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71.
探讨了热处理制度中合成温度,保温时间及原料中Mn/Li摩尔比诸因素对LiMn2O4和结构和电性能的影响,为制备性能优良的LiMn2O4材料提供了理论依据。 相似文献
72.
73.
74.
强化木地板耐磨性能及国产化耐磨纸的研究 总被引:1,自引:0,他引:1
对强化木地板的耐磨性能和国产化耐磨纸进行了研究,重点考察耐磨纸的生产方式和热压工艺过程对产品耐磨转数和磨耗量的影响。结果表明Al2O3添加量和添加方式对产品的耐磨性能有很大影响,新研制的B型耐磨纸和进口耐磨纸有相似的磨损曲线,其耐磨转数与Al2O3添加量之间呈线性正相关,耐磨转数的增加主要表现在延长第二磨损区域,即提高初始磨损的IP值。热压工艺过程与产品的耐磨性能之间无明确关系。 相似文献
75.
Anther culture of an interspecific rice hybrid from a cross of Oryza sativa× O. rufipogon was attempted. Of the 117 regenerated pollen clones, 56 could survive to maturity. A majority of these were either haploids or doubled haploids and very few turned out to be chromosomal variants. Comparative study of doubled haploids and the seed derived F2 plants indicate the distinct advantages of anther culture techniques. (1) Androgenic plants, though few in number, showed greater ariation for all the traits with the exception of ear bearing tillers. (2) Predominance of recombinants with wild traits was observed in F2 segregation. (3) It was possible to recover indica type recombinants among the anther-derived plants with one or two traits introgressed from O. rufipogon. These results suggest the feasibility and utility of anther culture in distant hybridization for incorporation of alien variation into cultivated rice. 相似文献
76.
Tomosaburo Yabuno 《Euphytica》1987,36(2):529-534
Summary It is shown that the restorer gene Rf
j
extracted from the Japanese rice variety Akebono is effective on pollen restoration in the cytoplasm substitution line having the nucleus of Oryza glaberrima and japonica or indica cytoplasm of O. sativa, and is of the sporophytic type.The Asian perennial type of the wild rice species O. rufipogon is considered to be the progenitor of O. sativa. Two substitution lines having the cytoplasm of a perennial strain of O. rufipogon from Sri Lanka and the nucleus of O. glaberrima with or without the gene Rf
j
in homozygous condition have been bred by means of successive backcrosses. These lines have now reached the BC5 generation. Plants of the lines resemble morphologically the recurrent parent, but do not show pollen restoration, indicating that the cytoplasm of the rufipogon strain induced male sterility and that the gene Rf
j
does not act as the restorer. 相似文献
77.
The composite material of nano-Al 2O 3 and UHMW-PE was made by the way of pressing and agglomeration. Effect of nano-Al 2O 3 on the friction, wear characteristic of Ultra High Molecular Weight Polyethylene plastic was studied by using MPV-200 model friction and wear tester and caustic wear one. At the same time, the hardness of UHMW-PE was mensurated in sclerometer. The results showed that nano-Al 2O 3 not only decreases the friction coefficient of UHMW-PE, but also greatly reduce the wear of UHMW-PE.The hardness of UHMW-PE is improved. Which possesses important theoretic significance for optimizing of structure and property of UHMW-PE material. 相似文献
78.
灌水和施用钾肥对玉米果穗叶片光合特性及产量的影响 总被引:5,自引:0,他引:5
在玉米生育期间进行灌水和施用钾肥,对玉米果穗叶片的叶绿素含量、光合强度和玉米籽粒灌浆及最终的籽粒产量均有明显的促进作用;灌水与施用钾肥之间有一定的互作效应;钾肥(K2O)的适宜施用量在90—135kg/hm^2为宜。 相似文献
79.
