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131.
This paper gives a new viscous regularization of the Riemann problem for Burgers' equation u_t + (\frac{u²}{2})_z = 0 with Riemann initial data u = u_(x ≤ 0), u = u_+(x > 0} at t = 0. The regularization is given by u_t + (\frac{u²}{2})_z = εe^tu_{zz} with appropriate initial data. The method is different from the classical method, through comparison of three viscous equations of it. Here it is also shown that the difference of the three regularizations approaches zero in appropriate integral norms depending on the data as ε → 0_+ for any given T > 0. 相似文献
132.
Chen Jun Xu Haifeng Guo Ying Dai Jinghua Zhang Limin Liu Shilin Ma Xingxiao 《化学物理学报(中文版)》2001,14(4):389-396
Photodissociation dynamics of CS2+molecular ions has been investigated by (1+two-photon resonance technique. CS2+were prepared by (3+1) resonance-enhanced multi-photon ionization (REMPI) of CS2molecules at 483. 2nm. The photofragment S+excitati (PHOFEX) spectra were recorded by scanning another laser in the 424~482nm region, and we assigned essentially to CS2+(~A2Πu,3/2(v′=0~4)←~X2Πg,3/2(0,0,0)) and (~A2Πu,1/2(v′=0,4)←~X2Πg,1/2(0,0,0)) (herev′=v1′+(1/2)v2′) transitions. The S+production channel wpreliminarily attributed to, (i) one-photon excitation CS2+from the ground state~X2Πgto texcited state~A2Πu; (ii) vibronic coupling between the~A2Πustate and the high vibrational lev in the~X2Πgstate; (iii) second photon excitation from the coupling vibrational levels to the excied state~B2Σu+and dissociation to produce S++ CS via the repulsive4Σ-state through spin-orb interaction between the~B2Σu+and4Σ-states. 相似文献
133.
报道了500mW激光二极管端面泵浦Cr:LiSAF激光器连续运转的实验研究结果.特别是在分析了泵浦光与腔模的耦合情况后,提出了一套与泵浦源相适应的准直聚焦系统,提高了耦合效率.实验对两种不同掺杂浓度和不同形状的Cr:LiSAF晶体进行了研究,在850nm的中心波长处获得最大输出功率分别为20mW和13mW,斜效率分别为10.3%和7.8%,并对实验结果作了讨论. 相似文献
134.
离子色谱法同时测定水源水中的5种生物胺 总被引:4,自引:0,他引:4
建立了离子色谱(IC)同时测定水源水中5种生物胺(BA)(腐胺、尸胺、组胺、亚精胺和精胺)的方法。样品经0.45 μm水膜过滤后,用TSK-GEL SuperIC阳离子交换柱(150 mm×4.6 mm)分离,以甲磺酸水溶液为流动相梯度淋洗,流速为1.0 mL/min,非抑制电导检测,进样量为100 μL。实验结果表明,5种生物胺可以实现基线分离;在1.0~30.0 mg/L范围内,其峰面积与质量浓度之间的线性关系良好;保留时间的相对标准偏差(RSD)均不高于0.02%,峰面积的RSD小于2.08%;加标回收率为96.0%~107.0%。该法简便、快捷、准确,可以用于水源水中腐胺、尸胺、组胺、亚精胺和精胺5种生物胺的同时测定。 相似文献
135.
An ultrasensitive photoelectrochemical (PEC) immunoassay of cancer biomarker carcinoembryonie antigen (CEA) is proposed that uses rhombic titanium dioxide nanocrystals (TiO2 NCs) coupled with Ab2–RGO-Ru bioconjugate, which featured CEA signal antibody (Ab2) and ruthenium tris(bipyridine) (Ru complex) labels linked to reduced graphene oxide (RGO) for signal amplification. Herein, the Ru complex acts as an electron donor, while RGO serves as an electron acceptor which facilitates charge separation and suppresses recombination of photoexcited electron–hole pairs in the hybridized species. The rhombic TiO2 NCs were fabricated through a solvothermal technique in anhydrous ethanol, followed by spin-coating process and calcination, an ITO/TiO2 electrode was obtained. Chitosan (CS) and glutaraldehyde (GLD) were used to modify the prepared ITO/TiO2 electrode to covalently immobilize antibodies. With a sandwich-type immunoreaction, CEA and Ab2–RGO-Ru were conjugated successively to form a sandwich-type immunocomplex. Thus, a sandwich-type PEC immunosensor was fabricated for the detection of CEA was developed by monitoring the changes in the photocurrent signals of the electrode resulting from the immunoreaction. The proposed PEC immunosensor showed high sensitivity, selectivity, excellent stability, and good reproducibility, and thus has great potential to be used for other biological assays. 相似文献
136.
