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991.
LI Jianbin GAO Chengxiu HU Wei YANG Lei 《武汉大学学报:自然科学英文版》2007,12(6):979-984
We consider a distribution system with one supplier and two retailers. For the two retailers, they face different demand and are both risk averse. We study a single period model which the supplier has ample goods and the retailers order goods separately. Market search is measured as the fraction of customers who unsatisfied with their "local" retailer due to stock-out, and search for the goods at the other retailer before leaving the system. We investigate how the retailers game for order quantity in a Conditional Value-at-Risk framework and study how risk averse degree, market search level, holding cost and backorder cost influence the optimal order strategies. Furthermore, we use uniform distribution to illustrate these results and obtain Nash equilibrium of order strategies. 相似文献
992.
ZHANG Wei HUANG Shengyou YU Tao ZOU Xianwu 《武汉大学学报:自然科学英文版》2007,12(6):1034-1038
Some highly designable protein structures have dented on the surface of their native structures, and are not full compactly folded. According to hydrophobic-polar (HP) model the most designable structures are full compactly folded. To investigate the designability of the dented structures, we introduce the hydrogen bond energy in the secondary structures by using the secondary-structure-favored HP model proposed by Ou-yang etc. The result shows that the average designability increases with the strength of the hydrogen bond. The designabilities of the structures with same dented shape increase exponentially with the number of secondary structure sites. The dented structures can have the highest designabilities for a certain value of hydrogen bond energy density. 相似文献
993.
LIU Junbo 《武汉大学学报:自然科学英文版》2007,12(6):1109-1112
A new type in situ Cr7C3/γ-Fe ceramal composite coating was fabricated on substrate of hardened and tempered grade C steel by plasma cladding with Fe-Cr-C alloy powders. The ceramal composite coating has a rapidly solidified microstructure consisting of primary Cr7C3/γ- and the Cr7C3/γ-Fe eutectics, and is metallurgically bonded to the degree C steel substrate. The corrosion resistances of the coating in water solutions of 0.5 mol/L H2SO4 and 3.5% NaCl were evaluated utilizing the electrochemical polarization corrosion-test method. Because of the inherent excellent corrosion-resisting properties of the constituting phase and the rapidly solidified homogeneous microstructure, the plasma clad ceramal composite coating exhibits excellent corrosion resistance in the water solutions of 0.5 mol/L H2SO4 and 3.5% NaCl. 相似文献
994.
ZHAN JingLin SUN XiaoDan CUI FuZhai KONG XiangDong 《科学通报(英文版)》2007,52(13):1791-1795
In this study, silk scaffolds with appropriate porous structures were prepared by adjusting solution concentrations and providing treatment with methanol solutions in the way of freeze drying. The effects of the preparation conditions on the microstructures and properties of the scaffolds were discussed. Fibroin solutions with different concentrations of 4, 6, 8, 10 wt% were used respectively to prepare the scaffolds. The effects of the addition of 20 vol% methanol before or after freeze drying to the 4 wt% fibroin solution were investigated. As demonstrated by Scanning Electron Microscope (SEM), the fib-roin scaffolds prepared without methanol had porous microstructures composed of thin sheets, and the sizes of the pores decreased with the increase of the fibroin solution concentrations, while the scaffolds prepared in the presence of methanol showed porous microstructures formed by fine-particle aggregates. The porosities and mechanical properties of the prepared fibroin scaffolds under different conditions were tested. The crystalline structures and conformations of the fibroin scaffolds were detected by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). 相似文献
995.
SHEN Ji XIAO HaiFeng WANG SuMin AN ZhiSheng QIANG XiaoKe XIAO XiaYun 《科学通报(英文版)》2007,52(13):1813-1819
Based on the analysis of carbonate content and loss on ignition for a long sediment core (737 m in length) drilled in Heqing, the orbital scale evolution of the Southwest Monsoon is revealed, by using overlapped spectral analysis and filter methods. It is shown that the obliquity cycle and precession cycle are the key factors for the Southwest Monsoon evolution and that the change of the global ice volume and the uplift of the Qinghai-Tibetan Plateau also impose great influences on it. 相似文献
996.
Single grain Rb-Sr dating of euhedral and cataclastic pyrite from the Qiyugou gold deposit in western Henan, central China 总被引:3,自引:0,他引:3
HAN YiGui LI XiangHui ZHANG ShiHong ZHANG YuanHou CHEN FuKun 《科学通报(英文版)》2007,52(13):1820-1826
The Rb-Sr isotopic dating of pyrite mineral from ore deposits can directly provide mineralization age. However, many geological factors may affect the Rb-Sr isotopic system,which baffles application of this method. Employing ultra-low procedural blank Rb-Sr method,we have dated pyrites separated from the No. 4 breccia pipe of the Qiyugou gold deposit,western Henan Province. Single grains of euhedral pyrite crystal with few microcracks yield an isochron age of 126 ± 11 Ma, which represents time of the main mineralization stage of the deposit. Pyrite grains of cataclastic type show nevertheless scattered Rb-Sr isotopic composition and no reasonable isochron can be defined. Crystal morphology and mineral inclusion studies reveal that Rb and Sr of pyrite mineral probably are preserved mainly in biotite, K-feldspar, and sericite mineral inclusions. The dating results likely suggest that cataclastic pyrite is not suitable for the Rb-Sr dating due to modification of the Rb-Sr isotopic system by later hydrothermal activity of fluid. 相似文献
997.
