长白山4种森林凋落物分解过程中养分动态变化

于2003年5月至2004年9月,在长白山自然保护区北坡垂直植被带的4种林分(阔叶红松林、红松云冷杉林、岳桦云冷杉林和岳桦林)内,利用凋落物原位减少法对凋落物分解过程中的养分动态变化进行了研究。结果表明:4种森林凋落物分解过程中C质量分数变化幅度不大,N和P质量分数都是先上升后下降;K质量分数呈逐渐降低的趋势;阔叶红松林、红松云冷杉林、岳桦云冷杉林和岳桦林凋落物的养分年释放总量依次为1380.80、1145.46、418.74和599.91kg.hm-2.a-1。

黄土高原气候变迁、植被演替与土壤干层的形成

2 .5Ma B.P.以来 ,受地球轨道要素周期性变化和青藏高原阶段性强烈隆升的影响 ,黄土高原地区气候存在着干期与湿润交替出现的现象 ,但总的趋势是向干旱化方向演化。黄土高原第四纪以来草本植物一直较为繁茂 ,木本植物仅在少数几个时期处于优势地位。现代黄土高原人工林草植被普遍存在着土壤干层问题。土壤干层的形成是气候干旱化过程中必然出现的现象 ,它是导致植被演替的直接原因之一。人工植被激发并强化了土壤干层的形成。土壤干层的形成是气候干旱化和人工植被选择不当两个方面综合作用的结果 ,但有望通过有关人工措施使其危害得到缓解

Utilizing a CdTe quantum dots-enzyme hybrid system for the determination of both phenolic compounds and hydrogen peroxide

In this paper, we attempt to construct a simple and sensitive detection method for both phenolic compounds and hydrogen peroxide, with the successful combination of the unique property of quantum dots and the specificity of enzymatic reactions. In the presence Of H2O2 and horseradish peroxidase, phenolic compounds can quench quantum dots' photoluminescence efficiently, and the extent of quenching is severalfold to more than 100-fold increase. Quinone intermediates produced from the enzymatic catalyzed oxidation of phenolic compounds were believed to play the main role in the photoluminescence quenching.

聚碳酸亚丙酯对聚(β-羟基丁酸酯-β-羟基戊酸酯)结晶行为的影响

用 FTIR和 DSC研究了 PHBV及其与聚碳酸亚丙酯 ( PPC)熔融共混样的熔融结晶行为和等温结晶动力学 .结果表明 ,PHBV与 PPC熔融共混过程中发生了酯交换反应 ,两组分间存在一定的相互作用 .PPC虽然能降低 PHBV结晶折迭链的表面自由能 ,但同时也能够降低 PHBV的结晶度、球晶径向生长速率、平衡熔点和结晶能力.

End-column amperometric detection of 6-mercaptopurine by capillary zone electrophoresis

End-column amperometric detection of 6-mercaptopurine by capillary zone electrophoresis was described with high resolution and speed. The detection conditions were optimized and the electrochemical behavior was observed. Under the optimal conditions: detection potential of 1.2 V ( vs. Ag/AgCl), operating voltage of 15 kV, sample injection of 3 s at 15 kV and 10 mmol/l Na2HPO4 buffer, the detection limit for 6-MP was as low as 1 x 10(-7) mol/L and the linear range was from 5 x 10(-4) to 5 x 10(-6) mol/L with the relative coefficient of 0.995. The RSD of reproducibility for peak current and migration time was 2.5% and 1.2%, respectively. This method was utilized in assay real sample of human mine and bovine serum albumin containing 6-mercaptopurine.

毛细管区带电泳柱端安培检测抗癌药物巯嘌吟

报道了一种高效快速检测抗癌药物巯嘌呤的方法——毛细管区带电泳柱端安培检测.考察了巯嘌呤的电化学行为.在最佳操作条件下,获得此药物的检测限为1×10~(-7)mol/L;线性范围为5×10~(-4)～5×10~(-6)mol/L;相关系数为0.995,重现性良好.并用该法检测了人尿样及牛血清蛋白中的巯嘌呤.

