头孢呋辛酯在丙酮溶液中的降解动力学研究

为了研究头孢呋辛酯丙酮溶液的稳定性,应用高效液相色谱,采用单因素方式考察初始溶液pH值、温度、氧化剂种类等条件下,头孢呋辛酯在溶液中的含量随时间的变化规律,依据化学反应动力学方法建立得到了头孢呋辛酯在不同条件下的降解反应动力学模型,回归得到了模型参数、预测半衰期(t_(1/2))。利用Materials Studio模拟软件从分子尺度对头孢呋辛酯的降解机理进行了分析。结果表明:头孢呋辛酯丙酮溶液的降解符合一级反应动力学;pH值9.54时头孢呋辛酯丙酮溶液基本稳定,pH值≥9.54时其化学稳定性变差,随着pH值的增大降解速率迅速加快、溶液颜色加深;头孢呋辛酯丙酮溶液的化学稳定性随温度的升高而变差。研究结果可为相关产品的生产过程、结晶工艺设计、存储和应用提供数据支撑。     

银莲花的抗氧化、抑菌和抗肿瘤活性

为了有效利用野生银莲花资源,将银莲花的乙醇提取物进行石油醚-丙酮梯度洗脱,得到5个组分,分别采用DPPH法、琼脂孔扩散法、MTT法进行了抗氧化、抑菌和抗人乳腺肿瘤细胞(MDA-MB-231)活性研究.结果表明:5个组分均有氧自由基清除能力,其中组分工抗氧化活性最好,半数抑制质量浓度为30.58 μg/mL;5个组分均有抑菌活性,其中组分Ⅴ抑菌活性最好.各组分和单体化合物对人乳腺肿瘤细胞均有一定的抑制作用,组分Ⅱ对人乳腺肿瘤细胞的抑制率最高,达到50.32％.     

自然风非稳态特性及其对室内环境的影响

 目前大部分自然通风的研究只考虑了简单的平均特性,假定自然风为恒定风会造成与实际效果较大误差。鉴于此,为了能更加客观精确地探讨自然通风建筑通风效果,详细综述了自然风的波动特性,并讨论了自然风波动特性对自然通风量的影响,将通风量的预测方法归纳为基于稳态条件下的修正方法和基于波动条件下的非稳态模型方法,分析了自然风的湍流强度和波动频率两个参数对人体热舒适的影响。指出需尽快建立适用于中国工程设计用的基于非稳态边界条件下的自然通风模型。     

辽河东部凸起太原组页岩孔隙结构特征研究

以辽河拗陷东部凸起海陆过渡相石炭系太原组为例,观察、描述太原组岩芯并系统采集佟2905井样品及辽宁省盘锦市小市泉山煤矿样品。通过XRD衍射、高压压汞、低温液氮吸附、场发射扫描电镜等实验手段,全面刻画了海陆过渡相页岩孔隙发育形态和孔隙结构特征。压汞实验结果显示,页岩孔径呈双峰分布,双峰分布在10 100 nm与10 000 100 000 nm,其中孔径小于100 nm孔占主体。低温液氮吸附实验弥补了压汞实验在表征页岩小孔隙上的不足,对100 nm以下的孔隙进行了更为精细的划分,实验结果表明,中孔（10 50 nm）提供了主要的孔体积,占总孔体积的33.48% 43.96%。比表面积的分布与孔径大小呈负相关,极小孔（<2 nm）和小孔（2 10 nm）为比表面积的主要贡献者,提供的比表面积占整个比表面积的82.92% 91.58%,均值为87.36%。单因素分析结果表明,页岩的比表面积主要受控于黏土含量,其相关系数为0.901,有机质影响不明显。孔隙以四面开放的平行板状孔和狭缝状孔为主,这种开放纳米孔可提高页岩气解吸效率和储层渗透率,提高页岩气产量。     

微波辅助酸改性粉煤灰对活性艳红的吸附性能研究

以浓盐酸为改性剂,微波辅助制备酸改性粉煤灰,利用SEM、FTIR对其结构进行表征,利用分光光度法研究其对活性艳红的吸附性能.结果表明:盐酸用量为4 mL/g、微波功率为400 W、微波时间为10 min时,制得的酸改性粉煤灰做吸附剂,常温下,当吸附剂用量为26 g/L、废水pH为9、吸附时间为60 min时,活性艳红脱色率达96.6%以上.     

