72 resultados para 578
Resumo:
ZnO thin films were implanted at room temperature with 80 keV N+ or 400 keV Xe+ ions. The implantation fluences of N+ and Xe+ ranged from 5.0 x 10(14) to 1.0 x 10(17)/cm(2), and from 2.0 x 10(14) to 5.0 x 10(15)/cm(2), respectively. The samples were analyzed using Raman spectroscopy and the Raman scattering modes of the N- and Xe-ion implanted samples varying with implantation fluences were investigated. It was found that Raman peaks (bands) at 130 and 578 cm(-1) appeared in the spectra of ion-implanted ZnO samples, which are independent of the ion species, whereas a new peak at 274 cm(-1) was found only in N-ion implanted samples, and Raman band at 470 cm(-1) was found clearly in Xe-ion implanted samples. The relative intensity (peak area) increased with the increasing of the implantation fluences. From the comparison of the Raman spectra of N- and Xe-ion implanted ZnO samples and considering the damage induced by the ions, we analyzed the origin of the observed new Raman peaks (bands) and discussed the structure changes of ZnO films induced by N- and Xe-ion implantations.
Resumo:
根际试验研究表明,水分、有机质、土壤酸度是影响白浆土磷素生物有效性的重要因子.调节土壤水分含量,能增强土壤中铁、铝磷酸盐的溶解,加速磷酸根离子从根际土壤向非根际土壤扩散.增加土壤有机质含量,降低了土壤对P 素的吸附自由能( K 值) ,提高土壤中的速效磷含量.适量施用石灰,调节白浆土酸度,由于化学溶解作用的影响,促进了土壤中铁、铝磷酸盐的溶解,增强了土壤中磷素的生物有效性
Resumo:
通过测定长武塬区2005年降水水样的氢氧同位素组成,分析了该区降水氢氧同位素组成的基本特征。结果表明,长武塬区大气降水线方程为δD=7.44δ~(18)O+1.69,其斜率和截距与全球以及我国大气降水线相比均偏小,这与研究区地理位置和气候条件有关;降水氘盈余d值4—6月份较大,大于或接近10,7—10月份则小于10;以天为时间单位采集的次降水,其氢氧同位素组成的温度效应和降水量效应均不显著,而连续2 d长历时降水的雨量效应极显著;降水氢氧同位素组成季节变化明显,春季降水的氢氧同位素值较高,夏季同位素值降低,秋季同位素值最小,这在以次降水量为权重的加权平均值中表现得更加明显。
Resumo:
黄土丘陵区是水土流失治理的重点区,由于大规模以植被恢复重建的生态建设和以石油资源开发引起的山区道路建设对本地区侵蚀环境和侵蚀动力机制产生了巨大影响,坡面水土流失与道路水土流失对比发生了新变化,在坡面侵蚀得到初步治理的新环境下,水土流失源于道路侵蚀则上升为主要地位。本文分析了2005年7月2日次降雨引起的支道山路(植物路)、干道山路、石油运输道路和农林草地小区、小支沟的径流、泥沙系统监测结果,提出在本次降雨条件下,三类道路的产沙强度分别为:支道山路500 t.km-2、干道山路3163 t.km-2和运油道路13500 t.km-2,而农林草地下垫面的产沙强度则仅为:5.68~184.38 t.km-2,道路产沙强度远大于农林草地的产沙强度,道路产沙量占流域总产沙量的42%。而灌草地侵蚀产沙仅占流域的26.7%。进而提出黄土高原丘陵区水土流失治理应该重点放在道路防蚀的观点,成果有助于社会主义新农村建设。
Resumo:
地统计学方法的应用已由最初的地质学领域广泛推广到土壤学、生态学等领域,但在地下水特征的时空模拟方面应用还较少,结合地理信息系统(GIS),运用地统计学方法分析了石羊河下游民勤绿洲近15年来地下水特征的时空变异规律及其与土地利用变化的关系,并对其变化趋势进行了预测.得到了如下结果:(1)地下水埋深的随机变异特征随着开采强度的不断增大,从1987年的26.32%降到了2001年的0.03%,完全被较大尺度上的结构性变异所取代;而矿化度一直是中尺度上的结构性变异高达99.9%.(2)Kriging插值结果表明,民勤绿洲地下水埋深的分布一直是水质较好的绿洲南部最深厚,从南到北随着水质变差,埋深也变浅.地下水矿化度在空间分布上从南到北逐渐增大;在变化趋势上,高矿化度等值线由北向南持续推进.(3)民勤绿洲近15年来耕地面积增加了3.1×10~4hm~2,使得分布于地下水埋深17m以上的耕地面积净增528.3 km~2,分布于地下水埋深11m以下的林地减少200km~2.同样,分布于地下水矿化度3.0g/L以上的耕地面积净增2×10~4hm~2,其中>4.5g/L的增加了1.072×10~4hm~2.(4)预测至2015年,地下水埋深下降趋势明显,分布于地下水埋深20m以上的绿洲面积将净增1689.88km~2,达整个绿洲面积的68%;至2015年地下水矿化度高于5.0g/L的绿洲面积将达578.15km~2,全部集中在水质较差的绿洲湖区最北部,部分区域甚至高达7.0g/L以上.