The origin,evolution, cultivation,dissemination, and diversification of Asian and African rices 总被引:28,自引:0,他引:28
Te-Tzu Chang 《Euphytica》1976,25(1):425-441
Summary Available evidences drawn from biosystematics, evolutionary biology, biogeography, archaeology, history, anthropology, paleo-geology and paleo-meteorology are pooled to reconstruct the series of events that led to the cosmopolitan cultivation of the Asian cultivated rice (O. sativa) and the regionalized planting of the African cultigen (O. glaberrima) in West Africa. The genus Oryza originated in the Gondwanaland continents and, following the fracture of the supercontinent, became widely distributed in the humid tropics of Africa, South America, South and Southeast Asia, and Oceania. The two cultivated species have had a common progenitor in the distant past. Parallel and independent evolutionary processes occurred in Africa and in Asia, following the sequence of: wild perennialwild annualcultivated annual. The weed races also contributed to the differentiation of the cultivated annuals. The corresponding members of the above series are O. longistaminata
Chev. et Roehr., O. barthii
A. Chev., O. glaberrima
Steud., and the stapfii forms of O. glaberrima in Africa; O. rufipogon
Griff., O. nivara
Sharma et Shastry, O. sativa L., and the spontanea forms of O. sativa in Asia.The differentiation and diversification of the annuals in South Asia were accelerated by marked climatic changes following the last glacial age, dispersal of plants over latitude or altitude, human selection, and manipulation of the cultural environment.Cultivation of rice began in many parts of South and Southeast Asia, probably first in Ancient India. Cultural techniques such as puddling and transplanting were first developed in north and central China and later transmitted to Southeast Asia. Wetland culture preceded dryland culture in China, but in hilly areas of Southeast Asia, dryland cultivation is older than lowland culture. The planting method progressed from shifting cultivation to direct sowing in permanent fields, then to transplanting in bunded fields.Widespread dispersal of the Asian cultigen led to the formation of three eco-geographic races (Indica. Sinica or Japonica, and Javanica) and distinct cultural types in monsoon Asia (upland, lowland, and deep water). Varietal types changed readily within the span of a millenium, largely due to cultivators' preferences, socio-religious traditions, and population pressure. Genetic differentiation developed parallel to the ecologic diversification process.The African cultigen developed later than the Asian cultigen and has undergone less diversification. The wild races in South America and Oceania retain their primitive features mainly due to lack of cultivation pressure or dispersal.Both the African and Asian rices are still undergoing evolutionary changes at habitats where the wild, weed, and cultivated races co-exist. 相似文献
80.
V. Vorne K. Ojanper L. De Temmerman M. Bindi P. Hgy M. B. Jones T. Lawson K. Persson 《European Journal of Agronomy》2002,17(4):369-381
Potato (Solanum tuberosum L cv. Bintje) was exposed to ambient and elevated carbon dioxide (CO2), to ambient and elevated ozone (O3) and to elevated levels of both gases during two growing seasons, 1998 and 1999. Experiments in open-top chambers (OTC) were carried out in Finland, Sweden, Ireland, United Kingdom, Germany and Belgium and a FACE (Free Air Carbon dioxide Enrichment) experiment was carried out in Italy. In OTCs the plants were grown under ambient CO2 concentrations or with 550 and 680 μl l−1 CO2 alone or in combination with ambient or elevated O3 concentrations (target seasonal mean of 60 nl l−1 8 h per day). In the FACE systems the plants were exposed to ambient or 550 μl l−1 CO2. In the OTC experiments the reducing sugar content of potato tubers decreased significantly with increased concentration of O3. The starch content of potato tubers decreased, with negative impact on tuber quality, but the ascorbic acid concentration increased as a function of the AOT40 (The sum of the differences between hourly ozone concentration and 40 nl l−1 for each hour when the concentration exceeds 40 nl l−1 during a relevant growing season). However, simultaneous exposure to elevated CO2 counteracted the ozone effect. With increase in the CO2 exposure, glycoalkaloid and nitrate concentrations decreased yielding improved quality, while the citric acid concentration decreased causing a higher risk for discoloration after cooking. The amount of dry matter and starch increased significantly in the FACE experiment. 相似文献