[Zn（bipy）（H2O）2SO4]的合成及晶体结构研究

在乙醇水溶液中合成了标题配位聚合物[Zn（bipy）（H2O）2SO4]（bipy=2,2’-bipyri—dine）,进行了元素分析、X射线衍射等表征。X射线衍射结果表明,此配合物属单斜晶系,空间群为Cc,晶胞参数为：a=1．5434（5）nm,b=1．2706（6）nm,C=0．6699（8）nm,β=102．106（0）°,V—1．2847（4）nm^3,Z=4,Dc=1．828g／cm^3,μ=2．101mm^-1,F（000）-720。配合物中的金属锌离子与一个2,2’-联吡啶、2个水分子和一个硫酸根离子配位,形成一个变形的四方锥结构。配合物通过硫酸根形成一维直链,一维链再通过π-π堆积形成双链结构,双链结构通过O—H…O氢键扩展成二维网,二维网进一步通过C—H…O氢键构建为三维超分子。     

测定工业废水中铬（Ⅵ）的新方法

基于在HAc—NaAc缓冲介质中,Cr（Ⅵ）能显著催化高碘酸钾氧化罗丹明B进行褪色,同时加入十六烷基三甲基溴化铵作为增敏剂,灵敏度大大提高,建立了测定工业废水中Cr（Ⅵ）的新方法．研究了影响催化褪色反应速度的条件,在最优化条件下,Cr（Ⅵ）浓度在0．004～0．28μg／mL范围内与吸光度呈良好的线性关系,方法的检出限为3×10^-5μg／mL,对浓度为0．012μg／mL Cr（Ⅵ）标准溶液进行11次平行测定的相对标准偏差（RSD）为0．1％．该法具有灵敏度高、选择性好等特点,已用于工业废水中Cr（Ⅵ）的测定,回收率为90％～102％,结果令人满意．     

Microbial activity and community diversity in a variable charge soil as affected by cadmium exposure levels and time

Effects of cadmium （Cd） on microbial biomass, variable charge soil （Typic Aquult） using an incubation study activity and community diversity were assessed in a representative Cadmium was added as CdCNO3）2 to reach a concentration range of 0-16 mg Cd/kg soil. Soil extractable Cd generally increased with Cd loading rate, but decreased with incubation time. Soil microbial biomass was enhanced at low Cd levels （0.5-1 mg/kg）, but was inhibited consistently with increasing Cd rate. The ratio of microbial biomass C/N varied with Cd treatment levels, decreasing at low Cd rate （〈0.7 mg/kg available Cd）, but increasing progressively with Cd loading. Soil respiration was restrained at low Cd loading （〈1 mg/kg）, and enhanced at higher Cd levels. Soil microbial metabolic quotient （MMQ） was generally greater at high Cd loading （1-16 mg/kg）. However, the MMQ is also affected by other factors. Cd contamination reduces species diversity of soil microbial communities and their ability to metabolize different C substrates. Soils with higher levels of Cd contamination showed decreases in indicator phospholipids fatty acids （PLFAs） for Gram-negative bacteria and actinomycetes, while the indicator PLFAs for Gram-positive bacteria and fungi increased with increasing levels of Cd contamination.     

Attenuating effect of daidzein on polychlorinated biphenyls-induced oxidative toxicity in mouse testicular cells

The attenuating effect of daidzein （DAI） on oxidative toxicity induced by Aroclor 1254 （A1254） was investigated in mouse testicular cells. Cells were exposed to A1254 alone or with DAI. The oxidative damage was estimated by measuring malondialdehyde （MDA） formation, superoxide dismutase （SOD） activity and glutathione （GSH） content. Results show that A1254 induced a decrease of germ cell number, an elevation in thiobarbituric acid reactive substances （TBARS） but a decrease in SOD activity and GSH content. However, simultaneous supplementation with DAI decreased TBARS level and increased SOD activity and GSH content. Consequently, dietary DAI may restore the intracellular antioxidant system to attenuate the oxidative toxicity of A 1254 in testicular cells.     