A 457-year reconstruction of precipitation in the southeastern Qinghai-Tibet Plateau, China using tree-ring records

This paper presents a 457-year reconstruction of precipitation in the southeastern Qinghai-Tibet Plateau using tree-ring records.Tree-ring samples were collected from the Hengduan Mountains in the southeastern part of the Qinghai-Tibet Plateau,China.A nearly 500-year chronology was developed using tree-ring width records.Correlation analysis shows moisture is the main factor limiting tree growth in this region.Ring-widths were significantly positively correlated with the Palmer Drought Severity Index(PDSI) and precipitation in many months.The highest correlation coefficient was found between the annual growth of trees and precipitation from the previous September to the current June(0.738).Based on this relationship,we reconstructed the precipitation history from 1509 to 2006.The reconstruction explains 54.4%(Radj2=53.5%,N=49,F=56.12) of the actual precipitation variation during the calibration period(1958-2006).During the reliable period of the reconstruction(1549-2006),some low-frequency climate signals are included,indicating this region has been getting wetter in the last 20 years.The reconstruction documents six apparently dry and five pluvial periods and the 17th century dry period lasted longer than any other.When compared with other recent studies,this study and these earlier reconstructions show a similar trend in the variation of drought and pluvial.Further spatial correlation analysis confirms that the reconstructed precipitation adequately represents the rainfall history of the entire Hengduan Mountain area.The Multi-taper method,a type of spectral analysis,reveals that precipitation in this area had significant(P<0.01) spectral peaks at 3-5 a,60 a and 79-85 a.     

在物化之后寻找人——卢卡奇《历史与阶级意识》解读

青年卢卡奇创造性地提出了物化的概念,这与马克思的异化劳动十分相像。不过,卢卡奇的物化主要是对资本主义的负面批评,而马克思的异化劳动则看到了辩证性的一面。卢卡奇认为克服物化的方法是总体性,而总体性的执行者是无产阶级,但这种思想却有使无产阶级物化的危险。今天,克服物化仍是这个社会的主要问题,我们还是应该回到马克思关于实践的前提下,以更加丰富和多元的姿态来理解总体性,从而寻找人本身。     

第三代蜜网在园区网中的应用

蜜网（Honeynet）是信息安全领域相对较新的一个概念,主要作用是收集黑客的攻击信息。随着蜜网技术的引入,可以将安全防护从被动方式变为主动方式。阐述了第三代蜜网体系结构,分析了数据控制、数据捕获、数据采集和数据分析模块在蜜网中的实现,并介绍了蜜网在校园网中的应用。     

One-step disposal of Cr (Ⅵ)-bearing wastewater by natural pyrrhotite

Cr(VI)-bearing wastewater can be treated by natural pyrrhotite which is used for reductant to reduce Cr(VI) and precipitant to precipitate Cr(III) simultaneously. The disposal products can be divided into three parts in the beakers, namely supernatant in the upper part, the yellowish colloidal precipitates in the middle part and the pyrrhotite in the lower part. The content of total Cr=Cr(VI)+Cr(III) in the supernatant liquid is 0.06 mg/L, which is lower than 1.5 mg/L of the discharge standard of China and near to 0.05 mg/L of the standard of potable water. This one-step disposal composing of both reduction and precipitation which is traditionally divided into two independent steps called reducing technology and precipitating technology respectively. The new method is of obvious economic advantage and favourable to decreasing surplus mud derived from adding Ca(OH)₂ to precipitate Cr(III) traditionally so as to avoid recontamination. In fact, sodium sulfite (Na₂SO₃) used in disposal of Cr(VI) was traditionally produced from natural mineral of pyrrhotite (FeS). One molecule of FeS is 4 times more than that of Na₂SO₃ from a view point of rational use of mineral resources. Therefore the prospective of application of the one-step disposal of Cr(VI) method is full of promise.