植物器官生理年龄划分方法的研究

生理年龄是植物学家为描述植物生长过程而提出的,它的合理划分对于分析树木的生长变化规律、构建树木的生长模型具有重要意义。对于拓扑结构复杂的多年生高大树木而言,生理年龄的划分并不简单,目前还没有一个系统的划分方法。为了快速、合理地划分植物各器官的生理年龄,基于欧美杨107的实测数据,根据生理年龄的概念,提出了一种自动划分多年生高大树木生理年龄的新方法。结果表明:本文提出的划分方法是可行的,并在一定程度上克服了人工方法存在的误差大、操作复杂等问题。该方法也可以被借鉴应用于其他多年生树木生理年龄的确定。     

Paleontologic Technique for Defining Ancient Pole Positions

Taxonomnic diversity gradients appear to offer a quantitative paleontologic technique for obtaining ancient positions of the rotational pole of the earth. Statistical analysis of a model based on the taxonomic diversity of Recent planktonic foramninifera shows a close relationship to the latitudinal temperature gradient and, thus permits location of the pole. A similar analysis for Permian orthotetaceid brachiopods suggests a pole near the present position. A vailable data on diversity fit a present earth mizodel better than one based on Permian paleomagnetic results and thus suggest that it may be necesary to consider a model for the earth's magnetic field which does not require coincidence of the magnetic and rotational poles.     

Defining lipid transport pathways in animal cells

A new technique for studying the metabolism and intracellular transport of lipid molecules in living cells based on the use of fluorescent lipid analogs is described. The cellular processing of various intermediates (phosphatidic acid and ceramide) and end products (phosphatidylcholine and phosphatidylethanolamine) in lipid biosynthesis is reviewed and a working model for compartmentalization during lipid biosynthesis is presented.     

森林资产界定指标体系研究

建立森林资产的统计指标体系对于森林资源的资产化管理具有非常重要的意义，界定森林资产的指标体系要符合管理体制的适应性，技术上的适用性和量化计算上的可行性。森林资产界定的一级指标应包括３类：（１）预备指标，即林区界定指标；（２）资产客体指标，主要指用材林界定指标；（３）资产延伸指标，主要指森林环境界定指标。     

Enhanced distress vocalization through selective reinforcement

Eighteen Peking ducklings were imprinted and tested for their tendency to emit distress calls during the presentation and withdrawal of the imprinted stimulus. A subsequent arrangement in which each distress vocalization led to a 5-second presentation of the imprinted stimulus resulted in an enhanced tendency to emit distress calls.     

Defining the inside and outside of a catalytic RNA molecule

Ribozymes are RNA molecules that catalyze biochemical reactions. Fe(II)-EDTA, a solvent-based reagent which cleaves both double- and single-stranded RNA, was used to investigate the structure of the Tetrahymena ribozyme. Regions of cleavage alternate with regions of substantial protection along the entire RNA molecule. In particular, most of the catalytic core shows greatly reduced cleavage. These data constitute experimental evidence that an RNA enzyme, like a protein enzyme, has an interior and an exterior. Determination of positions where the phosphodiester backbone of the RNA is on the inside or on the outside of the molecule provides major constraints for modeling the three-dimensional structure of the Tetrahymena ribozyme. This approach should be generally informative for structured RNA molecules.     

龙胆苦苷和龙胆碱的生物转化和药理活性研究进展

\t\t\t\t\t目的\t\t\t\t\t在脂多糖(LPS)致小鼠急性肺损伤(ALI)模型上评价龙胆苦苷抗急性肺损伤的活性。\t\t\t\t\t\t\t\t\t\t\t\t\t方法\t\t\t\t\t健康雄性成年SPF级昆明小鼠40只,随机分为4组：假手术组、ALI模型组(气管滴入脂多糖LPS 5 mg/kg)、阳性药物对照组(腹腔注射氢化可的松3.3 mg/kg,每日1次,连续3 d,24 h后气管滴入LPS 5 mg/kg)、龙胆苦苷组(腹腔注射龙胆苦苷20 mg/kg,每日1次,连续3 d,24 h后气管滴入LPS 5 mg/kg)。在气管滴入LPS后24 h处死动物,检测肺系数、支气管肺泡灌洗液(BALF)中炎症细胞计数和肺组织病理变化。\t\t\t\t\t\t\t\t\t\t\t\t\t结果\t\t\t\t\t阳性药物对照组和龙胆苦苷组小鼠肺系数明显低于ALI模型组(P<0.05),阳性药物对照组和龙胆苦苷组比较差异无统计学意义。ALI模型组小鼠BALF中炎症细胞及中性粒细胞比例明显高于假手术组(P<0.01),阳性药物对照组和龙胆苦苷组明显低于ALI模型组(P<0.01),阳性药物对照组明显低于龙胆苦苷组(P<0.05)。假手术组小鼠肺组织结构基本完整,肺泡腔内无渗出物和炎细胞,ALI模型组肺泡上皮细胞大量增生,肺泡壁增厚,肺间质、肺泡腔内可见大量炎细胞浸润,部分肺间质发生实变,阳性药物对照组和龙胆苦苷组肺组织炎症病理明显减轻。\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t结论\t\t\t\t\t龙胆苦苷能够明显减轻脂多糖致ALI小鼠肺组织炎症反应程度,具有较好的抗急性肺损伤活性。\t\t\t\t     

议对农林贫困大学生的心理扶贫

教育部门曾经做过调查,目前我国高校中贫困学生占在校生总数的20%,在农林等院校这一比例高达30%。这些学生经济拮据,学杂费、生活费甚至基本生活费无法保障。他们在背负经济压力的同时,心理上也承受着巨大的精神压力。如何保证这些贫困大学生正常的学习和生活,已成为社会和高等院校关