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Fangzhou Liu Xiang Li Muhua Zhao Mengjian Guo Kehong Han Xinxin Dong Jing Zhao Wanlun Cai Qifa Zhang Hongxia Hua 《国家科学评论(英文版)》2020,7(7):1181
Rice planthoppers, the most devastating rice pests, occur in two wing forms: the short-wing form for rapid population growth and long-wing form for long-distance migration, which together create the mechanism for outbreak. Here we show that Ultrabithorax (Ubx) is a key regulator for switching between the long- and short-wing forms of rice planthoppers. Ubx is expressed in both forewing and hindwing pads, which is different from the canonical model of Ubx expression. In brown planthoppers, expression of Ubx (NlUbx) is regulated by nutritional status of the rice host. High-quality young plants induce NlUbx expression leading to the short-wing form; low-quality ripe plants reduce NlUbx expression resulting in long-wing form. We also showed that NlUbx is regulated by the insulin receptors NlInR1 and NlInR2. The default expression of NlInR1 inhibits NlUbx resulting in long-wings, while high-quality hosts induce NlInR2 expression, which represses NlInR1 thus promoting NlUbx expression to produce short-wings. 相似文献
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王贞贞 《湖北函授大学学报》2007,20(1):58-60
二十世纪二十年代末到三十年代,国家内忧外患,国民党进行文化“围剿”。面对这种景象,在文化界掀起了左翼文化运动,这是继五四运动之后又一次思想文化的解放。在这次运动中,以宣传革命文学为主,又对革命文学进行了激烈的论争,指引宣传走向正确的方向。 相似文献
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蜻蜓拍翼前飞中模型翼动态柔性变形的气动效应研究 总被引：1，自引：0，他引：1
根据蜻蜓拍翼前飞激发的流场具有St>>1/Re的特点，在理论模化框架下，本文采用势流假设，用二维变形体前、后缘脱涡的面元法研究了前飞模型蜻蜓翼在周期性拍动中动态柔性变形引起的气动力响应。通过比较柔性模型翼和刚性模型翼气动力随时间的变化，发现在下拍行程中动态柔性变形显著地提高了升力和推力；值得注意的是，蜻蜓前飞时，翼的实际柔性变形幅值恰处于一个最佳范围内，它大幅地提高了升力，同时使消耗的气动功率趋近于最低，有利于蜻蜓维持前飞状态。 相似文献
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为研究风帆助航技术,选取6种形状的风帆,利用某大学的低速风洞实验室对其进行风洞测力试验,获得相应的空气动力学特性.结果表明,圆弧形风帆空气动力性能比较优良,操作简便,比较适合安装在现代大型船舶上. 相似文献
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Aiming at exploring the excellent structural performance of the vein-stiffening membrane structure of dragonfly hind wings, we analyzed two planar computational models and three 3D computational models with cambered corrugation based on the finite element method. It is shown that the vein size in different zones is proportional to the magnitude of the vein internal force when the wing structure is subjected to uniform out-of-plane transverse loading. The membrane contributes little to the flexural stiffness of the planar wing models, while exerting an immense impact upon the stiffness of the 3D wing models with cambered corrugation. If a lumped mass of 10% of the wing is fixed on the leading edge close to the wing tip, the wing fundamental fre- quency decreases by 10.7%-13.2%; if a lumped mass is connected to the wing via multiple springs, the wing fundamental frequency decreases by 16.0%-18.0%. Such decrease in fundamental frequency explains the special function of the wing pterostigma in alleviating the wing quivering effect. These particular features of dragonfly wings can be mimicked in the design of new-style reticulately stiffening thin-walled roof systems and flapping wings in novel intelligent aerial vehicles. 相似文献
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王尔龄 《天津师范大学学报(社会科学版)》2001,(3):50-52
周而复于1933年考取光华大学后不久即参加“左联”，并于其时进入文学门径，除了本人创作，周而复还参与编辑出版《文学丛报》和《小说家》。1938年在光华大学毕业后告别上海，奔向延安。 相似文献
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刘小新 《华侨大学学报(哲学社会科学版)》2012,(3):81-88
"后现代主义"与"左翼"的结合是《岛屿边缘》的思想特色,作为一种思想方案,"后现代左翼"的提出,是90年代台湾进步知识分子对全球社会主义运动重大挫折问题的思想回应方式,也是对台湾多元化的新社会运动的积极应对方式。 相似文献
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我国经济发展已经步入了转变经济发展方式的攻坚阶段,新时期国民经济建设对国企党建工作提出了新的要求,党建和思想政治工作在国企改革发展中有着不可替代的作用。面临基层建设年的绝佳时机,基层国有企业如何才能把握机会,实现更高层次的发展,党建和思想政治工作大有可为。加强"三型"党建工作,既可以加强党组织在国有企业中的政治核心作用,同时也是助推生产经营的利器。 相似文献