建立小流域治理成果的巩固机制

建立小流域治理成果的巩固机制中国科学院沈阳应用生态研究所殷秀岩在生态环境恶化，经济贫困的辽酉低山丘陵地区，推进农业生产，发展农村经济，实现农业现代化经营，还存在着许多困难。其中整治生态环境，巩固其治理成果，改善生存条伴，增加人们的经济收入是最突出的问...

辽细辛提取物对灰葡萄孢菌的抑制效果

采用生长速率法和孢子萌发法测定了辽细辛根的不同溶剂(石油醚、氯仿、乙酸乙酯、乙醇)粗提取物和精油对引起黄瓜灰霉病的灰葡萄孢菌菌丝生长和孢子萌发的作用。结果表明,细辛不同溶剂提取物和精油对灰葡萄孢菌的菌丝生长和孢子萌发均有一定的抑制作用,且对孢子萌发的抑制效果好于对其菌丝生长的抑制效果;石油醚提取物和精油的抑菌效果较好,对菌丝生长的EC50分别为177.44 mg/L和159.98 mg/L,对孢子萌发的EC50分别为173.23 mg/L和125.29 mg/L;试验还显示细辛所含的主要抑菌活性成分易被极性小的有机溶剂所提取。

水稻重金属镉含量与土壤质量关系的研究

采用盆栽试验的方法,考察了土壤中不同浓度的镉对水稻生长、结实及重金属镉富集的影响以及镉在水稻植株的分布情况,并进一步研究了糙米(可食部位)对镉的富集量与土壤中镉总量和有效态镉含量的关系。研究表明:低浓度的镉对水稻生长稍有促进作用,高浓度的镉对其生长并没有明显的抑制作用;镉在水稻植株中总的分布趋势为根>茎>稻壳>糙米;用4种有效态提取剂(0.1 mol/L CaCl2、DTPA、0.05 mol/L EDTA和1 mol/L NH4OAc)浸提出的有效态镉的含量和土壤中镉总量与水稻糙米中镉含量均达到显著相关水平,并确定了它们的临界值分别为CaCl2-Cd=0.71 mg/kg,DTPA-Cd=1.34 mg/kg,EDTA-Cd=0.76 mg/kg,NH4OAc-Cd=0.77 mg/kg。

影响油脂茴香胺值和过氧化值的因素

<正>油脂氧化的最初产物是氢过氧化物,其数量可用测定碘化钾与它作用放出的游离碘多少而定量,每千克油脂所产生的碘的毫克当量数即该油的过氧化值,它是测量油脂最初氧化程度的指标。

Compatibilization effects of block copolymers in high density polyethylene/syndiotactic polystyrene blends

Three triblock copolymers of poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) of different molecular weights and one diblock copolymer of poly[styrene-b-(ethylene-co-butylene)] (SEB) were used to compatibilize high density polyethylene/syndiotactic polystyrene (HDPE/sPS, 80/20) blend. Morphology observation showed that phase size of the dispersed sPS particles was significantly reduced on addition of all the four copolymers and the interfacial adhesion between the two phases was dramatically enhanced. Tensile strength of the blends increased at lower copolymer content but decreased with increasing copolymer content. The elongation at break of the blends improved and sharply increased with increments of the copolymers. Drop in modulus of the blend was observed on addition of the rubbery copolymers. The mechanical performance of the modified blends is strikingly dependent not only on the interfacial activity of the copolymers but also on the mechanical properties of the copolymers, particularly at the high copolymer concentration. Addition of compatibilizers to HDPE/sPS blend resulted in a significant reduction in crystallinity of both HDPE and sPS. Measurements of Vicat softening temperature of the HDPE/sPS blends show that heat resistance of HDPE is greatly improved upon incorporation of 20 wt% sPS.

Radiation crosslinking of biodegradable poly(butylene succinate) at high temperature

Poly(butylene succinate), (PBS) with different molecular weight was gamma -irradiated at different temperatures and various doses. PBS with high molecular weight and smaller peak area of crystal melting gave the highest gel content at the same temperatures and dose. A two-step irradiation (irradiation in molten state after irradiation at room temperature) gave the highest gel content in different conditions. This is due to the formation of network structure by pre-irradiation at room temperature that leads to less degradation. PBS prepared by two step irradiation was effective for improvement of heat stability because of high gel content formation. Unirradiated PBS sheets broke immediately at 110 degrees, while the irradiated sample (gel fraction, 50%) by a two step-method did not break even up to 200 minutes at 130 degreesC. The PBS sheets are biodegradable even after crosslinking.

人工合成聚己内酯体内降解的研究

探讨新型可降解材料聚己内酯(PCL)生物体内的降解性质。方法采用重量、分子量以及弯曲强度和弯曲模量、热力学性质等指标，观察植入兔背部肌肉中3、6、9、12周的聚己内酯材料的降解性能。结果材料在植入12周时，重量变化不明显，分子量下降不到15%，材料弯曲强度由植入前的(30.52±2.94)mPa变化为(31.96±1.33)mPa；弯曲模量由植入前的(242.32±16.06)mPa变化为(231.05±23.30)mPa；超微形态及热力学性质改变也比较缓慢。结论PCL降解速度慢，初始强度高、力学强度持续时间长，更适于作为骨折内固定物的生物材料。

Viologen-thiol self-assembled monolayers for immobilized horseradish peroxidase at gold electrode surface

