30 resultados para 850-1.07[Alighieri]
Resumo:
Nickel catalyst supported on carbon was made by reduction of nickelous nitrate with hydrogen at high temperature. Ni/ C catalyst characterization was carried out by XRD. It was found that the crystal phase of NiS and NiS2 appeared in the impregnated catalyst. Ni/ C and Pt/ C catalysts gave high performance as the positive and negative electrodes of a sodium polysulfide/ bromine energy storage cell, respectively. The overpotentials of the positive and negative electrodes were investigated. The effect of the electrocatalyst loading and operating temperature on the charge and discharge performance of the cell was investigated. A power density of up to 0.64 W cm(-2) ( V = 1.07 V) was obtained in this energy storage cell. A cell potential efficiency of up to 88.2% was obtained when both charge and discharge current densities were 0.1 A cm(-2).
Resumo:
Capillary zone electrophoresis (CZE) was applied to study the interaction between netropsin and a 14mer double stranded DNA (dsDNA). The binding constant of this interaction calculated from Scatchard plot was (1.07+/-0.10) X 10(5) (mol/L)(-1). The binding stoichiometry was 1:1. The use of polyacrylamide coated capillary showed better effect in the analysis of DNA than noncoated capillary.
Resumo:
气候变化问题越来越受到公众的关注,我国许多学者对中国近代气候变化规律等方面做了诸多研究。河南作为粮食大省和水资源缺乏的省份之一,影响粮食生产的降水量的具体变化研究尤显重要。通过分析河南省49个台站近50年来的日降水资料,对河南省春季降水量的变化进行统计分析。结果表明,河南省春季及其代表月4月份的平均降水日数均具有显著的下降趋势,且可以通过0.001的显著性检验;气候倾向率分别为-1.74和-1.07 d/10 a。利用滑动t检验法发现春季及其代表月4月份的降水日数均发生了均值突变,突变年份分别在1973和1977年。
Resumo:
Capillary zone electrophoresis (CZE) and affinity capillary electrophoresis (ACE) were applied to study the interaction between netropsin and a 14mer double-stranded DNA (dsDNA). The use of a polyacrylamide coated capillary can suppress the electroosmotic flow (EOF) and the adsorption of DNA onto the wall. Better analysis of the DNA was achieved in a coated capillary upon Tris-acetate. In CZE, the peak width broadened due to the affinity interaction between dsDNA and netropsin. In ACE, o-toluic acid, a negatively charged molecule was used as the indicator to monitor the changes of EOF when netropsin was added to the running buffer. The 14mer dsDNA showed different mobilities upon various concentrations of netropsin due to the affinity interaction between the dsDNA and netropsin. The binding constants of this interaction were (1.07 +/- 0.10) . 10(5) M-1 calculated from CZE and (4.75 +/- 0.30) . 10(4) M-1 from ACE using a Scatchard plot. The binding stoichiometry was 1:1 calculated from CZE which was superior to ACE in this study. (C) 2002 Elsevier Science B.V. All rights reserved.
