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941.
Employing the Gleeble-1500D thermal analogue machine and the STA449 synthesis thermal analyzer,the study on hot ductility and parts of thermology performance of 20CrMo steel has been carried out , many consulted foundation data has been obtained, the optimum ductility temperature arrange has been found, contraction of cross sectional area is only 30% between 600 degree and 775 degree, but contraction of cross sectional area is more than 80% between 800 degree and 1 250 degree, contraction of cross sectional area drops to under 60% rapidly between 1 350 degree and melting point,a curve is drawn showing the relationshi Pbetween heat capacity and the variation of temperature for the first time, the counting formulas of the heat capacity are regressed by disjunction. A curve is drawn showing the relationshi Pbetween the coefficient of thermal expansion and the variation of temperature, and their application in continuous casting is discussed herein. 相似文献
942.
943.
944.
利用塑料薄膜小棚,采用电热人工控温,以平均45~46℃的气温,对已抽穗的小麦处理2~3小时,收到较好的杀雄效果,其雌蕊仍有较好的受精结实能力.杀雄处理时期距始花期越近效果越好,以处理当天进入始花期的效果最佳.在控温杀雄条件下,不同部位的小穗和不同部位的小花杀雄效果不同.品种问对杀雄反应有所差异. 相似文献
945.
Summary A monogenic dominant male sterility is used for hybrid production in autumn and winter cauliflower. The ratio of male sterile plants in the backcross progenies of autumn cauliflower was 1:1 over five years (1987–1991). However, a significant deficit of male sterile plants was observed in the winter type over the same period.The influence of the temperature on the male sterile phenotype was studied within backcross progenies planted inside polythene tunnels. Six classes of phenotype were defined during the flowering period (from May to November). At low temperature, some male sterile plants developed partial to complete male fertility, whereas at high temperature, male fertile plants became male sterile.Segregation among the progenies of self-pollinated unstable male sterile plants did not deviate from the expected 3:1 ratio. Plants homozygous for the male sterility allele have been revealed by test crosses with a male fertile plant.For use in seed production, stable male sterile plants are vegetatively maintained; however, crossing lines isogenic except at the MS locus would allow male sterile plants to be raised from seed. 相似文献
946.
947.
948.
Dormancy of wheat grains, the property conferring sprouting resistance, is affected by environmental conditions experienced
during grain development. We investigated the hypothesis that short dormancy duration in U.K. wheat grain (thus a high risk
of post-maturity sprouting) is related to weather conditions, i.e. high temperatures during grain development. Four wheat
varieties were grown at four sites ranging from the far south to the far north of the country in the years 1995–1997,ensuring
different temperature and rainfall conditions during grain development. This paper focuses on one variety, Hornet, which has
a high sprouting resistance rating. Other varieties gave similar results. Serial laboratory germination tests (seven days,
20°C) at 100°C-dayintervals were used to measure dormancy duration, which was assessed from logistic curves fitted to the
data. During the experiment the mean temperatures during grain development differed by over4°C, due to the site × year effect.
Significant effects (p>0.05) of site and year (i.e. weather) on dormancy were found, when definitions of dormancy duration of DA (number of days from anthesis to 50% germination in seven days at 20°C) or DP (number of days from physiological maturity at 45% grain moisture to 50% germination) were used. Dormancy was markedly shorter
in the hot, dry year 1995 compared to the cooler, wetter years 1996 and 1997. A relationship, as postulated by Belderok, between
accumulated temperature during the dough stage of grain filling and dormancy duration was not found. However, a relationship
of dormancy duration to the mean temperature during grain development was found, with short dormancy periods occurring after
high mean temperatures were experienced.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
949.
A theoretical analysis is presented for heat transfer in micro-annular channel with an adiabatic wall and a heated wall with uniform wall temperature in slip flow regime. The energy equations with the boundary conditions of temperature jump are solved for the hydrodynamical and thermal fully developed laminar flow of the incompressible fluid in this microchannel. The influences of the Kn number, the ratio of inner diameter to outer diameter on the heat transfer characteristics are discussed respectively. The results show that the Nusselt number in microchannel decreases with the increasing of Kn number comparing with that in macrochannel. 相似文献
950.
储藏条件对水稻种子发芽活性影响的研究 总被引:5,自引:1,他引:5
文章讨论了储藏中水稻种子的水分含量、储藏温度和气体条件(如CO2气体、脱氧剂等)对水稻处子发芽活性的影响。 相似文献