高效液相色谱法测定扭盔马先蒿中毛蕊花苷的含量

[目的]建立HPLC法测定扭盔马先蒿中毛蕊花苷含量的方法。[方法]采用HPLC法Kromasil C18柱（250mm×4．6mm,5μm）,乙腈-1％冰醋酸溶液（1：4）为流动相,在330nm波长下测定样品中毛蕊花苷的含量。[结果]该方法专属性强,平均加样回收率为96．87％,RSD值为2．18％（n=5）。[结论]该方法方便,分离效果好,适用于扭盔马先蒿的鉴别和质量的控制。     

钙掺杂钛酸钡陶瓷纤维的研究

采用溶胶-凝胶法,以醋酸钡、醋酸钙和钛酸丁酯为原料,冰醋酸为催化剂,制备了钙掺杂钛酸钡陶瓷纤维.发现当钙的掺杂量物质的量分数为0.05,0.10,0.15,0.20,0.25时溶胶具有可纺性,掺杂量物质的量分数为0.30,0.35时能形成溶胶,但溶胶不具有可纺性,掺钙量物质的量分数为0.40时不能形成溶胶.应用热分析、...     

Manipulation of the wettability of surfaces on the 0.1- to 1 -micrometer scale through micromachining and molecular self-assembly

Micromachining allows the formation of micrometer-sized regions of bare gold on the surface of a gold film supporting a self-assembled monolayer (SAM) of alkanethiolate. A second SAM forms on the micromachined surfaces when the entire system-the remaining undisturbed gold-supported SAM and the micromachined features of bare gold-is exposed to a solution of dialkyl disulfide. By preparing an initial hydrophilic SAM from HS(CH(2))(15)COOH, micromachining features into this SAM, and covering these features with a hydrophobic SAM formed from [CH(3)(CH(2))(11)S](2), it is possible to construct micrometer-scale hydrophobic lines in a hydrophilic surface. These lines provide new structures with which to manipulate the shapes of liquid drops.     

杀菌剂离体生物测定的稳定性探讨

研究了药剂稀释方法、药液保存时间、溶解药剂的溶剂对杀菌剂平板法生物测定稳定性的影响.结果表明:药剂以2/3的比例系列稀释时多次测定标准差最小,表现最稳定.戊唑醇溶解于丙酮冰箱保存13 d,对水稻纹枯病菌的活性影响不大,说明这种药剂在溶剂中较稳定.福美双用丙酮溶解后降解速度较快,降解方程为y=0.301 6x+2.167 8,r=0.943 2.戊唑醇溶于丙酮、二甲基甲酰胺、氯仿、二氯甲烷、甲苯等多种溶剂,对水稻纹枯病菌的活性影响不大,多菌灵溶于盐酸、甲酸、乙酸、硫酸后,使水稻纹枯病菌的活性产生较大差异,这可能是多菌灵与这些溶剂形成不同的轭合物后导致活性的变化.     

多元协同萃取的研究(Ⅱ)——ABB类三元体系对Nd(Ⅲ)的协同萃取

本文用单浓度递变斜率法研究了两组酸性螫合—中性络合—中性络合三元体系对Nd(Ⅲ)的协同萃取机理,分别测定了Nd~(3+)(≤10~(-4)M)/NaClO_4,HClO_4(μ=0.1)/PMHP-D;AMP-DASO-C_6H_5CH_3体系的协萃物组成为NdA_3BS,协萃平衡常数K_(ABS)=0.50。用同样的方法,测定了Nd~(3+)(≤10~(-4)M)/NaClO_4,HClO_4(μ=0.1)/TTA-D;AMP-DASO-C_6H_5CH_3体系的协萃物组成为NdT_3BS,协萃平衡常数为K_(TBS)=2.4,并对结果进行了比较和讨论,结果表明:配位体的空间位阻效应对同类协萃物的稳定性影响很大,也是导致K_(TBS)>K_(ABS)结果的主要原因。     

