模拟结果为什么比实际更暖:简化气候模型结果（英文）

设计了一个非专业人士能够使用、最简化的气候敏感模型,用来研究人类活动所导致的全球变暖的幅度问题.在1990年的第一次IPCC评估报告中,IPCC对其报告中预测的未来全球变暖幅度很有信心,但是随后的观测结果显示全球的变暖幅度只有预测的一半.而自2001年起,全球变暖出现停滞,但是仅仅考虑到二氧化碳浓度的增加,很少有模型能够模拟出这一变化.在已出版的IPCC第五次评估报告的草稿中,IPCC大幅度削减了近期变暖的幅度,并以专家评估代替了模型预测.但是报告中关于未来气候长期变化的预测仍被保留.如果把IPCC模型的总反馈从1.9 W m–2 K–1调整到1.5 W m–2 K–1,气候敏感模型中模拟的温度将从3.2 K降至2.2 K.同时由于反馈很可能是净负反馈,更合适的估计应该是1.0 K.1.0 K是一个能够实现的增幅,21世纪的实际变暖将会小于1 K.即使燃烧所有可开采的化石燃料也不会使全球变暖的幅度超过2.2 K,这一增加幅度也将趋于平稳.本文认为解决IPCC第四、五次报告中评估方法的差异非常关键.一旦这些差异得到解决,人类活动导致的全球变暖在22世纪以及几个世纪以后的平稳态将有可能不会超过IPCC当前模型预测的1/3~1/2.     

智能流域管理的关键问题与模型技术

在总结流域问题现状及流域管理决策需求的基础上,基于仿生学原理,类比人的思维特征和决策过程,提出了包括流域信息获取、输入-输出因果关联模拟以及优化决策等步骤在内的智能流域管理模式,并对比分析了智能流域管理和传统流域管理的差异性。提出了智能流域管理的4个关键问题：管理目标的确定、基于智能因子关联与流动的模型开发与信息获取、...     

多色集合在加工系统建模与分析时的应用

提出了多色集合、合取多色集合和析取多色集合的基本概念及其数学表达式,合取多色集合和析取多色集合是2种常见的多色集合的压缩形式,它们能使具体系统的建模得到简化,给出了对象性质和多色集合元素的逻辑表示方法,这样多色集合既能方便描绘加工及其元素,又很容易用于计算机编程,最后,举例指出了多色集合工具能被用来建立自动设计系统的不同数学模型之间的接口,有利于对加工系统进行深入描绘,研究表明,多色集合不仅能描绘加工系统的元素和加工系统整体的性质,还能描绘元素的性质和系统整体性质间不同的关系和联系。     

Effects of female sex hormones on polyamine-oxidizing enzyme activities and polyamine concentrations in immature rat uterus and liver

17-estradiol (E₂) and progesterone (P) treatment of immature female rats (10 g/100 g body weight) respectively resulted in 1.38-fold (p<0.02) and 1.42-fold (p<0.02) increase in the uterine polyamine oxidase activity, and 2.45-fold (p<0.001) and 1.43-fold (p<0.02) increase in the uterine diamine oxidase activity, as compared to the controls. E₂ caused a 5-fold (p<0.05) and a 1.36-fold (p<0.05) increase in putrescine and spermidine concentration respectively in rat uterus. Increases of 1.7-fold (p<0.02) and 1.6-fold (p<0.05) in putrescine and spermine concentration were determined in the P-treated uterus, as compared to the controls. The spermidine/spermine ratio, which is regarded as an index of growth rate, was higher in the E₂-treated uterus and lower in the P-treated uterus than in the control uterus. No statistically significant hormonal effects were estimated in the immature liver. The data reported suggest the possibility of an involvement of polyamine-oxidizing enzymes in the modulation of polyamine concentrations in rat uterus by the female sex hormones.     

Distribution of polyamine oxidase activity in rat tissues and subcellular fractions

The activity of polyamine oxidase (PAO) in rat tissues, and its subcellular distribution, were assayed using a simple polarographic method. The highest PAO activity was measured in the liver and the lowest in the skeletal muscle. In liver, kidney and uterus the highest specific PAO activity was found in the light mitochondrial fraction. PAO was not found in the microsomal fraction except in the kidney.     