Resumo:
在信息产业、生物医学等科技领域越来越受关注的今天,新型光电子、光通信科技必将以更快的速度发展。Si基光电子集成采用成熟价廉的微电子加工工艺,将光学器件与多种功能的微电子电路集成,是实现光通信普及发展和光互连的有效途径。Si基光电探测器是Si基光通信系统的关键器件之一。随着近年来Si基Ge材料外延技术的突破性进展,Si基Ge光电探测器因为兼顾了Si基光电子集成和对光通讯波段(1.31和1.55μm)的高效探测,成为了当今研究的一大热点。
半导体光电探测器的性能与其结构密切相关。PIN型光电探测器是最常见的探测器,可以普遍应用于光通讯光互连系统;雪崩光电二极管(APD)因为具有较高的响应度和内部增益,在实现单光子探测方面具备很大的优越性,适用于当今迅猛发展的生物光子学和量子信息学;共振腔增强型的光电探测器(RCE-PD),集波长选择器、高速光信号接收器于一体,而且具备共振增强作用、高饱和功率输出等特点,是局域网、光纤入户和现代波分复用(Wavelength-Division Multiplexing,WDM)系统光通信网络的一种优选方案;波导结构探测器(Waveguide-PD)可以解除探测器的响应带宽和量子效率之间的矛盾,而且其结构特点更易于实现与调制器等光波导器件的集成,是片上光互连的首选探测器。
本论文围绕高性能Si基Ge光电探测器这一研究目标,开展了多种结构的光电探测器的研制,包括PIN型PD的研制及其优化、吸收区与倍增区分离结构(SACM)的Ge-on-Si APD、RCE-PD和Waveguide-PD,主要研究结果如下:
1. 成功研制了PIN型Ge-on-Si光电探测器,器件在-1V外加偏压下暗电流密度为46.6mA/cm2,在1.31μm和1.55μm波长下器件的量子效率分别为40%和17%;然后改进了实验方法,在制作器件之前将Ge-on-Si材料在850℃条件下快速退火1分钟,从而改善材料质量,器件的暗电流密度降低至4mA/cm2,这是目前国际上报道的最好结果之一。
2. 研制出了PIN型Ge-on-SOI光电探测器,在1.31μm和1.55μm波长的量子效率分别为62%和25%。在-3V外加偏压下,器件的3dB带宽为12.6GHz。25μm直径器件,3dB带宽更是达到了13.4GHz。同时,制作了均匀性很好的1×4探测器阵列,单个器件的3dB带宽达13.3GHz。
3. 在国际上首次研究了硅基锗光电探测器的高饱和特性。在-1V和-2V外加偏压下,探测器的1-dB小信号压缩电流分别为22mA和40mA,相应的光功率分别为67.5mW和110.5mW。
4. 成功研制了吸收区和倍增区分离的Si基Ge雪崩光电二极管,器件的穿通电压Vpt约为29V,击穿电压Vbd(暗电流等于100μA时的电压)为39.5V。在击穿电压附近,如39V时,SACM-Ge-on-Si APD的增益为40。
5. 解决了背面ICP深刻蚀工艺难题,成功制备了中心波长在1.55μm,量子效应高达62%的共振腔增强型Si基Ge光电探测器。
提出一种横向波导型结构Ge-on-SOI光电探测器结构,并对该结构探测器进行了理论计算。
Resumo:
Novel water resistant sulfonated poly[bis(benzimidazobenzisoquinolinones)] (SPBIBIs) were synthesized from 6,6'-disulfonic-4,4'-binaphthy]-1,1',8,8'-tetracarboxylic dianhydride (SBTDA) and various aromatic ether tetraamines. The resulting polymers with IEC in the range of 2.17-2.87 mequiv g(-1) have a combination of desired properties such as high solubility in common organic solvents, film-forming ability, and excellent thermal and mechanical properties. Flexible and tough membranes, obtained by casting from m-cresol solution, had tensile strength, elongation at break, and tensile modulus values in the range of 87.6-98.4 MPa, 35.8-52.8%, and 0.94-1.07 GPa. SPBIBI membranes with a high degree of sulfonation displayed high proton conductivity and a good resistance to water swelling as well. SPBIBI-b with IEC of 2.80 mequiv g(-1) displayed the conductivity of 1.74 x 10(-1) S cm(-1) at 100 degrees C, which was comparable to that of Nafion (R) 117 (1.78 x 10(-1) S cm(-1), at 100 degrees C).
Resumo:
The anodic voltammetric behavior of inosine (I) was investigated by linar-sweep voltammetry, differential-pulse voltammetry and cyclic voltammetry at a glassy carbon electrode. In a medium of 0.1 mol/L N2HPO4, inosine showed a well defined anodic peak. The peak potential was about 1.42 V (vs. Ag/AgCl). A linear relationship held between the peak current and the concentration of inosine in the rang of 5 x 10(-4) similar to 8 x 10(-2) g/L. The peak potential decreased with the decrease of the acidity of the solution. The four anodic peaks of inosine with hypoxanthine, xanthine and uric acid were obtained. Their peak potentials were about at 1.42, 1.07, 0.72 and 0.26 Vt vs. Ag/AgCl). The method has been used for the direct determination of inosine in injections. Recoveries of inosine in urine samples were about 85%. Experimental result proved that the electrode reaction was diffusion-controlled and irreversible.
