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、...     

Relationship between action potential, contraction-relaxation pattern, and intracellular Ca2+ transient in cardiomyocytes of dogs with chronic heart failure

Abnormalities of contractile function have been identified in cardiomyocytes isolated from failed human hearts and from hearts of animals with experimentally induced heart failure (HF). The mechanism(s) responsible for these functional abnormalities are not fully understood. In the present study, we examined the relationship between action potential duration, pattern of contraction and relaxation, and associated intracellular Ca²⁺ transients in single cardiomyocytes isolated from the left ventricle (LV) of dogs (n = 7) with HF produced by multiple sequential intracoronary microembolizations. Comparisons were made with LV cardiomyocytes isolated from normal dogs. Action potentials were measured in isolated LV cardiomyocytes by perforated patch clamp, Ca²⁺ transients by fluo 3 probe fluorescence, and cardiomyocyte contraction and relaxation by edge movement detector. HF cardiomyocytes exhibited an abnormal pattern of contraction and relaxation characterized by an attenuated initial twitch (spike) followed by a sustained contracture ('dome') of 1 to 8 s in duration and subsequent delayed relaxation. This pattern was more prominent at low stimulation rates (58% at 0.2 Hz, n = 211, 21% at 0.5 Hz, n = 185). Measurements of Ca²⁺ transients in HF cardiomyocytes at 0.2 Hz manifested a similar spike and dome configuration. The dome phase of both the contraction/relaxation pattern and Ca²⁺ transients seen in HF cardiomyocytes coincided with a sustained plateau of the action potential. Shortening of the action potential duration by administration of saxitoxin (100 nM) or lidocaine (30 μM) reduced the duration of the dome phase of both the contraction/relaxation profile as well as that of the Ca²⁺ transient profile. An increase of stimulation rate up to 1 Hz caused shortening of the action potential and disappearance of the spike-dome profile in the majority of HF cardiomyocytes. In HF cardiomyocytes, the action potential and Ca²⁺ transient duration were not significantly different from those measured in normal cells. However, the contraction-relaxation cycle was significantly longer in HF cells (314 ± 67 ms, n = 21, vs. 221 ± 38 ms, n = 46, mean ± SD), indicating impaired excitation-contraction uncou pling in HF cardiomyocytes. The results show that, in cardiomyocytes isolated from dogs with HF, contractile abnormalities and abnormalities of intracellular Ca²⁺ transients at low stimulation rates are characterized by a spike-dome configuration. This abnormal pattern appears to result from prolongation of the action potential. Received 22 January 1998; received after revision 16 March 1998; accepted 27 March 1998     

Down-regulation of sodium current in chronic heart failure: effect of long-term therapy with carvedilol

Evidence has accumulated recently about the importance of alterations in Na⁺ channel function and slow myocardial conduction for arrhythmias in the infarcted and failing heart. The present study tested a hypothesis that Na⁺ current (I_Na/C) density decreases in chronic heart failure (HF) and that Na⁺ channel (NaCh) functional density can be restored by long-term therapy with carvedilol, a mixed α- and β-adrenergic blocker. Studies were performed using a canine model of chronic HF produced in dogs by sequential intracoronary embolizations with microspheres. HF developed approximately 3 months after the last embolization (left ventricle, LV, ejection fraction = 28 ± 1 %). Ventricular cardiomyocytes (VCs) were isolated enzymatically from LV mid-myocardium, and I_Na was measured by whole-cell patch-clamp. The maximum I_NA/C was decreased in failing (n = 19) compared to normal (n = 12) hearts (33.1 ± 1.6 vs 48.5 ± 5.1 pA/pF, mean ± SE, p < 0.001). The steady-state inactivation and activation of I_Na remained unchanged in failing compared to normal hearts. Long-term treatment with carvedilol (1 mg/kg, twice daily for 3 months) normalized I_Na/C in dogs with HF. I_Na/C in HF dogs (n = 6) treated with carvedilol was higher compared to that of non-treated HF dogs (n = 6) (49.4 ± 0.9 vs 29 ± 4.8 pA/pF, p < 0.007). In vitro culture of VCs of failing hearts for 24 h did not restore I_Na/C. However, I_Na/C was partially restored when VCs were incubated for 24 h with BAPTA-AM, an intracellular Ca²⁺ buffer. Thus, we conclude that experimental chronic HF in dogs results in down-regulation of the functional density of NaCh that can be restored by long-term therapy with carvedilol. The mechanism of NaCh down-regulation in HF may be linked to poor Ca²⁺ handling in this stage of disease. Received 4 June 2002; received after revision 1 July 2002; accepted 17 July 2002 RID="*" ID="*"Corresponding author.     