A flexible asymmetric supercapacitor is assembled using MnO2 nanosheets/carbon fabric and Fe2O3/carbon fabric electrodes. By optimizing the reaction condition of the two electrodes, the device shows high energy densities and excellent flexibility. 相似文献
137.
138.
A simple and high-resolution analytical method for the determination of dimethylsulfoniopropionate (DMSP) in sugarcane and marine algae is described. Effective extraction of DMSP from plant samples was also investigated using organic solvents, 5% perchloric acid or deionised water. To increase the sensitivity, DMSP in the extracts was first converted to a phenacyl ester, and the reaction mixture was applied directly to capillary electrophoresis without any pretreatment. Water extraction followed by esterification in a pH 4 reaction buffer was found most suitable for the measurement of alkaline-labile DMSP. This method was applied to the determination of DMSP levels in marine algae samples collected from the seashore of Nagasaki, Japan. An increase in DMSP content in Ulva pertusa in the winter period was observed. 相似文献
139.
Beisheng Kang Hanqin Liu Jinghua Cai Liangren Huang Qiutian Liu Daxu Wu Linghong Weng Jiaxi Lu 《Transition Metal Chemistry》1989,14(6):427-438
Summary Dicubane cluster compounds (Et4N)4[Mo2Fe7S8(SR)12] (2A) (R=Ph,a;o-tolyl,b;m-tolyl,c;p-tolyl,d) were made by reaction of (Et4N)2[Fe4(SR)10] (1) with (Et4N)2MoS4 in MeCN at room temperature. The structure,1Hn.m.r.,57Fe Mössbauer spectrum, magnetic susceptibility and cyclic voltammogram are described. (Et4N)3[Mo2Fe6S8Cl6(SR)3] (3) (R=Ph,a;m-tolyl,b) was obtained from the reaction of (2Aa) or (2Ac) with acetyl chloride in MeCN. This is the first time that compound of structural type (2) is transformed into that of structural type (3) by chemical conversion. Compound (2Aa) crystallizes in the triclinic space group P
with Z=1 and unit cell dimensionsa=12.775(4),b=13.076(3), andc=20.576(4) Å; the structure was refined to R=7.7% using 4031 unique data with I>3(Io). Compound (2Ac) 2THF crystallizes in the monoclinic space group P21/n with Z=2 and unit cell dimensionsa=18.022(2),b=18.375(2) andc=22.254(3) Å; the structure was refined to R=6.4% using 5173 unique data with I>3(Io). Compound (3b) crystallizes in the hexagonal space groupP63/m with Z=2 and unit cell dimensionsa=b=16.827(3) andc=15.951(16) Å; the structure was refined to R=4.9% using 1296 unique data with I>3(Io). Its characteristics are discussed and compared with those of known compounds. The ratios of core volumes S4/M4 are within the 2.34–2.40 range for core oxidation level [MoFe3S4]3+ indicating that distortion of the cubane core is a general phenomenon. Different thiolato ligands induce significant changes of structural parameters only at the Fe(SR)6 region for compound (2A) while terminal chlorides induce changes over the whole molecule of (3b) with the latter structure more comparable to [Mo2Fe6S8(SPh)9]5– (3f) with [MoFe3S4]2+ core than to [Mo2Fe6S8(SPh)9]3– (3d). The isotropic shifts of (2A) originate mainly from -contact interaction. Both1H n.m.r. spectra and magnetic susceptibility measurements indicate practically no magnetic interaction among the three magnetic centres,i.e. a Fe(SR)6 bridge and two [MoFe3S4(SR)3] units. CV studies showed that the reduction of cubane unit having aromatic thiolates is easier than that having aliphatic thiolates as the aliphatic group is electron-donating. In addition, the very similar differences of Ep,c for first and second cubane units in compounds (2A) and in (3d) and (3e) imply that the effect of the first reduced unit [MoFe3S4]2+ upon the second unit [MoFe3S4]3+ is very similar in the two types of dicubane cluster compounds. Synergism in Mo–Fe–S cluster compounds is thus proposed to play an important role in their structural correlation with reactivities and must function in nitrogenase. 相似文献
140.
纤维素亲和膜用于内毒素的去除 总被引:5,自引:0,他引:5
报道了用于内毒素去除的3种新型纤维素亲和膜的制备及应用,并对它们的性能进行了比较。结果表明,这3种亲和膜均能有效去除盐溶液中的内毒素,去除率在90%以上。对人血清白蛋白溶液,季铵盐和壳聚糖亲和膜对内毒素的去除率较高,仍然在90%以上,金属螯合物亲和膜的去除效果不如前两种,去除率仅为83.3%。实验选择不同的亲和膜,考察了它们对内毒素的吸附容量、样品处理量以及再生效果,结果表明吸附量在 2.4×106EU/g以上,样品处理量较大,适合用于小批量医药制剂的生产过程;再生效果较好,可重复使用。 相似文献