Resumo:
本文用DSC研究了尼龙1010熔体以—320K/min速率骤冷样品在不同升温速率(R)时的冷结晶与熔融过程。发现冷结晶温度不随R变化,冷结晶时间t_c=153R~(-1.07),冷结晶热ΔH_c=-19.1R~(-0.75);R对熔融温度无影响,当R≤40K/min时,熔融热ΔH_m变化不大;由ΔH_m和ΔH_c求得的结晶度有一定差值,是由于熔融过程伴有结晶作用所致,可定性地用熔融峰的ΔT_1=T_(onset)—T_i表征。
Resumo:
The geochemical and U-series isotopic characteristics of hydrothermal sulfide samples from the Jade site (127A degrees 04.5'E, 27A degrees 15'N, water depth 1300-1450 m) at Jade site in the Okinawa Trough were analyzed. In the hydrothermal sulfide samples bearing sulfate (samples HOK1 and HOK2), the LREEs are relatively enriched. All the hydrothermal sulfide samples except HOK1 belong to Zn-rich hydrothermal sulfide. In comparison with Zn-rich hydrothermal sulfides from other fields, the contents of Zn, Pb, Ag, Cd, Au and Hg are higher, the contents of Fe, Al, Cr, Co, Ni, Sr, Te, Cs, Ti and U lower, and the Pb-210 radioactivity ratios and Pb-210/Pb ratios very low. In the hydrothermal sulfide mainly composed of sphalerite, the correlations between rare elements Hf and U, and Hf and Mn as well as that between dispersive elements Ga and Zn, are strongly positive; also the contents of Au and Ag are related to Fe-sulfide, because the low temperature promotes enrichment of Au and Ag. Meanwhile, the positive correlations between Fe and Bi and between Zn and Cd are not affected by the change of mineral assemblage. Based on the Pb-210/Pb ratios of hydrothermal sulfide samples (3.99x10(-5)-5.42x10(-5)), their U isotopic composition (U-238 content 1.15-2.53 ppm, U-238 activity 1.07-1.87 dpm/g, U-234 activity 1.15-2.09 dpm/g and U-234/U-238 ratio 1.07-1.14) and their Th-232 and Th-230 contents are at base level, and the chronological age of hydrothermal sulfide at Jade site in the Okinawa Trough is between 200 and 2000 yr.
Resumo:
Annual variations of egg production rate (EPR) and clutch size of Calanus sinicus, as well as body size of females (prosome length and dry weight), were investigated at a series of stations in the Southern Yellow Sea by onboard incubation. Calanus sinicus was spawning in all the 11 cruises investigated, and the annual variation of EPR was bimodal. Monthly average EPR was highest from May to July, respectively, 5.97, 5.36 and 6.30 eggs female(-1) d(-1), then decreased dramatically to only 1.37 eggs female(-1) d(-1) in August and attained the lowest 1.07 eggs female(-1) d(-1) in October. In November, average EPR increased again to 4.31 eggs female(-1) d(-1). Seasonal variation of clutch size was similar to EPR, except that it decreased gradually after August rather than dramatically as did EPR. Prosome length of females was maximum in May and minimum in October, but dry weight was highest in November. Monthly average EPR correlated better with prosome length than dry weight, while clutch size was rather determined by dry weight of females. It is suggested that egg production of C. sinicus was active during two discontinuous periods when both surface and bottom temperature fell into its favorite range (i.e. 10-23degreesC), and different reproductive strategies were adopted in these two reproductive peaks: other than the highest EPR, longer prosome length was also achieved by C. sinicus from May to July, while females in November developed shorter bodies but accumulated more energy for reproduction.