A stable, well-behaved self-assembled monolayer (SAM) of viologen-functionalized thiol was used to immobilize and electrically connect horseradish peroxidase (HRP) at gold electrode. Viologen groups in SAMs facilitated the electron transfer from the electrode to the protein active site so that HRP exhibited a quasi-reversible redox behavior. HRP adsorbed in the SAMs is very stable, and close to a monolayer with the surface coverage of 6.5 x 10(-11) mol/cm(2). The normal potential of HRP is -580 mV vs Ag/AgCl corresponding to ferri/ferro active center and the standard electron transfer rate constant is 3.41 s(-1) in 0.1 M phosphate buffer solution (pH 7.1). This approach shows a great promise for designing enzyme electrodes with other redox proteins and practical use in tailoring a variety of amperometric biosensor devices. Copyright (C) 1997 Elsevier Science Ltd.

Poly(epsilon-caprolactone)/poly(ethylene oxide) diblock copolymer .1. Isothermal crystallization and melting behavior

The isothermal crystallization and melting behavior of the poly(epsilon-caprolactone) (PCL)/poly(ethylene oxide)(PEO) diblock copolymer has been studied by WAXD, SAXS, and DSC methods. Only the PCL block is crystallizable; the PEO block of weight fraction 20% cannot crystallize, although its corresponding homopolymer has strong crystallizability. The long period, amorphous layer, and crystalline lamella of the PCL/PEO block copolymer all increase with the rise in the crystallization temperature, and the thickness of the amorphous layer is much larger than that of crystalline lamella due to the existence of the PEO block in the amorphous region. The isothermal crystallization of the PCL/PEO block copolymer is investigated by using the theory of Turnbull and Fischer. It is found that the amorphous PEO block has a great influence on the nucleation of PCL block crystallization, and the extent of this influence depends on crystallization conditions, especially temperature. The outstanding characteristics are the phenomenon of the double melting peaks in the melting process of the PCL/PEO block copolymer after isothermal crystallization at different temperatures and the transformation of melting peaks from double peaks to a single peak with variations in the crystallization condition. They are related mainly to the existence of the PEO block bonding chemically with the PCL block. In summing up results of investigations into the crystallization and melting behavior of the PCL/PEO block copolymer, it is interesting to notice that when the PCL/PEO block copolymer crystallizes at three different crystallization temperatures, i.e., below 0 degrees C, between 0 and 35 degrees C, and above 35 degrees C, the variation of peak melting temperature is similar to that of overall crystallization rates in the process of isothermal crystallization. The results can be elucidated by the effect of the PEO block on the crystallization of the PCL block, especially its nucleation. (C) 1996 John Wiley & Sons, Inc.

活性炭表面含氧基团对NO的还原作用

通过Ｃ、Ｈ、Ｎ元素分析和Ｂｏｅｈｍ滴定及ＮＨ_３－ＴＰＤ实验揭示了活性炭表面含氧基团数量及分布情况。结果表明，表面含氧基团数量和分布决定了活性炭自身还原性及对ＮＯ的还原能力。活性炭表面含氧基团，特别是－ＣＯＯ基团，可能是最重要的ＮＯ还原反应活性中心。提出了该还原反应的机理。

沸石微孔材料中Ce（Ⅲ）对Tb（Ⅲ）的敏化发光

采用水相离子交换法合成出双掺Ｃｅ（Ⅲ）、Ｔｂ（Ⅲ）沸石材料，讨论了光谱特征和浓度猝灭。在沸石基质中观察到稀土离子间的能量传递，通过荧光光谱和荧光寿命等实验技术，系统地研究了能量传递过程，其传递机理主要是无辐射多极子近场力作用。

[Li(THF)_4][GdCl_4(THF)_2]的晶体结构

氯化钆与对-甲基苯基锂在四氢呋喃中反应得到产物之一为[Li(THF)_4][GdCl_4-(THF)_2],(M_r=738.2),在-70℃下进行X-射线衍射研究。其晶体属单斜晶系,P2/n空间群。晶体学参数为a=13.263(2),b=8.474(1),c=14.961(0);β=99.72(1)°,V=1657.23(?)~3,Z=2,D_c=1.48g/cm~3,F(000)=750,μ_c=24.2cm~(-1),最终偏离子为R=0.0614。研究结果表明,本题晶体是离子型晶体,围绕Gd~(3+)的四个Cl~-离子和两个THF分子的氧原子构成畸变的八面体。Li~+周围的四个THF分子的氧原子构成一个近似的四面体。

STRUCTURE OF HEXAMETHYLENETETRATELLURAFULVALENE DIIODIDE

C12H12I2Te4, M(r) = 920.44, monoclinic, P2(1)/n, a = 10.942 (2), b = 14.924 (2), c = 11.415 (2) angstrom, beta = 104.32 (1)-degrees, V = 1806.0 (5) angstrom 3, Z = 4, D(x) = 3.38 g cm-3, lambda(Mo K-alpha) = 0.71069 angstrom, mu = 100.7 cm-1, F(000) = 1592, T = 294 K, R = 0.033 for 1828 observed reflections. One of the Te atoms is bonded to the two I atoms, which are on either side of the molecular plane. The Te-I distances are 2.963 (1) and 2.961 (1) angstrom, which means oxidation at the Te atom instead of at the C = C bonds.