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水稻苗期水分亏缺产生补偿节水效应的亏缺阈值研究 总被引：1，自引：0，他引：1
为探讨调亏灌溉对水稻苗期的光合产物分配及氮素积累的影响,采用人工气候室内盆栽实验,在水稻三叶一心期至分蘖前期为止设计持续干旱0 d、3 d、6 d、9 d和12 d五个处理组。结果表明：1）在水分胁迫条件下,光合速率和蒸腾速率均下降,前者下降略为缓慢使得水分利用效率得到提高。同化产物在叶片中的含量高于茎鞘,但叶片中的氮素含量低于茎鞘。2）恢复灌溉后,受到胁迫的处理组的光合速率、蒸腾速率都迅速升高,干旱3 d和6 d的处理组光合水平超过对照,然后又有所下降,水分利用效率因为蒸腾速率的骤然升高而降低,之后有所恢复。干旱处理组的叶片中积累的同化产物转移至茎鞘和其他部位供其生长,使得叶片占总干重的比例下降。所有干旱组的茎鞘含氮量都在复水后增加明显且均高于对照组。3）各亏水处理组均表现出一定的补偿生长,包括根系的吸收补偿和光合系统的生理补偿。其中干旱3-6 d的水稻苗期亏水阈值产生的补偿效应明显。苗期水稻干旱引起光合产物的分配和氮素的积累的改变,从而发生复水后的补偿效应,提高植株的素质,提高水稻的分蘖能力和结实能力。 相似文献
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1951-2012年科尔沁沙地气温在突变前后的时空对比 总被引：3，自引：0，他引：3
为促进科尔沁沙地生态环境保护、农牧业发展、水资源合理开发利用等的顺利开展,本文利用1951-2012年科尔沁沙地气温资料,分析了该区气温突变特征及突变前后时空演变情况,结果表明：①时间上,年（季）最低气温首先发生突变（1981-1987年）,平均气温次之（1981-1994年）,最高气温最晚（1985-1999年）;冬、春、秋、夏季依次发生突变;②年最低气温突变后比突变前、冬季气温比夏季气温变化更剧烈;年、春（秋）季气温变化剧烈程度按最低、平均、最高气温依次减弱,冬季与之相反;③突变前春季最低气温升温速率为0.50℃/10a、突变后秋季最高气温升温速率为0.75℃/10a,二者对升温贡献最大;④突变前后多年均值增量最大为冬季最低气温（1.86℃）,气候倾向率增量最大为秋季最高气温（0.72℃/10a）;年内季节多年均值增量变化顺序与其增温速率增量变化相反;⑤空间上,年气温各要素突变后倾向率变化范围均较突变前增大,年最低气温突变后显著升温面积比突变前增大6.79%;突变后,除科左中旗地区平均气温外,自东向西沿新开河到西辽河以北地区升温速率大于以南地区升温速率。 相似文献
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河道疏浚底泥农业利用可行性分析 总被引：1，自引：0，他引：1
《科技通报》2017,(1)
为探索河道疏浚底泥的农业利用可行性,通过盆栽试验分析了不同比例的河道疏浚底泥添加对土壤理化性质及玉米苗期生长的影响。结果表明,疏浚底泥添加能显著提高土壤有机质、碱解氮、速效磷和速效钾等养分,但同时重金属含量也增加。底泥与土壤添加比例达到1∶2时,玉米苗期的根长、株高、生物量、叶绿素及地上部分植株中累积的C、P含量显著提高;混合比例达到1∶1时,速效磷和速效钾含量远高于植物生长所需的营养水平,但全量Cd含量超过《土壤环境质量标准》(GB15618-2008)二级标准,植株体内C、P含量下降,叶绿素含量也低于对照。因此,河道疏浚底泥添加能显著提高土壤养分含量,促进植物生长,但添加比例不宜超过1∶1。 相似文献
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利用西藏色林错流域气象观测站1961～2008年逐月平均气温、降水量等资料,分析了近50牟流域气温、降水的年际和年代际变化特征和异常年份,结果表明：近50年流域年平均气温以0．40℃／10a的速率显著升高,冬季增温最突出。平均最高气温除夏季变化趋势不大外,其它各季以0．21～0．35℃／10a的速度显著升高;年平均最低气温以0．56℃／10a的速度显著升高,明显高于最高气温的井幅。流域年降水量以20．4mm／10a的速率呈显著的增加趋势,四季降水量表现为增加趋势,为0．8～10．4mm／10a,以夏季增幅最大。20世纪60年代至90年代,除夏季外,其它3季和年平均气温都表现为逐年代增加趋势。年、季平均最高气温的年代际变化特征不明显。60年代流域降水表现为偏少的年代际变化特征;70年代夏季降水偏多,其它季节偏少;80年代夏、秋两季降水正常,冬、春季偏多;90年代,夏季偏少,秋、冬季偏多;进入21世纪前8年,秋季降水偏少,其它三季降水偏多,年降水量增幅明显。 相似文献
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芦笋,又名石刁柏,学名(Asparagusofficinalis.L),百合科天门冬属,雌雄异株的多年生宿根性植物。可食用部分形似芦苇茎和竹笋,故俗称芦笋。芦笋不仅味道鲜美,且营养成分丰富而均衡,蛋白质、多种维生素和碳水化合物的含量均显著高于普通蔬菜。特别是芦笋中含有的天门冬酰胺、抗坏血酸、胆碱、精氨酸、拓扑异构酶和硒元素,令其具有防癌抗癌、降低血脂、清肺保肝、增强免疫力等多种人体保健功能。故而芦笋素有"蔬菜之王"的美誉。 相似文献
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试验以蚓粪进行西瓜育苗,研究不同处理的蚓粪对西瓜幼苗生长的影响。蚓粪设5个预处理分别为过60目筛蚓粪(60M)、过20目筛蚓粪(20M)、灭活蚓粪(DL)、新鲜蚓粪(F)、晾干蚓粪(D)。结果表明,过60目筛的蚓粪处理的西瓜幼苗株高、茎粗分别为78.9、4.35 mm,显著高于其他处理。过60目筛蚓粪处理的西瓜叶片数最多,植株氮、磷、钾含量最高,壮苗指数显著高于其他各处理。过60目蚓粪、新鲜蚓粪两处理的西瓜单株干重显著高于其他各处理,分别达0.8913g、0.7736g。试验条件下灭活蚓粪处理的西瓜植株各项指标处于最低。 相似文献
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本文利用1961～2010年玛多气象站气象观测资料,通过对其地区气温、降水量及蒸发量的年变化和春、夏、秋、冬四季及年代的变化分析,结果表明：近50年来玛多地区年平均气温和降水量均呈上升趋势,蒸发量呈下降趋势;气温的四季变化均有明显上升趋势,其中冬季的气温上升最为明显,增温率为0．71℃／10a。近50年极值气温变化更大,最低气温极值21世纪初10年比上世纪70年代偏高12-2℃,最高气温极值21世纪初10年比上世纪60年代偏高2．0℃;玛多县降水量呈上升趋势,冬季上升趋势相对较小;近50年的蒸发量虽然呈下降趋势,但蒸发量远远大于降水量,所以干旱期延长,气候趋于暖干化,对牧草的生长极为不利,气候原因使草场的退化速度加快。 相似文献
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《Research Policy》2023,52(6):104761