麝鼠香化学成分的色谱-质谱分析

用常规化学分析法测得麝鼠香含粗脂肪９３．０％，含水分６．８％。ＧＣ／ＭＳ联机分析麝鼠香醚提物，共鉴定出１９种化学成分，主要是大环酮类和脂肪酸类化合物，其中环十七烷酮、环十七烯酮、环十五烷酮和环十五烯酮的含量较高，色谱峰面积分别占１３．５０％、６．３２％、７．２１％和４．１５％。７种大环酮的ＥＩ电离质谱图有相似的谱态和一些相同的碎片离子，烯丙基离子（ｍ／ｚ ４１）和烯羰基离子（ｍ／ｚ ５５）是基峰。

Study on relationship between partition coefficient of compounds and topological indices

In this work, the A(m) indices and the molecular connectivity indices of fifty aromatic compounds have been calculated, and applied for studying on relationship between partition coefficient and structure of aromatic compounds. The results demonstrate that the property of compounds can be described better with revisionary A(m) indices.

有机化合物的疏水参数与拓扑指数相关性的研究

本文计算了50个芳烃类化合物的A_m指数与分子联接性指数,并将其用于芳烃类化合物的结构与疏水参数lgP的相关性研究,结果表明,经改进的A_m指数能更好地反映这类化合物的结构特性.

EXTENDED ADJACENCY MATRIX INDEXES AND THEIR APPLICATIONS

In this paper, new topological indices, EA Sigma and EAmax, are introduced. They are based on the extended adjacency matrices of molecules, in which the influences of factors of heteroatoms and multiple bonds were considered. The results show that EA Sigm

蓖麻油-甲基丙烯酸甲酯AB交联聚合物的研究

将蓖麻油与顺丁烯二酸酐反应,合成端乙烯基蓖麻油,再与甲基丙烯酸甲酯共聚,制得了组成不同的一系列AB交联聚合物,研究了它们的动态性能、力学性能和形态结构与组成的关系.

Gas hydrate occurrence on the continental slope of the northern South China Sea

High-resolution multi-channel seismic data and geological samples were collected during two research cruises of the R/V FENDOU 4 in 1999 and 2000. Studies on these data and samples together with results from sites 1143-1145 and 1148 of ODP Leg 184 suggest that the geological structure on the continental slope of the northern South China Sea is favorable for the formation of gas hydrates. Bottom simulating reflectors (BSRs) and geochemical anomalies which indicate the existence of gas hydrates have been recognized in sediments of the Xisha Trough, the Dongsha Rise and the accretionary wedge of the Manila subduction zone. These gas hydrates are generated by two different mechanisms depending on the tectonic regime and the seismic and geochemical characteristics. The first applies to the passive continental margin of the nor-them South China Sea on the Dongsha Rise and in the Xisha Trough. The gas hydrates are associated with diapiric structures, active faults, slumps and gravity flows as well as high Late Cenozoic sedimentation rates. Their seismic expression includes BSRs, seismic blanking zones and velocity anomalies. The second mechanism is operative on the active continental margin along the Manila subduction zone, especially in the accretionary wedge. Here, gas hydrate occurrence is marked by widespread BSRs and acoustic 'pull-down' possibly related to the existence of free gas in the sediments beneath the BSR. The thickness of the seismic blanking zones averages 250 m, suggesting that the stable gas hydrate zone has about the same thickness. (c) 2005 Elsevier Ltd. All rights reserved.

回转器及其应用

叙述了在自动控制、仪器仪表、信号变换以及传感器信号采集与处理等电路中实现大时间常数的一种新方法。根据近代电工理论中的回转器原理 ,利用运算放大器及电阻、电容器件可以实现模拟电容和模拟电感。给出了理论计算与应用实例