明代长江流域人口大量死亡事件时空特征及原因分析

通过检索古籍文献,整理了明代（公元1368—1644年）长江流域人口大量死亡事件（mass death events,MDE）10 a尺度的频次与县次序列,利用自然断点分级法、空间分析法等分析了MDE的时空特征及发生原因。结果表明：276 a间,长江流域有158 a发生MDE,明代后期发生频次和影响规模最大;季节上,表现为夏季多发（44.3%）,春、秋季次之;空间上,集中分布于长江中下游、尤其是长江三角洲地区,且呈从各省交界处向各省中心扩散的趋势。“未记录原因的饥荒”和“旱灾+其他灾害-饥荒”是造成明代长江流域MDE的主要原因。气候冷干期发生频次多,影响范围广,暖湿期相反,与温度和湿度呈显著负相关;人口规模和社会脆弱程度是主要的社会影响因素。在人口规模大和社会脆弱的明代后期,MDE发生频次高,波及范围广,是气候变化与社会因素共同作用的结果。     

Synthesis of condensed tetrahydroimidazo[1,2-a]quinazoline-1,5-dione derivatives

Heating of N-{2-[(R-amino)carbonyl]phenyl}prolinamides in triethyl orthoformate solution was found to give 6-R-5,6,6a,8,9,10,10a,11-octahydropyrrolo[1′,2′:3,4]imidazo[1,2-a]quinazoline-5,11-diones. Similar reaction of N-{2-[(R-amino)carbonyl]phenyl}thiazolidine-4-carboxamides afforded 6-R-5,6,6a,10,10a,11-hexahydrothiazolo[3′,4′:3,4]imidazo[1,2-a]quinazoline-5,11-diones. The relative configuration of C-6a and C-10a centres of the tetracyclic compounds obtained was assigned as trans on the basis of X-ray crystallographic study.     

A novel synthesis and transformations of isothiochroman 2,2-dioxide

A convenient synthesis of isothiochromen-4-one 2,2-dioxide was carried out via cyclisation of o-cyanobenzyl thioacetate by a Thorpe reaction. The reactions of isothiochromen-4-one 2,2-dioxide with nitrogen-containing nucleophilic reagents have been investigated.     

李萨如图形在检测系统中的应用

李萨如图形可以检测两个相同频率信号的相位差．主要论述具有惯性质量、弹簧和阻尼器的二阶加速度测量系统,其动态响应特性的分析方法,如何利用李萨如图形来检测力平衡式加速度传感器的动态特性,即幅频特性和相频特性,从而确定传感器的固有频率ω_n和阻尼比ξ,以此来评定传感器的综合特性．     

Preparation of fibrous CoMo/Al2O3 hydrotreating catalysts by the sol-gel method

Fibrous CoMo–Al oxide hydrotreating catalysts have been prepared by the sol-gel method. It is shown that their catalytic properties are similar to the properties of commercial catalysts prepared by traditional methods.     

用均相的稀土催化剂进行丁二烯-异戊二烯本体共聚合的研究

本工作用均相的稀土催化体系Nd(naph)_3-Al(i-Bu)_2H-CH_3SiHCl_2进行了丁二烯和异成二烯的本体共聚合,研究了聚合规律和产物的结构性能.结果表明,在适当的催化剂组分比条件下,该催化体系具有较高的催化活性,用DSC测定了共聚物的玻璃化转变温度,~1H-NMR和IR分别测定了共聚物的组成和微观结构,证明共聚物的组成主要决定于单体原料的配料比,共聚物中两种单体单元都具有高顺式结构,生胶和硫化胶的性能测定表明,在丁二烯和异戊二烯两种单体的配料比为30比70时,得到的共聚胶的综合性能较好.     

A 1.2 to 6 keV soft X-ray beamline at Beijing Synchrotron Radiation Facility

A new soft X-ray beamline with double-crystal monochromator and double direction focus has been constructed at Beijing Synchrotron Radiation Facility (BSRF). The beamline covers the soft X-ray energy range from 1.2 keV up to 6 keV. There are three pairs of crystals (Si (111), InSb (111), KTP(011)) for the monochromator, separately. The performance of the crystals in respect to flux, resolving power and higher orders is discussed, and some representative results from the beamline are given. The beamline is used for a variety of experiments, for example, calibration detector, measurements of optics element characteristics and soft X-ray spectroscopy (SXS).     

稀土催化合成等规聚苯乙烯

稀土催化合成等规聚苯乙烯刘丽郑玉莲龚志＊景遐斌（中国科学院长春应用化学研究所长春１３００２２）关键词等规聚苯乙烯，稀土配位催化剂，苯乙烯，配位聚合１９９７－０１－０４收稿，１９９７－０６－０３修回催化合成等规聚苯乙烯的催化剂主要有钛、镍等体系［１，２...     

2-Amino- and 2-hydroxymethylbenzimidazolium bromides as protein tyrosine phosphatase 1В (PTP1В) inhibitors and other targets associated with diabetes mellitus

Russian Chemical Bulletin - New 2-amino- and 2-hydroxymethylbenzimidazoles were synthesized and used to prepare the previously unknown 1,2,3-tri- and 1,2,3,5-tetrasubstituted benzimidazolium...     

Metabolism of cyadox by the intestinal mucosa microsomes and gut flora of swine,and identification of metabolites by high‐performance liquid chromatography combined with ion trap/time‐of‐flight mass spectrometry

Cyadox (CYX), 2‐formylquinoxaline‐1,4‐dioxide cyanoacetylhydrazone, is an antimicrobial and growth‐promoting feed additive for food‐producing animals. To reveal biotransformation of CYX in swine intestine, CYX was incubated with swine intestinal microsomes and mucosa in the presence of an NADPH‐generating system and swine ileal flora and colonic flora, respectively. The metabolites of CYX were identified using high‐performance liquid chromatography combined with ion trap/time‐of‐flight mass spectrometry (LC/MS‐ITTOF). Structural elucidation of the metabolites was precisely performed by comparing their changes in molecular mass, full scan MS/MS spectra and accurate mass measurements with those of the parent drug. Finally, seven metabolites were identified as follows: three reduced metabolites (cyadox 1‐monoxide (Cy1), cyadox 4‐monoxide (Cy2) and bisdesoxycyadox (Cy4)); hydroxylation metabolite (3‐hydroxylcyadox 1‐monoxide (Cy3)); hydrolysis metabolite of the amide bond (N‐decyanoacetyl cyadox (Cy5)); a hydrogenation metabolite (11,12‐dihydro‐bisdesoxycyadox (Cy6)) and a side‐chain cleavage metabolite (2‐hydromethylquinoxaline (Cy7)). Only one metabolite (Cy1) was found in intestinal microsomes. Cy1, Cy2 and Cy4 were detected in intestinal mucosa, ileal and colonic flora. In addition, Cy3 and Cy5 were only obtained from ileal flora, and Cy6 and Cy7 alone were observed in colonic bacteria. The results indicated that N → O group reduction was the main metabolic pathway of CYX metabolism in swine ileal flora, intestinal microsomes and mucosa. New metabolic profiles of hydrogenation and cleavage on the side chain were found in colonic bacteria. Among the identified metabolites, two new metabolites (Cy6, Cy7) were detected for the first time. These studies will contribute to clarify comprehensively the metabolism of CYX in animals, and provide evidence to explain the pharmacology and toxicology effects of CYX in animals. Copyright © 2011 John Wiley & Sons, Ltd.