Standard-setting organizations (SSOs) are collectively self-governed industry associations, formed by innovators and implementers. They are a key organizational form to agree on and manage technical standards, and form the foundation for many technological and economic sectors. We develop a model of endogeneous SSO participation that highlights different incentives for joining (namely licensing, learning, and implementation). We analyze equilibrium selection and conduct comparative statics for a policy parameter that is related to implementer-friendly Intellectual Property Rights policies, or alternatively, minimum viable implementation. The results can reconcile existing evidence, including that many SSO member firms are small. The extent of statutory participation of implementers in SSO control has an inverted U-shape effect on industry profits and welfare. 相似文献
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Quinlan S 《Endeavour》2010,34(4):142-150
During the French Revolution, there appeared a striking and far-ranging medical literature on heredity, reproduction and biological 'perfectibility'. In some ways anticipating ideas associated with modern eugenics, these writings emerged from radical revolutionary projects for 'physical and moral regeneration' and incarnated deep-seated desires to transform French society and make a 'new man' in mind and body. But by breaking down boundaries between public and private life, doctors did more than just try to regulate intimate sexual behaviour. Instead, they proffered a more intimate vision of civic volunteerism, in which sexual hygiene and domestic practices allowed their patients to imagine new forms of society and gave them ways to attain these socio-political dreams. Moreover, they were responding to powerful new worries about heredity and sought to counsel their patients in the ways of family panning. By the end of revolutionary period, then, medical and lay thinkers had transformed the marriage bed and household into a specially controlled environment - a kind of affective laboratory - in which conscientious parents could make healthy children and raise them in the context of specific political and social values. 相似文献
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Bhupendra Pal Singh Shailendra Dwivedi Urmila Dhakad Ramesh Chandra Murthy Vimal Kumar Choubey Apul Goel Satya Narayan Sankhwar 《Indian journal of clinical biochemistry : IJCB》2016,31(1):50-56
Deficiency or excess of certain trace elements has been considered as risk factor for prostate cancer. This study was aimed to detect differential changes and mutual correlations of selected trace elements in prostate cancer tissue versus benign prostatic hyperplasia tissue. Zinc, copper, iron, calcium and selenium were analysed in histologically proven 15 prostate cancer tissues and 15 benign prostatic hyperplasia tissues using atomic absorption spectrophotometer. Unpaired two tailed t test/Mann–Whitney U test and Pearson correlation coefficient were used to compare the level of trace elements, elemental ratios and their interrelations. As compared to benign prostatic tissue, malignant prostatic tissue had significantly lower selenium (p = 0.038) and zinc (p = 0.043) concentrations, a lower zinc/iron ratio (p = 0.04) and positive correlation of selenium with zinc (r = 0.71, p = 0.02) and iron (r = 0.76, p = 0.009). Considerably divergent interrelationship of elements and elemental ratios in prostate cancer versus benign prostatic hyperplasia was noted. Understanding of differential elemental changes and their interdependence may be useful in defining the complex metabolic alterations in prostate carcinogenesis with potential for development of element based newer diagnostic, preventive and therapeutic strategies. Further studies may be needed to elucidate this complex relationship between trace elements and prostate carcinogenesis. 相似文献