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。     

Brominated diphenyl ethers from a marine bacterium associated with the spongeDysidea sp.

Summary BacteriaVibro sp. isolated from the spongeDysidea sp. were shown to biosynthesize brominated diphenyl ethers. We identified one of the bacterial brominated metabolites using gas liquid chromatography and mass spectrometry to compare this product with standard 3,5-dibromo-2-(3,5-dibromo-2-methoxyphenoxy)phenol. The latter has been isolated from ethanol extracts of the spongeDysidea sp.     

Repolarization abnormalities in cardiomyocytes of dogs with chronic heart failure: role of sustained inward current

We previously showed that a canine model of chronic heart failure (HF) produced by multiple coronary microembolizations manifests ventricular arrhythmias similar to those observed in patients with chronic HF. In the present study, we used single canine cardiomyocytes isolated from the left ventricle (LV) of normal dogs (n = 13) and dogs with HF (n = 15) to examine the cellular substrate of these arrhythmias. Action potentials (APs) and ion currents were measured by perforated and whole cell patch clamp, respectively. We found prolonged APs and alterations of AP duration resulting in early afterdepolarizations (EADs) at the low pacing rates of 0.5 Hz and 0.2 Hz. Na+ channel blockers saxitoxin (STX, 100 nM) and lidocaine (90 microM) reduced AP duration dispersion and abolished EADs in HF cardiomyocytes. The steady-state current (Iss)-voltage relation, in the voltage range from -25 mV to 25 mV analogous to the AP plateau level, was significantly shifted inward in HF cardiomyocytes. STX and lidocaine shifted the Iss-voltage relationship in an outward direction. The shifts produced by both drugs was significantly greater in cardiomyocytes of dogs with HF, indicating an increase in inward current. In the experimental configuration in which K+ currents were blocked, the density of the steady-state Ca2+ current (ICa) was found to decrease in HF cardiomyocytes by approximately 33%. In contrast, the density of the steady-state Na+ current (INa) significantly (P < 0.01) increased in HF cardiomyocytes (0.17 +/- 0.06 pA/pF) compared with normal cells (0.08 +/- 0.02 pA/pF). The relative contribution of INa to the net inward current was greater in HF cardiomyocytes, as evident from the increased ratio of INa/ICa (from 0.22 to 0.68). These observation support a hypothesis that anomalous repolarization of HF cardiomyocytes is due, at least in part, to an increased steady-state inward Na+ current.     

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。     

长白山地区幔源捕虏体的硫化物相及其演化

长白山地区新生代玄武岩的一些层位广布地幔岩捕虏体,在其橄榄石、辉石等矿物内发现有较多的硫化物相,按产出特征可鉴别出3种类型,即早期硫化物颗粒、硫化物包裹体和裂隙中硫化物。硫化物包裹体可以单相硫化物、硫化物－硅酸盐熔体、CO2－硫化物－硅酸盐熔体形式存在。早期硫化物颗粒以磁黄铁矿为主,并发现有方黄铜矿;硫化物包裹体以镍黄铁矿为主,并有黄铜矿、硫铜铁矿出现;裂隙中硫化物均为镍黄铁矿,并具有比硫化物包裹体高的Ni/Fe和（Fe Ni)／S值。地幔岩中存在自早期硫化物颗粒、硫化物包裹体至裂隙硫化物,Ni/Fe和（Fe Ni)/S比值逐渐增加的规律。这种演化不仅受温度和压力制约,而且受Ni,Fe,Cu的地球化学特性和硫逸度的控制。     

Relationship between steady-state activation and availability of cardiac sodium channel: evidence of uncoupling

The coupling between steady-state activation and availability from inactivation was characterized for the cardiac Na⁺ channel. To evaluate this coupling, we plotted the relationship between the conductance and availability curve midpoint potentials measured in 92 rat ventricular cardiomyocytes and applied a correlation analysis. We found a high correlation between the midpoints (correlation coefficient = 0.86, slope = 0.95) within the availability midpoint potential range positive to -100 mV. In contrast, the midpoints were not correlated in the myocytes (37 of 92 cells) having mid point potential negative to -100 mV, indicating an uncoupling between activation and availability. Received 1 October 1997; received after revision 28 October 1997; accepted 13 November 1997