环保型麻风树种子蛋白胶黏剂的制备及机理研究

以麻风树种子蛋白为原料,以三聚氰胺乙二醛（MG）树脂和环氧树脂（EPR）为交联剂,旨在为相关人造板产品尤其是胶合板制备另一种新型蛋白胶黏剂。采用红外光谱（FT-IR）、核磁共振碳谱（¹³C-NMR）、电喷雾电离质谱（ESI-MS）等分析其制备机理,同时通过检测蛋白胶胶合板性能,分析胶黏剂制备机理与实际应用之间的关系。结果表明,MG含有大量支链型的-NH-(CH)OH基团,与蛋白质的氨基等活性基团具有较好亲和性。环氧树脂与蛋白氨基反生反应,主要以N-1取代为主。单独以EPR或MG交联改性的蛋白胶不能同时满足Ⅰ、Ⅱ类胶合板强度要求。MG和EPR两者共同作为交联剂时,可以增加改性后麻风树种子蛋白胶黏剂的内聚强度和交联密度,使改性后蛋白胶同时满足Ⅰ、Ⅱ类胶合板胶接强度和耐水性能要求。综合改性后麻风树种子蛋白胶黏剂的制备成本和使用性能,4%三聚氰胺-乙二醛树脂+1%环氧树脂为最佳交联剂配方。     

Watching vibrational energy transfer in liquids with atomic spatial resolution

Ultrafast spectroscopy was used to study vibrational energy transfer between vibrational reporter groups on different parts of a molecule in a liquid. When OH stretching vibrations of different alcohols were excited by mid-infrared laser pulses, vibrational energy was observed to move through intervening CH2 or CH groups, taking steps up and down in energy, ending up at terminal CH3 groups. For each additional CH2 group in the path between OH and CH3, the time for vibrational energy transfer increased by about 0.4 picosecond.     

木材用淀粉基复合胶黏剂的制备与性能

采用次氯酸钠对玉米淀粉进行氧化制备淀粉胶黏剂,再用功能内交联剂(异氰酸酯)共混改性制备淀粉基复合胶黏剂。考查了复合胶黏剂体系的pH、PVA质量分数与用量、淀粉用量、异氰酸酯加入比例对淀粉基复合胶黏剂胶接性能的影响。胶接实验结果表明:利用变性的氧化淀粉,PVA质量分数为10%,PVA加入比例为3/5,淀粉与水比为3/8时,获得最佳的胶结强度和耐水性能。采用XPS分析胶层化学结构,结果表明:异氰酸酯与淀粉胶黏剂、木材中的羟基反应形成化学键结合是提高胶接强度和耐水性关键所在。所制得的改性淀粉胶黏剂性能更加优异,符合Ⅱ类胶合板的使用要求。     

中国稻田甲烷排放及其影响因素的统计分析

【目的】阐明中国不同稻作类型CH4排放的区域特征以及稻田CH4排放与环境因子和水肥管理的定量关系。【方法】通过文献调研,获得1987-2011年中国稻田CH4排放观测的有效文献111篇,含生长季CH4排放总量或平均排放通量的有效观测数据495组,涵盖67个观测点。采用方差分析、相关分析和逐步回归方法对上述观测数据进行分析。【结果】中国单季稻、双季早稻和晚稻田的CH4季节排放总量（均值±标准误差）分别为（383.5±31.1）、（234.3±16.8）和（361.8±25.0）kg•hm-2。西南单季稻区CH4排放分别是华北、华中和东北单季稻区的2.3、2.2和4.3倍;华中早、晚稻区的CH4排放分别是两广早、晚稻区的2.6和1.9倍。稻田CH4排放与有机肥施用量呈正相关,与化肥氮施用量及土壤pH呈负相关;单季稻区CH4排放随纬度升高和经度增加而降低,双季稻区CH4排放则随纬度升高而增加;单季稻区CH4排放随土壤全氮含量的增加而降低,但晚稻区则反之。综合影响中国单季稻田CH4排放的因子为纬度、土壤C/N比、砂粒含量、水分管理方式、有机肥和化肥氮施用量,这6个因子的变化可解释CH4排放空间变异的72%;早稻田CH4排放空间变异的35%可由土壤C/N比、砂粒含量、移栽-抽穗期平均温度、水分管理和有机肥施用量等5个因子的变化得以解释;纬度、土壤C/N比、黏粒含量、pH值、全生育期平均温度和有机肥施用量等6个因子可解释中国晚稻田CH4排放空间变异的47%。【结论】中国稻田单位面积CH4排放量总体为单季稻＞晚稻＞早稻,但单季稻与晚稻田的CH4排放无显著差异。西南单季稻区的CH4排放显著高于其它单季稻区,华中双季稻区的CH4排放显著高于两广稻区。由环境和水肥管理因子决定的多元统计模型能较好地解释中国稻田CH4排放的空间变异,单季稻CH4排放模型的可解释性优于双季稻。     