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Rebecca Knuth 《The Information Society》2013,29(1):11-19
Because of rapid developments in information technology, abuses of sovereignty by authoritarian governments have received much publicity in recent years, raising public consciousness of massive human rights violations to new levels. Contributing to the dialogue on the influence of information technology on social systems, this article explores (1) the contested role of information in disaster relief efforts, (2) the clash of political and social values emerging from the use of information within the international community's involvement in high-profile crises, such as those in Somalia, Bosnia, and Rwanda, and (3) the resultant rethinking of government's power within national borders, sovereignty. With life-anddeath stakes, international affirmation of a free flow of information during disasters is emerging as a global human rights mandate. 相似文献
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Rebecca Knuth 《The Information Society》1999,15(1):11-19
Because of rapid developments in information technology, abuses of sovereignty by authoritarian governments have received much publicity in recent years, raising public consciousness of massive human rights violations to new levels. Contributing to the dialogue on the influence of information technology on social systems, this article explores (1) the contested role of information in disaster relief efforts, (2) the clash of political and social values emerging from the use of information within the international community's involvement in high-profile crises, such as those in Somalia, Bosnia, and Rwanda, and (3) the resultant rethinking of government's power within national borders, sovereignty. With life-anddeath stakes, international affirmation of a free flow of information during disasters is emerging as a global human rights mandate. 相似文献
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针对国内不少企业在与外方合资过程中陷入被动这一现状,本文从资源观角度对中外合资企业内的控制权问题进行了探讨。文章认为,中外合资企业内的控制取决于双方的资源投入特别是关键资源投入状况,并且是一个动态变化的过程,改变初始控制权的动力来源于学习,通过学习与随之而来的创新,合资方可以加强对关键资源的投入与进入权,并朝着有利于自己的方向配置控制权。文章结合达能这一外资饮料巨头在华一系列合资企业的控制权演变过程,从各方的资源投入及学习加以分析,从而对目前合资企业的状况给出解释和相应建议。 相似文献
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Observers, objects, and the embedded eye; or, seeing and knowing in Ptolemy and Galen 总被引：1，自引：0，他引：1
Lehoux D 《Isis; an international review devoted to the history of science and its cultural influences》2007,98(3):447-467
This essay explores the ways in which theories and entities are culturally and intellectually embedded in historical and disciplinary contexts by looking at the development of a set of related theories of perception that emerged in response to contemporary Sceptical criticisms of the very possibility of doing empirical science. At the same time, it attempts to bring into focus a puzzle about precisely how (and how deeply) seeing itself is conditioned. 相似文献