Programmed and non-programmed theories of aging

There are compelling reasons to regard aging as an evolved adaptive program. The evidence is diverse, deriving from genetics, breeding experiments, and plasticity of life span in stressful environments. But based on the classical neo-Darwinian understanding of population genetics, there are powerful theoretical reasons to believe that aging could not have evolved as an adaptation. This paradox is one of the most challenging scientific problems of our age.     

Conformational effects in the hydrogenation of hemimellitic and cyclohex-1-ene-1,2,3-tricarboxylic acids

The three possible isomers of cyclohexane-1,2,3-tricarboxylic acid were synthesised and separated in order to study the regiospecificity and stereoselectivity of the α-C alkylation of their trimethyl esters. No definitive conclusions could be reached on this aspect for reasons which became apparent in the course of the work. However, the three independent methods adopted for the synthesis of the isomeric tricarboxylic acids have given dramatically different isomer compositions. The reasons are explored in this paper.     

对广东某地引起中年妇女秃头的环境地球化学因素的初步调查

用环境地球化学的研究方法，对广东某地区引起妇女秃头的因素进行了调考，初步结果显示该病与当地河水呈弱碱性，缺钙，锡、铝偏高和人体必需元素K、Mg、Fe、Zn、Cu、Mn偏低可能有关。     

高效液相色谱仪常见故障及解决方法

介绍高效液相色谱仪的常见故障，原因及解决方法。     

Photoinduced charge transfer in poly(phenylene-vinylene) and its derivatives

Photoinduced absorption measurements on poly(phenylenevinylene), PPV, or its derivatives, illuminated with photons of energy past the absorption edge revealed that some percentage of the photons create a long-lived excitation rather than the expected excitons. We present the evidence that these excitations are polaron pairs, which are essentially excimers. The reasons why this percentage varies from sample to sample are discussed. Also discussed are the reasons why polaron pairs in some derivatives of PPV emit light while in others they do not. Calculations with a relatively simple Hamiltonian can account well for the peaks in the photoinduced absorption produced by these pairs.     

Is there an unambigous answer to the question: Whether the aging program exists or not?

The article discusses up-to-date viewpoints on the reasons of aging in respect to their compliance with the concepts of programmed or stochastic aging.     

关于钙营养的调查与分析

为了解妇女乳钙、尿钙和儿童尿钙水平，找出低钙的原因和防治因缺钙引起的一系列疾病，用ＥＤＴＡ没定法对３７５名妇女和１１６９名３￣６岁儿童尿钙进行检测，对６６名产妇初乳钙及其所生新儿尿钙进行检测，对５０名低钙儿童补钙后的尿钙进行复测。结果表明，孕妇（包括正常与非正常孕妇）尿钙低钙率７４．８％，其中正常孕妇尿钙低钙率７１．２％，妊高征妇女尿钙低钙率９２．９％，非孕妇尿钙低钙率６４．５％，产妇初乳钙低钙率     

Mechanism and controlling strategy of the production and accumulation of propionic acid for anaerobic wastewater treatment

The production and accumulation of propionic acid affect significantly anaerobic wastewater treatment system, but the reasons are not approached until now. Based on the results of continuous-flow tests and the analysis of biochemistry and ecology, two mechanisms of producing propionic acid have been put forward. It is demonstrated that the reasons of propionic acid production and accumulation are not caused by higher hydrogen partial pressure. The combination of specific pH value and ORP is the ecological factor affecting propionic acid production, and the equilibrium regulation of NADH/NAD+ ratio in cells is the physiological factor. Meanwhile, it is put forward that using the two-phase anaerobic treatment process and the ethanol type fermentation in anaerobic reactor to avoid propionic acid accumulation are efficient methods.     

影响火焰光度计稳定度的原因及解决方法

根据实践经验,系统地分析了影响火焰光度计稳定度的三种原因,并通过分析找出了相应的判断方法和解决措施。     

Regioselective ozonolytic cleavage of unsymmetric cycloalkenes

Aldehyde 2 was prepared in a one-pot sequence from olefin 12; olefin 6 did not react similarly. Possible reasons for the differences are discussed.     

Is quantum chemistry concerned with materials science?

The reasons for the surprisingly little contact between quantum chemists and materials scientists are discussed. Examples of areas where such contacts could be very beneficial are given.     

Static polarizabilities at large internuclear separations for homonuclear diatomic ions

Certain static polarizabilities for charged diatomic molecules become exceedingly large when the internuclear separation is increased. The reasons for, and implications of, this are discussed.     

Comparative studies of calculation methods for activity coefficients of unsymmetrical mixed electrolytes

Several methods for the calculation of activity coefficients for binary mixed electrolytes are compared. Their accuracies are analysed and the reasons for the different degrees of accuracies are given.     

化学专业研究生学术诚信建立的探究

针对研究生学术诚信的建立,使用质性研究方法,研究了6所一流高校化学专业的10个课题组,采用开放式访谈交流、参与式观察和实地记录等方法,深入调查了研究生学术诚信缺失的表现、原因和对策。研究发现社会不良风气、学校制度的压力和刺激、导师管理的有限性以及研究生自身问题是导致学术失信的主要原因;课题组导师使用了重复验证、附原始数据和共同完成实验的方法有效地防范了研究生学术失信行为,建立了学术诚信的观念和习惯。研究表明虽然研究生存在学术失信的可能性,但是通过采取一定的措施能够防范学术失信行为,并建立研究生的学术诚信。本研究结果可以为化学专业等实验学科的学术诚信的建立提供有用的借鉴和启发。     

Elevated rice 137Cs concentrations near the water inlet in paddy fields after the Fukushima nuclear accident

Journal of Radioanalytical and Nuclear Chemistry - The reasons why rice 137Cs concentrations increase near the water inlet were investigated using rectangular experimental plots settled in paddy...     

Hydrogen Peroxide as a Polymerization Initiator for Silicate Bleaching Solution Stabilizers

Russian Journal of General Chemistry - The article is devoted to identifying the reasons for the formation of insoluble silicate deposits on fabrics and equipment during peroxide bleaching of...     

Trimethylsilylmethyl derivatives of thallium(III)

Some trimethylsilylmethyl derivatives of thallium(III) have higher stability and unusual coordination behavior in comparison with simple alkylthallim(III) analogs for steric reasons.