淀粉−糠醛共缩聚木材胶黏剂的制备

在酸性和碱性条件下采用糠醛与淀粉反应制备生物基热固性淀粉−糠醛树脂胶黏剂,对其基本理化性能、胶合板干状和湿状剪切强度进行测试,应用电喷雾质谱对其结构进行测定应用差示扫描量热法对其固化行为进行分析。结果表明：在pH为5、糠醛与淀粉质量比为1∶2的条件下,淀粉与糠醇发生了共缩聚反应,其分子结构主要通过－CH₂－O－键连接;糠醛的加入降低了淀粉胶黏剂的凝胶时间,弱酸性条件下合成的淀粉−糠醛胶黏剂制备胶合板的干状、湿状剪切强度较碱性条件下合成的淀粉−糠醛基刨花板的剪切强度值高。     

Silver-catalyzed C-C bond formation between methane and ethyl diazoacetate in supercritical CO₂

Even in the context of hydrocarbons' general resistance to selective functionalization, methane's volatility and strong bonds pose a particular challenge. We report here that silver complexes bearing perfluorinated indazolylborate ligands catalyze the reaction of methane (CH(4)) with ethyl diazoacetate (N(2)CHCO(2)Et) to yield ethyl propionate (CH(3)CH(2)CO(2)Et). The use of supercritical carbon dioxide (scCO(2)) as the solvent is key to the reaction's success. Although the catalyst is only sparingly soluble in CH(4)/CO(2) mixtures, optimized conditions presently result in a 19% yield of ethyl propionate (based on starting quantity of the diazoester) at 40°C over 14 hours.     

超微粉碎对鱼腥草中金丝桃苷和槲皮苷溶出的影响

应用高效液相色谱法(HPLC)比较了普通粉碎和超微粉碎对鱼腥草中主要功能性成分金丝桃苷和槲皮苷溶出量的影响.色谱条件为:Sh im adzu C18(250 mm×4.6 mm,5μm)、流动相为乙腈和1%(体积分数)冰醋酸(体积比为16∶84)、流速1.0 m.m in-1、检测波长360 nm.结果表明,超微粉碎不会改变鱼腥草固有的功能性成分,还能提高金丝桃苷和槲皮苷的溶出量,超微粉分别比细粉提高34.45%和40.21%.     

Untangling desmosomal knots with electron tomography

Cell adhesion by adherens junctions and desmosomes relies on interactions between cadherin molecules. However, the molecular interfaces that define molecular specificity and that mediate adhesion remain controversial. We used electron tomography of plastic sections from neonatal mouse skin to visualize the organization of desmosomes in situ. The resulting three-dimensional maps reveal individual cadherin molecules forming discrete groups and interacting through their tips. Fitting of an x-ray crystal structure for C-cadherin to these maps is consistent with a flexible intermolecular interface mediated by an exchange of amino-terminal tryptophans. This flexibility suggests a novel mechanism for generating both cis and trans interactions and for propagating these adhesive interactions along the junction.     

草木樨籽实有毒成分及用作家禽饲料的研究

本试验主要利用呼市地区所产草木樨籽实为原料，选择不同的方法脱毒，筛选出焙炒法。０．２％ＮａＨＣＯ３法，Ｏ．６％乙酸法、浸泡法、发酵法、沸石粉法，进行肉鸡的饲喂试验，其中对照组日粮不含草木樨籽实，其它各处理组的５０％豆饼用相应的草木樨籽实取代，得出结论为：用焙炒法处理后的草木樨籽实用于喂鸡，采食量日增重不受影响，且鸡体不受毒素侵害，用发酵法、ＮａＨＣＯ３法、浸泡法、乙酸法处理的草木樨籽实喂鸡，采食量、日增重不受明显影响，鸡体受到轻微毒害；用未经处理和沸石粉处理的草木樨籽实喂鸡，鸡体受到较严重侵害，同时采食量、日增重下降。     