YUAN YiZhong KANG HaiFeng SUN ZhenRong WANG ZuGeng 《科学通报(英文版)》2007,52(14):1897-1901
The thin film of a heptamethine cyanine chromophore HC was prepared by spin-coating technique. Its surface morphology and linear optical property were characterized by atomic force microscopy (AFM) and UV-visible absorption spectroscopy. The results show that HC molecules are arranged in a well-ordered H-aggregate type. The third-order nonlinear optical properties of the spin-coating film were also measured by degenerate four-wave mixing (DFWM) measurement. Enhanced third-order nonlinear susceptibility can be attributed to molecular aggregation effects, and the corresponding mechanism was dealt with by collective electronic oscillator (CEO) approach. 相似文献
998.
A tubular focused sonochemistry reactor 总被引:1,自引:0,他引:1
ZHOU GuangPing LIANG ZhaoFeng LI ZhengZhong ZHANG YiHui 《科学通报(英文版)》2007,52(14):1902-1905
This paper presents a new sonochemistry reactor, which consists of a cylindrical tube with a certain length and piezoelectric transducers at tube’s end with the longitudinal vibration. The tube can effectively transform the longitudinal vibration into the radial vibration and thereby generates ultrasound. Furthermore, ultrasound can be focused to form high-intensity ultrasonic field inside tube. The reactor boasts of simple structure and its whole vessel wall can radiate ultrasound so that the electroacoustic transfer efficiency is high. The focused ultrasonic field provides good condition for sonochemical reaction. The length of the reactor can be up to 2 meters, and liquids can pass through it continuously, so it can be widely applied in liquid processing such as sonochemistry. 相似文献
999.
ZHAO HuaBing LI YongJun CHEN Wei CAI BaoLi 《科学通报(英文版)》2007,52(14):1942-1948
A novel salicylaldehyde dehydrogenase involved in catabolism of naphthalene from Pseudomonas putida ND6, NahV, has been identified. NahV exhibited lower identity in amino acid sequence with the classic salicylaldehyde dehydrogenase, NahF, from P. putida ND6. This is the first report of an isofunctional enzyme of bacterial salicylaldehyde dehydrogenase. Comparison of Km and Vmax values of NahV and NahF demonstrated that NahF has a more efficient catalytic reaction than NahV, while NahV has much higher affinity for salicylaldehyde and NAD^+. Both enzymes exhibited broad substrate specificities and catalyzed the oxidation of salicylaldehyde, 5-chlorosalicylaldehyde, formaldehyde, m-nitrobenzaldehyde, o-nitrobenzaldehyde, o-methoxybenxaldehyde, glutaraldehyde, caprylic aldehyde, and glyoxal. However, the relative rates at which the substituted analogs are transformed differ considerably. NahV activity could be enhanced by Fe^2+, Cu^2+ and Zn^2+; whereas NahF activity could only be stimulated by Fe^2+, NahF is more stable than NahV at elevated temperatures. Dot-blot hybridization analyses showed that nahF-like genes occurred in all naphthalene-degradation bacteria isolated in this study, whereas nahV-like genes were present in only some naphthalene-degrading bacteria. 相似文献
1000.
Nickel accumulation and its effects on the survival rate of Spodoptera litura Fabricius under continuous nickel stress 总被引:2,自引:0,他引:2
SUN HongXia SHU YingHua TANG WenCheng WANG Qi ZHOU Qiang ZHANG GuRen 《科学通报(英文版)》2007,52(14):1957-1963
The artificial diets mixed with various concentrations of nickel were offered to the larvae of the phytophagous insect Spodoptera litura Fabricius for 3 generations. Nickel accumulations in the 6th instar larvae, pupae and newly emerged adults of the corresponding generations of S. litura were investigated by Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES), and the effects of nickel accumulations on the survival rate of S. litura were also evaluated by individual rearing. The results showed that nickel accumulated in the 6th instar larvae, pupae and adults of S. litura, and the accu- mulated nickel in all the tested developmental stages within a generation increased with the increase of the nickel doses in the treated diets and showed significant dose-dependent relationship with the nickel doses in the artificial diets. The results also indicated that the nickel accumulations in the 6th instar larvae, pupae, and newly emerged adults from the 3rd generation were higher than those from the 2nd generation, which were also higher than those from the 1st generation. Nickel concentrations in pupae and adults were significantly lower than those in larvae, which indicated that the excessive nickel might be excreted during metamorphosis. Furthermore, larval survival rate, pupation rate and eclosion rate of S. litura in the tested three generations all decreased with the increase of the nickel doses in the treated diets. 相似文献