Ab initio prediction of 29Si-NMR chemical shifts

The ability of several ab initio models to predict experimental ²⁹Si-NMR chemical shift is examined. The shielding values of trimethylsilyl chloride (A), t-butyldimethylsilyl chloride (B) and allytrimethylsilane (C) are calculated by GIAO, CSGT and IGAIM methods, using HF/6–31G^*, B3LYP/6-31G^*, HF/6–311+G^**, B3LYP/6–311+G^** and MPW1PW91/6–311+G^** models respectively. The ²⁹Si chemical shifts calculated by GIAO method using HF/6–311+G^** model are highly in agreement with those obtained experimentally. All of the models above reproduce the trends of chemical shifts in all cases studied, suggesting that the models are of practical value.     

RESOLUTION OF MULTICOMPONENT FLUORESCENT MIXTURES BY ANALYSIS OF THE EXCITATION-EMISSION-FREQUENCY ARRAY

Fluorescence lifetime provides a third independent dimension of information for the resolution of totalluminescence spectra of multicomponent mixtures.The incorporation of this parameter into theexcitation-emission matrix(EEM)by the phase modulation technique results in a three-dimensionalexcitation-emission-frequency array (EEFA).Multicomponent analysis based on the three-dimensionalEEFA brings a qualitative change for the resolved spectra,i.e.individual spectra can be uniquely resolved,which is impossible with any two-dimensional analysis.In this paper we present a method for analyzingthe EEFA.We show mathematically that with the three-dimensional analysis of the EEFA individualspectra and lifetimes can be obtained.Our algorithm is developed in mathematical detail and isdemonstrated by its application to a two-component mixture.     

上海中心城区河流水系百年变化及影响因素分析

分析上海中心城区河流水系1860~2003年变化情况,研究表明:①140余年来中心城区有历史记载河流消失至少310条段,总长超520 km,水面积减少约10.46 km²,水面率下降3.61%。中心城区所在水利片河流水系结构破坏,水系分枝比受河道消亡影响明显降低,水系分维数异常;②中心城区河流水系阶段性集中消亡,消亡驱动力因消亡时期而异;③初步估算,140余年来中心城区河道槽蓄容量减少超过2 029×10⁴m3、单位面积可调蓄容量减少5.06×10⁴m³/km²。河道槽蓄容量较百年前减少超过80%,城市河网调蓄能力明显削弱,且1950~1990年市政雨水泵站累积增加数目与同期区域内河道累积消失数量、长度和槽蓄容量间均呈显著正相关性。     

腾格里沙漠东南缘降尘粒度特征和沉积速率

从多年降尘实测资料入手，分析了粉尘粒度特征、沉积速率和时变过程。提出了气象要素相关估测模型．确定０．２５ｍｍ为本区粉尘沉积粒径上限。周围沙漠是粉尘沉积细砂部分的尘源，粉砂和粘土部分沉积来自一个较大的时空范围，二者几乎各占降尘量的１／２。研究区年平均粉尘沉积速率４３５８ｋｇ／ｈｍ２，每年５月的季风转期具有年内最大沉积速率。     

Variograms with zonal anisotropies and noninvertible kriging systems

Zonal anisotropies are usually simply defined as those that are not geometric (i.e., that cannot be removed by an affine transformation). Such anisotropies have often been associated with zonations and models have been proposed to reflect that association. It is shown by example that such models can lead to noninvertible coefficient matrices in kriging systems, because the models are only (conditionally) semidefinite instead of positive definite. The relationship to the construction used in turning bands algorithm and also to spatial-temporal models is discussed.     

武夷山脉主峰黄岗山两种山地草甸土的研究

选取武夷山脉主峰黄岗山典型山地草甸土和黄壤性山地草甸土的代表剖面，研究了土壤形成的条件和特点，推断在气候和植被条件相近的情况下，地形因素的差异引起的水环境的不同，是造成两种土壤理化性质差异的主要原因。     

近10 a来松嫩平原湿地研究的回顾与展望

松嫩平原是中国内陆湿地集中分布区之一。该区湿地类型有沼泽、湖泊、盐沼和稻田,此外还有水库和少量泥炭地。概述了该区湿地的研究现状,并指出目前研究热点。重点探讨了未来本区湿地的研究趋势,主要体现在湿地生态系统结构、功能和过程研究,湿地的区域生态功能评价,湿地污染及其治理,退化湿地恢复和重建,湿地多样性与湿地保护,湿地资源综合利用,湿地对全球变化响应和全球变化对湿地影响,湿地-草地-盐碱地转换机制和过程和驱动力等方面。     

国家风景名胜区景观遗产的三维培育研究--以青海湖为例

国家风景名胜区以其自然与人文美成为旅游与研究的热点。将国家风景名胜区的景观遗产划分为自然景观遗产、物质性历史文化遗产、非物质及口头文化遗产三维,并且探讨了景观遗产的培育理念。以青海湖国家风景名胜区为例,实证研究了其自然景观遗产的培育、物质性历史文化遗产的培育、非物质及口头文化遗产的培育。最后讨论了三个问题：对资源的重新认识、实证对其他案例的借鉴、三维培育模式的提取。     

俄罗斯科学院N.S.库尔纳可夫普通和无机化学研究所(IGIC RAS)简介

俄罗斯科学院Ｎ．Ｓ．库尔纳可夫普通和无机化学研究所,是由铂和其它贵金属研究所的普通化学研究室与物理化学分析研究所及物理化学部的高压实验室在１９３４年合并而成。由于上述两个研究所均创建于１９１８年,所以,该研究所的创建日定为１９１８年５月１１日。由于科学院士Ｎ．Ｓ．Ｋｕｒｎａｋｖ,Ｌ．Ａ．Ｃｈｕｇａｅｖ教授,Ｉ．Ｉ．Ｃｈｅｒｎｙａｅｖ院士,Ｎ．Ｍ．Ｚｈａ－ｖｏｒｏｎｋｏｖ,Ａ．Ａ．Ｇｒｉｎｂｅｒｇ,Ｉ．Ｖ．Ｏｂｒｅｉｍｏｖ,Ｙａ．Ｋ．Ｓｙｒｋｉｎ,Ｇ．Ｇ．Ｕｒａｚｏｖ和Ｉ．Ｖ．Ｔａｎａｎａｅｖ等人…