8种新疆产干果的红外光谱特征研究

分析了新疆产8种干果的红外光谱特征。这8种干果可分为两类，其红外图谱在官能团区有很大差异。巴旦木、核桃仁、花生仁、带壳杏仁富含蛋白质和脂类物质，红外图谱显示出在2914，2847cm^-1附近的CH伸缩振动和1742cm^-1附近的C=O伸缩振动；枸杞子、红枣、葡萄干和无花果干富含多糖、蛋白类物质，其红外图谱显示出在3370cm^-1附近的OH变形振动、NH伸缩振动和2920cm^-1附近的CH伸缩振动。     

N,O-羧甲基壳聚糖抗菌染料的制备研究

以壳聚糖(CTS)和活性艳蓝KN-R染料为原材料,通过两步反应法制备新型N,O-羧甲基壳聚糖染料,用红外光谱(FTIR)、X射线衍射(XRD)、元素分析仪分析其结构和化学基团,并用紫外可见分光光度计对其水溶性进行检测;采用常压浸渍法制备N,O-羧甲基壳聚糖染料染色薄木,用光谱光度仪进行表面颜色及日晒和水洗色差测量;用菌落计数法定量表征其抗菌性能。结果表明:CTS分子中大量—OH、少量—NH2基团被—CH2COOH基团取代,染料中的—SO-3和N,O-羧甲基壳聚糖中质子化的—NH+3发生反应;羧甲基化和染料接枝反应使得CTS结晶度下降;N,O-羧甲基壳聚糖染料的水溶性得到显著改善;N,O-羧甲基壳聚糖染料可明显改善薄木的染色效果,且染色薄木的耐日晒和耐水洗牢度均提高;N,O-羧甲基壳聚糖染料染色薄木的抗菌性能优于活性艳蓝KN-R染色薄木。      

中国不同草本功能群叶片钾含量的空间格局及控制因素

[目的]钾是维持植物生长和水分高效利用的重要生命元素,特别在当前干旱化趋势增强的背景下尤为重要.但是,前人关于植物钾元素的研究主要集中在局部尺度上,仍然不清楚大尺度上不同草本功能群叶片钾含量的空间格局及控制因素有何差异.[方法]本研究基于中国164个地点739种草本植物,旨在揭示不同功能群叶片钾含量的空间格局及其与气候...     

Atmospheric residence time of CH3Br estimated from the junge spatial variability relation

The atmospheric residence time for methyl bromide (CH3Br) has been estimated as 0.8 +/- 0.1 years from its empirical spatial variability relative to C2H6, C2Cl4, CHCl3, and CH3Cl. This evaluation of the atmospheric residence time, based on Junge's 1963 general proposal, provides an estimate for CH3Br that is independent of source and sink estimates. Methyl bromide from combined natural and anthropogenic sources furnishes about half of the bromine that enters the stratosphere, where it plays an important role in ozone destruction. This residence time is consistent with the 0.7-year value recently calculated for CH3Br from the combined strength estimates for its known significant sinks.     

C-cadherin ectodomain structure and implications for cell adhesion mechanisms

Cadherins are transmembrane proteins that mediate adhesion between cells in the solid tissues of animals. Here we present the 3.1 angstrom resolution crystal structure of the whole, functional extracellular domain from C-cadherin, a representative "classical" cadherin. The structure suggests a molecular mechanism for adhesion between cells by classical cadherins, and it provides a new framework for understanding both cis (same cell) and trans (juxtaposed cell) cadherin interactions. The trans adhesive interface is a twofold symmetric interaction defined by a conserved tryptophan side chain at the membrane-distal end of a cadherin molecule from one cell, which inserts into a hydrophobic pocket at the membrane-distal end of a cadherin molecule from the opposing cell.     

酸枣仁总生物碱提取方法研究

[目的]确定从酸枣仁中提取总生物碱的最适方法和最佳提取条件.[方法]在单因素优化试验的基础上采用正交试验设计,比较优化了溶剂回流法提取酸枣仁总生物碱的工艺条件.[结果]溶剂回流法提取酸枣仁总生物碱的最佳条件为:以乙醇为提取溶剂,乙酸辅助提取,质量分数为20％乙酸的乙醇溶液(即,乙醇∶乙酸=80∶20(v/v)),以20∶1的液固比,在60℃下回流提取4.0h.[结论]该方法得到的提取物较之正交优化前酸枣仁提取物中的总生物碱含量可提高60％以上,且获得的总生物碱粗提物得率可达11％.