则，采用层次分析法对目标层山区道路生态环境评价指标进行了筛选、优化，最终形成了2大类准则层（自然环境指标、社会环境指标）和17个指标层的山区道路生态环境评价指标体系。     

“龙江清酒”的加工与营销策略

为研制并开发地产新饮品，以黑龙江地产稻米为原料，采取制酒的工艺流程，研制香气独特的龙江清酒。提出了龙江清酒的加工工艺及技术要点，并策划了该产品的营销策略。加工工艺关键是筛选优良的酒曲霉菌和特定酵母菌、优化制曲工艺和发酵工艺条件等；营销关键是打品牌、强宣传、重营销。     

Improving the Field Emergence Performance of Super Sweet Corn by Sand Priming

Abstract

A priming method called sand priming was developed using sand as a priming solid matrix. The effect of sand priming on improving the field emergence performance of five super sweet corn cultivars was investigated. Sand priming significantly improved field emergence performance of all super sweet corn cultivars, and there was marked improvement by priming at 20ºC for 24 hr. After sand priming at 20ºC for 24 hr, field emergence percentage (FEP) of “Green Superman”, “Huatian 1”, “Yangtian 1”, “Mitian 8”, and “Chaotian 43” was increased by 52.1%, 37.5%, 38.0%, 40.9%, and 33.3%, respectively. Their field emergence speed (FES) was 2.3, 1.8, 2.0, 2.0, and 1.8 times of the control, respectively. To further elucidate the effect of sand priming on improving the field emergence performance of super sweet corn, we analyzed the membrane system integrity, α-amylase activity and protein content. Sand priming at 20ºC for 24 hr improved membrane system integrity and α-amylase activity in all super sweet corn cultivars. Furthermore, sand priming at 20ºC for 24 hr accelerated the degradation of embryo protein after 1 d germination in “Green Superman”.     

Varietal Differences in Cell Wall β-(1→3),(1→4)-Glucan and Nonstructural Carbohydrate in Rice Stems during the Grain Filling Stage

Abstract

The contribution of cell wall components and nonstructural carbohydrate (NSC) to grain filling in rice (Oryza sativa L.) was clarified by investigating the differences in the dynamics of hemicellulose, sugar composition of hemicellulose, β-(1→3),(1→4)-glucan, and NSC among cultivars with different grain filling capacities. This investigation was performed using the stems of standard, high yield and low harvest index (HI) cultivars. Hemicellulose concentration in stems tended to decrease slightly during the grain filling stage. This decrease was attributed to a decrease in β-(1→3),(1→4)-glucan concentration, which was detected as a decrease in glucose composition of hemicellulose in the stems during the grain filling stage. The rate of decrease and decrease in the amount of β-(1→3),(1→4)-glucan in the stems differed among the cultivars. These were higher in high yield and high HI cultivars than in relatively low yield and low HI cultivars. Moreover, a positive correlation was observed between the rate of decrease in β-(1→3),(1→4)-glucan and NSC, indicating similarities in the dynamics of β-(1→3),(1→4)-glucan and NSC among the cultivars. When the top half of panicle was removed, β-(1→3),(1→4)-glucan and NSC concentrations in the culm and leaf sheath did not decrease during the grain filling stage. Therefore, the β-(1→3),(1→4)-glucan in stems might be one of the sources that supply substrate to panicle as well as NSC.     

Decomposition of (1–3,1–4)-β-Glucan and Expression of the (1–3,1–4) -β-Glucanase Gene in Rice Stems during Ripening

Abstract

To elucidate the possible participation of hemicellulose decomposition in lodging resistance, we studied the change of hemicellulose and cellulose content in the stems of rice during the ripening stage by methylation analysis and the expression of related genes by Northern blotting. In the rice stem in ripening stage, content of (1-3,1-4)-β-glucan, a component of hemicellulose, decreased markedly although the content of arabinoxylan, a major component of hemicellulose, and cellulose showed little change during the same growth period. On the other hand, expression of the Gns 1 gene, which may encode (1-3,1-4) -β-glucanase that catalyzes the degradation of (1-3,14) -β-glucan, increased sharply in the stem. The mechanism of decomposition of (1-3,1-4) -β-glucan in rice stem and the possible association with lodging resistance is discussed.     

Complexity of indica-japonica varietal differentiation in Bangladesh rice landraces revealed by microsatellite markers

To understand the genetic diversity and indica-japonica differentiation in Bangladesh rice varieties, a total of 151 accessions of rice varieties mostly Bangladesh traditional varieties including Aus, Boro, broadcast Aman, transplant Aman and Rayada varietal groups were genotyped using 47 rice nuclear SSRs. As a result, three distinct groups were detected by cluster analysis, corresponding to indica, Aus and japonica rice. Among deepwater rice varieties analyzed some having particular morphological features that mainly corresponded to the japonica varietal group. Some small seeded and aromatic varieties from Bangladesh also corresponded to the japonica varietal group. This research for the first time establishes that the japonica varietal group is a prominent component of traditional varieties in Bangladesh, particularly in deepwater areas.     

Iron uptake in a bicarbonate-resistant cell line of tobacco

Abstract

In alkaline soils, plant growth is impaired mainly by high pH and high concentration of bicarbonates. The bicarbonate concentration increases the pH value, and causes deficiency of iron. A bicarbonate-resistant cell line (BR line) of tobacco (Nicotiana tabacum L. cv. Burley21) was selected by adding excess bicarbonate ions (20 mmol L^?1) to the culture medium. The pH of the medium was buffered 8.0 to 8.3. Under these conditions, about 80% of iron in the medium became insoluble. However, under such conditions, the BR line grew well. In this report, we examined some characteristics of the growth and iron uptake in the BR line under iron-deficient (i.e. high pH or no-iron) condition. At pH 5.8, the Fe³⁺ reduction activity was not significantly different between the non-selected line and the BR line. At pH 8.0, however, the Fe³⁺ reduction activity of the BR line was higher than that of the non-selected line. In no-iron condition, the growth of the non-selected line was markedly reduced after 2 weeks, while the BR line was not affected. The content of malic acid in both lines increased with the medium pH, and the content in the BR line was higher than that in the non-selected line. The BR line was able to adapt to the conditions, which restricted iron uptake, such as high bicarbonate concentration, high pH, and low iron conditions. The high ability of Fe³⁺ reduction was maintained at even high pH conditions. Further, the BR line may be able to improve the utilization of iron in the cells.     

多穗型青贮玉米科多8号制种技术比较

科多8号是中国科学院遗传研究所选育的青饲青贮玉米专用品种,深受北方农牧市场的欢迎。但由于制种生产比较效益较低等原因,群众没有制种积极性。文章结合多年来制种工作的经验和近年进行的一些试验研究,从播种期、父母本安排、去雄方法等方面进行深入研究探讨,并提出高效制种模式。