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“农业是国民经济的基础”,我国是农业大国,虽然幅员辽阔,但实际可利用的耕地并不多,全国耕地面积仅95133万hm2,其中水田面积2400多万hm2,旱田面积7000多万hm2,人均占有耕地仅008hm2。耕地面积约占世界耕地面积的7%,而人口却占... 相似文献
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Sun-Ok Chung 《农机科技推广》2010,(12):17-17
<正>韩国的人口总数由1970年的约3200万增加至2008年的近4900万,与此同时农业人口却由约1442万降至319万。不仅如此,韩国的农业人口中老龄化问题日益突出。现在在韩国的乡村,60多岁的老人都自称"年轻人"。 相似文献
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<正> 作者1992年随北京农业节水考察团对以色列进行了短期访问。现将访问了解情况介绍如下。 以色列是世界上农业节水技术最先进的国家之一。农业是以色列最大的用水部门,占全国总用水量的60%以上,农业节水成为全国节水的关键。 以色列全国国土面积 2.1万km~2(不含被占领土),人口约500万,其中农业人口占 相似文献
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德国现有耕地面积1730万hm2,约占其国土面积的50%。其主要农作物是小麦,约290多万hm2。在农业生产中,畜牧业占有重要的地位。目前,农业企业全年经济收入为430亿欧元,其中约一半为畜牧业收入,在畜牧业中,牛奶的收入占90%,是农业企业收入的主要来源。二战以来,德国的农业生产结构发生了很大的变化,农业企业每户经营面积不断扩大,农业企业数量则逐年减少,目前不到100万个,其中面积2hm2以上的农场为41万多个(平均每个农场规模为41.4hm2)。农业从业人数到2001年约94万人,农业人口占全社会人口比重,1950年为24.1%、2000年则只有2.5%;每一个农民供… 相似文献
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安图县位于吉林省延边朝鲜族自治州西南部,土地面积7438km2,辖7镇2乡180个行政村,总人口约22万人,农业人口10万多人,约占全县人口的一半,经济以农业为主。近年来,在国家支农、惠农政策的扶持下, 相似文献
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0概况巴西联邦共和国,位于南美洲东部.全国总面积851.20万km2,约占南美洲总面积的一半,是南美洲面积最大的国家。总人口为18065.4万人(2004年),也是南美洲人口最多的一个国家,其中55%为白种人,38%为混血种人,葡萄牙语为其官方语言, 相似文献
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《Journal of Agricultural Engineering Research》1998,69(3):249-254
A model to represent the discolouration of dried powder of carrots as a function of temperature was developed. Two types of carrots, Asian and European, containing large amount of lycopene and β-carotene, respectively, were tested. The dried powder was stored under an atmosphere with O2and at three different temperatures, 5,20 and 35°C. The surface colour of the powder was monitored during storage by a Hunter colour ratioa/b. In the proposed model, the rate of oxidation was assumed to be represented by the product of the fraction of concentration of oxidized pigment at arbitrary time and a specific rate of oxidation of pigment. The rate parameters in the proposed model were calculated by fitting the experimental data with smooth curves by trial and error at the end of the induction period but before discolouration took place. The frequency constant and activation energy, expressing the temperature dependence of the rate parameters, were expressed by the Arrhenius relation. The simulation results of a Hunter colour ratioa/bof dried powder at 25°C showed good agreement with the experimental data, suggesting that the proposed model was effective for the prediction of discolouration of dried powder of both types of carrot. The use of the induction period in the manner described may enable the shelf life of dried powder to be predicted. 相似文献
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感官检验棉花的品级,这是农村常见的一种检测手段.它的一个主要特点就是存在不确定性.这是由于检验员的品级检验水平存在一定的差异,其中有很多因素制约着检验的结果.文章对影响感官检验结果的因素进行了系统的分析. 相似文献
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The fractional outflow rate of water from the rumen, measured as the rate of disappearance of the chromium complex of ethylenediamine tetra-acetic acid, was related to a number of dietary factors. A multiple regression equation was derived which expressed fractional outflow rate as a function of the intakes of dry matter, ash, acid-detergent fibre and crude protein.The data analysed consisted of 243 observations for sheep on 59 diets, including forage, concentrate and mixed diets. The ranges covered by the data were: fractional outflow rate 0.7–3.6 day?1; dry matter intake 560–1400g/day; ash 4–30%, acid-detergent fibre 7–41%, crude protein 5–26 % of dry matter; there were no observations for sheep of less than 34 kg liveweight.The equation accounted for 56·3 % of the total variance. Between-sheep variance could not be calculated for the whole of the data but was undoubtedly substantial since, for a sixth of the data, it was known to account for 38 % of the total variance. 相似文献
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从灾害经济学的角度探讨了城镇供水优化调度的必要性和可能性,认为在缺水不可避免的情况下,对供水进行优化调度可以减小缺水带来的损失,产生较好的减灾效益,特别是可以大大减小严重干旱的灾害效应。并根据水资源的特性,提出了缺水损失的计算模式以及优化调度的原则和方法。 相似文献