On indexing in the Web of Science and predicting journal impact factor

We discuss what document types account for the calculation of the journal impact factor （JIF） as published in the Journal Citation Reports （JCR）. Based on a brief review of articles discussing how to predict JIFs and taking data differences between the Web of Science （WoS） and the JCR into account, we make our own predictions. Using data by cited-reference searching for Thomson Scientific＇s WoS, we predict 2007 impact factors （1Fs） for several journals, such as Nature, Science, Learned Publishing and some Library and Information Sciences journals. Based on our colleagues＇ experiences we expect our predictions to be lower bounds for the official journal impact factors. We explain why it is useful to derive one＇s own journal impact factor.     

Accuracy of a combined score of zygote and embryo morphology for selecting the best embryos for IVF

Objective： To evaluate the accuracy of a scoring system combining zygote and embryo morphology in predicting the outcome of in vitro fertilization （IVF） treatment. Methods： In a study group, 117 consecutive IVF or intracytoplasmic sperm injection （ICSI） cycles with embryo transfer were carried out and 312 embryos were scored using a combined scoring system （CSS） of zygote and embryo morphology before transplantation. In a control group, a total of 420 IVF or ICSI cycles were carried out and 1176 embryos were scored using a cumulative embryo score （CES）. The effects of the combined scoring system on the embryo implantation rate and pregnancy rate per cycle were analyzed. Results： Using the combined scoring system, the embryo implantation rate （27.6%） and the clinical pregnancy rate （48.7%） were significantly higher than those in the control group （20.8% and 38.6%, respectively）. Also, the implantation rate of embryos scoring ≥70 （38.5%： 82 sacs/213 embryos） was significantly higher （P〈0.001） than that of embryos scoring 〈70 （4%： 4 sacs/99 embryos）. The pregnancy rate of patients with embryos scoring ≥70 using the combined scoring system （66.7%） was significantly higher （P〈0.001） than that of patients with embryos scoring ≥20 using the cumulative embryo score （59.0%）. Conclusion： The results suggest that selecting embryos with a high score （≥70） using the combined scoring system could increase the implantation rate and pregnancy rate, and that using a scoring system combining assessments of human zygotes and pre-implantation embryos might predict IVF outcomes more accurately than using a cumulative embryo score.     

浅论两汉时期常用词“皮”、“肤”的历时替换

考察了常用词“皮”、“肤”在两汉时期的历时更替情况,认为先秦时期,总体上看,“皮”表示动物的皮,“肤”表示人的皮肤,二者有着明确的分工。在口语中,“皮”对“肤”的取代从东汉中前期开始,到东汉末年这种替代关系基本完成,“皮”成为表示人和动物皮肤的常用词,同时,复音词“皮肤”逐渐活跃。“皮”和“肤”之间的替换过程鲜明地反映出了两汉时期,尤其是东汉时期的词汇特点。     

HPMBP缩对氟苄胺合Ni（Ⅱ）配合物的合成、表征和量化计算

合成1-苯基-3-甲基-4-苯甲酰基-吡唑啉酮-5（HPMBP）缩对氟苄胺席夫碱合Ni（Ⅱ）配合物,用红外、紫外光谱及元素分析进行结构表征,并对其进行了量子化学计算.结果表明,参与配位的N、O原子具有很强的接受和转移电子的能力,此配合物的活性部位主要是芳香环.     

Ce（NH4）2（NO3）6对玉米种子萌发和幼苗根系活力的影响

用不同浓度Ce（NH4）2（NO3）6对玉米种子浸种,探讨了外源Ce（NH4）2（NO3）6对种子萌发、幼苗根系活力、脯氨酸含量及细胞膜透性的影响.结果表明：用10-20 mg/L Ce（NH4）2（NO3）6浸种24 h,可增强玉米种子在萌发时的α-淀粉酶活性,提高种子活力、萌发率及幼苗根系活力,脯氨酸含量增加,幼苗细胞膜相对透性降低;用50-100 mg/L Ce（NH4）2（NO3）6浸种后,发现种子活力、脯氨酸含量及幼苗根系活力下降,幼苗细胞膜相对透性增加.     

基于直接数字频率合成技术的信号发生器

本文利用直接数字频率合成技术,以单片机PIC16F818作为控制中心,选用AD9850作为信号发生器,可编程产生0Hz-400MHz间任意频率信号,并以产生频率为100kHz的正弦信号为实例。采用直接数字频率合成技术产生的信号频率稳定,分辨率高且操作方便,在工程应用中前景非常广泛。