Leptin regulates striatal regions and human eating behavior     

Farooqi IS  Bullmore E  Keogh J  Gillard J  O'Rahilly S  Fletcher PC 《Science (New York, N.Y.)》2007,317(5843):1355

Studies of the fat-derived hormone leptin have provided key insights into the molecular and neural components of feeding behavior and body weight regulation. An important challenge lies in understanding how the rewarding properties of food interact with, and can override, physiological satiety signals and promote overeating. We used functional magnetic resonance imaging to measure brain responses in two human patients with congenital leptin deficiency who were shown images of food before and after 7 days of leptin replacement therapy. Leptin was found to modulate neural activation in key striatal regions, suggesting that the hormone acts on neural circuits governing food intake to diminish the perception of food reward while enhancing the response to satiety signals generated during food consumption.  相似文献   

THE WORK OF THE BUREAU OF GOVERNMENT LABORATORIES,OF THE PHILIPPINE ISLANDS     

Freer PC 《Science (New York, N.Y.)》1904,20(499):105-109

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论"缄默"的教师实践知识     

梁红 《国家林业局管理干部学院学报》2006,5(1):23-26

教师的实践知识具有"缄默"的本质.教师知识缄默性的生成是由"内隐学习"的存在、教师作为实践者的角色以及实践知识本身的特征决定的.促进教师实践知识的习得对教师的成长非常重要.教师要在教学实践中善于借助自己的缄默知识来开展教学活动,同时也要不断地揭示实践过程中生成的缄默知识,使其显现出来,达到系统化、明晰化.  相似文献   

Saturn's small inner satellites: clues to their origins     

Porco CC  Thomas PC  Weiss JW  Richardson DC 《Science (New York, N.Y.)》2007,318(5856):1602-1607

Cassini images of Saturn's small inner satellites (radii of less than approximately 100 kilometers) have yielded their sizes, shapes, and in some cases, topographies and mean densities. This information and numerical N-body simulations of accretionary growth have provided clues to their internal structures and origins. The innermost ring-region satellites have likely grown to the maximum sizes possible by accreting material around a dense core about one-third to one-half the present size of the moon. The other small satellites outside the ring region either may be close to monolithic collisional shards, modified to varying degrees by accretion, or may have grown by accretion without the aid of a core. We derived viscosity values of 87 and 20 square centimeters per second, respectively, for the ring material surrounding ring-embedded Pan and Daphnis. These moons almost certainly opened their respective gaps and then grew to their present size early on, when the local ring environment was thicker than it is today.  相似文献   

作物育种学教学与科研的结合     

梁红 《高等农业教育》1993,(5)

作物育种学是农学类专业的主要专业课之一,是实践性较强的应用学科。生物科学的迅速发展和高新技术的应用促进了作物育种学的发展,使知识更新加快,为教学增添了新的内容。农业生产结构的调整和布局区域化的逐步形成,以及社会主义市场经济的影响,对作物育种的教学提出了更高的要求。因此,必须坚持教学与科研相结合,改革教学内容和教学方法,加强对学生能力的培养,才能把握作物育种学的发展方向,提高教学水平和教学质量,主动适应新形势的要求。 一、科学研究与课堂教学 教学是以大钢为指导,以教材为依据来  相似文献   

Astronomy and solar physics: measurement of the solar spectral irradiance from 200 to 3000 nanometers     

Thuillier G  Goutail JP  Simon PC  Pastiels R  Labs D  Neckel H 《Science (New York, N.Y.)》1984,225(4658):182-184

The solar spectrum experiment on Spacelab 1 measured 98 percent of the sun's total energy output. It improved the absolute accuracy of solar irradiance data, especially in the ultraviolet and infrared regions. In order to detect any variation in the spectrum on future shuttle flights, the data were obtained in a radiation scale that can be preserved with high precision over many years. The instrument performance and preliminary data reduction are described.  相似文献   

Growth of Isolated Mesophyll Cells of Arachis hypogaea in Simple Defined Medium in vitro     

Joshi PC  Noggle GR 《Science (New York, N.Y.)》1967,158(3808):1575-1577

Isolated mesophyll cells from leaflets of Arachis hypogaea can be cultured in a simple, defined liquid nutrient medium containing minerals, with an appropriate source of ammonia, sugar, 2,4-dichlorophenoxyacetic acid, and kinetin. The significance of such a simple medium in understanding the problems of cell metabolism, growth, and morphogenesis is discussed.  相似文献   

APPLYING COLCHICINE TO PLANTS BY THE AEROSOL METHOD     

McKay JW  Burrell PC  Goodhue LD 《Science (New York, N.Y.)》1945,101(2615):154-156

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The struggle to govern the commons   总被引：8，自引：0，他引：8  

Dietz T  Ostrom E  Stern PC 《Science (New York, N.Y.)》2003,302(5652):1907-1912

Human institutions--ways of organizing activities--affect the resilience of the environment. Locally evolved institutional arrangements governed by stable communities and buffered from outside forces have sustained resources successfully for centuries, although they often fail when rapid change occurs. Ideal conditions for governance are increasingly rare. Critical problems, such as transboundary pollution, tropical deforestation, and climate change, are at larger scales and involve nonlocal influences. Promising strategies for addressing these problems include dialogue among interested parties, officials, and scientists; complex, redundant, and layered institutions; a mix of institutional types; and designs that facilitate experimentation, learning, and change.  相似文献   

Antarctic marine flora: uniquely devoid of kelps     

Moe RL  Silva PC 《Science (New York, N.Y.)》1977,196(4295):1206-1208

The discovery of embryonic stages of the common large Antarctic brown seaweed Himantothallus has led to the conclusion that this plant, hitherto assigned equivocally to the Laminariales (kelps), is a member of the Desmarestiales. Moreover, field study of a large sample of Himantothallus and two other enigmatic brown algae, Phyllogigas and Phaeoglossum, has led to the merger of these three genera with the recognition of a single species, Himantothallus grandifolius. The correct placement of these kelp-like algae underscores the uniqueness of the Antarctic marine flora as the only cold-water flora without kelps.  相似文献