Biochemical effects and growth inhibition in MCF-7 cells caused by novel sulphonamido oxa-polyamine derivatives

The novel polyamine derivatives sulphonamido oxa-spermine (oxa-Spm) and sulphonamido oxa-spermidine (oxa-Spd) exhibited rapid cytotoxic action towards MCF-7 human breast cancer cells with IC₅₀ values of 4.35 and 6.47 μM, respectively, after 24-h drug exposure. Neither compound is a substrate of serum amine oxidase. Both oxa-Spm and oxa-Spd caused cell shrinkage, as determined by phase-contrast microscopy. After incubation with 10 μM of either compound for 8 h, the cells underwent chromatin condensation and nuclear fragmentation. However, no clear DNA ladder was obtained by electrophoresis. The sulphonamido oxa-polyamine derivatives and especially oxa-Spd enhanced the activity of polyamine oxidase (PAO), an enzyme capable of oxidising N¹-acetylated spermine and spermidine to spermidine and putrescine, respectively, generating cytotoxic H₂O₂ and 3-acetamidopropanal as by-products. The intracellular polyamine content was only marginally reduced in response to drug treatment. In conclusion, our data show that these novel sulphonamido oxa-polyamine derivatives possess high cytotoxic activity against MCF-7 cells and indicate that induction of PAO may mediate their cytotoxicity via apoptosis. Received 17 January 2002; received after revision 22 February 2002; accepted 22 February 2002     

Distribution of polyamine oxidase activity in rat tissues and subcellular fractions.

The activity of polyamine oxidase (PAO) in rat tissues, and its subcellular distribution, were assayed using a simple polarographic method. The highest PAO activity was measured in the liver and the lowest in the skeletal muscle. In liver, kidney and uterus the highest specific PAO activity was found in the light mitochondrial fraction. PAO was not found in the microsomal fraction except in the kidney.     

Purification and some properties of an amine oxidase from soybean seedlings

Summary An amine oxidase was purified 447-fold from soybean seedlings and some of its properties were investigated. The molecular weight of the enzyme was estimated to be 25,000. It was most active towards putrescine, followed by spermidine and spermine. K_m-values for these substrates were relatively close. The enzyme was strongly inhibited by carbonyl reagents, such as semicarbazide and aminoguanidine.     

全球纳米技术研究文献计量分析

本研究采用文本挖掘技术，从在全球公开的纳米科学和技术研究文献数据库（SCI/SSCI 数据
库）中提取技术情报。在SCI/SSCI数据库中利用纳米科学和技术领域的300多个术语进行相关文献的检
索；利用摘要共现词汇的自相关图来揭示的技术核心领域；通过词汇间的互相关图来揭示因共现而发生
关系的词汇的技术核心领域；采用因子矩阵进一步量化研究机构之间、国家之间的关系强度，并对图中
揭示的合作出版网络给予确证。     

中美科技产出比较

该文以科技文献为分析基础,从数量与质量方面比较了中美之间科技发展的差距。数量比较选择了
SCI、INSPEC、Ei Compendex三大数据库,而质量比较则是应用了SCI中的引文分析。根据作者以前对中国
科技产出的评估,该文选择了30个技术研究领域,全面考察了中国在物质科学、环境、工程和生命科学重点
发展方向上论文数量情况。
SCI数据显示在几乎所有的技术领域内,虽然中国在论文数量方面增幅很大,但美国仍然处于领先地位
(2002－2007)。到2007年,INSPEC数据表明,在大多数技术领域内,中国的科技论文数量赶上或超过了美国;
但在生物医学和部分环境科学领域,美国仍然保持着较大的领先优势。Ei Compendex的数据分析结果表明,对
于大多数技术领域,到2007年中国的科技论文产量更大;而与日益增长的科研经费恰恰相反,美国发表论文的
数量似乎在2005年就已经到达了顶峰。如果不考虑生物医学领域,中国显然已经成为美国的强劲竞争对手。
为了对质量进行比较,该文对论文和引文数量进行了归一化处理,但仅限于纳米技术领域(1998－2003
年)。结果表明,虽然在过去的10年里美国在质量方面明显地领先中国(以及其他主要纳米技术研究国家),但
依然不能改表中国的论文质量持续提升的事实。中国目前已经达到可以与法国、意大利、日本和澳大利亚的
论文质量相提并论的地步。