Erythropoietin: hypothesis of action tested by analog computer

The action of erythropoietin on the pool of undifferentiated bone marrow cells has been examined with the aid of a model tested with an analog computer. The model is consistent with reported experimental results. The essential aspects of the action are (i) the effect is exerted during the S phase of the cell's cycle; (ii) " effective " erythropoietin is present in the cell only during G(1) and part of S; and, (iii) hormone molecules survive in the cell for only a limited time in effective form and require a certain time to assume this form.     

A clathrate reservoir hypothesis for Enceladus' south polar plume

We hypothesize that active tectonic processes in the south polar terrain of Enceladus, the 500-kilometer-diameter moon of Saturn, are creating fractures that cause degassing of a clathrate reservoir to produce the plume documented by the instruments on the Cassini spacecraft. Advection of gas and ice transports energy, supplied at depth as latent heat of clathrate decomposition, to shallower levels, where it reappears as latent heat of condensation of ice. The plume itself, which has a discharge rate comparable to Old Faithful Geyser in Yellowstone National Park, probably represents small leaks from this massive advective system.     

青稞蚜虫及黄矮病发生规律及防治技术研究

迪庆青稞蚜虫发生种类是禾谷缢蚜[Sitobion graminis(Takahashi)]和麦无网长管蚜[Acyrthosiphon dirhodum(Walker)]．优势种是禾谷缢蚜,可周年繁殖。田间混合种群有翅蚜发生高峰在5月下旬,蚜量高峰在6月中旬。青稞黄矮病潜伏期为20～25d．发病高峰在6月中下旬。蚜虫种群数量与黄矮病发生程度成正相关。采用“治虫防病”的防治策略,重点控制青稞拔节期前蚜虫种群数量及切断病毒抟播循环链的方法,控制了青稞黄矮病成灾的局面,青稞黄矮病的发病率控制到3％以下,产量增幅达到25％～60％,取得了显著的控病及增产效果。     

沿海地区高产大麦磷肥施用技术

研究了在沿海地区土壤富磷的情况下，磷肥不同用量和不同使用时期对啤酒大麦港啤1号产量的影响。试验结果表明，增施磷肥能显著提高产量，但施磷过多，产量不再增加，成本加大，经济效益下降；磷肥一次性基施比分两次施用效果好；基施五氧化二磷120—180kg／hm^2可以增加产量，改善群体质量，提高大麦对磷肥的利用率，增加施磷肥的经济效益。     

Mechanism of transmitter release: voltage hypothesis and calcium hypothesis

The calcium hypothesis of synaptic transmission has been challenged by experimental results using the crayfish neuromuscular junction that suggest that presynaptic depolarization can trigger transmitter release directly without calcium influx. Results from electrophysiological experiments using the same preparation do not support this voltage hypothesis, but are consistent with the calcium hypothesis. Voltage may modulate, but not elicit, transmitter release.     

HPLC法测定不同葡萄品种成熟过程中单体酚的变化

建立了用HPLC法同时测定黑比诺、梅尔诺、霞多丽葡萄成熟过程中6种酚(没食子酸、安息香酸、儿茶素、丁香酸、芦丁、阿魏酸)的方法,测定了其含量,并比较了其变化差异。结果表明,采用Hibar RT Lichrospher C18柱(250 mm×4．0 mm×5μm),16％乙腈水溶液(含1％乙酸),1．0 mL／min等压洗脱,可以较好地分离测定葡萄中的主要单体酚。在葡萄成熟过程中,红葡萄(梅尔诺和黑比诺)中单体酚含量均高于白葡萄(霞多丽)。儿茶素、芦丁和丁香酸含量随着葡萄成熟逐渐减少,其中儿茶素含量减少幅度最大;安息香酸含量在葡萄成熟前期迅速减少,其后下降缓慢,采收前1周迅速增加;在梅尔诺中没食子酸含量先增加后减少,而在黑比诺和霞多丽中呈先增加后减少再增加的趋势。在供试葡萄品种中,儿茶素含量最高,阿魏酸含量最低,依次为儿茶素>安息香酸>没食子酸>芦丁>丁香酸>阿魏酸。