Resumo:
[目的]探讨短穗兔耳草个体对模拟增温的响应。[方法]采用国际冻原计划(ITEX)模拟增温对植物影响的研究方法,将温棚从小到大的顺序依次设为A、B、C、D、E5个温度梯度,分析不同温度梯度下短穗兔耳草个体生长特征的变化,研究模拟增温对短穗兔耳草生长特征的影响。[结果]随着温棚直径的减小,温度(地表温度和土壤温长)逐渐升高。与对照相比,A、B、C、D、E5个处理分别提高了2.68、1.57、1.20、1.07和0.69℃(地表气温),1.74、1.06、0.80、0.60和0.30℃(土壤温度)。短穗兔耳草从对照至A温室随着温度的升高,叶片数、叶片高度逐渐增加,而匍匐茎逐渐减少。[结论]叶片数变化与温度(地表温度和地温)呈正相关关系,增温促进了短穗兔耳草的营养生长,抑制了它的克隆繁殖能力。
Resumo:
经过两年牦牛放牧试验表明,夏季草场不同土壤层有机质、有机碳、全磷、全氮和速效磷的含量及0~20cm土壤层营养因子的平均含量与放牧率呈线性回归关系,速效氮含量与放牧率呈二次回归关系;冬季草场不同土壤层有机质、有机碳和全氮与放牧率呈线性回归关系,全磷、速效磷和速效氮的含量及0~20cm土壤层营养因子的平均含量与放牧率呈二次回归关系。随着放牧率的逐渐增加,夏季草场不同土壤深度速效氮含量也逐渐减小,当放牧率达到1.07、1.08和1.22头·hm-2时,0~5、5~10、10~20cm土壤速效氮含量依此达到最小;冬季草场不同土壤层全磷、速效磷和速效氮含量逐渐增加,当放牧率达到0.81、0.78和1.00头·hm-2,1.03、1.09和1.03头·hm-2,1.36、1.35和1.30头·hm-2时,0~5、5~10、10~20cm土壤层全磷、速效磷和速效氮含量分别依此达到最大。在夏季草场,0~20cm土壤层速效氮平均含量达到最小放牧率是1.07头·hm-2;冬季草场0~20cm土壤层全磷、速效磷和速效氮含量达到最大放牧率分别是0.90、0.83和1.21头·hm-2。
Resumo:
两年的牦牛放牧试验结果表明:随放牧率的增加, 夏季草场各土壤层有机质、有机碳、全氮和全磷的含量呈下降趋势,它们的含量与放牧率呈显著的线性回归关系, 速效氮的含量与放牧率呈二次回归关系, 各土壤营养因子平均含量与放牧率也有类似的关系.而且当放牧率分别达到1.07 heads/hm2、1.08 heads/hm2和1.22 heads/hm2时, 0~5 cm、 5~10 cm、 10~20 cm土壤速效氮含量依此达到最小,若放牧率继续增加,各土壤层速效氮的含量依此开始增加, 而速效氮的平均含量达到最小的放牧率是1.08 heads/hm2.在相同放牧率下, 有机质和有机碳的含量在各土壤层之间差异极显著(P<0.01),全磷差异显著(P<0.05),全氮和速效氮差异不显著(P>0.05),而且放牧率和土壤深度的交互作用对土壤各营养因子含量的影响极显著(P<0.01).放牧率对各土壤层的含水量有显著的影响(P<0.05),不同年度间同一土壤层含水量的差异不显著(P>0.05).
Resumo:
本研究以西南喀斯特地区的王家寨小流域为研究对象,以植物叶片δ13C值为植物水分利用效率的指示值,结合利用氢氧同位素对植物的水分来源进行确认,通过研究小流域中不同土壤类型石漠化样地、不同季节、不同等级石漠化样地及喀斯特不同小生境中常见植物种水分利用效率及水分来源的差异,旨在从小生境、植物种、植物群落等不同尺度上探讨石漠化发生过程对植物长期水分利用的影响,了解不同水源的利用对植物水分利用效率的影响,了解喀斯特生态系统特有生境中植物对水分的竞争和利用策略,以加深对生态系统水分平衡的认识。通过研究,得出了以下几点认识:
1 喀斯特石漠化区植物叶片δ13C值的时空变化
(1)在本研究区,不同土壤类型区域植物群落δ13C值均随着石漠化的进行趋正,方差分析结果显示黄壤序列植物群落叶片δ13C值存在显著差异(F(3,80)0.01=2.72