Resumo:
本文报道产于中国北方北京地区的非褶菌目孔状真菌72种,并列出了每种的寄主。其中大部分种类为该地区首次报道。王氏薄孔菌为一新种,它的主要特征为子实体平伏反转,孔口表面奶油色至浅黄色,担孢子圆柱型并略弯曲,生长在李属树木上。该新种与垫状薄孔菌相似,但后者孢子较宽且是完全平伏的种类。
Resumo:
Two bromo rhenium(I) carbonyl complexes with the formula of [Re(CO)(3)(L)Br], where L = 1,10-phenanthroline (Phen-Re) and 5-(1H-pyrrol-1-yl)-1,10-phenanthroline (Pyph-Re), were successfully synthesized with the aim to analyze the effect of the pyrrole (Py) moiety on the photophysical properties of Pyph-Re. It was found that the triplet metal-to-ligand charge-transfer d pi (Re) --> pi*(N-N) emission of Phen-Re and Pyph-Re centered at ca. 527 nm with the luminescence quantum yield (LQY) of 0.015 and ca. 578 nm with the LQY of 0.011, respectively. At the same time, the geometrical structures of the ground state and the absorption spectral properties of Phen-Re and Pyph-Re were also calculated with the 6-31G* basis set employed on C, H, N, O, and Br atoms, and LANL2DZ adopted on Re atom.
Resumo:
The sulphonated phenol novolac (PNBS) which was used as a curing agent of epoxy was synthesised from phenol novolac (PN) and 1,4-butane sultone and confirmed by FTIR and H-1 NMR. The degree of sulphonation (DS) in PNBS was calculated by H-1 NMR. The semi-IPN membranes composed of sulphonated tetramethyl poly(ether ether ketone) (STMPEEK) (the value of ion exchange capacity is 2.01 meq g(-1)), epoxy (TMBP) and PNBS were successfully prepared. The semi-IPN membranes showed high thermal properties which were measured by differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA) With the introduction of the corss-linked TMBP/PNBS, the mechanical properties, dimensional stability, methanol resistance and oxidative stability of the membranes were improve in comparison to the pristine STMPEEK membrane.
Resumo:
A flow-injection electrochemiluminescent method for L-cysteine determination has been developed based on its enhancement of the electrochemiluminecence of luminol at a glassy carbon electrode. This method is simple and sensitive for cysteine determination. Under the selected experimental parameters, the linear range for cysteine concentration was 1.0 x 10(-6) - 5.0 x 10(-5) mol/l, and the detection limit was 0.67 mumol/l (SIN = 3). The relative standard deviation for 11 measurements of 1.0 x 10(-5) mol/l cysteine was 4.5%. The proposed method has been applied to. the detection of cysteine in pharmaceutical injections with satisfactory results.
Resumo:
Optically active 2,2'-dimethoxy-6,6'-diacetyl-1,1'-binaphthyl (DMDABN) was prepared from 2,2'-dimethoxy-1,1'-binaphthyl, and its structure was comfirmed by elemental analysis, NRM, IR and MS. Optically active polyquinolines were synthesized with DMDABN and 4,4'-diamino-3,3'-dibenzoyldiphenyl ether by Friedlander reaction. These polyquinolines showed high glass transition temperatures (474-578 K), high decomposition temperatures (703-770 K), insolubility in many common organic solvents and strong chiral activity.
Resumo:
A series of light-emitting poly(p-phenylene vinylene)s with triphenylamine units as hole-transporting moieties in the main chain were synthesized via Wittig condensation in good yields. The newly formed vinylene double bonds possessed a trans configuration, which was confirmed by Fourier transform infrared and NMR spectroscopy. The high glass-transition temperature (83-155 degreesC) and high decomposition temperature (> 300 degreesC) suggested that the resulting copolymers possessed high thermal stability. These copolymers, especially TAAPV1, possessed a high weight-average molecular weight (47,144) and a low polydispersity index (1.55). All the copolymers could be dissolved in common organic solvents, such as tetrahydrofuran (THF), CHCl3, CH2Cl2, and toluene, and exhibited intense photoluminesence in THF (the emission maxima were located from 478 to 535 nm) and in film (from 478 to 578 nm). The low onsets of the oxidation potential (0.6-0.75 V) suggested that the alternating copolymers possessed a good hole-transporting property due to the incorporation of triphenylamine moieties. (C) 2001 John Wiley & Sons, Inc.
Resumo:
以金属硝酸盐为反应原料 ,分别采用柠檬酸 凝胶法、共沉淀法和固相法制备了YAG和YAG∶RE3+ (RE =Eu ,Dy) (1% ,摩尔分数 )发光粉 ,并通过XRD ,TG DTA和发光光谱对样品进行了表征。柠檬酸 凝胶法、共沉淀法和固相法制备的YAG和YAG∶Eu的晶相形成温度分别是 80 0和 90 0℃。Eu3+ 在非晶态和晶态YAG中其激发和发射光谱有明显差异 ,在一定温度范围内 ,发光强度随烧结温度的升高而增强。由于碳杂质的存在 ,90 0和 10 0 0℃下柠檬酸 凝胶法制备样品的发射强度较其他两种方法低。
Resumo:
The orientational behavior of liquid crystalline polymers with para-nitro azobenzene as side chains under electric field was studied by UV-visible spectroscopy. The results showed that lambda(max) of the poled polymer films was around 394nm, compared to that of the unpoled films, the absorption decreased due to poling. The orientational parameters increased linearly with the increase of the electric field. The temporal stability of the poled polymer film is good at room temperature. This kind of materials showed promise application as nonlinear optical component in photorefractive polymers.
Resumo:
用两相滴定法测定异丙基膦酸单(1-己基-4-乙基)辛酯(PT-2,HL)在水中的溶解度S,在水中的解离常数K在水-正庚烷中的分配常数Kd及二聚常数K2,利用SOLWR计算程序,简单快速地处理两相滴定数据,得到结果为:S=3.68×10-5mol/L,pKa=5.49,logK2=4.67,logKd=2.67(25±0.5℃)